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Sample records for anaerobic aggregates determined

  1. Distribution of Sulfate-Reducing and Methanogenic Bacteria in Anaerobic Aggregates Determined by Microsensor and Molecular Analyses

    PubMed Central

    Santegoeds, Cecilia M.; Damgaard, Lars Riis; Hesselink, Gijs; Zopfi, Jakob; Lens, Piet; Muyzer, Gerard; de Beer, Dirk

    1999-01-01

    Using molecular techniques and microsensors for H2S and CH4, we studied the population structure of and the activity distribution in anaerobic aggregates. The aggregates originated from three different types of reactors: a methanogenic reactor, a methanogenic-sulfidogenic reactor, and a sulfidogenic reactor. Microsensor measurements in methanogenic-sulfidogenic aggregates revealed that the activity of sulfate-reducing bacteria (2 to 3 mmol of S2− m−3 s−1 or 2 × 10−9 mmol s−1 per aggregate) was located in a surface layer of 50 to 100 μm thick. The sulfidogenic aggregates contained a wider sulfate-reducing zone (the first 200 to 300 μm from the aggregate surface) with a higher activity (1 to 6 mmol of S2− m−3 s−1 or 7 × 10−9 mol s−1 per aggregate). The methanogenic aggregates did not show significant sulfate-reducing activity. Methanogenic activity in the methanogenic-sulfidogenic aggregates (1 to 2 mmol of CH4 m−3 s−1 or 10−9 mmol s−1 per aggregate) and the methanogenic aggregates (2 to 4 mmol of CH4 m−3 s−1 or 5 × 10−9 mmol s−1 per aggregate) was located more inward, starting at ca. 100 μm from the aggregate surface. The methanogenic activity was not affected by 10 mM sulfate during a 1-day incubation. The sulfidogenic and methanogenic activities were independent of the type of electron donor (acetate, propionate, ethanol, or H2), but the substrates were metabolized in different zones. The localization of the populations corresponded to the microsensor data. A distinct layered structure was found in the methanogenic-sulfidogenic aggregates, with sulfate-reducing bacteria in the outer 50 to 100 μm, methanogens in the inner part, and Eubacteria spp. (partly syntrophic bacteria) filling the gap between sulfate-reducing and methanogenic bacteria. In methanogenic aggregates, few sulfate-reducing bacteria were detected, while methanogens were found in the core. In the sulfidogenic aggregates, sulfate-reducing bacteria were

  2. Microbial aggregates in anaerobic wastewater treatment.

    PubMed

    Kosaric, N; Blaszczyk, R

    1990-01-01

    The phenomenon aggregation of anaerobic bacteria gives an opportunity to speed up the digestion rate during methanogenesis. The aggregates are mainly composed of methanogenic bacteria which convert acetate and H2/CO2 into methane. Other bacteria are also included in the aggregates but their concentration is rather small. The aggregates may also be formed during acetogenesis or even hydrolysis but such aggregates are not stable and disrupt quickly when not fed. A two stage process seems to be suitable when high concentrated solid waste must be treated. Special conditions are necessary to promote aggregate formation from methanogenic bacteria but aggregates once formed are stable without feeding even for a few years. The structure, texture and activity of bacterial aggregates depend on several parameters: (1)--temperature and pH, (2)--wastewater composition and (3)--hydrodynamic conditions within the reactor. The common influence of all these parameters is still rather unknown but some recommendations may be given. Temperature and pH should be maintained in the range which is optimal for methanogenic bacteria e.g. a temperature between 32 and 50 degrees C and a value pH between 6.5 and 7.5. Wastewaters should contain soluble wastes and the specific loading rate should be around one kgCOD(kgVSS)-1 d-1. The concentration of the elements influences aggregate composition and probably structure and texture. At high calcium concentration a change in the colour of the granules has been observed. Research is necessary to investigate the influence of other elements and organic toxicants on maintenance of the aggregates. Hydrodynamic conditions seem to influence the stability of the granules over long time periods. At low liquid stream rates, aggregates may starve and lysis within the aggregates is possible which results in hollowing of aggregates and their floating. At high liquid stream rates the aggregates may be disrupted and washed out of the reactor as a flocculent

  3. Anaerobic Nitrogen Turnover by Sinking Diatom Aggregates at Varying Ambient Oxygen Levels

    PubMed Central

    Stief, Peter; Kamp, Anja; Thamdrup, Bo; Glud, Ronnie N.

    2016-01-01

    In the world’s oceans, even relatively low oxygen levels inhibit anaerobic nitrogen cycling by free-living microbes. Sinking organic aggregates, however, might provide oxygen-depleted microbial hotspots in otherwise oxygenated surface waters. Here, we show that sinking diatom aggregates can host anaerobic nitrogen cycling at ambient oxygen levels well above the hypoxic threshold. Aggregates were produced from the ubiquitous diatom Skeletonema marinoi and the natural microbial community of seawater. Microsensor profiling through the center of sinking aggregates revealed internal anoxia at ambient 40% air saturation (∼100 μmol O2 L-1) and below. Accordingly, anaerobic nitrate turnover inside the aggregates was evident within this range of ambient oxygen levels. In incubations with 15N-labeled nitrate, individual Skeletonema aggregates produced NO2- (up to 10.7 nmol N h-1 per aggregate), N2 (up to 7.1 nmol N h-1), NH4+ (up to 2.0 nmol N h-1), and N2O (up to 0.2 nmol N h-1). Intriguingly, nitrate stored inside the diatom cells served as an additional, internal nitrate source for dinitrogen production, which may partially uncouple anaerobic nitrate turnover by diatom aggregates from direct ambient nitrate supply. Sinking diatom aggregates can contribute directly to fixed-nitrogen loss in low-oxygen environments in the ocean and vastly expand the ocean volume in which anaerobic nitrogen turnover is possible, despite relatively high ambient oxygen levels. Depending on the extent of intracellular nitrate consumption during the sinking process, diatom aggregates may also be involved in the long-distance export of nitrate to the deep ocean. PMID:26903977

  4. Determining anaerobic degradation kinetics from batch tests.

    PubMed

    Moreda, Iván López

    2016-01-01

    Data obtained from a biomethane potential (BMP) test were used in order to obtain the parameters of a kinetic model of solid wastes anaerobic degradation. The proposed model considers a hydrolysis step with a first order kinetic, a Monod kinetic for the soluble organic substrate degradation and a first order decay of microorganisms. The instantaneous release of methane was assumed. The parameters of the model are determined following a direct search optimization procedure. A 'multiple-shooting' technique was used as a first step of the optimization process. The confidence interval of the parameters was determined by using Monte Carlo simulations. Also, the distribution functions of the parameters were determined. Only the hydrolysis first order constant shows a normal distribution.

  5. Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates

    PubMed Central

    Klawonn, Isabell; Bonaglia, Stefano; Brüchert, Volker; Ploug, Helle

    2015-01-01

    Colonies of N2-fixing cyanobacteria are key players in supplying new nitrogen to the ocean, but the biological fate of this fixed nitrogen remains poorly constrained. Here, we report on aerobic and anaerobic microbial nitrogen transformation processes that co-occur within millimetre-sized cyanobacterial aggregates (Nodularia spumigena) collected in aerated surface waters in the Baltic Sea. Microelectrode profiles showed steep oxygen gradients inside the aggregates and the potential for nitrous oxide production in the aggregates' anoxic centres. 15N-isotope labelling experiments and nutrient analyses revealed that N2 fixation, ammonification, nitrification, nitrate reduction to ammonium, denitrification and possibly anaerobic ammonium oxidation (anammox) can co-occur within these consortia. Thus, N. spumigena aggregates are potential sites of nitrogen gain, recycling and loss. Rates of nitrate reduction to ammonium and N2 were limited by low internal nitrification rates and low concentrations of nitrate in the ambient water. Presumably, patterns of N-transformation processes similar to those observed in this study arise also in other phytoplankton colonies, marine snow and fecal pellets. Anoxic microniches, as a pre-condition for anaerobic nitrogen transformations, may occur within large aggregates (⩾1 mm) even when suspended in fully oxygenated waters, whereas anoxia in small aggregates (<1 to ⩾0.1 mm) may only arise in low-oxygenated waters (⩽25 μM). We propose that the net effect of aggregates on nitrogen loss is negligible in NO3−-depleted, fully oxygenated (surface) waters. In NO3−-enriched (>1.5 μM), O2-depleted water layers, for example, in the chemocline of the Baltic Sea or the oceanic mesopelagic zone, aggregates may promote N-recycling and -loss processes. PMID:25575306

  6. Aerobic and anaerobic nitrogen transformation processes in N2-fixing cyanobacterial aggregates.

    PubMed

    Klawonn, Isabell; Bonaglia, Stefano; Brüchert, Volker; Ploug, Helle

    2015-06-01

    Colonies of N(2)-fixing cyanobacteria are key players in supplying new nitrogen to the ocean, but the biological fate of this fixed nitrogen remains poorly constrained. Here, we report on aerobic and anaerobic microbial nitrogen transformation processes that co-occur within millimetre-sized cyanobacterial aggregates (Nodularia spumigena) collected in aerated surface waters in the Baltic Sea. Microelectrode profiles showed steep oxygen gradients inside the aggregates and the potential for nitrous oxide production in the aggregates' anoxic centres. (15)N-isotope labelling experiments and nutrient analyses revealed that N(2) fixation, ammonification, nitrification, nitrate reduction to ammonium, denitrification and possibly anaerobic ammonium oxidation (anammox) can co-occur within these consortia. Thus, N. spumigena aggregates are potential sites of nitrogen gain, recycling and loss. Rates of nitrate reduction to ammonium and N(2) were limited by low internal nitrification rates and low concentrations of nitrate in the ambient water. Presumably, patterns of N-transformation processes similar to those observed in this study arise also in other phytoplankton colonies, marine snow and fecal pellets. Anoxic microniches, as a pre-condition for anaerobic nitrogen transformations, may occur within large aggregates (⩾1 mm) even when suspended in fully oxygenated waters, whereas anoxia in small aggregates (<1 to ⩾0.1 mm) may only arise in low-oxygenated waters (⩽25 μM). We propose that the net effect of aggregates on nitrogen loss is negligible in NO(3)(-)-depleted, fully oxygenated (surface) waters. In NO(3)(-)-enriched (>1.5 μM), O(2)-depleted water layers, for example, in the chemocline of the Baltic Sea or the oceanic mesopelagic zone, aggregates may promote N-recycling and -loss processes.

  7. Intracellular Nitrate of Marine Diatoms as a Driver of Anaerobic Nitrogen Cycling in Sinking Aggregates

    PubMed Central

    Kamp, Anja; Stief, Peter; Bristow, Laura A.; Thamdrup, Bo; Glud, Ronnie N.

    2016-01-01

    Diatom-bacteria aggregates are key for the vertical transport of organic carbon in the ocean. Sinking aggregates also represent pelagic microniches with intensified microbial activity, oxygen depletion in the center, and anaerobic nitrogen cycling. Since some of the aggregate-forming diatom species store nitrate intracellularly, we explored the fate of intracellular nitrate and its availability for microbial metabolism within anoxic diatom-bacteria aggregates. The ubiquitous nitrate-storing diatom Skeletonema marinoi was studied as both axenic cultures and laboratory-produced diatom-bacteria aggregates. Stable 15N isotope incubations under dark and anoxic conditions revealed that axenic S. marinoi is able to reduce intracellular nitrate to ammonium that is immediately excreted by the cells. When exposed to a light:dark cycle and oxic conditions, S. marinoi stored nitrate intracellularly in concentrations >60 mmol L-1 both as free-living cells and associated to aggregates. Intracellular nitrate concentrations exceeded extracellular concentrations by three orders of magnitude. Intracellular nitrate was used up within 2–3 days after shifting diatom-bacteria aggregates to dark and anoxic conditions. Thirty-one percent of the diatom-derived nitrate was converted to nitrogen gas, indicating that a substantial fraction of the intracellular nitrate pool of S. marinoi becomes available to the aggregate-associated bacterial community. Only 5% of the intracellular nitrate was reduced to ammonium, while 59% was recovered as nitrite. Hence, aggregate-associated diatoms accumulate nitrate from the surrounding water and sustain complex nitrogen transformations, including loss of fixed nitrogen, in anoxic, pelagic microniches. Additionally, it may be expected that intracellular nitrate not converted before the aggregates have settled onto the seafloor could fuel benthic nitrogen transformations. PMID:27847498

  8. Determinants of aerobic and anaerobic exercise performance in cystic fibrosis.

    PubMed

    Shah, A R; Gozal, D; Keens, T G

    1998-04-01

    We examined aerobic and anaerobic exercise performance in 17 subjects with cystic fibrosis (CF) (age 25+/-10 [SD] yr; 47% females; FEV1 62+/-21% pred) and 17 age- and sex-matched control subjects (age 25+/-8 [SD] yr; 41% females; FEV1 112+/-15% pred) in relation to pulmonary function and nutritional status. Aerobic capacity was determined as maximal oxygen consumption (VO2max) (ml/kg/min) and anaerobic threshold (AT; ml VO2/kg/min) from a graded exercise stress test on an electronically braked bicycle ergometer. Anaerobic performance was assessed from the average work of two bouts of pedaling to exhaustion at a load corresponding to 130% Vo2max from graded exercise. Both aerobic and anaerobic performances were decreased in subjects with CF (p < 0.001). The duration of anaerobic exercise in subjects with CF was similar to control subjects. In control subjects, pulmonary function did not correlate to aerobic or anaerobic exercise. In subjects with CF significant relationships between FEV1, vital capacity, and FEF25-75% to AT were found, suggesting the pulmonary limitation to aerobic capacity. In both patients with CF and control subjects, lean body mass and arm muscle area significantly correlated with anaerobic performance but not with VO2max or AT. We conclude that nutritional status, rather than pulmonary function, is the major determinant of anaerobic exercise capacity in CF. The preserved duration of anaerobic exercise at equivalent workloads (corresponding to 130% of VO2max from graded exercise) suggests that readily available energy stores in muscle may be similar in CF and normal individuals.

  9. Anaerobic

    MedlinePlus

    ... more prolonged exercise like walking or jogging. Anaerobic reactions are faster. We need them during shorter, more intense activities like sprinting. Anaerobic exercise leads to a buildup of lactic acid in our tissues. We need oxygen to remove ...

  10. NMR and MALDI-TOF MS based characterization of exopolysaccharides in anaerobic microbial aggregates from full-scale reactors.

    PubMed

    Gonzalez-Gil, Graciela; Thomas, Ludivine; Emwas, Abdul-Hamid; Lens, Piet N L; Saikaly, Pascal E

    2015-09-22

    Anaerobic granular sludge is composed of multispecies microbial aggregates embedded in a matrix of extracellular polymeric substances (EPS). Here we characterized the chemical fingerprint of the polysaccharide fraction of EPS in anaerobic granules obtained from full-scale reactors treating different types of wastewater. Nuclear magnetic resonance (NMR) signals of the polysaccharide region from the granules were very complex, likely as a result of the diverse microbial population in the granules. Using nonmetric multidimensional scaling (NMDS), the (1)H NMR signals of reference polysaccharides (gellan, xanthan, alginate) and those of the anaerobic granules revealed that there were similarities between the polysaccharides extracted from granules and the reference polysaccharide alginate. Further analysis of the exopolysaccharides from anaerobic granules, and reference polysaccharides using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) revealed that exopolysaccharides from two of the anaerobic granular sludges studied exhibited spectra similar to that of alginate. The presence of sequences related to the synthesis of alginate was confirmed in the metagenomes of the granules. Collectively these results suggest that alginate-like exopolysaccharides are constituents of the EPS matrix in anaerobic granular sludge treating different industrial wastewater. This finding expands the engineered environments where alginate has been found as EPS constituent of microbial aggregates.

  11. NMR and MALDI-TOF MS based characterization of exopolysaccharides in anaerobic microbial aggregates from full-scale reactors

    PubMed Central

    Gonzalez-Gil, Graciela; Thomas, Ludivine; Emwas, Abdul-Hamid; Lens, Piet N. L.; Saikaly, Pascal E.

    2015-01-01

    Anaerobic granular sludge is composed of multispecies microbial aggregates embedded in a matrix of extracellular polymeric substances (EPS). Here we characterized the chemical fingerprint of the polysaccharide fraction of EPS in anaerobic granules obtained from full-scale reactors treating different types of wastewater. Nuclear magnetic resonance (NMR) signals of the polysaccharide region from the granules were very complex, likely as a result of the diverse microbial population in the granules. Using nonmetric multidimensional scaling (NMDS), the 1H NMR signals of reference polysaccharides (gellan, xanthan, alginate) and those of the anaerobic granules revealed that there were similarities between the polysaccharides extracted from granules and the reference polysaccharide alginate. Further analysis of the exopolysaccharides from anaerobic granules, and reference polysaccharides using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) revealed that exopolysaccharides from two of the anaerobic granular sludges studied exhibited spectra similar to that of alginate. The presence of sequences related to the synthesis of alginate was confirmed in the metagenomes of the granules. Collectively these results suggest that alginate-like exopolysaccharides are constituents of the EPS matrix in anaerobic granular sludge treating different industrial wastewater. This finding expands the engineered environments where alginate has been found as EPS constituent of microbial aggregates. PMID:26391984

  12. Antartic Krill Cohort Determines Dominant Aggregation Structure

    NASA Astrophysics Data System (ADS)

    Bernard, K. S.; Cimino, M. A.; Fraser, W.; Kohut, J. T.; Oliver, M. J.; Patterson-Fraser, D.; Paxton, D.; Raycroft, S.; Statscewich, H.; Steinberg, D. K.; Winsor, P.

    2016-02-01

    Antarctic krill is a key prey item to numerous top predators along the western Antarctic Peninsula. Krill form aggregations of varying size and packing density, found at a wide range of depths within the water column, either sparsely or densely spaced together. Differences in the structure of krill aggregations will impact the availability of krill as prey. The population of Antarctic krill fluctuates over a 5-year period, typically with two strong recruitment years followed by 3 poor recruitment years, resulting in significant variability in the biomass and dominant cohort from year to year. We hypothesized that a shift in the dominant cohort would be accompanied by a shift in the dominant aggregation type. We investigated the aggregation structure of nearshore Antarctic krill over four sequential summers (2011-12 through 2014-15). The summers of 2011-12 and 2012-13 showed strong krill recruitment (juveniles < 30 mm dominated), while 2013-14 and 2014-15 were marked by reduced recruitment (adults > 30 mm dominated). Krill were acoustically mapped (Biosonics DT-X echo sounder) from a Zodiac within a 2-mile radius of Palmer Station. Aggregation parameters (e.g. depth, thickness, length, krill biomass, etc.) were described for each individual aggregation. These were used to group aggregations into similar types using a Principle Components Analysis followed by a Partitioning Around Medoids cluster analysis. Four distinctly different aggregation types were identified and the frequency at which these were observed varied significantly between summers. In particular, in 2011-12, krill aggregations were dominated by those that were near-surface, long and narrow, with high biomass and closely spaced together. Conversely in 2013-14, large, sparsely distributed, near-bottom aggregations, with high biomass dominated. Our results suggest a shift in aggregation structure and, consequently, availability to foraging top predators, with dominant cohort. Understanding inter annual

  13. Anaerobic threshold determination with analysis of salivary amylase.

    PubMed

    Calvo, F; Chicharro, J L; Bandrés, F; Lucía, A; Pérez, M; Alvarez, J; Mojares, L L; Vaquero, A F; Legido, J C

    1997-12-01

    The purpose of this study was to determine the anaerobic threshold from analysis of amylase concentration in total saliva during a laboratory exercise test. Each of 20 healthy young men performed both a submaximal and a maximal test on a treadmill. During the submaximal test, capillary blood and total saliva samples were collected for determination of anaerobic threshold (AT) and saliva threshold (Tsa), respectively. Tsa was defined as the point at which the first continuous increase in amylase concentration occurred during exercise. The results showed no significant difference between values of AT and Tsa when both were expressed either as running velocity or as heart rate. In addition, there existed a high correlation between AT and Tsa (r = .93, p < .001). It was therefore concluded that the analysis of amylase concentration in total saliva during exercise might be used as a valid new method for determining AT.

  14. STAND: Surface Tension for Aggregation Number Determination.

    PubMed

    Garrido, Pablo F; Brocos, Pilar; Amigo, Alfredo; García-Río, Luis; Gracia-Fadrique, Jesús; Piñeiro, Ángel

    2016-04-26

    Taking advantage of the extremely high dependence of surface tension on the concentration of amphiphilic molecules in aqueous solution, a new model based on the double equilibrium between free and aggregated molecules in the liquid phase and between free molecules in the liquid phase and those adsorbed at the air/liquid interface is presented and validated using literature data and fluorescence measurements. A key point of the model is the use of both the Langmuir isotherm and the Gibbs adsorption equation in terms of free molecules instead of the nominal concentration of the solute. The application of the model should be limited to non ionic compounds since it does not consider the presence of counterions. It requires several coupled nonlinear fittings for which we developed a software that is publicly available in our server as a web application. Using this tool, it is straightforward to get the average aggregation number of an amphiphile, the micellization free energy, the adsorption constant, the maximum surface excess (and so the minimum area per molecule), the distribution of solute in the liquid phase between free and aggregate species, and the surface coverage in only a couple of seconds, just by uploading a text file with surface tension vs concentration data and the corresponding uncertainties.

  15. Determination of the dynamic elastic constants of recycled aggregate concrete

    NASA Astrophysics Data System (ADS)

    Tsoumani, A. A.; Barkoula, N.-M.; Matikas, T. E.

    2015-03-01

    Nowadays, construction and demolition waste constitutes a major portion of the total solid waste production in the world. Due to both environmental and economical reasons, an increasing interest concerning the use of recycled aggregate to replace aggregate from natural sources is generated. This paper presents an investigation on the properties of recycled aggregate concrete. Concrete mixes are prepared using recycled aggregates at a substitution level between 0 and 100% of the total coarse aggregate. The influence of this replacement on strengthened concrete's properties is being investigated. The properties estimated are: density and dynamic modulus of elasticity at the age of both 7 and 28 days. Also, flexural strength of 28 days specimens is estimated. The determination of the dynamic elastic modulus was made using the ultrasonic pulse velocity method. The results reveal that the existence of recycled aggregates affects the properties of concrete negatively; however, in low levels of substitution the influence of using recycled aggregates is almost negligible. Concluding, the controlled use of recycled aggregates in concrete production may help solve a vital environmental issue apart from being a solution to the problem of inadequate concrete aggregates.

  16. Determinants of aggregate fertility in Pakistan.

    PubMed

    Soomro, G Y

    1986-01-01

    Data were obtained from the government of Pakistan's Census Organization and the Population Welfare Division to investigate and identify policy-relevant factors which influence fertility at an aggregate level by examining the supply, demand, and cost factors of fertility regulation. Information on fertility, mortality, nuptiality, and other socioeconomic variables was gathered for the 63 districts of Pakistan. The 3 districts of Karachi division were taken together as there appeared to be no appreciable variation among those districts. The unit of analysis was a district, which, as an administrative unit, ranks in importance after a province and a division. The dependent variable of an aggregate fertility measure is Total Fertility Rate (TFR). The TFR was measured indirectly from the age structure through the application of the stable population model. Only 2 variables appeared significant in their effect on fertility, i.e., enrollment ratio and marriage age, which tended to show a negative effect on fertility when controlled for other socioeconomic development variables. The effect of urbanization, although insignificant, showed a positive association with fertility; it was expected to have a negative association. The mean age at marriage was dropped from the equation in Table 2 because of its association with infant mortality. Only enrollment appeared to be a significant variable. In Table 3, only 3 variables, including urbanization, were controlled to rank individual variables in regard to their effect on their fertility. The results did not show any change from those of the 1st equation. In the 4th equation (Table 4), electrification substituted for the variable of urbanization; the results did not differ from those of the previous equation. In the 5th equation (Table 5), the composite variable was controlled with the family planning clinics variable. The effect of family planning clinics was insignificant. The enrollment variable appeared to be the most

  17. [Analysis of meteorological factors of forming feculent and anaerobic water aggregation induced by algal bloom in Taihu Lake].

    PubMed

    Wang, Cheng-Lin; Zhang, Yong; Zhang, Ning-Hong; Qian, Xin; Kong, Fan-Xiang

    2011-02-01

    The water quality pollution problem about feculent and anaerobic water aggregation (FAWA) induced by algal bloom in Taihu Lake, which is often called 'hufan' in Chinese, was studied. Its forming process is divided into 3 phases, i. e., material elements forming of FAWA, anaerobic products to be brought to the water surface and the maintaining of FAWA in the water surface. The conventional observational data from Wuxi meteorological station was analyzed. The result shows that there are similar meteorological characteristics of two FAWA phenomena in Taihu Lake in May, 2007 and May, 2008. A numerical simulation was performed to prove the analysis results. It indicates that propitious meteorological condition is one of the necessary forming factors of FAWA, which provides thermal and dynamical environment for FAWA. During the first phase, the weather conditions, such as high air temperature, gentle breeze and nearly invariable wind direction, maintain for more than 3 days and cause algal bloom to aggregate, then die, sink and anaerobic decay near lake bank. All these provide the precondition for FAWA. During the second phase, when the cold air mass passes across the Taihu basin, almost counter-direction wind, which maintains for more than 1 day with higher speed and lower air temperature, makes anaerobic products to be brought to the water surface by uplifted current. This is the trigger mechanism of FAWA. During the last phase, continual high air temperature and gentle breeze is favorable for FAWA in the water surface. Because meteorological factors are predictable, this research provides a way and basis for the further study of warning and controlling approaches of FAWA.

  18. Magnetic microparticle aggregation for viscosity determination by MR.

    PubMed

    Hong, Rui; Cima, Michael J; Weissleder, Ralph; Josephson, Lee

    2008-03-01

    Micron-sized magnetic particles were induced to aggregate when placed in homogeneous magnetic fields, like those of MR imagers and relaxometers, and then spontaneously returned to their dispersed state when removed from the field. Associated with the aggregation and dispersion of the magnetic particles were time-dependent increases and decreases in the spin-spin relaxation time (T2) of the water. Magnetic nanoparticles, with far smaller magnetic moments per particle, did not undergo magnetically induced aggregation and exhibited time-independent values of T2. The rate of T2 change associated with magnetic microparticle aggregation was used to determine the viscosity of liquid samples, providing a method that can be of particular advantage for determining the viscosity of small volumes of potentially biohazardous samples of blood or blood plasma. (c) 2008 Wiley-Liss, Inc.

  19. Magnetic Microparticle Aggregation For Viscosity Determination By Magnetic Resonance

    PubMed Central

    Hong, Rui; Cima, Michael J.; Weissleder, Ralph; Josephson, Lee

    2009-01-01

    Micron-sized magnetic particles were induced to aggregate when placed in homogeneous magnetic fields, like those of magnetic resonance (MR) imagers and relaxometers, and then spontaneously returned to their dispersed state when removed from the field. Associated with the aggregation and dispersion of the magnetic particles were time dependent increases and decreases in the spin-spin relaxation time (T2) of the water. Magnetic nanoparticles, with far smaller magnetic moments per particle, did not undergo magnetically induced aggregation, and exhibited time independent values of T2. The rate of T2 change associated with magnetic micro-particle aggregation was used to determine the viscosity of liquid samples, providing a method that can be of particular advantage for determining the viscosity of small volumes of potentially biohazardous samples of blood or blood plasma. PMID:18306403

  20. Metabolic determinants in Listeria monocytogenes anaerobic listeriolysin O production.

    PubMed

    Wallace, Nathan; Newton, Eric; Abrams, Elizabeth; Zani, Ashley; Sun, Yvonne

    2017-03-13

    Listeria monocytogenes is a human pathogen and a facultative anaerobe. To better understand how anaerobic growth affects L. monocytogenes pathogenesis, we first showed that anaerobic growth led to decreased growth and changes in surface morphology. Moreover, compared to aerobically grown bacteria, anaerobically grown L. monocytogenes established higher level of invasion but decreased intracellular growth and actin polymerization in cultured cells. The production of listeriolysin O (LLO) was significantly lower in anaerobic cultures-a phenotype observed in wild type and isogenic mutants lacking transcriptional regulators SigB or CodY or harboring a constitutively active PrfA. To explore potential regulatory mechanisms, we established that the addition of central carbon metabolism intermediates, such as acetate, citrate, fumarate, pyruvate, lactate, and succinate, led to an increase in LLO activity in the anaerobic culture supernatant. These results highlight the regulatory role of central carbon metabolism in L. monocytogenes pathogenesis under anaerobic conditions.

  1. Superhydrophobicity determines the buoyancy performance of kapok fiber aggregates

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyan; Fu, Wangyang; Duan, Chunting; Xiao, Hong; Shi, Meiwu; Zhao, Ning; Xu, Jian

    2013-02-01

    Superhydrophobicity is commonly regarded as a surface property that has important consequences for self-cleaning applications. Here we show interestingly that the superhydrophobicity is closely connected to the bulk buoyancy performance of kapok fiber aggregates, a natural material endowed with superhydrophobicity and extraordinary high porosity. First of all, we have determined the superhydrophobicity of a single kapok fiber, which can be ascribed to its micro-nano-binary structure (MNBS) and the thin hydrophobic paraffinic wax layer covered on the surface. Second, based on classic capillary and wicking theory, the buoyancy performance of the kapok fiber aggregates can be modeled and we demonstrate that their buoyancy performance is actually determined by the superhydrophobicity of individual kapok fibers. Our results also suggest an optimized density ˜0.015 g cm-3 for using kapok fiber aggregates as the lightest natural buoyancy.

  2. Selenite Reduction by Anaerobic Microbial Aggregates: Microbial Community Structure, and Proteins Associated to the Produced Selenium Spheres

    PubMed Central

    Gonzalez-Gil, Graciela; Lens, Piet N. L.; Saikaly, Pascal E.

    2016-01-01

    Certain types of anaerobic granular sludge, which consists of microbial aggregates, can reduce selenium oxyanions. To envisage strategies for removing those oxyanions from wastewater and recovering the produced elemental selenium (Se0), insights into the microbial community structure and synthesis of Se0 within these microbial aggregates are required. High-throughput sequencing showed that Veillonellaceae (c.a. 20%) and Pseudomonadaceae (c.a.10%) were the most abundant microbial phylotypes in selenite reducing microbial aggregates. The majority of the Pseudomonadaceae sequences were affiliated to the genus Pseudomonas. A distinct outer layer (∼200 μm) of selenium deposits indicated that bioreduction occurred in the outer zone of the microbial aggregates. In that outer layer, SEM analysis showed abundant intracellular and extracellular Se0 (nano)spheres, with some cells having high numbers of intracellular Se0 spheres. Electron tomography showed that microbial cells can harbor a single large intracellular sphere that stretches the cell body. The Se0 spheres produced by the microorganisms were capped with organic material. X-ray photoelectron spectroscopy (XPS) analysis of extracted Se0 spheres, combined with a mathematical approach to analyzing XPS spectra from biological origin, indicated that proteins and lipids were components of the capping material associated to the Se0 spheres. The most abundant proteins associated to the spheres were identified by proteomic analysis. Most of the proteins or peptide sequences capping the Se0 spheres were identified as periplasmic outer membrane porins and as the cytoplasmic elongation factor Tu protein, suggesting an intracellular formation of the Se0 spheres. In view of these and previous findings, a schematic model for the synthesis of Se0 spheres by the microorganisms inhabiting the granular sludge is proposed. PMID:27199909

  3. Selenite Reduction by Anaerobic Microbial Aggregates: Microbial Community Structure, and Proteins Associated to the Produced Selenium Spheres.

    PubMed

    Gonzalez-Gil, Graciela; Lens, Piet N L; Saikaly, Pascal E

    2016-01-01

    Certain types of anaerobic granular sludge, which consists of microbial aggregates, can reduce selenium oxyanions. To envisage strategies for removing those oxyanions from wastewater and recovering the produced elemental selenium (Se(0)), insights into the microbial community structure and synthesis of Se(0) within these microbial aggregates are required. High-throughput sequencing showed that Veillonellaceae (c.a. 20%) and Pseudomonadaceae (c.a.10%) were the most abundant microbial phylotypes in selenite reducing microbial aggregates. The majority of the Pseudomonadaceae sequences were affiliated to the genus Pseudomonas. A distinct outer layer (∼200 μm) of selenium deposits indicated that bioreduction occurred in the outer zone of the microbial aggregates. In that outer layer, SEM analysis showed abundant intracellular and extracellular Se(0) (nano)spheres, with some cells having high numbers of intracellular Se(0) spheres. Electron tomography showed that microbial cells can harbor a single large intracellular sphere that stretches the cell body. The Se(0) spheres produced by the microorganisms were capped with organic material. X-ray photoelectron spectroscopy (XPS) analysis of extracted Se(0) spheres, combined with a mathematical approach to analyzing XPS spectra from biological origin, indicated that proteins and lipids were components of the capping material associated to the Se(0) spheres. The most abundant proteins associated to the spheres were identified by proteomic analysis. Most of the proteins or peptide sequences capping the Se(0) spheres were identified as periplasmic outer membrane porins and as the cytoplasmic elongation factor Tu protein, suggesting an intracellular formation of the Se(0) spheres. In view of these and previous findings, a schematic model for the synthesis of Se(0) spheres by the microorganisms inhabiting the granular sludge is proposed.

  4. The maximum specific hydrogen-producing activity of anaerobic mixed cultures: definition and determination

    NASA Astrophysics Data System (ADS)

    Mu, Yang; Yang, Hou-Yun; Wang, Ya-Zhou; He, Chuan-Shu; Zhao, Quan-Bao; Wang, Yi; Yu, Han-Qing

    2014-06-01

    Fermentative hydrogen production from wastes has many advantages compared to various chemical methods. Methodology for characterizing the hydrogen-producing activity of anaerobic mixed cultures is essential for monitoring reactor operation in fermentative hydrogen production, however there is lack of such kind of standardized methodologies. In the present study, a new index, i.e., the maximum specific hydrogen-producing activity (SHAm) of anaerobic mixed cultures, was proposed, and consequently a reliable and simple method, named SHAm test, was developed to determine it. Furthermore, the influences of various parameters on the SHAm value determination of anaerobic mixed cultures were evaluated. Additionally, this SHAm assay was tested for different types of substrates and bacterial inocula. Our results demonstrate that this novel SHAm assay was a rapid, accurate and simple methodology for determining the hydrogen-producing activity of anaerobic mixed cultures. Thus, application of this approach is beneficial to establishing a stable anaerobic hydrogen-producing system.

  5. The maximum specific hydrogen-producing activity of anaerobic mixed cultures: definition and determination.

    PubMed

    Mu, Yang; Yang, Hou-Yun; Wang, Ya-Zhou; He, Chuan-Shu; Zhao, Quan-Bao; Wang, Yi; Yu, Han-Qing

    2014-06-10

    Fermentative hydrogen production from wastes has many advantages compared to various chemical methods. Methodology for characterizing the hydrogen-producing activity of anaerobic mixed cultures is essential for monitoring reactor operation in fermentative hydrogen production, however there is lack of such kind of standardized methodologies. In the present study, a new index, i.e., the maximum specific hydrogen-producing activity (SHAm) of anaerobic mixed cultures, was proposed, and consequently a reliable and simple method, named SHAm test, was developed to determine it. Furthermore, the influences of various parameters on the SHAm value determination of anaerobic mixed cultures were evaluated. Additionally, this SHAm assay was tested for different types of substrates and bacterial inocula. Our results demonstrate that this novel SHAm assay was a rapid, accurate and simple methodology for determining the hydrogen-producing activity of anaerobic mixed cultures. Thus, application of this approach is beneficial to establishing a stable anaerobic hydrogen-producing system.

  6. The maximum specific hydrogen-producing activity of anaerobic mixed cultures: definition and determination

    PubMed Central

    Mu, Yang; Yang, Hou-Yun; Wang, Ya-Zhou; He, Chuan-Shu; Zhao, Quan-Bao; Wang, Yi; Yu, Han-Qing

    2014-01-01

    Fermentative hydrogen production from wastes has many advantages compared to various chemical methods. Methodology for characterizing the hydrogen-producing activity of anaerobic mixed cultures is essential for monitoring reactor operation in fermentative hydrogen production, however there is lack of such kind of standardized methodologies. In the present study, a new index, i.e., the maximum specific hydrogen-producing activity (SHAm) of anaerobic mixed cultures, was proposed, and consequently a reliable and simple method, named SHAm test, was developed to determine it. Furthermore, the influences of various parameters on the SHAm value determination of anaerobic mixed cultures were evaluated. Additionally, this SHAm assay was tested for different types of substrates and bacterial inocula. Our results demonstrate that this novel SHAm assay was a rapid, accurate and simple methodology for determining the hydrogen-producing activity of anaerobic mixed cultures. Thus, application of this approach is beneficial to establishing a stable anaerobic hydrogen-producing system. PMID:24912488

  7. A novel weight determination method for time series data aggregation

    NASA Astrophysics Data System (ADS)

    Xu, Paiheng; Zhang, Rong; Deng, Yong

    2017-09-01

    Aggregation in time series is of great importance in time series smoothing, predicting and other time series analysis process, which makes it crucial to address the weights in times series correctly and reasonably. In this paper, a novel method to obtain the weights in time series is proposed, in which we adopt induced ordered weighted aggregation (IOWA) operator and visibility graph averaging (VGA) operator and linearly combine the weights separately generated by the two operator. The IOWA operator is introduced to the weight determination of time series, through which the time decay factor is taken into consideration. The VGA operator is able to generate weights with respect to the degree distribution in the visibility graph constructed from the corresponding time series, which reflects the relative importance of vertices in time series. The proposed method is applied to two practical datasets to illustrate its merits. The aggregation of Construction Cost Index (CCI) demonstrates the ability of proposed method to smooth time series, while the aggregation of The Taiwan Stock Exchange Capitalization Weighted Stock Index (TAIEX) illustrate how proposed method maintain the variation tendency of original data.

  8. Anaerobic capacity may not be determined by critical power model in elite table tennis players.

    PubMed

    Zagatto, Alessandro M; Papoti, Marcelo; Gobatto, Claudio A

    2008-01-01

    The aim of the present study was to verify the applicability of anaerobic work capacity (AWC) determined from the critical power model in elite table tennis players. Eight male international level table tennis players participated in the study. The tests undertaken were: 1) A critical frequency test used to determinate the anaerobic work capacity; 2) Wingate tests were performed using leg and arm ergometers. AWC corresponded to 99.5 ± 29.1 table tennis balls. AWC was not related to peak (r = -0.25), mean (r = -0.02), relative peak (r = -0.49) or relative mean power (r = 0.01), nor fatigue index (r = -0.52) (Wingate leg ergometer). Similar correlations for peak (r = -0.34), mean (r = -0.04), relative peak (r = -0.49), relative mean power (r = -0.14) and peak blood lactate concentration (r = -0.08) were determined in the Wingate arm ergometer test. Based on these results the AWC determined by a modified critical power test was not a good index for measurement of anaerobic capacity in table tennis players. Key pointsAnaerobic work capacity (AWC) was not good index of anaerobic capacity in table tennis.AWC determined using the table tennis ergometer showed low correlations with the Wingate test measures for cycle and arm ergometry.A sport-specific protocol is required for measuring anaerobic capacity in table tennis.

  9. A study of the aggregation of cyclodextrins: Determination of the critical aggregation concentration, size of aggregates and thermodynamics using isodesmic and K2-K models.

    PubMed

    Do, Thao Thi; Van Hooghten, Rob; Van den Mooter, Guy

    2017-04-15

    The aggregation of three different cyclodextrins (CDs): 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CD) and sulfobutylether-β-cyclodextrin (SBE-β-CD) was studied. The critical aggregation concentration (cac) of these three CDs is quite similar and is situated at ca. 2% (m/v). There was only a small difference in the cac values determined by DLS and (1)H NMR. DLS measurements revealed that CDs in solution have three size populations wherein one of them is that of a single CD molecule. The size of aggregates determined by TEM appears to be similar to the size of the aggregates in the second size distribution determined by DLS. Isodesmic and K2-K self-assembly models were used for studying the aggregation process of HP-β-CD, HP-γ-CD and SBE-β-CD. The results showed that the aggregation process of these CDs is a cooperative one, where the first step of aggregation is less favorable than the next steps. The determined thermodynamic parameters showed that the aggregation process of all three CDs is spontaneous and exothermic and it is driven by an increase of the entropy of the environment. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Antimicrobial susceptibility of anaerobic bacteria in Belgium as determined by E-test methodology.

    PubMed

    Glupczynski, Y; Berhin, C; Nizet, H

    2009-03-01

    The objective was to collect recent data on the antibiotic susceptibility of clinically significant anaerobes in Belgium. A total of 333 anaerobic clinical isolates from various body sites were prospectively collected between 2005 and 2007 at two tertiary care hospitals in Belgium. The minimal inhibitory concentrations (MICs) were determined using the E-test method for nine anti-anaerobic antibiotics. Sixty-one percent of the isolates were beta-lactamase producers, which explains the poor activity of penicillin. Amoxicillin/clavulanic acid, piperacillin/tazobactam, metronidazole and meropenem were very active against most anaerobes, but around 10% of the Bacteroides fragilis group strains were non-susceptible to the two beta-lactam/beta-lactamase inhibitors. No resistance was observed to metronidazole, while 3% of the Bacteroides spp. had decreased susceptibility to meropenem (MIC > or = 4 mg/L). Cefoxitin, clindamycin and moxifloxacin were less active, with 33%, 52% and 57% of the B. fragilis group being non-susceptible respectively. Tigecycline showed consistently good activity against most anaerobes with MIC(50) and MIC(90) of 0.25 and 2 mg/L. Metronidazole, amoxicillin/clavulanate, piperacillin/tazobactam and meropenem remain good empirical choices when anaerobes are expected in our setting. Because of the occurrence of resistance to most classes of current anti-anaerobic antibiotics, it is recommended that the antimicrobial resistance patterns be monitored regularly in order to guide empirical therapy.

  11. Geobotanical remote sensing for determination of aggregate source material

    NASA Technical Reports Server (NTRS)

    Minor, Timothy; Mouat, David; Myers, Jeff

    1988-01-01

    Aggregate source material suitable for facility and roadbed construction is often a very limited and highly valuable resource. The location of suitable source material is crucial to construction operations once facility requirements are established. The application of airborne and spaceborne remote sensing to terrain information requirements has proved attractive because of the rapid processing time and extensive spatial coverage associated with remotely gathered imagery. Source material identification may be improved by the remote sensing of vegetation associated with the material, particularly in areas of high vegetative cover. A research study employing remote sensing techniques was initiated to determine if vegetation could be used to discriminate parent materials for suitability as aggregate source material. Two test sites representing potential alluvial and residual source areas were selected in a semiarid region of Central California. Methods developed for the study included field observations of vegetation characteristics associated with the two parent material types along with the analysis of Thematic Mapper Simulator data flown over the test sites. The most useful images were those composites that included bands from two of the techniques (i.e., a Perpendicular Vegetation Index (PVI) band combined with principal components bands).

  12. Individual Preferences and Social Interactions Determine the Aggregation of Woodlice

    PubMed Central

    Devigne, Cédric; Broly, Pierre; Deneubourg, Jean-Louis

    2011-01-01

    Background The aggregation of woodlice in dark and moist places is considered an adaptation to land life and most studies are focused on its functionality or on the behavioural mechanisms related to the individual's response to abiotic factors. Until now, no clear experimental demonstration was available about aggregation resulting from inter-attraction between conspecifics. Methodology/Main Findings We present the dynamics of aggregation, not previously described in detail in literature, as being independent of the experimental conditions: homogeneous and heterogeneous environments with identical or different shelters. Indeed whatever these conditions, the aggregation is very quick. In less than 10 minutes more than 50% of woodlice were aggregated in several small groups in the homogeneous environment or under shelters in the heterogeneous environment. After this fast aggregation, woodlice progressively moved into a single aggregate or under one shelter. Conclusions/Significance Here we show for the first time that aggregation in woodlice implies a strong social component and results from a trade-off between individual preferences and inter-attraction between individuals. Moreover, our results reveal that the response to the heterogeneities affects only the location of the aggregates and not the level of aggregation, and demonstrate the strong inter-attraction between conspecifics which can outweigh individual preferences. This inter-attraction can lead to situations that could seem sub-optimal. PMID:21364761

  13. Ammonia and temperature determine potential clustering in the anaerobic digestion microbiome.

    PubMed

    De Vrieze, Jo; Saunders, Aaron Marc; He, Ying; Fang, Jing; Nielsen, Per Halkjaer; Verstraete, Willy; Boon, Nico

    2015-05-15

    Anaerobic digestion is regarded as a key environmental technology in the present and future bio-based economy. The microbial community completing the anaerobic digestion process is considered complex, and several attempts already have been carried out to determine the key microbial populations. However, the key differences in the anaerobic digestion microbiomes, and the environmental/process parameters that drive these differences, remain poorly understood. In this research, we hypothesized that differences in operational parameters lead to a particular composition and organization of microbial communities in full-scale installations. A total of 38 samples were collected from 29 different full-scale anaerobic digestion installations, showing constant biogas production in function of time. Microbial community analysis was carried out by means of amplicon sequencing and real-time PCR. The bacterial community in all samples was dominated by representatives of the Firmicutes, Bacteroidetes and Proteobacteria, covering 86.1 ± 10.7% of the total bacterial community. Acetoclastic methanogenesis was dominated by Methanosaetaceae, yet, only the hydrogenotrophic Methanobacteriales correlated with biogas production, confirming their importance in high-rate anaerobic digestion systems. In-depth analysis of operational and environmental parameters and bacterial community structure indicated the presence of three potential clusters in anaerobic digestion. These clusters were determined by total ammonia concentration, free ammonia concentration and temperature, and characterized by an increased relative abundance of Bacteroidales, Clostridiales and Lactobacillales, respectively. None of the methanogenic populations, however, could be significantly attributed to any of the three clusters. Nonetheless, further experimental research will be required to validate the existence of these different clusters, and to which extent the presence of these clusters relates to stable or sub

  14. Sequence determinants of protein aggregation: tools to increase protein solubility

    PubMed Central

    Ventura, Salvador

    2005-01-01

    Escherichia coli is one of the most widely used hosts for the production of recombinant proteins. However, very often the target protein accumulates into insoluble aggregates in a misfolded and biologically inactive form. Bacterial inclusion bodies are major bottlenecks in protein production and are hampering the development of top priority research areas such structural genomics. Inclusion body formation was formerly considered to occur via non-specific association of hydrophobic surfaces in folding intermediates. Increasing evidence, however, indicates that protein aggregation in bacteria resembles to the well-studied process of amyloid fibril formation. Both processes appear to rely on the formation of specific, sequence-dependent, intermolecular interactions driving the formation of structured protein aggregates. This similarity in the mechanisms of aggregation will probably allow applying anti-aggregational strategies already tested in the amyloid context to the less explored area of protein aggregation inside bacteria. Specifically, new sequence-based approaches appear as promising tools to tune protein aggregation in biotechnological processes. PMID:15847694

  15. Polyglutamine Aggregation in Huntington Disease: Does Structure Determine Toxicity?

    PubMed

    Hoffner, Guylaine; Djian, Philippe

    2015-12-01

    Huntington disease is a dominantly inherited disease of the central nervous system. The mutational expansion of polyglutamine beyond a critical length produces a toxic gain of function in huntingtin and results in neuronal death. In the course of the disease, expanded huntingtin is proteolyzed, becomes abnormally folded, and accumulates in oligomers, fibrils, and microscopic inclusions. The aggregated forms of the expanded protein are structurally diverse. Structural heterogeneity may explain why polyglutamine-containing aggregates could paradoxically be either toxic or neuroprotective. When defined, the toxic structures could then specifically be targeted by prophylactic or therapeutic drugs aimed at inhibiting polyglutamine aggregation.

  16. Molecular determinants of the platelet aggregation inhibitory activity of carbamoylpiperidines.

    PubMed

    Feng, Z; Gollamudi, R; Dillingham, E O; Bond, S E; Lyman, B A; Purcell, W P; Hill, R J; Korfmacher, W A

    1992-08-07

    A series of alpha,alpha'-bis[3-(N,N-dialkylcarbamoyl)piperidino]-p- xylenes were synthesized and tested for their inhibitory activity on ADP-induced aggregation of human platelets. A parabolic curve was obtained when log 1/C (activity) was plotted against log P (octanol/water partition coefficient). Using this as a model, a new analogue, alpha,alpha'-bis-[3-(N-methyl-N-butylcarbamoyl)piperidino]-p-xylen e (3g), was synthesized with a predicted IC50 of 25 microM. When this compound was subsequently evaluated, the IC50 was 22.1 +/- 5.5 microM, demonstrating the applicability of this model. The amide oxygen of the carbamoyl substituent appeared necessary for activity. Thus, for example, when the amide carbonyl group of 3a (IC50 = 44.5 microM) was reduced to CH2, the resulting compound 4 had a dramatically reduced activity, IC50 = 1565 microM. Compound 3a was resolved into (+) and (-) enantiomers and a meso (0) diastereomer using fractional crystallization, diastereomeric tartrate formation, and chiral HPLC. Compared to (-)-3a, the (+) isomer was 15 times more potent when ADP was the agonist and 19 times more active when collagen was used as the agonist. Molecular modeling of R,R- and S,S-3a using the SYBYL program was used to examine their interactions with phosphatidylinositol (PI). There was a better fit between PI and the R,R-3a with the energy of interaction being 17.6 kcal/mol less than that of the S,S-3a/PI complex. Although the absolute stereochemistry of individual enantiomers is not known, this study shows that R,R-3a interacts more favorably with PI than does S,S-3a and that (+)-3a is a more potent inhibitor of human platelet aggregation than (-)-3a. It is postulated that because of their lipophilicity, these compounds penetrate the platelet membrane and are then protonated at the pH of the cytosol. The protonated N then neutralizes the anionic charge on the membrane phosphoinositides, thereby rendering them less susceptible to hydrolysis by phospholipase C

  17. Fundamental factors determining the nature of parasite aggregation in hosts.

    PubMed

    Gourbière, Sébastien; Morand, Serge; Waxman, David

    2015-01-01

    The distribution of parasites in hosts is typically aggregated: a few hosts harbour many parasites, while the remainder of hosts are virtually parasite free. The origin of this almost universal pattern is central to our understanding of host-parasite interactions; it affects many facets of their ecology and evolution. Despite this, the standard statistical framework used to characterize parasite aggregation does not describe the processes generating such a pattern. In this work, we have developed a mathematical framework for the distribution of parasites in hosts, starting from a simple statistical description in terms of two fundamental processes: the exposure of hosts to parasites and the infection success of parasites. This description allows the level of aggregation of parasites in hosts to be related to the random variation in these two processes and to true host heterogeneity. We show that random variation can generate an aggregated distribution and that the common view, that encounters and success are two equivalent filters, applies to the average parasite burden under neutral assumptions but it does not apply to the variance of the parasite burden, and it is not true when heterogeneity between hosts is incorporated in the model. We find that aggregation decreases linearly with the number of encounters, but it depends non-linearly on parasite success. We also find additional terms in the variance of the parasite burden which contribute to the actual level of aggregation in specific biological systems. We have derived the formal expressions of these contributions, and these provide new opportunities to analyse empirical data and tackle the complexity of the origin of aggregation in various host-parasite associations.

  18. The Global Anaerobic Regulator Anr, Is Involved in Cell Attachment and Aggregation Influencing the First Stages of Biofilm Development in Pseudomonas extremaustralis

    PubMed Central

    Tribelli, Paula M.; Hay, Anthony G.; López, Nancy I.

    2013-01-01

    Pseudomonas extremaustralis is a versatile Antarctic bacterium, able to grow under microaerobic and anaerobic conditions and is related to several non-pathogenic Pseudomonads. Here we report on the role of the global anaerobic regulator Anr, in the early steps of P. extremaustralis biofilm development. We found that the anr mutant was reduced in its ability to attach, to form aggregates and to display twitching motility but presented higher swimming motility than the wild type. In addition, microscopy revealed that the wild type biofilm contained more biomass and was thicker, but were less rough than that of the anr mutant. In silico analysis of the P. extremaustralis genome for Anr-like binding sites led to the identification of two biofilm-related genes as potential targets of this regulator. When measured using Quantitative Real Time PCR, we found that the anr mutant expressed lower levels of pilG, which encodes a component of Type IV pili and has been previously implicated in cellular adhesion. Levels of morA, involved in signal transduction and flagella development, were also lower in the mutant. Our data suggest that under low oxygen conditions, such as those encountered in biofilms, Anr differentially regulates aggregation and motility thus affecting the first stages of biofilm formation. PMID:24146909

  19. The global anaerobic regulator Anr, is involved in cell attachment and aggregation influencing the first stages of biofilm development in Pseudomonas extremaustralis.

    PubMed

    Tribelli, Paula M; Hay, Anthony G; López, Nancy I

    2013-01-01

    Pseudomonas extremaustralis is a versatile Antarctic bacterium, able to grow under microaerobic and anaerobic conditions and is related to several non-pathogenic Pseudomonads. Here we report on the role of the global anaerobic regulator Anr, in the early steps of P. extremaustralis biofilm development. We found that the anr mutant was reduced in its ability to attach, to form aggregates and to display twitching motility but presented higher swimming motility than the wild type. In addition, microscopy revealed that the wild type biofilm contained more biomass and was thicker, but were less rough than that of the anr mutant. In silico analysis of the P. extremaustralis genome for Anr-like binding sites led to the identification of two biofilm-related genes as potential targets of this regulator. When measured using Quantitative Real Time PCR, we found that the anr mutant expressed lower levels of pilG, which encodes a component of Type IV pili and has been previously implicated in cellular adhesion. Levels of morA, involved in signal transduction and flagella development, were also lower in the mutant. Our data suggest that under low oxygen conditions, such as those encountered in biofilms, Anr differentially regulates aggregation and motility thus affecting the first stages of biofilm formation.

  20. Aggregate size and structure determination of nanomaterials in physiological media: importance of dynamic evolution

    NASA Astrophysics Data System (ADS)

    Afrooz, A. R. M. Nabiul; Hussain, Saber M.; Saleh, Navid B.

    2014-12-01

    Most in vitro nanotoxicological assays are performed after 24 h exposure. However, in determining size and shape effect of nanoparticles in toxicity assays, initial characterization data are generally used to describe experimental outcome. The dynamic size and structure of aggregates are typically ignored in these studies. This brief communication reports dynamic evolution of aggregation characteristics of gold nanoparticles. The study finds that gradual increase in aggregate size of gold nanospheres (AuNS) occurs up to 6 h duration; beyond this time period, the aggregation process deviates from gradual to a more abrupt behavior as large networks are formed. Results of the study also show that aggregated clusters possess unique structural conformation depending on nominal diameter of the nanoparticles. The differences in fractal dimensions of the AuNS samples likely occurred due to geometric differences, causing larger packing propensities for smaller sized particles. Both such observations can have profound influence on dosimetry for in vitro nanotoxicity analyses.

  1. [Determination of the anaerobic threshold by the rate of ventilation and cardio interval variability].

    PubMed

    Seluianov, V N; Kalinin, E M; Pak, G D; Maevskaia, V I; Konrad, A H

    2011-01-01

    The aim of this work is to develop methods for determining the anaerobic threshold according to the rate of ventilation and cardio interval variability during the test with stepwise increases load on the cycle ergometer and treadmill. In the first phase developed the method for determining the anaerobic threshold for lung ventilation. 49 highly skilled skiers took part in the experiment. They performed a treadmill ski-walking test with sticks with gradually increasing slope from 0 to 25 degrees, the slope increased by one degree every minute. In the second phase we developed a method for determining the anaerobic threshold according dynamics ofcardio interval variability during the test. The study included 86 athletes of different sports specialties who performed pedaling on the cycle ergometer "Monarch" in advance. Initial output was 25 W, power increased by 25 W every 2 min. The pace was steady--75 rev/min. Measurement of pulmonary ventilation and oxygen and carbon dioxide content was performed using gas analyzer COSMED K4. Sampling of arterial blood was carried from the ear lobe or finger, blood lactate concentration was determined using an "Akusport" instrument. RR-intervals registration was performed using heart rate monitor Polar s810i. As a result, it was shown that the graphical method for determining the onset of anaerobic threshold ventilation (VAnP) coincides with the accumulation of blood lactate 3.8 +/- 0.1 mmol/l when testing on a treadmill and 4.1 +/- 0.6 mmol/1 on the cycle ergometer. The connection between the measure of oxygen consumption at VAnP and the dispersion of cardio intervals (SD1), derived regression equation: VO2AnT = 0.35 + 0.01SD1W + 0.0016SD1HR + + 0.106SD1(ms), l/min; (R = 0.98, error evaluation function 0.26 L/min, p < 0.001), where W (W)--Power, HR--heart rate (beats/min), SD1--cardio intervals dispersion (ms) at the moment of registration of cardio interval threshold.

  2. Anaerobic threshold in children: determination from saliva analysis in field tests.

    PubMed

    Chicharro, J L; Calvo, F; Alvarez, J; Vaquero, A F; Bandrés, F; Legido, J C

    1995-01-01

    The purpose of this study was to determine the anaerobic threshold of children by the analysis of saliva collected during field tests. A group of 25 children (mean age, 10.5 years) performed an incremental exercise test on a track, consisting of 4-min stages at increasing running velocities. Before each test (at rest) and at the end of each stage, both blood (via finger pricks) and saliva samples (for measurement of salivary concentrations of Na+ and Cl-) were collected to determine lactate threshold (Thla-) and saliva threshold (Thsa), respectively. There were no significant differences between values of Thla- and Thsa when expressed either as running velocity [mean Thla-, 10.73 (SD 1.96) km.h-1; mean Thsa, 10.89 (SD 1.69) km.h-1)] or heart rate [Thla-, 182(SD 14) beats. min-1 Thsa 183 (SD 11) beats.min-1]. In addition, correlations between Thsa and Thla were high, when both values were expressed as running velocity in kilometres per hour (r = 0.89; P < 0.001), or heart rate in beats per minute (r = 0.90; p < 0.001). In conclusion, these findings suggested that saliva analysis would be a valid method for anaerobic threshold determination in field tests.

  3. Determination of operating conditions in an anaerobic acid-phase reactor treating dairy wastewater

    SciTech Connect

    Kasapgil, B.; Ince, O.; Anderson, G.K.

    1996-11-01

    Anaerobic digestion of organic material is a multistep process. Two groups of bacteria, namely acidogenic and methanogenic bacteria, are responsible for the acidification and for the methane formation, respectively. The growth requirements of the two groups of bacteria are rather different. In order to create optimum conditions for the process, it was first proposed to separate the process into two phases. Operating variables applicable for the selection and enrichment of microbial populations in phased digesters include digester loading, hydraulic retention time (HRT), pH, temperature, reactor design, and operating mode. By proper manipulation of these operating parameters it is possible to prevent any significant growth of methane bacteria and at the same time achieve the required level of acidification in the first reactor. Further enrichment of two cultures is possible by biomass recycle around each phase. Since the 1970s, phase separation has been introduced into anaerobic digestion technology. However, data concerning the optimization of operating conditions in both acidogenic and methanogenic phase reactors are scarce. This study was therefore carried out for the purposes given below. These were: (1) to determine the best combination of pH and temperature within the ranges studied for the pre-acidification of dairy wastewater; (2) to determine the maximum acidogenic conversion from COD to VFAs, and (3) to determine the changes in the distribution of major VFAs being produced during the pre-acidification of dairy wastewater.

  4. Texture independent determination of residual stress in polycrystalline aggregates using Rayleigh waves

    NASA Astrophysics Data System (ADS)

    Sayers, C. M.

    1984-09-01

    The Rayleigh wave velocity for a polycrystalline aggregate of cubic crystals with orthorhombic symmetry is derived. The formalism of Rod for treating the texture of polycrystalline aggregates is used. It is shown that surface wave velocity measurements can be combined with the normal shear wave birefringence technique to give a texture independent determination of the difference in principal stresses. The accuracy of the theory is demonstrated for rolled aluminum and steel plates.

  5. Shear stress tolerance of Streptococcus mutans aggregates determined by microfluidic funnel device (μFFD).

    PubMed

    Shumi, Wahhida; Kim, So Hyun; Lim, Jeesun; Cho, Kyung-Suk; Han, Hwataik; Park, Sungsu

    2013-05-01

    Dental caries are initiated by the attachment of Streptococcus mutans aggregates to the surface of teeth. Bacterial adhesion to the interproximal space, the space between adjacent teeth, has not been investigated due to the lack of devices that mimic the space. Herein, we describe a method for determining the effect of shear stress and sucrose on the attachment of S. mutans aggregates to the interproximal space using microfluidic funnel device (μFFD). Using μFFD, the shear stress tolerance of sucrose-independent and sucrose-dependent S. mutans aggregates (larger than 50 μm in diameter) trapped in the funnel was tested against various flow rates of saliva solution (5 to 50 μl/min). Sucrose-independent aggregates were completely removed from the funnel walls at a low flow rate (10 μl/min) within 7 min., while sucrose-dependent aggregates were removed from the walls only at higher flow rates (25 and 50 μl/min) within several minutes. These results suggest that sucrose-dependent aggregates are more tolerant of shear stress than sucrose-independent aggregates, and are more likely to remain in the region with the smallest shear stress in the teeth.

  6. Sequential extraction of anaerobic digestate sludge for the determination of partitioning of heavy metals.

    PubMed

    Zhu, Neng-min; Qiang-Li; Guo, Xu-jing; Hui-Zhang; Yu-Deng

    2014-04-01

    In China, agricultural use of anaerobic digestate sludge is considered a concern due to high heavy metal content of the sludge. In this study, sequential extraction procedure (SEP) was conducted to determine metal speciation which affects release and mobility of metal significantly. The results of SEP showed that each heavy metal possessed different distribution characteristics. Cu mainly reacted with carboxyl functional group to form the fraction bound to organic matter. Zn and Mn were dominated in the fraction bound to Fe-Mn oxides and carbonates, respectively. Pb, Ni, Cr, Cd and As were present as the residual fraction. Examination of mobility factors (MFs) indicated that Zn, Pb, Ni, Mn and Cd were more mobile whereas Cr and As were immobilized in anaerobic digestate. Based on the results, it can be stated that Cu, Zn, Mn, Ni and Cd may be grouped as toxic and active components in sludge and should be regarded as the priority pollutants for elimination. Pb should be monitored in terms of its high mobility factors (MF). Cr and As, nevertheless, were the most stable components in sludge.

  7. Determination of main components and anaerobic rumen digestibility of aquatic plants in vitro using near-infrared-reflectance spectroscopy.

    PubMed

    Yue, Zheng-Bo; Zhang, Meng-Lin; Sheng, Guo-Ping; Liu, Rong-Hua; Long, Ying; Xiang, Bing-Ren; Wang, Jin; Yu, Han-Qing

    2010-04-01

    A near-infrared-reflectance (NIR) spectroscopy-based method is established to determine the main components of aquatic plants as well as their anaerobic rumen biodegradability. The developed method is more rapid and accurate compared to the conventional chemical analysis and biodegradability tests. Moisture, volatile solid, Klason lignin and ash in entire aquatic plants could be accurately predicted using this method with coefficient of determination (r(2)) values of 0.952, 0.916, 0.939 and 0.950, respectively. In addition, the anaerobic rumen biodegradability of aquatic plants, represented as biogas and methane yields, could also be predicted well. The algorithm of continuous wavelet transform for the NIR spectral data pretreatment is able to greatly enhance the robustness and predictive ability of the NIR spectral analysis. These results indicate that NIR spectroscopy could be used to predict the main components of aquatic plants and their anaerobic biodegradability.

  8. Higher Education and the Determination of Aggregate Male Employment by Age

    ERIC Educational Resources Information Center

    Stenberg, Anders; Wikstrom, Magnus

    2004-01-01

    This paper studies the determinants of age-specific employment rates among Swedish males, focusing on the effect of education on employment. We use cohort specific data for the time period 1984-1996 covering male cohorts aged 21-45. It is found that aggregate age-group-specific employment rates increase with the proportion of the cohort with an…

  9. Determination of the Degree of Gravel Aggregate-Bitumencoverage by Multi-Directional Reflectance Measurements

    NASA Astrophysics Data System (ADS)

    Mulsow, C.

    2012-07-01

    The paper describes the determination of the percentage area of bitumen on partly covered aggregate. This task is a typical issue in material testing in road construction. The asphalt components bitumen and aggregate are subjected to defined mechanical stress in the presence of water in order to test the affine properties of the components. The degree to which the bitumen separates from the aggregate surface serves as an indicator for the quality of the affinity. Until now, examiners have been judging the coverage degree of samples by visual rating. Several research projects attempted to replace the error-prone subjective assessment by automatic procedures. These procedures analyse the different chromaticities of aggregate and bitumen in RGB images. However, these approaches as a whole are not reliable enough because of the rather specific requirements that are made on the environmental conditions when the picture is taken (illumination, exclusion of extraneous light) and also on the lab assistant (manual definition of training areas, management of camera and illumination parameters). Moreover, the analysis is not suitable for all types of rock because of the necessary difference in colour between bitumen and aggregate (e.g. dark rock samples). Contrary to previous approaches, the new multi-directional reflectance measurements use the different surface characteristics of bitumen and aggregate instead of the chromaticities as separation criteria. These differences are made visible by directional lighting with a laser. The diffuse reflection from the aggregate surface and the directional reflection from the optically smoother bitumen produce definitely distinguishable brightnesses in the image. Thus the colour of the material is of no significance. The approach was used in a procedure and assessed. The paper presents the method itself, approaches for the elimination of reflections and first results. Moreover, the measuring principle is compared with existing

  10. An improved procedure for determination of the mean aggregation number of micelles

    NASA Astrophysics Data System (ADS)

    Wu, Shuangyan; Tachiya, Masanori; Yan, Zhenning

    2015-03-01

    In this paper, a theory of fluorescence quenching in micelles which enables a dynamic approach to the evaluation of the aggregation numbers of micelles is presented. This method is based on a detailed kinetic model of quenching of fluorescent probe developed by Tachiya (1975, 1982) and takes into account that a part of quenchers are associated with micelles but the remaining quenchers are in the aqueous phase. The approach presented is an improvement on a previous fluorescence quenching method (Turro and Yekta, 1978) and is applied to determine the aggregation number of sodium dodecyl sulfonate (SAS) in aqueous dipeptide solution using cetylpyridinium chloride as quencher. The values of aggregation number and association constant for quencher-micelle association are presented.

  11. Method of determination of stability of petroleum disperse systems against aggregation

    SciTech Connect

    Antoshkin, A.S.; Glagoleva, O.F.; Khaidura, K.M.; Syunyaev, R.Z.

    1984-03-01

    This article proposes that the stability of petroleum products against aggregation should be evaluated in a laboratory unit consisting of a thermostat holding the temperature to within + or - 0.02/sup 0/C, a thermostating compartment with 15 samples, and a laboratory stirrer (power 130 W). The problem of regulating the stability of petroleum products against aggregation (kinetic stability) is one of the most important problems in petroleum refining. The equilibrium temperature, the stability factor with respect to asphaltenes, and the distillation yield of the vacuum distillate as a function of the content of additive (lube oil solvent extract) are determined for an atmospheric resid from West Siberian crudes. It is concluded that the proposed method offers a means for a rapid and reliable evaluation of the stability of a petroleum stock against aggregation when exposed to the action of various factors, and a means for finding its active state.

  12. 40 CFR 355.14 - Do I have to aggregate extremely hazardous substances to determine the total quantity present?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... hazardous substances to determine the total quantity present? 355.14 Section 355.14 Protection of... to aggregate extremely hazardous substances to determine the total quantity present? You must aggregate (i.e., add together) the amounts of each EHS at your facility to determine if a TPQ is present...

  13. Useful multivariate kinetic analysis: Size determination based on cystein-induced aggregation of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Rabbani, Faride; Hormozi Nezhad, Mohammad Reza; Abdollahi, Hamid

    2013-11-01

    This study describes spectrometric monitored kinetic processes to determine the size of citrate-capped Au nanoparticles (Au NPs) based on aggregation induced by L-cysteine (L-Cys) as a molecular linker. The Au NPs association process is thoroughly dependent on pH, concentration and size of nanoparticles. Size dependency of aggregation inspirits to determine the average diameters of Au NPs. For this aim the procedure is achieved in aqueous medium at pH 7 (phosphate buffer), and multivariate data including kinetic spectra of Au NPs are collected during aggregation process. Subsequently partial least squares (PLS) modeling is carried out analyzing the obtained data. The model is built on the basis of relation between the kinetics behavior of aggregation and different Au NPs sizes. Training the model was performed using latent variables (LVs) of the original data. The analytical performance of the model was characterized by relative standard error. The proposed method was applied to determination of size in unknown samples. The predicted sizes of unknown samples that obtained by the introduced method are interestingly in agreement with the sizes measured by Transmission Electron Microscopy (TEM) images and Dynamic Light Scattering (DLS) measurement.

  14. Useful multivariate kinetic analysis: Size determination based on cystein-induced aggregation of gold nanoparticles.

    PubMed

    Rabbani, Faride; Hormozi Nezhad, Mohammad Reza; Abdollahi, Hamid

    2013-11-01

    This study describes spectrometric monitored kinetic processes to determine the size of citrate-capped Au nanoparticles (Au NPs) based on aggregation induced by l-cysteine (l-Cys) as a molecular linker. The Au NPs association process is thoroughly dependent on pH, concentration and size of nanoparticles. Size dependency of aggregation inspirits to determine the average diameters of Au NPs. For this aim the procedure is achieved in aqueous medium at pH 7 (phosphate buffer), and multivariate data including kinetic spectra of Au NPs are collected during aggregation process. Subsequently partial least squares (PLS) modeling is carried out analyzing the obtained data. The model is built on the basis of relation between the kinetics behavior of aggregation and different Au NPs sizes. Training the model was performed using latent variables (LVs) of the original data. The analytical performance of the model was characterized by relative standard error. The proposed method was applied to determination of size in unknown samples. The predicted sizes of unknown samples that obtained by the introduced method are interestingly in agreement with the sizes measured by Transmission Electron Microscopy (TEM) images and Dynamic Light Scattering (DLS) measurement.

  15. All-out Test in Tethered Canoe System can Determine Anaerobic Parameters of Elite Kayakers.

    PubMed

    Messias, L H D; Ferrari, H G; Sousa, F A B; Dos Reis, I G M; Serra, C C S; Gobatto, C A; Manchado-Gobatto, F B

    2015-10-01

    The aims of this study were to use a specific all-out 30-sec tethered test to determine the anaerobic parameters in elite kayakers and verify the relationship between these results and sports performance. Twelve elite slalom kayakers were evaluated. The tethered canoe system was created and used for the all-out 30-sec test application. Measurements of peak force, mean force, minimum force, fatigue index and impulse were performed. Performance evaluation was determined by measuring the time of race in a simulated race containing 24 gates on a white-water course. Blood was collected (25-µl) for analysis of lactate concentration at rest and at 2, 4, 6, 8 and 10-min intervals after both the all-out test and the simulated race. The Pearson product moment correlation shows a inverse and significant relationship of peak force, mean force and impulse with time of race. Blood lactate concentrations after the all-out test and the simulated race peak at same time (4 min). Additionally, no interaction was visualized between time and all-out test/simulated race for blood lactate concentrations (P <0.365). These results suggest a relationship between the parameters of the all-out test and performance. Thus, the tethered canoe system is a useful tool for determining parameters that could be used in training control of slalom kayakers.

  16. Unraveling the Early Events of Amyloid-β Protein (Aβ) Aggregation: Techniques for the Determination of Aβ Aggregate Size

    PubMed Central

    Pryor, N. Elizabeth; Moss, Melissa A.; Hestekin, Christa N.

    2012-01-01

    The aggregation of proteins into insoluble amyloid fibrils coincides with the onset of numerous diseases. An array of techniques is available to study the different stages of the amyloid aggregation process. Recently, emphasis has been placed upon the analysis of oligomeric amyloid species, which have been hypothesized to play a key role in disease progression. This paper reviews techniques utilized to study aggregation of the amyloid-β protein (Aβ) associated with Alzheimer’s disease. In particular, the review focuses on techniques that provide information about the size or quantity of oligomeric Aβ species formed during the early stages of aggregation, including native-PAGE, SDS-PAGE, Western blotting, capillary electrophoresis, mass spectrometry, fluorescence correlation spectroscopy, light scattering, size exclusion chromatography, centrifugation, enzyme-linked immunosorbent assay, and dot blotting. PMID:22489141

  17. Determination of Anaerobic Threshold by Monitoring the O2 Pulse Changes in Endurance Cyclists.

    PubMed

    Nikooie, Rohollah

    2016-06-01

    The purpose of this study was to determine the validity of anaerobic threshold (AnT)-equivalent to the second turn point for lactate (LTP2)-estimation using the O2 pulse changes in highly trained endurance cyclists who do not show heart rate deflection point (HRDP) during incremental testing. Sixteen endurance cyclists (age, 24.8 ± 4.7 years) and fifteen active men (age, 24.8 ± 3.7 years) performed an incremental cycling test to exhaustion. Pulmonary oxygen uptake (V[Combining Dot Above]O2) and other hemodynamic variables, heart rate, and blood lactate concentration were measured continuously throughout the test. O2 pulse anaerobic threshold (O2 pulse-AnT) was defined as the second turn point in O2 pulse-workload curve. LTP2 was considered as gold standard assessment of AnT and was applied to confirm the validity of O2 pulse-AnT. Intraclass correlation coefficients and the Bland-Altman method were used to determine the relationship and agreement between the O2 corresponding to LTP2 and O2 pulse-AnT, respectively. The active men and 68.7% of the endurance cyclists showed HRDP, whereas all subjects showed O2 pulse-AnT during incremental testing. In both groups, the values for V[Combining Dot Above]O2 corresponding to LTP2 were not significantly different from the V[Combining Dot Above]O2 at O2 pulse-AnT. The V[Combining Dot Above]O2 at LTP2 and O2 pulse-AnT were highly correlated (endurance cyclists: R = 0.68; standard error of estimate [SEE] = 3.74 ml·kg·min and active men: R = 0.58; SEE = 2.91 ml·kg·min) and Bland-Altman plot revealed the limit of agreement of O2 at LTP2 and O2 pulse-AnT differences between 5.1 and 8.6 ml·kg·min (95% CI). In summary, results of this study showed that the second turn point in the O2 pulse-workload curve occurs around LTP2. Therefore, using O2 pulse-AnT is recommended for the noninvasive determination of AnT in highly trained endurance cyclists who do not show HRDP during incremental exercise.

  18. Determination of the aggregation number of detergent micelles using steady-state fluorescence quenching.

    PubMed Central

    Tummino, P J; Gafni, A

    1993-01-01

    The development of a simple, reliable method for determination of detergent micelle aggregation number that relies solely on measurement of steady-state fluorescence quenching is presented. The degree of steady-state fluorescence quenching of a micelle-solubilized fluorophore (pyrene) by a quencher that partitions greatly into the micelles (coumarin 153) is dependent on the micelle concentration, which can therefore be determined. The aggregation number is calculated as the micelle concentration/detergent monomer concentration (the total detergent concentration above the critical micelle concentration). For the determination to be accurate, the partition coefficient of the quencher into the micelle phase is determined and used to calculate the micellar concentration of quencher. Also, the quenching of pyrene by a coumarin 153 molecule within the same micelle must be complete, and this was confirmed by time-resolved fluorescence measurements. Aggregation numbers were determined for one cationic and several nonionic detergents and were found to be consistent with literature values. The approach presented is an improvement on a previous luminescence quenching technique (Turro, N.J., and A. Yekta. 1978. J. Am. Chem. Soc. 100:5951-5952) and can be used on cationic, anionic, and nonionic detergents with micelles ranging greatly in size and under varying conditions, such as detergent concentration, ionic strength, or temperature. PMID:8324192

  19. Modelling of slaughterhouse solid waste anaerobic digestion: determination of parameters and continuous reactor simulation.

    PubMed

    López, Iván; Borzacconi, Liliana

    2010-10-01

    A model based on the work of Angelidaki et al. (1993) was applied to simulate the anaerobic biodegradation of ruminal contents. In this study, two fractions of solids with different biodegradation rates were considered. A first-order kinetic was used for the easily biodegradable fraction and a kinetic expression that is function of the extracellular enzyme concentration was used for the slowly biodegradable fraction. Batch experiments were performed to obtain an accumulated methane curve that was then used to obtain the model parameters. For this determination, a methodology derived from the "multiple-shooting" method was successfully used. Monte Carlo simulations allowed a confidence range to be obtained for each parameter. Simulations of a continuous reactor were performed using the optimal set of model parameters. The final steady-states were determined as functions of the operational conditions (solids load and residence time). The simulations showed that methane flow peaked at a flow rate of 0.5-0.8 Nm(3)/d/m(reactor)(3) at a residence time of 10-20 days. Simulations allow the adequate selection of operating conditions of a continuous reactor.

  20. Electromyographic response to exercise in cardiac transplant patients: a new method for anaerobic threshold determination?

    PubMed

    Lucía, A; Vaquero, A F; Pérez, M; Sánchez, O; Sánchez, V; Gómez, M A; Chicharro, J L

    1997-06-01

    The purpose of this study was to investigate the possible use of integrated surface electromyography (iEMG) in cardiac transplant patients (CTPs) as a new noninvasive determinant of the metabolic response to exercise by studying the relationship between the iEMG threshold (iEMGT) and other more conventional methods for anaerobic threshold (AT) determination, such as the lactate threshold (LT) and the ventilatory threshold (VT). Thirteen patients (age: 57+/-7 years, mean+/-SD; height: 163+/-7 cm; body mass: 70.5+/-8.6 kg; posttransplant time: 87+/-49 weeks) were selected as subjects. Each of them performed a ramp protocol on a cycle ergometer (starting at 0 W, the workload was increased in 10 W/min). During the tests, gas exchange data, blood lactate levels, and iEMG of the vastus lateralis were collected to determine VT, LT, and iEMGT, respectively. The results evidenced no significant difference between mean values of VT, LT, or iEMGT, when expressed either as oxygen uptake (11.1+/-2.4, 11.7+/-2.3, and 11.0+/-2.8 mL/kg/min, respectively) or as percent maximum oxygen uptake (61.6+/-7.5, 62.2+/-7.7, and 59.6+/-8.2%, respectively). In conclusion, our findings suggest that iEMG might be used as a complementary, noninvasive method for AT determination in CTPs. In addition, since the aerobic impairment of these patients is largely due to peripheral limitation, determination of iEMGT could be used to assess the effectiveness of an exercise rehabilitation program to improve muscle aerobic capacity in CTPs.

  1. Determining the anaerobic threshold in postpolio syndrome: comparison with current guidelines for training intensity prescription.

    PubMed

    Voorn, Eric L; Gerrits, Karin H; Koopman, Fieke S; Nollet, Frans; Beelen, Anita

    2014-05-01

    To determine whether the anaerobic threshold (AT) can be identified in individuals with postpolio syndrome (PPS) using submaximal incremental exercise testing, and to compare current guidelines for intensity prescription in PPS with the AT. Cohort study. Research laboratory. Individuals with PPS (N=82). Not applicable. Power output, gas exchange variables, heart rate, and rating of perceived exertion (RPE) were measured in an incremental submaximal cycle ergometry test. Two independent observers identified the AT. Comparison of current guidelines for training intensity prescription in PPS (40%-60% heart rate reserve [HRR] or RPE of 12) with the AT was based on correlations between recommended heart rate and the heart rate at the AT. In addition, we determined the proportion of individuals that would have been recommended to train at an intensity corresponding to their AT. The AT was identified in 63 (77%) of the participants. Pearson correlation coefficients between the recommended heart rate and the heart rate at the AT were lower in cases of 40% HRR (r=.56) and 60% HRR (r=.50) than in cases of prescription based on the RPE (r=.86). Based on the RPE, 55% of the individuals would have been recommended to train at an intensity corresponding to their AT. This proportion was higher compared with 40% HRR (41%) or 60% HRR (18%) as criterion. The AT can be identified in most individuals with PPS offering an individualized target for aerobic training. If the AT cannot be identified (eg, because gas analysis equipment is not available), intensity prescription can best be based on the RPE. Copyright © 2014 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

  2. Anaerobic fermentation of glycerol in Paenibacillus macerans: metabolic pathways and environmental determinants.

    PubMed

    Gupta, Ashutosh; Murarka, Abhishek; Campbell, Paul; Gonzalez, Ramon

    2009-09-01

    Paenibacillus macerans is one of the species with the broadest metabolic capabilities in the genus Paenibacillus, able to ferment hexoses, deoxyhexoses, pentoses, cellulose, and hemicellulose. However, little is known about glycerol metabolism in this organism, and some studies have reported that glycerol is not fermented. Despite these reports, we found that several P. macerans strains are capable of anaerobic fermentation of glycerol. One of these strains, P. macerans N234A, grew fermentatively on glycerol at a maximum specific growth rate of 0.40 h(-1) and was chosen for further characterization. The use of [U-13C]glycerol and further analysis of extracellular metabolites and proteinogenic amino acids via nuclear magnetic resonance (NMR) spectroscopy allowed identification of ethanol, formate, acetate, succinate, and 1,2-propanediol (1,2-PDO) as fermentation products and demonstrated that glycerol is incorporated into cellular components. A medium formulation with low concentrations of potassium and phosphate, cultivation at acidic pH, and the use of a CO2-enriched atmosphere stimulated glycerol fermentation and are proposed to be environmental determinants of this process. The pathways involved in glycerol utilization and synthesis of fermentation products were identified using NMR spectroscopy in combination with enzyme assays. Based on these studies, the synthesis of ethanol and 1,2-PDO is proposed to be a metabolic determinant of glycerol fermentation in P. macerans N234A. Conversion of glycerol to ethanol fulfills energy requirements by generating one molecule of ATP per molecule of ethanol synthesized. Conversion of glycerol to 1,2-PDO results in the consumption of reducing equivalents, thus facilitating redox balance. Given the availability, low price, and high degree of reduction of glycerol, the high metabolic rates exhibited by P. macerans N234A are of paramount importance for the production of fuels and chemicals.

  3. Determination of greenhouse gas emission reductions from sewage sludge anaerobic digestion in China.

    PubMed

    Liu, H-T; Kong, X-J; Zheng, G-D; Chen, C-C

    2016-01-01

    Sewage sludge is a considerable source of greenhouse gas (GHG) emission in the field of organic solid waste treatment and disposal. In this case study, total GHG emissions from sludge anaerobic digestion, including direct and indirect emissions as well as replaceable emission reduction due to biogas being reused instead of natural gas, were quantified respectively. The results indicated that no GHG generation needed to be considered during the anaerobic digestion process. Indirect emissions were mainly from electricity and fossil fuel consumption on-site and sludge transportation. Overall, the total GHG emission owing to relative subtraction from anaerobic digestion rather than landfill, and replaceable GHG reduction caused by reuse of its product of biogas, were quantified to be 0.7214 (northern China) or 0.7384 (southern China) MgCO2 MgWS(-1) (wet sludge).

  4. Rate determination of supercritical water gasification of primary sewage sludge as a replacement for anaerobic digestion.

    PubMed

    Wilkinson, Nikolas; Wickramathilaka, Malithi; Hendry, Doug; Miller, Andrew; Espanani, Reza; Jacoby, William

    2012-11-01

    Supercritical water gasification of primary sewage sludge sampled from a local facility was undertaken at different solids content. The performance of the process was compared with the anaerobic digestion system in use at the facility where the samples were taken. The mass and composition of the vapor products documented showed that the process generates more energy per gram of feed while rapidly destroying more volatile solids relative to the anaerobic digestion process. However, the energy input requirements are greater for supercritical water gasification. This study defines parameters for a model of the gasification reaction using the power law and Arrhenius equation. The activation energy was estimated to be 15 kJ/mol, and the reaction order was estimated to be 0.586. This model allows estimation of the size of a supercritical water reactor needed to replace the anaerobic digesters that are currently used at the wastewater treatment plant.

  5. A macro-driven Excel template for determining the anaerobic capacity using an air-braked ergometer.

    PubMed

    Finn, J P; Sainsbury, D A; Withers, R T

    1996-08-01

    This paper describes a microcomputer system for automating the process of data collection, calculation and display of anaerobic capacity tests on an air-braked ergometer. The use of the spreadsheet Excel and associated 'Dalog' program represents an advance on current software which estimates the anaerobic capacity from work performed alone. Numerous calculations are required when air-braked, rather than friction-braked erogometers are used. Each 1 s power output collected during an all-out sprint on the ergometer is corrected against the criterion of a dynamic calibration rig and adjusted for differences in barometric pressure, ambient temperature and humidity. The Excel template features a series of macros invoked by buttons imbedded in the spreadsheet. Their selection displays various dialogue boxes which request input related to the calculation of oxygen deficit and related variables. Selecting the final macro prints a summary table and charts which include: power output, fatigue index, mechanical work performed, % aerobic contribution to work, oxygen demand, oxygen consumption and anaerobic capacity as determined by the maximal accumulated oxygen deficit.

  6. Diversity of anaerobic fungi within cow manure determined by ITS1 analysis.

    PubMed

    Fliegerová, K; Mrázek, J; Hoffmann, K; Zábranská, J; Voigt, K

    2010-07-01

    The diversity of anaerobic fungi was evaluated in cow semiliquid manure obtained from input homogenizing tank of biogas plant. Among three sets of tested primers, the combination of fungal universal ITS1F and Neocallimastigales specific Neo QPCR Rev primers was selected and used for the construction of clone library. Eighty-four new complete internal transcribed spacers (ITS1) and partial 5.8S rDNA sequences generated within this study were analyzed by Bayesian inference and assigned to an existing order of the Neocallimastigales. Sixty-seven% of sequences were affiliated with Cyllamyces, 24% with Piromyces, 7% with Anaeromyces, only 2% with Neocallimastix, and no sequences with Orpinomyces. According to Bayesian analysis the genus Caecomyces was polyphyletic and disappeared from the presented ITSbased phylogram. This study gave a first insight into the diversity of anaerobic fungi in cow manure, where the prevalence of fungi with bulbous morphology was indicated.

  7. Aerobic and anaerobic determinants of repeated sprint ability in team sports athletes.

    PubMed

    Gharbi, Z; Dardouri, W; Haj-Sassi, R; Chamari, K; Souissi, N

    2015-09-01

    The aim of this study was to examine in team sports athletes the relationship between repeated sprint ability (RSA) indices and both aerobic and anaerobic fitness components. Sixteen team-sport players were included (age, 23.4 ± 2.3 years; weight, 71.2 ± 8.3 kg; height, 178 ± 7 cm; body mass index, 22.4 ± 2 kg · m(-2); estimated VO2max, 54.16 ± 3.5 mL · kg(-1) · min(-1)). Subjects were licensed in various team sports: soccer (n = 8), basketball (n = 5), and handball (n = 3). They performed 4 tests: the 20 m multi-stage shuttle run test (MSRT), the 30-s Wingate test (WingT), the Maximal Anaerobic Shuttle Running Test (MASRT), and the RSA test (10 repetitions of 30 m shuttle sprints (15 + 15 m with 180° change of direction) with 30 s passive recovery in between). Pearson's product moment of correlation among the different physical tests was performed. No significant correlations were found between any RSA test indices and WingT. However, negative correlations were found between MASRT and RSA total sprint time (TT) and fatigue index (FI) (r = -0.53, p < 0.05 and r = -0.65, p < 0.01, respectively). No significant relationship between VO2max and RSA peak sprint time (PT) and total sprint time (TT) was found. Nevertheless, VO2max was significantly correlated with the RSA FI (r = -0.57, p < 0.05). In conclusion, aerobic fitness is an important factor influencing the ability to resist fatigue during RSA exercise. Our results highlighted the usefulness of MASRT, in contrast to WingT, as a specific anaerobic testing procedure to identify the anaerobic energy system contribution during RSA.

  8. Aerobic and anaerobic determinants of repeated sprint ability in team sports athletes

    PubMed Central

    Dardouri, W; Haj-Sassi, R; Chamari, K; Souissi, N

    2015-01-01

    The aim of this study was to examine in team sports athletes the relationship between repeated sprint ability (RSA) indices and both aerobic and anaerobic fitness components. Sixteen team-sport players were included (age, 23.4 ± 2.3 years; weight, 71.2 ± 8.3 kg; height, 178 ± 7 cm; body mass index, 22.4 ± 2 kg · m−2; estimated VO2max, 54.16 ± 3.5 mL · kg−1 · min−1). Subjects were licensed in various team sports: soccer (n = 8), basketball (n = 5), and handball (n = 3). They performed 4 tests: the 20 m multi-stage shuttle run test (MSRT), the 30-s Wingate test (WingT), the Maximal Anaerobic Shuttle Running Test (MASRT), and the RSA test (10 repetitions of 30 m shuttle sprints (15 + 15 m with 180° change of direction) with 30 s passive recovery in between). Pearson's product moment of correlation among the different physical tests was performed. No significant correlations were found between any RSA test indices and WingT. However, negative correlations were found between MASRT and RSA total sprint time (TT) and fatigue index (FI) (r = -0.53, p < 0.05 and r = -0.65, p < 0.01, respectively). No significant relationship between VO2max and RSA peak sprint time (PT) and total sprint time (TT) was found. Nevertheless, VO2max was significantly correlated with the RSA FI (r = -0.57, p < 0.05). In conclusion, aerobic fitness is an important factor influencing the ability to resist fatigue during RSA exercise. Our results highlighted the usefulness of MASRT, in contrast to WingT, as a specific anaerobic testing procedure to identify the anaerobic energy system contribution during RSA. PMID:26424923

  9. Continuous determination of volatile products in anaerobic fermenters by on-line capillary gas chromatography.

    PubMed

    Diamantis, V; Melidis, P; Aivasidis, A

    2006-07-28

    Bio-ethanol and biogas produced during the anaerobic conversion of organic compounds has been a subject of great interest since the oil crisis of the 1970s. In ethanol fermentation and anaerobic treatment of wastewaters, end-product (ethanol) and intermediate-products (short-chain fatty acids, SCFA) cause inhibition that results in reduced process efficiency. Control of these constituents is of utmost importance for bioreactor optimization and process stability. Ethanol and SCFA can be detected with precision by capillary gas chromatography usually conducted in off-line measurements. In this work, an on-line monitoring and controlling system was developed and connected to the fermenter via an auto-sampling equipment, which could perform the feeding, filtration and dilution of the sample and final injection into the gas chromatograph through an automation-based programmed procedure. The sample was continuously pumped from the recycle stream of the bioreactor and treated using a microfiltration unit. The concentrate was returned to the reactor while the permeate was quantitatively mixed with an internal standard solution. The system comprised of a gas chromatograph with the flow cell and one-shot sampler and a PC with the appropriate software. The on-line measurement of ethanol and SCFA, directly from the liquid phase of an ethanol fermenter and a high-rate continuous mode anaerobic digester, was accomplished by gas chromatography. Also, this monitoring and controlling system was proved to be effective in the continuous fermentation of alcohol-free beer.

  10. Fractal dimensions of soy protein nanoparticle aggregates determined by dynamic mechanical method

    USDA-ARS?s Scientific Manuscript database

    The fractal dimension of the protein aggregates can be estimated by dynamic mechanical methods when the particle aggregates are imbedded in a polymer matrix. Nanocomposites were formed by mixing hydrolyzed soy protein isolate (HSPI) nanoparticle aggregates with styrene-butadiene (SB) latex, followe...

  11. Distinct β-sheet structure in protein aggregates determined by ATR-FTIR spectroscopy.

    PubMed

    Shivu, Bhavana; Seshadri, Sangita; Li, Jie; Oberg, Keith A; Uversky, Vladimir N; Fink, Anthony L

    2013-08-06

    Attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) was used to study the conformation of aggregated proteins in vivo and in vitro. Several different protein aggregates, including amyloid fibrils from several peptides and polypeptides, inclusion bodies, folding aggregates, soluble oligomers, and protein extracts from stressed cells, were examined in this study. All protein aggregates demonstrate a characteristic new β structure with lower-frequency band positions. All protein aggregates acquire this new β band following the aggregation process involving intermolecular interactions. The β sheets in some proteins arise from regions of the polypeptide that are helical or non β in the native conformation. For a given protein, all types of the aggregates (e.g., inclusion bodies, folding aggregates, and thermal aggregates) showed similar spectra, indicating that they arose from a common partially folded species. All of the aggregates have some nativelike secondary structure and nonperiodic structure as well as the specific new β structure. The new β could be most likely attributed to stronger hydrogen bonds in the intermolecular β-sheet structure present in the protein aggregates.

  12. Determination of anionic surface active agents using silica coated magnetite nanoparticles modified with cationic surfactant aggregates.

    PubMed

    Pena-Pereira, Francisco; Duarte, Regina M B O; Trindade, Tito; Duarte, Armando C

    2013-07-19

    The development of a novel methodology for extraction and preconcentration of the most commonly used anionic surface active agents (SAAs), linear alkylbenzene sulfonates (LAS), is presented herein. The present method, based on the use of silica-magnetite nanoparticles modified with cationic surfactant aggregates, was developed for determination of C10-C13 LAS homologues. The proposed methodology allowed quantitative recoveries of C10-C13 LAS homologues by using a reduced amount of magnetic nanoparticles. Limits of detection were in the range 0.8-1.9μgL(-1) for C10-C13 LAS homologues, while the repeatability, expressed as relative standard deviation (RSD), ranged from 2.0 to 3.9% (N=6). Finally, the proposed method was successfully applied to the analysis of a variety of natural water samples. Copyright © 2013 Elsevier B.V. All rights reserved.

  13. Structural insights into the multi-determinant aggregation of TDP-43 in motor neuron-like cells.

    PubMed

    Bozzo, F; Salvatori, I; Iacovelli, F; Mirra, A; Rossi, S; Cozzolino, M; Falconi, M; Valle, C; Carrì, M T

    2016-10-01

    TDP-43 is aggregated in patients with ALS and FLTD through mechanisms still incompletely understood. Since aggregation in the cytosol is most probably responsible for the delocalization and loss of proper RNA-binding function of TDP-43 in the nucleus, interception of the formation of aggregates may represent a useful therapeutic option. In this study, we investigated the relative importance of the N-terminal and C-terminal moieties of TDP-43 in the aggregation process and the weight of each of the six cysteine residues in determining unfolding and aggregation of the different domains. We report that cytoplasmic inclusions formed by WT and mutant TDP-43 in motor neuron-like NSC34 cells are redox-sensitive only in part, and contain at least two components, i.e. oligomers and large aggregates, that are made of different molecular species. The two N-terminal cysteine residues contribute to the seeding for the first step in oligomerization, which is then accomplished by mechanisms depending on the four cysteines in the RNA-recognition motifs. Cysteine-independent large aggregates contain unfolded isoforms of the protein, held together by unspecific hydrophobic interactions. Interestingly, truncated isoforms are entrapped exclusively in oligomers. Ab initio modeling of TDP-43 structure, molecular dynamics and molecular docking analysis indicate a differential accessibility of cysteine residues that contributes to aggregation propensity. We propose a model of TDP-43 aggregation involving cysteine-dependent and cysteine-independent stages that may constitute a starting point to devise strategies counteracting the formation of inclusions in TDP-43 proteinopathies. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. The Use of Multiple Regression Models to Determine if Conjoint Analysis Should Be Conducted on Aggregate Data.

    ERIC Educational Resources Information Center

    Fraas, John W.; Newman, Isadore

    1996-01-01

    In a conjoint-analysis consumer-preference study, researchers must determine whether the product factor estimates, which measure consumer preferences, should be calculated and interpreted for each respondent or collectively. Multiple regression models can determine whether to aggregate data by examining factor-respondent interaction effects. This…

  15. Anaerobic threshold, is it a magic number to determine fitness for surgery?

    PubMed Central

    2013-01-01

    The use of cardiopulmonary exercise testing (CPET) to evaluate cardiac and respiratory function was pioneered as part of preoperative assessment in the mid 1990s. Surgical procedures have changed since then. The patient population may have aged; however, the physiology has remained the same. The use of an accurate physiological evaluation remains as germane today as it was then. Certainly no ‘magic’ is involved. The author recognizes that not everyone accepts the classical theories of the anaerobic threshold (AT) and that there is some discussion around lactate and exercise. The article looks at aerobic capacity as an important predictor of perioperative mortality and also looks at some aspects of CPET relative to surgical risk evaluation. PMID:24472514

  16. Model demonstrating the potential for coupled nitrification denitrification in soil aggregates.

    PubMed

    Kremen, Arie; Bear, Jacob; Shavit, Uri; Shaviv, Avi

    2005-06-01

    A model of reactive, multi-species diffusion has been developed to describe N transformations in spherical soil aggregates, emphasizing the effects of irrigation with reclaimed wastewater. Oxygen demand for respiratory activity has been shown to promote the establishment of anaerobic conditions. Aggregate size and soil respiration rate were identified as the most significant parameters governing the existence and extent of the anaerobic volume in aggregates. The inclusion of kinetic models describing mineralization, nitrification, and denitrification facilitated the investigation of coupled nitrification/denitrification (CND), subject to O2 availability. N-transformations are shown to be affected by effluent-borne NH4+-N content, in addition to elevated BOD and pH levels. Their incremental contribution to O2 availability has been found to be secondary to respiratory activity. At the aggregate level, significant differences between apparent and gross rates of N-transformations were predicted (e.g., NH4+ oxidation and N2 formation), resulting from diffusive constraints due to aggregate size. With increasing anaerobic volume, the effective nitrification rate determined at the aggregates level decreases until its contribution to nitrification is negligible. It was found that the nitrification process was predominantly limited to aggregates <0.25 cm. Assuming that nitrification is the main source for NO3- formation, denitrification efficiency is predicted to peak in medium-sized aggregates, where aerobic and anaerobic conditions coexist, supporting CND. In effluent-irrigated soils, the predicted NO2- formation rate in small aggregates is enhanced when compared to freshwater-irrigated soils. The difference vanishes with increasing aggregate size as anaerobic NO2- consumption exceeds aerobic NO2- formation due to the coupling of nitrification and denitrification.

  17. A simple procedure to determine the infectivity and host range of viruses infecting anaerobic and hyperthermophilic microorganisms.

    PubMed

    Gorlas, Aurore; Geslin, Claire

    2013-03-01

    Plaque assay is the method traditionally used to isolate and purify lytic viruses, to determine the viral titer and host range. Whereas most bacterioviruses are either temperate or lytic, the majority of known archeoviruses are not lytic (i.e. they are temperate or chronic). In view of the widespread occurrence of such viruses in extreme environments, we designed an original method, called the inverted spot test, to determine the host range and infectivity of viruses isolated from anaerobic hyperthermophilic and sulfur-reducing microorganisms. Here, we used this approach to prove for the first time the infectivity of Pyrococcus abyssi virus 1 (PAV1) and to confirm the host range of Thermococcus prieurii virus 1 (TPV1), the only two viruses isolated so far from any of the described marine hyperthermophilic archaea (Euryarchaeota phylum, Thermococcales order).

  18. Conformation Determines the Seeding Potencies of Native and Recombinant Tau Aggregates

    PubMed Central

    Falcon, Benjamin; Cavallini, Annalisa; Angers, Rachel; Glover, Sarah; Murray, Tracey K.; Barnham, Luanda; Jackson, Samuel; O'Neill, Michael J.; Isaacs, Adrian M.; Hutton, Michael L.; Szekeres, Philip G.; Goedert, Michel; Bose, Suchira

    2015-01-01

    Intracellular Tau inclusions are a pathological hallmark of several neurodegenerative diseases, collectively known as the tauopathies. They include Alzheimer disease, tangle-only dementia, Pick disease, argyrophilic grain disease, chronic traumatic encephalopathy, progressive supranuclear palsy, and corticobasal degeneration. Tau pathology appears to spread through intercellular propagation, requiring the formation of assembled “prion-like” species. Several cell and animal models have been described that recapitulate aspects of this phenomenon. However, the molecular characteristics of seed-competent Tau remain unclear. Here, we have used a cell model to understand the relationships between Tau structure/phosphorylation and seeding by aggregated Tau species from the brains of mice transgenic for human mutant P301S Tau and full-length aggregated recombinant P301S Tau. Deletion of motifs 275VQIINK280 and 306VQIVYK311 abolished the seeding activity of recombinant full-length Tau, suggesting that its aggregation was necessary for seeding. We describe conformational differences between native and synthetic Tau aggregates that may account for the higher seeding activity of native assembled Tau. When added to aggregated Tau seeds from the brains of mice transgenic for P301S Tau, soluble recombinant Tau aggregated and acquired the molecular properties of aggregated Tau from transgenic mouse brain. We show that seeding is conferred by aggregated Tau that enters cells through macropinocytosis and seeds the assembly of endogenous Tau into filaments. PMID:25406315

  19. Application of the Hough transform for the automatic determination of soot aggregate morphology.

    PubMed

    Grishin, Igor; Thomson, Kevin; Migliorini, Francesca; Sloan, James J

    2012-02-10

    We report a new method for automated identification and measurement of primary particles within soot aggregates as well as the sizes of the aggregates and discuss its application to high-resolution transmission electron microscope (TEM) images of the aggregates. The image processing algorithm is based on an optimized Hough transform, applied to the external border of the aggregate. This achieves a significant data reduction by decomposing the particle border into fragments, which are assumed to be spheres in the present application, consistent with the known morphology of soot aggregates. Unlike traditional techniques, which are ultimately reliant on manual (human) measurement of a small sample of primary particles from a subset of aggregates, this method gives a direct measurement of the sizes of the aggregates and the size distributions of the primary particles of which they are composed. The current version of the algorithm allows processing of high-resolution TEM images by a conventional laptop computer at a rate of 1-2 ms per aggregate. The results were validated by comparison with manual image processing, and excellent agreement was found.

  20. Protein aggregation propensity is a crucial determinant of intracellular inclusion formation and quality control degradation.

    PubMed

    Villar-Piqué, Anna; Ventura, Salvador

    2013-12-01

    Protein aggregation is linked to many pathological conditions, including several neurodegenerative diseases. The aggregation propensities of proteins are thought to be controlled to a large extent by the physicochemical properties encoded in the primary sequence. We have previously exploited a set of amyloid β peptide (Aβ42) variants exhibiting a continuous gradient of intrinsic aggregation propensities to demonstrate that this rule applies in vivo in bacteria. In the present work we have characterized the behavior of these Aβ42 mutants when expressed in yeast. In contrast to bacteria, the intrinsic aggregation propensity is gated by yeast, in such a way that this property correlates with the formation of intracellular inclusions only above a specific aggregation threshold. Proteins displaying solubility levels above this threshold escape the inclusion formation pathway. In addition, the most aggregation-prone variants are selectively cleared by the yeast quality control degradation machinery. Thus, both inclusion formation and proteolysis target the same aggregation-prone variants and cooperate to minimize the presence of these potentially dangerous species in the cytosol. The demonstration that sorting to these pathways in eukaryotes is strongly influenced by protein primary sequence should facilitate the development of rational approaches to predict and hopefully prevent in vivo protein deposition. © 2013.

  1. The optical properties of tropospheric soot aggregates determined with the DDA (Discrete Dipole Approximation) method

    NASA Astrophysics Data System (ADS)

    Skorupski, Krzysztof

    2015-06-01

    Black carbon particles soon after emission interact with organic and inorganic matter. The primary goal of this work was to approximate the accuracy of the DDA method in determining the optical properties of such composites. For the light scattering simulations the ADDA code was selected and the superposition T-Matrix code by Mackowski was used as the reference algorithm. The first part of the study was to compare alternative models of a single primary particle. When only one material is considered the largest averaged relative extinction error is associated with black carbon (δCext ≍ 2.8%). However, for inorganic and organic matter it is lowered to δCext ≍ 0.75%. There is no significant difference between spheres and ellipsoids with the same volume, and therefore, both of them can be used interchangeably. The next step was to investigate aggregates composed of Np = 50 primary particles. When the coating is omitted, the averaged relative extinction error is δCext ≍ 2.6%. Otherwise, it can be lower than δCext < 0.2%.

  2. Anaerobic bacteria

    MedlinePlus

    Anaerobic bacteria are bacteria that do not live or grow when oxygen is present. In humans, these bacteria ... Goldstein EJ. Diseases caused by non-spore forming anaerobic bacteria. In: Goldman L, Schafer AI, eds. Goldman's Cecil ...

  3. Anaerobic monodigestion of poultry manure: determination of operational parameters for CSTR.

    PubMed

    Chamy, R; León, C; Vivanco, E; Poirrier, P; Ramos, C

    2012-01-01

    In this work the anaerobic monodigestion for the treatment of turkey manure was evaluated, without its codigestion with another substrate. The effect of the organic loading rate (OLR) and the substrate concentration (high total solids (TS) concentration) or product concentration (high volatile fatty acids (VFA) and/or ammonia (NH(3)-N) concentrations) was studied. The results show that for a continuous stirred tank reactor (CSTR) operation, a maximum of 40 g/L of TS and 4.0 g/L of ammonium (NH(4)(+)) was required. In addition, the maximum organic loading rate (OLR) will not exceed 1.5 kg VS/m(3)d. Higher TS and NH(4)(+) concentrations and OLR lead to a reduction on the methane productivity and volatile solids (VS) removal. During the CSTR operation, a high alkalinity concentration (above 10 g/L CaCO(3)) was found; this situation allowed maintaining a constant and appropriate pH (close to 7.8), despite the VFA accumulation. In this sense, the alkalinity ratio (α) is a more appropriate control and monitoring parameter of the reactor operation compared to pH. Additionally, with this parameter a VS removal of 80% with a methane productivity of 0.50 m(3)(CH4)/m(3)(R)d is achieved.

  4. Determinant impact of waste collection and composition on anaerobic digestion performance: industrial results.

    PubMed

    Saint-Joly, C; Desbois, S; Lotti, J P

    2000-01-01

    The performance of the anaerobic digestion process depends deeply on the quality of the waste to be treated. This has been already demonstrated at the lab-scale. The objective of this study is to confirm this result at the industrial scale, with very long representative period and with the same process, the Valorga process. According to the waste quality and the collection type and even with the same conditions of fermentation, the biogas yield can vary by a factor of 1.5 when it is expressed (under normal conditions of pressure and temperature) in m3 biogas/t fresh waste, and by a factor of 2 when it is expressed in m3 CH4/t volatile solids. So, the biogas performance does not characterise a process since it is deeply governed by waste composition. This biogas productivity becomes a pertinent parameter only with consistent and relevant hypothesis and/or analytical results on the waste composition which depends on the collection procedure, the site characteristics and the season.

  5. Carbon source--a strong determinant of microbial community structure and performance of an anaerobic reactor.

    PubMed

    Kundu, K; Bergmann, I; Hahnke, S; Klocke, M; Sharma, S; Sreekrishnan, T R

    2013-12-01

    Industrial effluents differ in their organic composition thereby providing different carbon sources to the microbial communities involved in its treatment. This study aimed to investigate the correlation of microbial community structure with wastewater composition and reactor's performance. Self-immobilized granules were developed in simulated wastewater based on different carbon sources (glucose, sugarcane molasses, and milk) in three hybrid anaerobic reactors operated at 37°C. To study archaeal community structure, a polyphasic approach was used with both qualitative and quantitative analysis. While PCR-denaturing gradient gel electrophoresis of 16S rRNA gene did not reveal major shifts in diversity of archaea with change in substrate, quantification of different groups of methanogens and total bacteria by real-time PCR showed variations in relative abundances with the dominance of Methanosaetaceae and Methanobacteriales. These data were supported by differences in the ratio of total counts of archaea and bacteria analyzed by catalyzed reporter deposition - fluorescence in situ hybridization. During hydraulic and organic shocks, the molasses-based reactor showed the best performance followed by the milk- and the glucose-based reactor. The study indicates that carbon source shapes the microbial community structure more in terms of relative abundance with distinct metabolic capacities rather than its diversity itself.

  6. Determination of Coefficient of Thermal Expansion (CTE) of 20MPa Mass Concrete Using Granite Aggregate

    NASA Astrophysics Data System (ADS)

    Chee Siang, GO

    2017-07-01

    Experimental test was carried out to determine the coefficient of thermal expansion (CTE) value of 20MPa mass concrete using granite aggregate. The CTE value was established using procedure proposed by Kada et al. 2002 in determining the magnitude of early-ages CTE through laboratory test which is a rather accurate way by eliminating any possible superimposed effect of others early-age thermal deformation shrinkages such as autogenous, carbonation, plastic and drying shrinkage. This was done by submitting granite concrete block samples instrumented with ST4 vibrating wire extensometers to thermal shocks. The response of the concrete samples to this shock results in a nearly instantaneous deformation, which are measured by the sensor. These deformations, as well as the temperature signal, are used to calculate the CTE. By repeating heat cycles, the variation in the early-ages of concrete CTE over time was monitored and assessed for a period of upto 7 days. The developed CTE value facilitating the verification and validation of actual maximum permissible critical temperature differential limit (rather than arbitrarily follow published value) of cracking potential. For thick sections, internal restraint is dominant and this is governed by differentials mainly. Of the required physical properties for thermal modelling, CTE is of paramount importance that with given appropriate internal restraint factor the condition of cracking due to internal restraint is governs by equation, ΔTmax= 3.663ɛctu / αc. Thus, it can be appreciated that an increase in CTE will lower the maximum allowable differential for cracking avoidance in mass concrete while an increase of tensile strain capacity will increase the maximum allowable temperature differential.

  7. Aggregates and their distributions determined from LOPC observations made using an autonomous profiling float

    NASA Astrophysics Data System (ADS)

    Petrik, Colleen M.; Jackson, George A.; Checkley, David M., Jr.

    2013-04-01

    The vertical flux of particles in the ocean drives the movement of organic carbon to the deep ocean. We have been studying the distribution and flux of these particles using the SOLOPC, a profiling Lagrangian (SOLO) float with a Laser Optical Particle Counter (LOPC). We have been able to distinguish between aggregate-like and zooplankton-like particles with diameters >2mm but needed a way to separate the smaller particles into aggregates and zooplankton. Observations included a lognormal-shaped fraction in the normalized volume distribution similar to that observed in results for simulations of particles in the euphotic zone. By fitting a lognormal distribution to the volume spectrum of particles with diameters ≤2mm, we have been successful at making a separation of marine snow material from other, presumably living, particles. The particle volumes derived using the separations are positively correlated with fluorescence, particulate organic carbon, and the volume of larger particles classified as aggregate-like, which supports the conclusion that these particles are truly aggregates, in some cases derived from phytoplankton. The residual volumes (total less the above fit) are highly correlated with the volumes of large, zooplankton-like particles. Downward velocities of the aggregate fraction calculated from time series of particle profiles are consistent with previous estimates of particle settling rates (20-70md-1). We now have a tool to estimate aggregate distributions, properties, and vertical fluxes in the euphotic zone, including when and where they change.

  8. Physicochemical properties that control protein aggregation also determine whether a protein is retained or released from necrotic cells

    PubMed Central

    Ho, Bosco; Au, Amanda E.; Schoenwaelder, Simone M.; Smyth, Mark J.; Bottomley, Stephen P.; Kleifeld, Oded; Medcalf, Robert L.

    2016-01-01

    Amyloidogenic protein aggregation impairs cell function and is a hallmark of many chronic degenerative disorders. Protein aggregation is also a major event during acute injury; however, unlike amyloidogenesis, the process of injury-induced protein aggregation remains largely undefined. To provide this insight, we profiled the insoluble proteome of several cell types after acute injury. These experiments show that the disulfide-driven process of nucleocytoplasmic coagulation (NCC) is the main form of injury-induced protein aggregation. NCC is mechanistically distinct from amyloidogenesis, but still broadly impairs cell function by promoting the aggregation of hundreds of abundant and essential intracellular proteins. A small proportion of the intracellular proteome resists NCC and is instead released from necrotic cells. Notably, the physicochemical properties of NCC-resistant proteins are contrary to those of NCC-sensitive proteins. These observations challenge the dogma that liberation of constituents during necrosis is anarchic. Rather, inherent physicochemical features including cysteine content, hydrophobicity and intrinsic disorder determine whether a protein is released from necrotic cells. Furthermore, as half of the identified NCC-resistant proteins are known autoantigens, we propose that physicochemical properties that control NCC also affect immune tolerance and other host responses important for the restoration of homeostasis after necrotic injury. PMID:27810968

  9. Simultaneous determination of protein aggregation, degradation, and absolute molecular weight by size exclusion chromatography-multiangle laser light scattering.

    PubMed

    Ye, Hongping

    2006-09-01

    The feasibility of size exclusion chromotography (SEC)-multiangle laser-light scattering as a technique to investigate aggregation and degradation of glycosylated and nonglycosylated proteins, and antibodies under various conditions such as addition of detergent, changes in pH, and variation of protein concentration and heat stress temperature was examined. Separation of proteins and their aggregates was performed using SEC-high-performance liquid chromatography. Detection of analytes was carried out with on-line UV, refractive index, and multiangle laser light-scattering detectors. Quantification and molecular weight determination were performed using commercial software. Aggregation and degradation were examined under various conditions and quantitative results are presented for bovine serum albumin, choriogonadotropin, glyceraldehyde-3-phosphate dehydrogenase, Herceptin, and ReoPro. This method can simultaneously determine both the quantities and the molecular weights of macromolecules from a single injection. The determination of molecular weight is absolute which avoids misleading results caused by molecular shape or interactions with the column matrix. This technique is valuable not only for assessing the extent of aggregation but also for effectively monitoring molecule degradation as evidenced by molecular weight reduction and change in monomer amount.

  10. Aggregate size and architecture determine microbial activity balance for one-stage partial nitritation and anammox.

    PubMed

    Vlaeminck, Siegfried E; Terada, Akihiko; Smets, Barth F; De Clippeleir, Haydée; Schaubroeck, Thomas; Bolca, Selin; Demeestere, Lien; Mast, Jan; Boon, Nico; Carballa, Marta; Verstraete, Willy

    2010-02-01

    Aerobic ammonium-oxidizing bacteria (AerAOB) and anoxic ammonium-oxidizing bacteria (AnAOB) cooperate in partial nitritation/anammox systems to remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about granulation so far. In this study, three suspended-growth oxygen-limited autotrophic nitrification-denitrification (OLAND) reactors with different inoculation and operation (mixing and aeration) conditions, designated reactors A, B, and C, were used. The test objectives were (i) to quantify the AerAOB and AnAOB abundance and the activity balance for the different aggregate sizes and (ii) to relate aggregate morphology, size distribution, and architecture putatively to the inoculation and operation of the three reactors. A nitrite accumulation rate ratio (NARR) was defined as the net aerobic nitrite production rate divided by the anoxic nitrite consumption rate. The smallest reactor A, B, and C aggregates were nitrite sources (NARR, >1.7). Large reactor A and C aggregates were granules capable of autonomous nitrogen removal (NARR, 0.6 to 1.1) with internal AnAOB zones surrounded by an AerAOB rim. Around 50% of the autotrophic space in these granules consisted of AerAOB- and AnAOB-specific extracellular polymeric substances. Large reactor B aggregates were thin film-like nitrite sinks (NARR, <0.5) in which AnAOB were not shielded by an AerAOB layer. Voids and channels occupied 13 to 17% of the anoxic zone of AnAOB-rich aggregates (reactors B and C). The hypothesized granulation pathways include granule replication by division and budding and are driven by growth and/or decay based on species-specific physiology and by hydrodynamic shear and mixing.

  11. Is heart rate variability a feasible method to determine anaerobic threshold in progressive resistance exercise in coronary artery disease?

    PubMed

    Sperling, Milena P R; Simões, Rodrigo P; Caruso, Flávia C R; Mendes, Renata G; Arena, Ross; Borghi-Silva, Audrey

    2016-01-01

    Recent studies have shown that the magnitude of the metabolic and autonomic responses during progressive resistance exercise (PRE) is associated with the determination of the anaerobic threshold (AT). AT is an important parameter to determine intensity in dynamic exercise. To investigate the metabolic and cardiac autonomic responses during dynamic resistance exercise in patients with Coronary Artery Disease (CAD). Twenty men (age = 63±7 years) with CAD [Left Ventricular Ejection Fraction (LVEF) = 60±10%] underwent a PRE protocol on a leg press until maximal exertion. The protocol began at 10% of One Repetition Maximum Test (1-RM), with subsequent increases of 10% until maximal exhaustion. Heart Rate Variability (HRV) indices from Poincaré plots (SD1, SD2, SD1/SD2) and time domain (rMSSD and RMSM), and blood lactate were determined at rest and during PRE. Significant alterations in HRV and blood lactate were observed starting at 30% of 1-RM (p<0.05). Bland-Altman plots revealed a consistent agreement between blood lactate threshold (LT) and rMSSD threshold (rMSSDT) and between LT and SD1 threshold (SD1T). Relative values of 1-RM in all LT, rMSSDT and SD1T did not differ (29%±5 vs 28%±5 vs 29%±5 Kg, respectively). HRV during PRE could be a feasible noninvasive method of determining AT in CAD patients to plan intensities during cardiac rehabilitation.

  12. Is heart rate variability a feasible method to determine anaerobic threshold in progressive resistance exercise in coronary artery disease?

    PubMed Central

    Sperling, Milena P. R.; Simões, Rodrigo P.; Caruso, Flávia C. R.; Mendes, Renata G.; Arena, Ross; Borghi-Silva, Audrey

    2016-01-01

    ABSTRACT Background Recent studies have shown that the magnitude of the metabolic and autonomic responses during progressive resistance exercise (PRE) is associated with the determination of the anaerobic threshold (AT). AT is an important parameter to determine intensity in dynamic exercise. Objectives To investigate the metabolic and cardiac autonomic responses during dynamic resistance exercise in patients with Coronary Artery Disease (CAD). Method Twenty men (age = 63±7 years) with CAD [Left Ventricular Ejection Fraction (LVEF) = 60±10%] underwent a PRE protocol on a leg press until maximal exertion. The protocol began at 10% of One Repetition Maximum Test (1-RM), with subsequent increases of 10% until maximal exhaustion. Heart Rate Variability (HRV) indices from Poincaré plots (SD1, SD2, SD1/SD2) and time domain (rMSSD and RMSM), and blood lactate were determined at rest and during PRE. Results Significant alterations in HRV and blood lactate were observed starting at 30% of 1-RM (p<0.05). Bland-Altman plots revealed a consistent agreement between blood lactate threshold (LT) and rMSSD threshold (rMSSDT) and between LT and SD1 threshold (SD1T). Relative values of 1-RM in all LT, rMSSDT and SD1T did not differ (29%±5 vs 28%±5 vs 29%±5 Kg, respectively). Conclusion HRV during PRE could be a feasible noninvasive method of determining AT in CAD patients to plan intensities during cardiac rehabilitation. PMID:27556384

  13. Fractal dimensions of soy protein nanoparticle aggregates determined by dynamic mechanical method

    USDA-ARS?s Scientific Manuscript database

    Soy protein isolate (SPI) is obtained from soybeans by removing soybean oil and soy carbohydrates. Soy protein nanoparticles were prepared by alkaline hydrolysis of SPI and centrifugal separation process. Structurally, SPI is a globular protein and its aggregates in water consist of sphere-like pr...

  14. Determination of the molecular parameters and studies of the aggregation behavior of polybenzimidazole in solution.

    NASA Astrophysics Data System (ADS)

    Shogbon, Christopher; Brousseau, Jean-Luc; Zhang, Haifeng

    2005-03-01

    Static light scattering using a seven angle BI-MwA instrument has been used for the first time to obtain the molecular parameters as well as study the aggregation behavior of previously synthesized m-PBI samples in DMAc/LiCl solvent mixtures. Depolarization ratios for the samples were obtained using a BI-200SM goniometer system. Molecular parameters obtained were m-PBI(118) Mw: 179,300 g/mol; Rg: 36.4 nm; A2: 0.0016 cm^3mol/g^2 and m-PBI(159) Mw: 206,500 g/mol; Rg: 46.6 nm; A2: 0.0020 cm^3mol/g^2. The aggregation behavior of m-PBI(159) was studied as a function of salt concentration (0 to 7 %) at a fixed polymer concentration of 0.3 mg/mL. With increasing salt concentration, Rg decreases initially and goes through three maxima with a minimum Rg of 31.0 nm at 4 % LiCl. This result parallels the previously observed aggregation behavior of corn amylase in DMAc/LiCl. Thus our results suggest a general mechanism for the aggregation of semiflexible polymers which can be controlled by varying polymer or salt concentration.

  15. Determination of the stereochemistry of the aggregation pheromone of harlequin bug, Murgantia histrionica

    USDA-ARS?s Scientific Manuscript database

    Preparation of a complete stereoisomeric library of 1,10-bisaboladien-3-ols and selected 10,11-epoxy-1-bisabolen-3-ols was earlier pivotal for the identification of the aggregation pheromone of the brown marmorated stink bug, Halyomorpha halys. Herein, we describe syntheses of remaining10,11-epoxy-1...

  16. Application of real-time PCR to determination of combined effect of antibiotics on Bacteria, Methanogenic Archaea, Archaea in anaerobic sequencing batch reactors.

    PubMed

    Aydin, Sevcan; Ince, Bahar; Ince, Orhan

    2015-06-01

    This study evaluated the long-term effects of erythromycin-tetracycline-sulfamethoxazole (ETS) and sulfamethoxazole-tetracycline (ST) antibiotic combinations on the microbial community and examined the ways in which these antimicrobials impact the performance of anaerobic reactors. Quantitative real-time PCR was used to determine the effect that different antibiotic combinations had on the total and active Bacteria, Archae and Methanogenic Archae. Three primer sets that targeted metabolic genes encoding formylterahydrofolate synthetase, methyl-coenzyme M reductase and acetyl-coA synthetase were also used to determine the inhibition level on the mRNA expression of the homoacetogens, methanogens and specifically acetoclastic methanogens, respectively. These microorganisms play a vital role in the anaerobic degradation of organic waste and targeting these gene expressions offers operators or someone at a treatment plant the potential to control and the improve the anaerobic system. The results of the investigation revealed that acetogens have a competitive advantage over Archaea in the presence of ETS and ST combinations. Although the efficiency with which methane production takes place and the quantification of microbial populations in both the ETS and ST reactors decreased as antibiotic concentrations increased, the ETS batch reactor performed better than the ST batch reactor. According to the expression of genes results, the syntrophic interaction of acetogens and methanogens is critical to the performance of the ETS and ST reactors. Failure to maintain the stability of these microorganisms resulted in a decrease in the performance and stability of the anaerobic reactors.

  17. Anaerobic Infections

    MedlinePlus

    ... doses of antibiotics taken by mouth for months. Bacteroides and Prevotella infections. Bacterial organisms from species called Bacteroides and Prevotella are anaerobic. They are common organisms ...

  18. Determination of the in vivo NAD:NADH ratio in Saccharomyces cerevisiae under anaerobic conditions, using alcohol dehydrogenase as sensor reaction.

    PubMed

    Bekers, K M; Heijnen, J J; van Gulik, W M

    2015-08-01

    With the current quantitative metabolomics techniques, only whole-cell concentrations of NAD and NADH can be quantified. These measurements cannot provide information on the in vivo redox state of the cells, which is determined by the ratio of the free forms only. In this work we quantified free NAD:NADH ratios in yeast under anaerobic conditions, using alcohol dehydrogenase (ADH) and the lumped reaction of glyceraldehyde-3-phosphate dehydrogenase and 3-phosphoglycerate kinase as sensor reactions. We showed that, with an alternative accurate acetaldehyde determination method, based on rapid sampling, instantaneous derivatization with 2,4 diaminophenol hydrazine (DNPH) and quantification with HPLC, the ADH-catalysed oxidation of ethanol to acetaldehyde can be applied as a relatively fast and simple sensor reaction to quantify the free NAD:NADH ratio under anaerobic conditions. We evaluated the applicability of ADH as a sensor reaction in the yeast Saccharomyces cerevisiae, grown in anaerobic glucose-limited chemostats under steady-state and dynamic conditions. The results found in this study showed that the cytosolic redox status (NAD:NADH ratio) of yeast is at least one order of magnitude lower, and is thus much more reduced, under anaerobic conditions compared to aerobic glucose-limited steady-state conditions. The more reduced state of the cytosol under anaerobic conditions has major implications for (central) metabolism. Accurate determination of the free NAD:NADH ratio is therefore of importance for the unravelling of in vivo enzyme kinetics and to judge accurately the thermodynamic reversibility of each redox reaction.

  19. Anaerobic performance at altitude.

    PubMed

    Coudert, J

    1992-10-01

    Anaerobic metabolism is usually evaluated by the determination of the anaerobic capacity and the maximal anaerobic mechanical external power (Wmax). Conflicting results are reported on anaerobic capacity evaluated by maximal oxygen deficit and debt, and maximal blood lactate concentration during acute or chronic hypoxia (acclimatized subjects). Data on muscle biopsies (lactate concentration, changes in ATP, phosphocreatine and glycogen stores, glycolytic enzyme activities) and the few studies on lactate flux give in most cases evidence of a non-alteration of the anaerobic capacity for altitudes up to 5,500 m. No differences are observed in Wmax measured at high altitudes up to 5,200 m during intense short-term exercises: (1) jumps on a force platform which is a good indicator of alactic Wmax, and (2) 7-10 s sprints (i.e. force-velocity test) which solicit alactic metabolism but also lactic pathway. For exercises of duration equal or more than 30 s (i.e. Wingate test), there are conflicting results because a lower participation of aerobic metabolism during this test at high altitude can interfere with anaerobic performance. In conclusion, we can admit that anaerobic performances are not altered by high altitudes up to 5,200 m if the length of exposure does not exceed 5 weeks. After this period, muscle mass begins to decrease.

  20. Substrate Type and Free Ammonia Determine Bacterial Community Structure in Full-Scale Mesophilic Anaerobic Digesters Treating Cattle or Swine Manure

    PubMed Central

    Li, Jiabao; Rui, Junpeng; Yao, Minjie; Zhang, Shiheng; Yan, Xuefeng; Wang, Yuanpeng; Yan, Zhiying; Li, Xiangzhen

    2015-01-01

    The microbial-mediated anaerobic digestion (AD) process represents an efficient biological process for the treatment of organic waste along with biogas harvest. Currently, the key factors structuring bacterial communities and the potential core and unique bacterial populations in manure anaerobic digesters are not completely elucidated yet. In this study, we collected sludge samples from 20 full-scale anaerobic digesters treating cattle or swine manure, and investigated the variations of bacterial community compositions using high-throughput 16S rRNA amplicon sequencing. Clustering and correlation analysis suggested that substrate type and free ammonia (FA) play key roles in determining the bacterial community structure. The COD: NH4+-N (C:N) ratio of substrate and FA were the most important available operational parameters correlating to the bacterial communities in cattle and swine manure digesters, respectively. The bacterial populations in all of the digesters were dominated by phylum Firmicutes, followed by Bacteroidetes, Proteobacteria and Chloroflexi. Increased FA content selected Firmicutes, suggesting that they probably play more important roles under high FA content. Syntrophic metabolism by Proteobacteria, Chloroflexi, Synergistetes and Planctomycetes are likely inhibited when FA content is high. Despite the different manure substrates, operational conditions and geographical locations of digesters, core bacterial communities were identified. The core communities were best characterized by phylum Firmicutes, wherein Clostridium predominated overwhelmingly. Substrate-unique and abundant communities may reflect the properties of manure substrate and operational conditions. These findings extend our current understanding of the bacterial assembly in full-scale manure anaerobic digesters. PMID:26648921

  1. Determination and variation of core bacterial community in a two-stage full-scale anaerobic reactor treating high-strength pharmaceutical wastewater.

    PubMed

    Ma, Haijun; Ye, Lin; Hu, Haidong; Zhang, Lulu; Ding, Lili; Ren, Hongqiang

    2017-08-25

    The functional characterization and temporal variation of anaerobic bacterial population is important to better understanding of microbial process of two-stage anaerobic reactor. However, due to the high diversity of anaerobic bacteria, close attention should be prioritized to be paid to the frequently abundant bacteria that were defined as core bacteria and putatively functionally important. Here in this study, using Miseq sequencing technology, the core bacterial community of 98 operational taxonomic units (OTUs) was determined in a two-stage upflow blanket filter reactors treating pharmaceutical wastewater. The core bacterial community accounted for 61.66% of the total sequences and accurately predicted the sample location in the principal coordinates analysis (PCoA) scatter plot as the total bacterial OTUs did. The core bacterial community in the first-stage (FS) and second-stage (SS) reactors were generally distinct that FS core bacterial community was indicated to be more related to higher-level fermentation process and SS core bacterial community contained more microbes in syntrophic cooperation with methanogens. Moreover, the different responses of FS and SS core bacterial community to the temperature shock and influent disturbance caused by solid contamination were fully investigated. Co-occurring analysis at the order level implied that Bacteroidales, Selenomonadales, Anaerolineales, Syneristales and Thermotogales might play keystone roles in anaerobic digestion due to their high abundance and tight correlation with other microbes. These findings advanced our knowledge about the core bacteria community and its temporal variability for future comparative research and the improvement of the two-stage anaerobic system operation.

  2. Determination of pegfilgrastim aggregates by size-exclusion high-performance liquid chromatography on a methacrylate-based column.

    PubMed

    Shahbazi, Majid; Tamaskany Zahedy, Elnaz; Kiumarsi, Shiva; Hadi Soltanabad, Mojtaba; Shahbazi Azar, Saleh; Amini, Hossein

    2017-03-01

    A size-exclusion high-performance liquid chromatographic method using a methacrylate-based column was developed, validated and implemented for the determination of pegfilgrastim aggregates. The samples were directly injected into a TSKgel G4000PWXL column (7.5 mm × 300 mm, 10 μm, <500 A°) with a mobile phase of 100 mM phosphate, pH 2.5. Detection was made at 215 nm and analyses were run at a flow-rate of 0.6 ml/min at 10 °C. Vortex-mixing of samples produced oligomers, however, very high molecular weight aggregates were formed at high temperatures. The method exhibited linearity over the concentration range of 0.1-14 mg/ml for pegfilgrastim monomer and high molecular weight aggregates with a correlation coefficient of greater than 0.99. The method was specific and sensitive, with a lower quantification limit of 0.1 mg/ml and a detection limit of 0.02 mg/ml. Over 1200 samples were analyzed by the present method without significant change in the column performance. Copyright © 2017 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

  3. Comparison of the aggregation of homologous β2-microglobulin variants reveals protein solubility as a key determinant of amyloid formation

    PubMed Central

    Pashley, Clare L.; Hewitt, Eric W.; Radford, Sheena E.

    2016-01-01

    The mouse and human β2-microglobulin protein orthologs are 70 % identical in sequence and share 88 % sequence similarity. These proteins are predicted by various algorithms to have similar aggregation and amyloid propensities. However, whilst human β2m (hβ2m) forms amyloid-like fibrils in denaturing conditions (e.g. pH 2.5) in the absence of NaCl, mouse β2m (mβ2m) requires the addition of 0.3 M NaCl to cause fibrillation. Here, the factors which give rise to this difference in amyloid propensity are investigated. We utilise structural and mutational analyses, fibril growth kinetics and solubility measurements under a range of pH and salt conditions, to determine why these two proteins have different amyloid propensities. The results show that, although other factors influence the fibril growth kinetics, a striking difference in the solubility of the proteins is a key determinant of the different amyloidogenicity of hβ2m and mβ2m. The relationship between protein solubility and lag time of amyloid formation is not captured by current aggregation or amyloid prediction algorithms, indicating a need to better understand the role of solubility on the lag time of amyloid formation. The results demonstrate the key contribution of protein solubility in determining amyloid propensity and lag time of amyloid formation, highlighting how small differences in protein sequence can have dramatic effects on amyloid formation. PMID:26780548

  4. Determination of thermodynamic potentials and the aggregation number for micelles with the mass-action model by isothermal titration calorimetry: A case study on bile salts.

    PubMed

    Olesen, Niels Erik; Westh, Peter; Holm, René

    2015-09-01

    The aggregation number (n), thermodynamic potentials (ΔG, ΔH, ΔS) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters of micelles with ITC were compared to a mass-action model (MAM) of reaction type: n⋅S⇌Mn. This analysis can provide guidelines for future ITC studies of systems behaving in accordance with this model such as micelles and proteins that undergo self-association to oligomers. Micelles with small aggregation numbers, as those of bile salts, are interesting because such small aggregates cannot be characterized as a separate macroscopic phase and the widely applied pseudo-phase model (PPM) is inaccurate. In the present work it was demonstrated that the aggregation number of micelles was constant at low concentrations enabling determination of the thermodynamic potentials by the MAM. A correlation between the aggregation number and the heat capacity was found, which implies that the dehydrated surface area of bile salts increases with the aggregation number. This is in accordance with Tanford's principles of opposing forces where neighbouring molecules in the aggregate are better able to shield from the surrounding hydrophilic environment when the aggregation number increases.

  5. Spectrophotometric determination of Blue Procion HEGN in effluents of textile industry exploiting the dye aggregation effect and flow injection analysis.

    PubMed

    Almeida, Vitor C; Costa, Willian F; Nozaki, Jorge; Oliveira, Cláudio C

    2006-03-01

    A new spectrophotometric method involving flow injection analysis and textile dye aggregation effect is proposed. The method is based on the aggregation effect of Blue Procion HEGN at pH 3, which relocates its maximum absorption wavelength from 620 to 776 nm, avoiding the interference of other blue textile dyes. For this task, a simple and robust flow injection system was designed, which became a very stable analytical method. When the system was applied to Blue Procion determination in effluent of textile industry, precise results were observed (RSD < 2% within 1.0 and 5.0 mg l(-1) HEGN). The analytical frequency was 80 measurements per hour; the analytical curve was linear from 1.0 to 5.0 mg l(-1) HEGN; the detection limit considering three times the standard deviation of the blank solution (n = 10) was estimated as 0.03 mg l(-1) HEGN; and recoveries between 95% and 105% were found. The system consumes 20 mg of sodium citrate and 125 microl of the sample per determination. No baseline drift was observed during extended (5 h) operation periods.

  6. Assessment of accuracy of the structure-factor-size-estimator method in determining red blood cell aggregate size from ultrasound spectral backscatter coefficient.

    PubMed

    Saha, Ratan K; Franceschini, Emilie; Cloutier, Guy

    2011-04-01

    A computer simulation study to produce ultrasonic backscatter coefficients (BSCs) from red blood cell (RBC) clusters is discussed. The simulation algorithm is suitable for generating non-overlapping, isotropic, and fairly identical RBC clusters. RBCs were stacked following the hexagonal close packing (HCP) structure to form a compact spherical aggregate. Such an aggregate was repeated and placed randomly under non-overlapping condition in the three-dimensional space to mimic an aggregated blood sample. BSCs were computed between 750 KHz and 200 MHz for samples of various cluster sizes at different hematocrits. Magnitudes of BSCs increased with mean aggregate sizes at low frequencies (<20 MHz). The accuracy of the structure-factor-size-estimator (SFSE) method in determining mean aggregate size and packing factor was also examined. A good correlation (R(2) ≥ 0.94) between the mean size of aggregates predicted by the SFSE and true size was found for each hematocrit. This study shows that for spherical aggregates there exists a region for each hematocrit where SFSE works most accurately. Typically, error of SFSE in estimating mean cluster size was <20% for dimensions between 14 and 17 μm at 40% hematocrit. This study suggests that the theoretical framework of SFSE is valid under the assumption of isotropic aggregates.

  7. Aggregation and secondary loop structure of oligonucleotides do not determine their ability to inhibit TLR9.

    PubMed

    Ashman, Robert F; Goeken, J Adam; Lenert, Petar S

    2011-08-01

    Toll-like receptor 9 (TLR9) is an endosomal DNA sensor that warns us of the presence of infectious danger and triggers a rapid pro-inflammatory response in dendritic cells, macrophages, and B cells. The consequences of uncontrolled TLR9 activation can be detrimental for the host, contributing to the pathogenesis of bacterial septic shock or autoimmune diseases, such as systemic lupus erythematosus. Therefore, we need to develop TLR9 antagonists. We and others have created inhibitory oligonucleotides (INH-ODN) that are capable of sequence-dependent inhibition of TLR9-induced activation in both human and mouse cells. However, it is not clear whether marked differences in INH-ODN activity related to base sequence derived from polymerization of INH-ODNs or their ability to complex with stimulatory CpG-oligonucleotides (ST-ODN). Furthermore, the 5' end of INH-ODNs may assume a particular loop configuration that may be needed for binding to a critical site on TLR9. Here, we show that 1) G-tetrads required for ODN stacking were compatible with INH-ODN activity but were not necessary; 2) there was no relationship between activity and self-association at endosomal pH; 3) there was no evidence for direct binding between ST-ODNs and INH-ODNs; 4) when a 3G sequence was disrupted, despite a preserved stem-loop formation, INH-ODN activity was abolished. These results support the conclusion that certain features of the primary linear sequence are critical for TLR9 inhibition, but changes in secondary structure or in ODN aggregation are irrelevant.

  8. Thermodynamics of Protein Aggregation

    NASA Astrophysics Data System (ADS)

    Osborne, Kenneth L.; Barz, Bogdan; Bachmann, Michael; Strodel, Birgit

    Amyloid protein aggregation characterizes many neurodegenerative disorders, including Alzheimer's, Parkinson's, and Creutz- feldt-Jakob disease. Evidence suggests that amyloid aggregates may share similar aggregation pathways, implying simulation of full-length amyloid proteins is not necessary for understanding amyloid formation. In this study we simulate GNNQQNY, the N-terminal prion-determining domain of the yeast protein Sup35 to investigate the thermodynamics of structural transitions during aggregation. We use a coarse-grained model with replica-exchange molecular dynamics to investigate the association of 3-, 6-, and 12-chain GNNQQNY systems and we determine the aggregation pathway by studying aggregation states of GN- NQQNY. We find that the aggregation of the hydrophilic GNNQQNY sequence is mainly driven by H-bond formation, leading to the formation of /3-sheets from the very beginning of the assembly process. Condensation (aggregation) and ordering take place simultaneously, which is underpinned by the occurrence of a single heat capacity peak only.

  9. Analysis of the methodology to determine anaerobic toxicity: evaluation of main compounds present in wastewater treatment plants (WWTPs).

    PubMed

    Urra, J; Poirrier, P; Segovia, J; Lesty, Y; Chamy, R

    2008-01-01

    The influence of the concentration of biomass on the level of inhibition and anaerobic degradation kinetics in batch systems was studied with toxic compounds that can generate destabilization in the operation of sludge anaerobic digesters. The compounds were grouped in four families; long chain fatty acids, polycyclic aromatic hydrocarbons, linear alkylbenzene sulphonates and organic acids. For the organic acids, there is no effect due to the biomass concentration variation, therefore it is a competitive inhibition; but that doesn't happen with the remaining compounds, where there is a dependence on the complexity of their structure, becoming a non-competitive inhibition. In addition, it was observed that the degradation kinetics is affected, whether diminishing the methane production (polycyclic aromatic hydrocarbons, linear alkylbenzene sulphonates, organics acids) or increasing the initial latency time (long chain fatty acids) without this becoming an obstacle to obtain the maximum methane productions for the latter ones.

  10. The determination of the real nano-scale sizes of bacteria in chernozem during microbial succession by means of hatching of a soil in aerobic and anaerobic conditions

    NASA Astrophysics Data System (ADS)

    Gorbacheva, M.

    2012-04-01

    M.A. Gorbacheva,L.M. Polyanskaya The Faculty of Soil Science, Moscow State University, Leninskie Gory, GSP-1, Moscow,119991,Russia In recent years there's been particular attention paid to the smallest life's forms- bacteria which size can be measured in nanometer. These are the forms of bacteria with diameter of 5-200 nm. Theoretical calculations based on the content of the minimum number of DNA, enzyme, lipids in and ribosome in cells indicates impossibility of existence of a living cells within diameter less than 300 nm. It is theoretically possible for a living cell to exist within possible diameter of approximately 140 nm. Using a fluorescence microscope there's been indicated in a number of samples from lakes, rivers, soil, snow and rain water that 200 nm is the smallest diameter of a living cell. Supposingly, such a small size of bacteria in soil is determined by natural conditions which limit their development by nutritious substances and stress-factors. Rejuvenescence of nanobacteria under unfavourable natural conditions and stress-factors is studied in laboratory environment. The object of the current study has become the samples of typical arable chernozem of the Central Chernozem State Biosphere Reserve in Kursk. The detailed morphological description of the soil profile and its basic analytical characteristics are widely represented in scientific publications. The soil is characterized by a high carbon content which makes up 3,96% ,3,8% , and 2,9% for the upper layers of the A horizon, and 0,79% for the layer of the B horizon. A microbial succession was studied under aerobic and anaerobic conditions by means of experiments with microcosms in upper A horizons and B horizon of a chernozem. The final aim is to identify the cells size of bacteria in aerobic and anaerobic soil conditions in chernozem during the microbial succession, by dampening and application of chitin by means of «cascade filtration» method. The study of the microcosms is important for

  11. Yeast vitality determination based on intracellular NAD(P)H fluorescence measurement during aerobic-anaerobic transition.

    PubMed

    Kurec, M; Kuncová, G; Brányik, T

    2009-01-01

    This work presents a yeast-cell vitality-assessment method based on on-line intracellular fluorescence measurement. The intracellular NAD(P)H fluorescence of a cell suspension is recorded during transition from aerobic to anaerobic conditions and the output signal is evaluated as a measure of yeast vitality (quality). This fluorescence method showed a highly satisfactory correlation with even low dead cell numbers where the acidification power test could not be applied.

  12. Determining the Effect of Aluminum Oxide Nanoparticles on the Aggregation of Amyloid-Beta in Transgenic Caenorhabditis elegans

    NASA Astrophysics Data System (ADS)

    Patel, Suhag; Matticks, John; Howell, Carina

    2014-03-01

    The cause of Alzheimer's disease has been linked partially to genetic factors but the predicted environmental components have yet to be determined. In Alzheimer's, accumulation of amyloid-beta protein in the brain forms plaques resulting in neurodegeneration and loss of mental functions. It has been postulated that aluminum influences the aggregation of amyloid-beta. To test this hypothesis, transgenic Caenorhabditis elegans, CL2120, was used as a model organism to observe neurodegeneration in nematodes exposed to aluminum oxide nanoparticles. Behavioral testing, fluorescent staining, and fluorescence microscopy were used to test the effects of aggregation of amyloid-beta in the nervous systems of effected nematodes exposed to aluminum oxide nanoparticles. Energy-dispersive x-ray spectroscopy was used to quantify the total concentration of aluminum oxide that the worms were exposed to during the experiment. Exposure of transgenic and wild type worms to a concentration of 4 mg mL-1 aluminum oxide showed a decrease in the sinusoidal motion, as well as an infirmity of transgenic worms when compared to control worms. These results support the hypothesis that aluminum may play a role in neurodegeneration in C. elegans, and may influence and increase the progression of Alzheimer's disease. This work was supported by National Science Foundation grants DUE-1058829, DMR-0923047 DUE-0806660 and Lock Haven FPDC grants.

  13. Comparison of the aggregation of homologous β2-microglobulin variants reveals protein solubility as a key determinant of amyloid formation.

    PubMed

    Pashley, Clare L; Hewitt, Eric W; Radford, Sheena E

    2016-02-13

    The mouse and human β2-microglobulin protein orthologs are 70% identical in sequence and share 88% sequence similarity. These proteins are predicted by various algorithms to have similar aggregation and amyloid propensities. However, whilst human β2m (hβ2m) forms amyloid-like fibrils in denaturing conditions (e.g. pH2.5) in the absence of NaCl, mouse β2m (mβ2m) requires the addition of 0.3M NaCl to cause fibrillation. Here, the factors which give rise to this difference in amyloid propensity are investigated. We utilise structural and mutational analyses, fibril growth kinetics and solubility measurements under a range of pH and salt conditions, to determine why these two proteins have different amyloid propensities. The results show that, although other factors influence the fibril growth kinetics, a striking difference in the solubility of the proteins is a key determinant of the different amyloidogenicity of hβ2m and mβ2m. The relationship between protein solubility and lag time of amyloid formation is not captured by current aggregation or amyloid prediction algorithms, indicating a need to better understand the role of solubility on the lag time of amyloid formation. The results demonstrate the key contribution of protein solubility in determining amyloid propensity and lag time of amyloid formation, highlighting how small differences in protein sequence can have dramatic effects on amyloid formation. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

  14. Critical Velocity and Anaerobic Paddling Capacity Determined by Different Mathematical Models and Number of Predictive Trials in Canoe Slalom

    PubMed Central

    Messias, Leonardo H. D.; Ferrari, Homero G.; Reis, Ivan G. M.; Scariot, Pedro P. M.; Manchado-Gobatto, Fúlvia B.

    2015-01-01

    The purpose of this study was to analyze if different combinations of trials as well as mathematical models can modify the aerobic and anaerobic estimates from critical velocity protocol applied in canoe slalom. Fourteen male elite slalom kayakers from Brazilian canoe slalom team (K1) were evaluated. Athletes were submitted to four predictive trials of 150, 300, 450 and 600 meters in a lake and the time to complete each trial was recorded. Critical velocity (CV-aerobic parameter) and anaerobic paddling capacity (APC-anaerobic parameter) were obtained by three mathematical models (Linear1=distance-time; Linear 2=velocity-1/time and Non-Linear = time-velocity). Linear 1 was chosen for comparison of predictive trials combinations. Standard combination (SC) was considered as the four trials (150, 300, 450 and 600 m). High fits of regression were obtained from all mathematical models (range - R² = 0.96-1.00). Repeated measures ANOVA pointed out differences of all mathematical models for CV (p = 0.006) and APC (p = 0.016) as well as R² (p = 0.033). Estimates obtained from the first (1) and the fourth (4) predictive trials (150 m = lowest; and 600 m = highest, respectively) were similar and highly correlated (r=0.98 for CV and r = 0.96 for APC) with the SC. In summary, methodological aspects must be considered in critical velocity application in canoe slalom, since different combinations of trials as well as mathematical models resulted in different aerobic and anaerobic estimates. Key points Great attention must be given for methodological concerns regarding critical velocity protocol applied on canoe slalom, since different estimates were obtained depending on the mathematical model and the predictive trials used. Linear 1 showed the best fits of regression. Furthermore, to the best of our knowledge and considering practical applications, this model is the easiest one to calculate the estimates from critical velocity protocol. Considering this, the abyss between

  15. Critical velocity and anaerobic paddling capacity determined by different mathematical models and number of predictive trials in canoe slalom.

    PubMed

    Messias, Leonardo H D; Ferrari, Homero G; Reis, Ivan G M; Scariot, Pedro P M; Manchado-Gobatto, Fúlvia B

    2015-03-01

    The purpose of this study was to analyze if different combinations of trials as well as mathematical models can modify the aerobic and anaerobic estimates from critical velocity protocol applied in canoe slalom. Fourteen male elite slalom kayakers from Brazilian canoe slalom team (K1) were evaluated. Athletes were submitted to four predictive trials of 150, 300, 450 and 600 meters in a lake and the time to complete each trial was recorded. Critical velocity (CV-aerobic parameter) and anaerobic paddling capacity (APC-anaerobic parameter) were obtained by three mathematical models (Linear1=distance-time; Linear 2=velocity-1/time and Non-Linear = time-velocity). Linear 1 was chosen for comparison of predictive trials combinations. Standard combination (SC) was considered as the four trials (150, 300, 450 and 600 m). High fits of regression were obtained from all mathematical models (range - R² = 0.96-1.00). Repeated measures ANOVA pointed out differences of all mathematical models for CV (p = 0.006) and APC (p = 0.016) as well as R² (p = 0.033). Estimates obtained from the first (1) and the fourth (4) predictive trials (150 m = lowest; and 600 m = highest, respectively) were similar and highly correlated (r=0.98 for CV and r = 0.96 for APC) with the SC. In summary, methodological aspects must be considered in critical velocity application in canoe slalom, since different combinations of trials as well as mathematical models resulted in different aerobic and anaerobic estimates. Key pointsGreat attention must be given for methodological concerns regarding critical velocity protocol applied on canoe slalom, since different estimates were obtained depending on the mathematical model and the predictive trials used.Linear 1 showed the best fits of regression. Furthermore, to the best of our knowledge and considering practical applications, this model is the easiest one to calculate the estimates from critical velocity protocol. Considering this, the abyss between science

  16. Chemiluminescence determination of trimetazidine via inducing the aggregation of gold nanoparticles

    NASA Astrophysics Data System (ADS)

    Li, Jiao; Quan, Jie; Du, Jianxiu; Liu, Mei

    2013-10-01

    A simple, rapid and sensitive chemiluminescence (CL) method combined with flow injection analysis was developed for the determination of trimetazidine. Trimetazidine was found to significantly increase the CL signal arising from N-bromosuccinimide-luminol reaction in the presence of gold nanoparticles. The enhanced CL intensity was proportional to trimetazidine concentration in the range of 0.01-5.0 μg/mL, with a limit of detection (3sb) of 6.7 ng/mL. The relative standard deviation was 2.8% for 11 repetitive measurements of 0.1 μg/mL trimetazidine solution. The practicality of the method was evaluated by determining trimetazidine in pharmaceutical formulations and in spiked human serum samples. Moreover, the possible CL reaction mechanism was also discussed.

  17. Validity, Reliability, and Performance Determinants of a New Job-Specific Anaerobic Work Capacity Test for the Norwegian Navy Special Operations Command.

    PubMed

    Angeltveit, Andreas; Paulsen, Gøran; Solberg, Paul A; Raastad, Truls

    2016-02-01

    Operators in Special Operation Forces (SOF) have a particularly demanding profession where physical and psychological capacities can be challenged to the extremes. The diversity of physical capacities needed depend on the mission. Consequently, tests used to monitor SOF operators' physical fitness should cover a broad range of physical capacities. Whereas tests for strength and aerobic endurance are established, there is no test for specific anaerobic work capacity described in the literature. The purpose of this study was therefore to evaluate the reliability, validity, and to identify performance determinants of a new test developed for testing specific anaerobic work capacity in SOF operators. Nineteen active young students were included in the concurrent validity part of the study. The students performed the evacuation (EVAC) test 3 times and the results were compared for reliability and with performance in the Wingate cycle test, 300-m sprint, and a maximal accumulated oxygen deficit (MAOD) test. In part II of the study, 21 Norwegian Navy Special Operations Command operators conducted the EVAC test, anthropometric measurements, a dual x-ray absorptiometry scan, leg press, isokinetic knee extensions, maximal oxygen uptake test, and countermovement jump (CMJ) test. The EVAC test showed good reliability after 1 familiarization trial (intraclass correlation = 0.89; coefficient of variance = 3.7%). The EVAC test correlated well with the Wingate test (r = -0.68), 300-m sprint time (r = 0.51), and 300-m mean power (W) (r = -0.67). No significant correlation was found with the MAOD test. In part II of the study, height, body mass, lean body mass, isokinetic knee extension torque, maximal oxygen uptake, and maximal power in a CMJ was significantly correlated with performance in the EVAC test. The EVAC test is a reliable and valid test for anaerobic work capacity for SOF operators, and muscle mass, leg strength, and leg power seem to be the most important determinants

  18. Struvite precipitation in anaerobic swine lagoon liquid: effect of pH and Mg:P ratio and determination of rate constant.

    PubMed

    Nelson, Nathan O; Mikkelsen, Robert L; Hesterberg, Dean L

    2003-09-01

    Because of increased concern about surface water eutrophication from nutrient-enriched agricultural runoff, many swine producers are encouraged to decrease application rates of waste-based P. Precipitation and subsequent removal of magnesium ammonium phosphate (MgNH(4)PO(4) x 6H(2)O), commonly known as struvite, is a promising mechanism for N and P removal from anaerobic swine lagoon effluent. The objectives of this research were to (i) quantify the effects of adjusting pH and Mg:P ratio on struvite precipitation and (ii) determine the rate constant pH effect for struvite precipitation in anaerobic swine lagoon liquid. Concentrations of PO(4)-P in liquid from two anaerobic swine lagoons were determined after 24 h of equilibration for a pH range of 7.5-9.5 and Mg:P ratios between 1:1 and 1.6:1. Struvite formation reduced the PO(4)-P concentration in the effluents to as low as 2 mgl(-1). Minimum concentrations of PO(4)-P occurred between pH 8.9 and 9.25 at all Mg:P ratios. Struvite precipitation decreased PO(4)-P concentrations by 85% within 20 min at pH 9.0 for an initial Mg:P ratio of 1.2:1. The rate of PO(4)-P decrease was described by a first-order kinetic model, with rate constants of 3.7, 7.9, and 12.3 h(-1) at pH 8.4, 8.7 and 9.0 respectively. Our results indicate that induced struvite formation is a technically feasible method to remove N and P from swine lagoon liquid and it may allow swine producers to recover nutrients for off-farm sale.

  19. The use of index tests to determine the mechanical properties of crushed aggregates from Precambrian basement complex rocks, Ado-Ekiti, SW Nigeria

    NASA Astrophysics Data System (ADS)

    Afolagboye, Lekan Olatayo; Talabi, Abel Ojo; Oyelami, Charles Adebayo

    2017-05-01

    This study assessed the possibility of using index tests to determine the mechanical properties of crushed aggregates. The aggregates used in this study were derived from major Precambrian basement rocks in Ado-Ekiti, Nigeria. Regression analyses were performed to determine the empirical relations that mechanical properties of the aggregates may have with the point load strength (IS(50)), Schmidt rebound hammer value (SHR) and unconfined compressive strength (UCS) of the rocks. For all the data, strong correlation coefficients were found between IS(50), SHR, UCS, and mechanical properties of the aggregates. The regression analysis conducted on the different rocks separately showed that correlations coefficients obtained between the IS(50), SHR, UCS and mechanical properties of the aggregates were stronger than those of the grouped rocks. The T-test and F-test showed that the derived models were valid. This study has shown that the mechanical properties of the aggregates can be estimated from IS(50), SHR and USC but the influence of rock type on the relationships should be taken into consideration.

  20. Evaluation of near infrared spectroscopy and software sensor methods for determination of total alkalinity in anaerobic digesters.

    PubMed

    Ward, Alastair J; Hobbs, Philip J; Holliman, Peter J; Jones, David L

    2011-03-01

    In this study two approaches to predict the total alkalinity (expressed as mg L(-1)HCO(3)(-)) of an anaerobic digester are examined: firstly, software sensors based on multiple linear regression algorithms using data from pH, redox potential and electrical conductivity and secondly, near infrared reflectance spectroscopy (NIRS). Of the software sensors, the model using data from all three probes but a smaller dataset using total alkalinity values below 6000 mg L(-1)HCO(3)(-) produced the best calibration model (R(2)=0.76 and root mean square error of prediction (RMSEP) of 969 mg L(-1)HCO(3)(-)). When validated with new data, the NIRS method produced the best model (R(2)=0.87 RMSEP=1230 mg L(-1)HCO(3)(-)). The NIRS sensor correlated better with new data (R(2)=0.54). In conclusion, this study has developed new and improved algorithms for monitoring total alkalinity within anaerobic digestion systems which will facilitate real-time optimisation of methane production. Copyright © 2010 Elsevier Ltd. All rights reserved.

  1. Determination and Visualization of pH Values in Anaerobic Digestion of Water Hyacinth and Rice Straw Mixtures Using Hyperspectral Imaging with Wavelet Transform Denoising and Variable Selection

    PubMed Central

    Zhang, Chu; Ye, Hui; Liu, Fei; He, Yong; Kong, Wenwen; Sheng, Kuichuan

    2016-01-01

    Biomass energy represents a huge supplement for meeting current energy demands. A hyperspectral imaging system covering the spectral range of 874–1734 nm was used to determine the pH value of anaerobic digestion liquid produced by water hyacinth and rice straw mixtures used for methane production. Wavelet transform (WT) was used to reduce noises of the spectral data. Successive projections algorithm (SPA), random frog (RF) and variable importance in projection (VIP) were used to select 8, 15 and 20 optimal wavelengths for the pH value prediction, respectively. Partial least squares (PLS) and a back propagation neural network (BPNN) were used to build the calibration models on the full spectra and the optimal wavelengths. As a result, BPNN models performed better than the corresponding PLS models, and SPA-BPNN model gave the best performance with a correlation coefficient of prediction (rp) of 0.911 and root mean square error of prediction (RMSEP) of 0.0516. The results indicated the feasibility of using hyperspectral imaging to determine pH values during anaerobic digestion. Furthermore, a distribution map of the pH values was achieved by applying the SPA-BPNN model. The results in this study would help to develop an on-line monitoring system for biomass energy producing process by hyperspectral imaging. PMID:26901202

  2. Determination of some aliphatic carboxylic acids in anaerobic digestion process waters by ion-exclusion chromatography with conductimetric detection on a weakly acidic cation-exchange resin column.

    PubMed

    Ito, Kazuaki; Takayama, Yohichi; Ikedo, Mikaru; Mori, Masanobu; Taoda, Hiroshi; Xu, Qun; Hu, Wenzhi; Sunahara, Hiroshi; Hayashi, Tsuneo; Sato, Shinji; Hirokawa, Takeshi; Tanaka, Kazuhiko

    2004-06-11

    The determination of seven aliphatic carboxylic acids, formic, acetic, propionic, isobutyric, n-butyric, isovaleric and n-valeric acids in anaerobic digestion process waters was examined using ion-exclusion chromatography with conductimetric detection. The analysis of these biologically important carboxylic acids is necessary as a measure for evaluating and controlling the process. The ion-exclusion chromatography system employed consisted of polymethacrylate-based weakly acidic cation-exchange resin columns (TSKgel OApak-A or TSKgel Super IC-A/C). weakly acidic eluent (benzoic acid), and conductimetric detection. Particle size and cation-exchange capacity were 5 microm and 0.1 meq./ml for TSKgel OApak-A and 3 microm and 0.2 meq./ml for TSKgel Super IC-A/C, respectively. A dilute eluent (1.0-2.0 mM) of benzoic acid was effective for the high resolution and highly conductimetric detection of the carboxylic acids. The good separation of isobutyric and n-butyric acids was performed using the TSKgel Super IC-A/C column (150 mm x 6.0 mm i.d. x 2). The simple and good chromatograms were obtained by the optimized ion-exclusion chromatography conditions for real samples from mesophilic anaerobic digestors, thus the aliphatic carboxylic acids were successfully determined without any interferences.

  3. Simultaneous determination of anionic and nonionic surfactants in commercial laundry wastewater and anaerobic fluidized bed reactor effluent by online column-switching liquid chromatography/tandem mass spectrometry.

    PubMed

    Motteran, Fabrício; Lima Gomes, Paulo C F; Silva, Edson L; Varesche, Maria Bernadete A

    2017-02-15

    This study presents a new method developed for the simultaneous determination of anionic surfactant (linear alkylbenzene sulfonate - LAS, 4 homologs) and nonionic surfactant (linear alcohol ethoxylate - LAE) in commercial laundry wastewater. The surfactants were identified and quantified using online column-switching solid-phase extraction (SPE) coupled with liquid chromatography/tandem mass spectrometry (LC-MS/MS). Ten and three transitions (m/z) were identified for LAS and LAE, respectively. The detection and quantification limits were 75 and 200μg/L for LAS, respectively, and 75μg/L for LAE. This method was applied to the determination of the surfactants in the influent and effluent of an anaerobic fluidized bed reactor that was used for the treatment of commercial laundry wastewater. After 480days of operation with a hydraulic retention time (HRT) of 18h, the removal of 45.9±5.6% LAS and 99.2±4.3% LAE from an influent with surfactant concentrations of 26.1±12.9mg/L and 23.8±6.8mg/L, respectively, was obtained. Under these conditions, the breakage of longer-chain LAS homologs with the release of carbon units was observed with an increase in the number of shorter homolog chains. This SPE online sample treatment method is simple, fast and effective for the analysis of both surfactants. This technique is pioneering in its simultaneous measurement of two surfactant categories in anaerobic fluidized bed reactors.

  4. Determination and Visualization of pH Values in Anaerobic Digestion of Water Hyacinth and Rice Straw Mixtures Using Hyperspectral Imaging with Wavelet Transform Denoising and Variable Selection.

    PubMed

    Zhang, Chu; Ye, Hui; Liu, Fei; He, Yong; Kong, Wenwen; Sheng, Kuichuan

    2016-02-18

    Biomass energy represents a huge supplement for meeting current energy demands. A hyperspectral imaging system covering the spectral range of 874-1734 nm was used to determine the pH value of anaerobic digestion liquid produced by water hyacinth and rice straw mixtures used for methane production. Wavelet transform (WT) was used to reduce noises of the spectral data. Successive projections algorithm (SPA), random frog (RF) and variable importance in projection (VIP) were used to select 8, 15 and 20 optimal wavelengths for the pH value prediction, respectively. Partial least squares (PLS) and a back propagation neural network (BPNN) were used to build the calibration models on the full spectra and the optimal wavelengths. As a result, BPNN models performed better than the corresponding PLS models, and SPA-BPNN model gave the best performance with a correlation coefficient of prediction (rp) of 0.911 and root mean square error of prediction (RMSEP) of 0.0516. The results indicated the feasibility of using hyperspectral imaging to determine pH values during anaerobic digestion. Furthermore, a distribution map of the pH values was achieved by applying the SPA-BPNN model. The results in this study would help to develop an on-line monitoring system for biomass energy producing process by hyperspectral imaging.

  5. Microbial community dynamics in soil aggregates shape biogeochemical gas fluxes from soil profiles - upscaling an aggregate biophysical model.

    PubMed

    Ebrahimi, Ali; Or, Dani

    2016-09-01

    Microbial communities inhabiting soil aggregates dynamically adjust their activity and composition in response to variations in hydration and other external conditions. These rapid dynamics shape signatures of biogeochemical activity and gas fluxes emitted from soil profiles. Recent mechanistic models of microbial processes in unsaturated aggregate-like pore networks revealed a highly dynamic interplay between oxic and anoxic microsites jointly shaped by hydration conditions and by aerobic and anaerobic microbial community abundance and self-organization. The spatial extent of anoxic niches (hotspots) flicker in time (hot moments) and support substantial anaerobic microbial activity even in aerated soil profiles. We employed an individual-based model for microbial community life in soil aggregate assemblies represented by 3D angular pore networks. Model aggregates of different sizes were subjected to variable water, carbon and oxygen contents that varied with soil depth as boundary conditions. The study integrates microbial activity within aggregates of different sizes and soil depth to obtain estimates of biogeochemical fluxes from the soil profile. The results quantify impacts of dynamic shifts in microbial community composition on CO2 and N2 O production rates in soil profiles in good agreement with experimental data. Aggregate size distribution and the shape of resource profiles in a soil determine how hydration dynamics shape denitrification and carbon utilization rates. Results from the mechanistic model for microbial activity in aggregates of different sizes were used to derive parameters for analytical representation of soil biogeochemical processes across large scales of practical interest for hydrological and climate models. © 2016 John Wiley & Sons Ltd.

  6. RBC aggregation: more important than RBC adhesion to endothelial cells as a determinant of in vivo blood flow in health and disease.

    PubMed

    Baskurt, Oguz K; Meiselman, Herbert J

    2008-10-01

    Although the shear-dependent and reversible phenomenon of red blood cell (RBC) aggregation has been studied for decades, its role as a determinant of in vivo blood flow in both health and disease has not yet been fully documented. In this brief review, we present compelling arguments, supported by literature evidence, that in vivo flow dynamics are more affected by RBC aggregation than by RBC adhesion to endothelial cells (ECs). A companion article (i.e., a "counter-point") published in this issue of the journal argues that in disease states, RBC-EC adhesion is the more important determinant.

  7. Determination of long chain fatty acids in anaerobic digesters using a rapid non-derivatisation GC-FID method.

    PubMed

    Jiang, Ying; Zhang, Yue; Banks, Charles J

    2012-01-01

    A rapid non-derivatisation gas chromatographic (GC) method for quantification of palmitic, stearic and oleic acids was achieved using a flame ionisation detector and a highly polar capillary column at elevated temperature. These long chain fatty acids (LCFA) can accumulate in anaerobic digesters and a simple extraction method was also developed to permit a more rapid sample turn-around time, facilitating more frequent monitoring. The GC method was satisfactory in terms of peak separation, signal response, reproducibility and linearity range. The extraction method achieved recoveries of 103.8, 127.2 and 84.2% for palmitic, stearic and oleic acid respectively. The method was tested on digestate from mesophilic laboratory-scale digesters fed with source-segregated domestic food waste, and showed good repeatability between replicate samples. It was observed that the concentrations of stearic and palmitic acid in digesters routinely supplemented with trace elements were lower in proportion to the applied lipid loading than those without supplementation.

  8. Determining the limits of anaerobic co-digestion of thickened waste activated sludge with grease interceptor waste.

    PubMed

    Wang, Ling; Aziz, Tarek N; de los Reyes, Francis L

    2013-07-01

    Anaerobic co-digestion of thickened waste activated sludge (TWAS) with grease interceptor waste (GIW) from a food service establishment was conducted in lab scale semi-continuous digesters. GIW included the entire contents of the grease interceptor (GI) including fat, oil, and grease (FOG), food residuals, and associated wastewater. GIW was added in step increases to identify the maximum methane production and the corresponding threshold input of GIW that led to inhibition of methanogenesis. The experiment was performed at mesophilic conditions (37 °C) with a solids retention time (SRT) of 20 days. The highest GIW addition rate achieved without digester failure was 20% (v/v), or 65.5% (w/w) of volatile solids (VS) added, enhancing the methane yield from 0.180 to 0.752 m3(CH4)/kg(VS added), biogas production from 2.2 × 10(-3) to 1.4 × 10(-2) m(3)/d, and methane content from 60.2% to 70.1%. The methane yield of 0.752 m3(CH4)/kg(VS added) is the highest value reported to date for co-digestion of GIW. Stepwise increases in co-substrate addition led to better microbial acclimation and reduced the GIW inhibitory effect. The limit for GIW addition leading to an inhibited digestion process was identified to be between 20 and 40% (v/v) or 65.5 and 83.5% (w/w) of VS added. The results show the significant benefits of anaerobic co-digestion of GIW and the positive impacts of gradual addition of GIW.

  9. Molecular Reorganization Energy as a Key Determinant of J-Band Formation in J-Aggregates of Polymethine Dyes.

    PubMed

    Petrenko, Alexander; Stein, Matthias

    2015-07-02

    This work demonstrates the feasibility of the theory of extended multiphonon electron transitions for the description of optical spectra of polymethine dyes and J-aggregates using quantum chemistry. The formation of a strong absorption band in dye monomers and a J-band in their aggregates is uniformly explained from the electron-nuclear resonance condition. The redistribution of optical band intensities among cyanine dyes with the solvent is also explained. The dependence of the possibility of J-band formation in aggregates on the dye structure is successfully predicted. The results presented provide an insight for rational molecular design and application of polymethine dyes.

  10. Determining the spatial coherence of excitons from the photoluminescence spectrum in charge-transfer J-aggregates

    NASA Astrophysics Data System (ADS)

    Hestand, Nicholas J.; Spano, Frank C.

    2016-12-01

    The importance of spatial coherence in energy and charge transfer processes in biological systems and photovoltaic devices has been hotly debated over the past several years. While larger spatial coherences are thought to benefit transport, a clear correlation has yet to be established, partly because a simple and accurate measure of the coherence length has remained elusive. Previously, it was shown that the number of coherently connected chromophores, NCoh , can be determined directly from the ratio (SR) of the 0-0 and 0-1 vibronic line strengths in the photoluminescence (PL) spectrum. The relation NCoh = λ02SR, where λ02 is the associated monomeric Huang-Rhys parameter, was derived in the Frenkel exciton limit. Here, it is shown that SR remains a highly accurate measure of coherence for systems characterized by significant charge transfer interactions (e.g. conjugated π-stacked systems). The only requirement is that the exciton band curvature must be positive, as in a J-aggregate.

  11. Effect of humic substances aggregation on the determination of fluoride in water using an ion selective electrode.

    PubMed

    Shen, Junjie; Gagliardi, Simona; McCoustra, Martin R S; Arrighi, Valeria

    2016-09-01

    The control of drinking water quality is critical in preventing fluorosis. In this study humic substances (HS) are considered as representative of natural organic matter (NOM) in water. We show that when HS aggregate the response of fluoride ion selective electrodes (ISE) may be perturbed. Dynamic light scattering (DLS) results of both synthetic solutions and natural water sample suggest that low pH and high ionic strength induce HS aggregation. In the presence of HS aggregates, fluoride concentration measured by ISE has a reduction up to 19%. A new "open cage" concept has been developed to explain this reversible phenomenon. The interference of HS aggregation on fluoride measurement can be effectively removed by centrifugation pretreatment. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Microbial community dynamics in soil aggregates shape biogeochemical gas fluxes from soil profiles

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Ali; Or, Dani

    2016-04-01

    Microbial communities inhabiting soil aggregates dynamically adjust their activity and composition in response to variations in hydration and other external conditions. These rapid dynamics shape signatures of biogeochemical activity and gas fluxes emitted from soil profiles. Mechanistic models of microbial processes in unsaturated aggregate pore networks revealed dynamic interplay between oxic and anoxic microsites that are jointly shaped by hydration and by aerobic and anaerobic microbial communities. The spatial extent of anoxic niches (hotspots) flicker in time (hot moments) and support significant anaerobic microbial activity even in aerated soil profiles. We employed an individual-based model for microbial community life in soil aggregate assemblies represented by 3-D angular pore networks with profiles of water, carbon, and oxygen that vary with soil depth as boundary conditions. The study integrates microbial activity within aggregates of different sizes and soil depth to obtain biogeochemical fluxes over the soil profile. The results quantify impacts of dynamic shifts in microbial community composition on CO2 and N2O production rates in soil profiles in good agreement with experimental data. Aggregate size distribution and the shape of resource profiles in a soil determine how hydration dynamics shape denitrification and carbon utilization rates. Results from the mechanistic model for microbial activity in aggregates of different sizes were used to derive parameters for analytical representation of soil biogeochemical processes across large scales of interest for hydrological and climate models.

  13. Determination of antimicrobial susceptibilities of clinically isolated anaerobic bacteria by E-test, ATB-ANA and agar dilution.

    PubMed

    Koru, Ozgur; Ozyurt, Mustafa

    2008-06-01

    A total of 60 anaerobic strains were isolated from 322 clinical specimens. These isolates were tested for susceptibility to seven antibiotics (penicillin G, amoxicillin/clavulanic acid, cefoxitin, imipenem, chloramphenicol, metronidazole, clindamycin) by using ATB-ANA and Epsilometer test (E-test) strips and the results were compared with the gold standard agar dilution method. Imipenem was found as the most effective agent in vitro among the agents tested (100%). Susceptibility to penicillin G, amoxicillin/clavulanic acid, cefoxitin, chloramphenicol, metronidazole and clindamycin are 36.7%, 83.3%, 88.3%, 96.6%, 85% and 90%, respectively. E-test has showed a good correlation (r=0.62, p=0.001) statistically with the results of agar dilution (total agreement for all antibiotics changing between 90.01% and 98.45%) and a moderate correlation (r=0.45, p=0.048) with the results of ATB-ANA method (total agreement for all antibiotics changing between 75.46% and 98.76%). However, the routine use of agar dilution procedure is concluded to be cumbersome, whereas E-test method offers a reliable alternative.

  14. The determination of fertilizer quality of the formed struvite from effluent of a sewage sludge anaerobic digester.

    PubMed

    Uysal, Ayla; Yilmazel, Y Dilsad; Demirer, Goksel N

    2010-09-15

    The formation of struvite (MgNH(4)PO(4).6H(2)O) in wastewater treatment plants can lead to scaling and thus operational problems reducing the treatment efficiency. However, struvite has significant commercial value as an agricultural fertilizer. Therefore, controlled struvite formation in wastewater treatment plants not only presents an opportunity to recover nutrients but also corresponds to the valorization of wastes. NH(4)-N and PO(4)-P removal and recovery from the effluent of a full-scale sewage sludge anaerobic digester via controlled struvite precipitation were investigated in this study. The effect of the residual heavy metal and micropollutant content of the formed struvite on fertilizer quality was also evaluated. Removal efficiencies of NH(4)-N, PO(4)-P and COD were 89.35%, 95% and 39.78% when Mg:N:P molar ratio was 1.5:1:1 and pH was 9.0. Mercury, nickel, zinc and chrome concentrations derived from struvite precipitation were below the regulatory limit for fertilizer usage in Turkey. The precipitate did not contain polychlorinated biphenyls (PCB). X-ray diffraction (XRD) analysis conducted on the precipitate indicated a struvite formation.

  15. Assessment of Determinants of Emission Potentially Affecting the Concentration of Airborne Nano-Objects and Their Agglomerates and Aggregates.

    PubMed

    Bekker, Cindy; Fransman, Wouter; Boessen, Ruud; Oerlemans, Arné; Ottenbros, Ilse B; Vermeulen, Roel

    2017-01-01

    Nano-specific inhalation exposure models could potentially be effective tools to assess and control worker exposure to nano-objects, and their aggregates and agglomerates (NOAA). However, due to the lack of reliable and consistent collected NOAA exposure data, the scientific basis for validation of the existing NOAA exposure models is missing or limited. The main objective of this study was to gain more insight into the effect of various determinants underlying the potential on the concentration of airborne NOAA close to the source with the purpose of providing a scientific basis for existing and future exposure inhalation models. Four experimental studies were conducted to investigate the effect of 11 determinants of emission on the concentration airborne NOAA close to the source during dumping of ~100% nanopowders. Determinants under study were: nanomaterial, particle size, dump mass, height, rate, ventilation rate, mixing speed, containment, particle surface coating, moisture content of the powder, and receiving surface. The experiments were conducted in an experimental room (19.5 m3) with well-controlled environmental and ventilation conditions. Particle number concentration and size distribution were measured using real-time measurement devices. Dumping of nanopowders resulted in a higher number concentration and larger particles than dumping their reference microsized powder (P < 0.05). Statistically significant more and larger particles were also found during dumping of SiO2 nanopowder compared to TiO2/Al2O3 nanopowders. Particle surface coating did not affect the number concentration but on average larger particles were found during dumping of coated nanopowders. An increase of the powder's moisture content resulted in less and smaller particles in the air. Furthermore, the results indicate that particle number concentration increases with increasing dump height, rate, and mass and decreases when ventilation is turned on. These results give an indication of

  16. Anaerobic Digestion.

    PubMed

    Liebetrau, Jan; Sträuber, Heike; Kretzschmar, Jörg; Denysenko, Velina; Nelles, Michael

    2017-04-09

    The term anaerobic digestion usually refers to the microbial conversion of organic material to biogas, which mainly consists of methane and carbon dioxide. The technical application of the naturally-occurring process is used to provide a renewable energy carrier and - as the substrate is often waste material - to reduce the organic matter content of the substrate prior to disposal.Applications can be found in sewage sludge treatment, the treatment of industrial and municipal solid wastes and wastewaters (including landfill gas utilization), and the conversion of agricultural residues and energy crops.For biorefinery concepts, the anaerobic digestion (AD) process is, on the one hand, an option to treat organic residues from other production processes. Concomitant effects are the reduction of organic carbon within the treated substance, the conversion of nitrogen and sulfur components, and the production of an energy-rich gas - the biogas. On the other hand, the multistep conversion of complex organic material offers the possibility of interrupting the conversion chain and locking out intermediates for utilization as basic material within the chemical industry.

  17. Aggregate Size and Architecture Determine Microbial Activity Balance for One-Stage Partial Nitritation and Anammox ▿

    PubMed Central

    Vlaeminck, Siegfried E.; Terada, Akihiko; Smets, Barth F.; De Clippeleir, Haydée; Schaubroeck, Thomas; Bolca, Selin; Demeestere, Lien; Mast, Jan; Boon, Nico; Carballa, Marta; Verstraete, Willy

    2010-01-01

    Aerobic ammonium-oxidizing bacteria (AerAOB) and anoxic ammonium-oxidizing bacteria (AnAOB) cooperate in partial nitritation/anammox systems to remove ammonium from wastewater. In this process, large granular microbial aggregates enhance the performance, but little is known about granulation so far. In this study, three suspended-growth oxygen-limited autotrophic nitrification-denitrification (OLAND) reactors with different inoculation and operation (mixing and aeration) conditions, designated reactors A, B, and C, were used. The test objectives were (i) to quantify the AerAOB and AnAOB abundance and the activity balance for the different aggregate sizes and (ii) to relate aggregate morphology, size distribution, and architecture putatively to the inoculation and operation of the three reactors. A nitrite accumulation rate ratio (NARR) was defined as the net aerobic nitrite production rate divided by the anoxic nitrite consumption rate. The smallest reactor A, B, and C aggregates were nitrite sources (NARR, >1.7). Large reactor A and C aggregates were granules capable of autonomous nitrogen removal (NARR, 0.6 to 1.1) with internal AnAOB zones surrounded by an AerAOB rim. Around 50% of the autotrophic space in these granules consisted of AerAOB- and AnAOB-specific extracellular polymeric substances. Large reactor B aggregates were thin film-like nitrite sinks (NARR, <0.5) in which AnAOB were not shielded by an AerAOB layer. Voids and channels occupied 13 to 17% of the anoxic zone of AnAOB-rich aggregates (reactors B and C). The hypothesized granulation pathways include granule replication by division and budding and are driven by growth and/or decay based on species-specific physiology and by hydrodynamic shear and mixing. PMID:19948857

  18. Physiologically anaerobic microorganisms of the deep subsurface

    SciTech Connect

    Stevens, S.E. Jr.; Chung, K.T.

    1991-06-01

    This study seeks to determine numbers, diversity, and morphology of anaerobic microorganisms in 15 samples of subsurface material from the Idaho National Engineering Laboratory, in 18 samples from the Hanford Reservation and in 1 rock sample from the Nevada Test Site; set up long term experiments on the chemical activities of anaerobic microorganisms based on these same samples; work to improve methods for the micro-scale determination of in situ anaerobic microbial activity;and to begin to isolate anaerobes from these samples into axenic culture with identification of the axenic isolates.

  19. Cell growth in aggregates determines gene expression, proliferation, survival, chemoresistance, and sensitivity to immune effectors in follicular lymphoma.

    PubMed

    Gravelle, Pauline; Jean, Christine; Familiades, Julien; Decaup, Emilie; Blanc, Amandine; Bezombes-Cagnac, Christine; Laurent, Camille; Savina, Ariel; Fournié, Jean-Jacques; Laurent, Guy

    2014-01-01

    Lymphomas grow as dense aggregates in patients, but whether this spatial organization affects lymphoma cell biology is unknown. We grew follicular lymphoma (FL) cells in vitro as multicellular aggregates of lymphoma cells to investigate this question. Gene expression analysis revealed that 612 genes were differentially expressed when cells grew in multicellular aggregates of lymphoma cells rather than in suspension. These genes correspond to several GO biological processes, such as hypoxia, activation of NF-κB pathway, and negative regulation of cell cycle, a gene signature also found in the transcriptomes from FL biopsies. Pimonidazole staining, HIF-1A accumulation, and VEGFA release confirmed that cells in multicellular aggregates of lymphoma cells actually respond to hypoxia. In adaptation to such conditions, they also displayed an activated NF-κB pathway and a quiescent status far more frequently than in suspension. When cultured in three dimensions, FL cells display resistance to doxorubicin and bendamustine, two drugs largely used in FL therapy, compared to FL cultured in suspension. Finally, multicellular aggregates of lymphoma cells were also found to be less sensitive to purified natural killer cells. To conclude, our study shows that in FL, spatial organization results in dramatic changes in FL biology, including gene expression, proliferation, drug resistance, and immune escape. Copyright © 2014 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  20. Anaerobic thermophiles.

    PubMed

    Canganella, Francesco; Wiegel, Juergen

    2014-02-26

    The term "extremophile" was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of "extreme" environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally "hot environments" on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has definitely

  1. Anaerobic Thermophiles

    PubMed Central

    Canganella, Francesco; Wiegel, Juergen

    2014-01-01

    The term “extremophile” was introduced to describe any organism capable of living and growing under extreme conditions. With the further development of studies on microbial ecology and taxonomy, a variety of “extreme” environments have been found and an increasing number of extremophiles are being described. Extremophiles have also been investigated as far as regarding the search for life on other planets and even evaluating the hypothesis that life on Earth originally came from space. The first extreme environments to be largely investigated were those characterized by elevated temperatures. The naturally “hot environments” on Earth range from solar heated surface soils and water with temperatures up to 65 °C, subterranean sites such as oil reserves and terrestrial geothermal with temperatures ranging from slightly above ambient to above 100 °C, to submarine hydrothermal systems with temperatures exceeding 300 °C. There are also human-made environments with elevated temperatures such as compost piles, slag heaps, industrial processes and water heaters. Thermophilic anaerobic microorganisms have been known for a long time, but scientists have often resisted the belief that some organisms do not only survive at high temperatures, but actually thrive under those hot conditions. They are perhaps one of the most interesting varieties of extremophilic organisms. These microorganisms can thrive at temperatures over 50 °C and, based on their optimal temperature, anaerobic thermophiles can be subdivided into three main groups: thermophiles with an optimal temperature between 50 °C and 64 °C and a maximum at 70 °C, extreme thermophiles with an optimal temperature between 65 °C and 80 °C, and finally hyperthermophiles with an optimal temperature above 80 °C and a maximum above 90 °C. The finding of novel extremely thermophilic and hyperthermophilic anaerobic bacteria in recent years, and the fact that a large fraction of them belong to the Archaea has

  2. Anaerobic bioprocessing of organic wastes.

    PubMed

    Verstraete, W; de Beer, D; Pena, M; Lettinga, G; Lens, P

    1996-05-01

    Anaerobic digestion of dissolved, suspended and solid organics has rapidly evolved in the last decades but nevertheless still faces several scientific unknowns. In this review, some fundamentals of bacterial conversions and adhesion are addressed initially. It is argued in the light of ΔG-values of reactions, and in view of the minimum energy quantum per mol, that anaerobic syntrophs must have special survival strategies in order to support their existence: redistributing the available energy between the partners, reduced end-product fermentation reactions and special cell-to-cell physiological interactions. In terms of kinetics, it appears that both reaction rates and residual substrate thresholds are strongly related to minimum ΔG-values. These new fundamental insights open perspectives for efficient design and operation of anaerobic bioprocesses. Subsequently, an overview is given of the current anaerobic biotechnology. For treating wastewaters, a novel and high performance new system has been introduced during the last decade; the upflow anaerobic sludge blanket system (UASB). This reactor concept requires anaerobic consortia to grow in a dense and eco-physiologically well-organized way. The microbial principles of such granular sludge growth are presented. Using a thermodynamic approach, the formation of different types of aggregates is explained. The application of this bioprocess in worldwide wastewater treatment is indicated. Due to the long retention times of the active biomass, the UASB is also suitable for the development of bacterial consortia capable of degrading xenobiotics. Operating granular sludge reactors at high upflow velocities (5-6 m/h) in expanded granular sludge bed (EGSB) systems enlarges the application field to very low strength wastewaters (chemical oxygen demand < 1 g/l) and psychrophilic temperatures (10°C). For the treatment of organic suspensions, there is currently a tendency to evolve from the conventional mesophilic

  3. Development of a fluorescence-based microplate method for the determination of volatile fatty acids in anaerobically digested and sewage sludges.

    PubMed

    Robert-Peillard, F; Palacio-Barco, E; Coulomb, B; Boudenne, J L

    2012-01-15

    This paper presents a simple, accurate and multi-sample method for the determination of volatile fatty acids (VFAs) thanks to a 96-well microplate technique. A procedure using an activating reagent of the carboxylic function (water-soluble carbodiimide EDC) and a fluorescent amino labeling reagent (N-(1-naphthyl)ethylenediamine, EDAN) allows the formation of an isoindole derivative that needs to be separated from initial fluorescent amine for efficient VFAs determination. Isolation of these fluorescent VFA-derivatives was carried out by use of the fluorescent quenching of EDAN with o-phthaldialdehyde (OPA). Quenching was most efficient at pH around 7 and by heating at 40°C within the microplate reader. This optimized procedure has been applied to various carboxylic acids and other organic compounds, demonstrating that VFA exhibit the highest fluorescence responses with homogeneous results for the main ones (acetic, propionic and butyric acid, all mass concentration expressed as acetic acid equivalents). This protocol was calibrated against acetic acid and determination of VFA was thus possible in the range 3.9-2,000 mg L(-1) (acetic acid equivalents). Subsequent application to real samples (sewage sludges or anaerobically digested samples) and comparison to gas chromatography analyses gave accurate results, proving the great potential of our high-throughput microplate-based technique for the analysis of VFA.

  4. STakeholder-Objective Risk Model (STORM): Determining the aggregated risk of multiple contaminant hazards in groundwater well catchments

    NASA Astrophysics Data System (ADS)

    Enzenhoefer, R.; Binning, P. J.; Nowak, W.

    2015-09-01

    Risk is often defined as the product of probability, vulnerability and value. Drinking water supply from groundwater abstraction is often at risk due to multiple hazardous land use activities in the well catchment. Each hazard might or might not introduce contaminants into the subsurface at any point in time, which then affects the pumped quality upon transport through the aquifer. In such situations, estimating the overall risk is not trivial, and three key questions emerge: (1) How to aggregate the impacts from different contaminants and spill locations to an overall, cumulative impact on the value at risk? (2) How to properly account for the stochastic nature of spill events when converting the aggregated impact to a risk estimate? (3) How will the overall risk and subsequent decision making depend on stakeholder objectives, where stakeholder objectives refer to the values at risk, risk attitudes and risk metrics that can vary between stakeholders. In this study, we provide a STakeholder-Objective Risk Model (STORM) for assessing the total aggregated risk. Or concept is a quantitative, probabilistic and modular framework for simulation-based risk estimation. It rests on the source-pathway-receptor concept, mass-discharge-based aggregation of stochastically occuring spill events, accounts for uncertainties in the involved flow and transport models through Monte Carlo simulation, and can address different stakeholder objectives. We illustrate the application of STORM in a numerical test case inspired by a German drinking water catchment. As one may expect, the results depend strongly on the chosen stakeholder objectives, but they are equally sensitive to different approaches for risk aggregation across different hazards, contaminant types, and over time.

  5. Construction aggregates

    USGS Publications Warehouse

    Tepordei, V.V.

    1995-01-01

    Part of the 1994 Industrial Minerals Review. The production, consumption, and applications of construction aggregates are reviewed. In 1994, the production of construction aggregates, which includes crushed stone and construction sand and gravel combined, increased 7.7 percent to 2.14 Gt compared with the previous year. These record production levels are mostly a result of funding for highway construction work provided by the Intermodal Surface Transportation Efficiency Act of 1991. Demand is expected to increase for construction aggregates in 1995.

  6. Composition and aggregation of extracellular polymeric substances (EPS) in hyperhaline and municipal wastewater treatment plants

    PubMed Central

    Zeng, Jie; Gao, Jun-Min; Chen, You-Peng; Yan, Peng; Dong, Yang; Shen, Yu; Guo, Jin-Song; Zeng, Ni; Zhang, Peng

    2016-01-01

    As important constituents of activated sludge flocs, extracellular polymeric substances (EPS) play significant roles in pollutants adsorption, the formation and maintenance of microbial aggregates, and the protection of microbes from external environmental stresses. In this work, EPS in activated sludge from a municipal wastewater treatment plant (M-WWTP) with anaerobic/anoxic/oxic (A2/O) process and a hyperhaline wastewater treatment plant (H-WWTP) with anaerobic/oxic (A/O) process were extracted by ultrasound method. The proteins and polysaccharides contents in EPS were determined by using a modified Lowry method and anthrone colorimetry respectively to analyze the detail differences in two types of WWTPs. Fourier transform-infrared spectroscopy and three-dimensional excitation-emission matrix fluorescence spectroscopy demonstrated proteins and polysaccharides were the dominant components of the two types of EPS, and the aromatic protein-like substances accounted for a larger proportion in EPS proteins. The results of the aggregation test indicated that EPS were good for the sludge aggregation, and the EPS in oxic sludge were more beneficial to sludge aggregation than that in anoxic sludge. Anoxic sludge EPS in H-WWTP showed a negligible effect on sludge aggregation. Comparative study on EPS of different tanks in the M-WWTP and H-WWTP was valuable for understanding the characteristics of EPS isolated from two typical wastewater treatment processes. PMID:27220287

  7. The SAWO (Small And Well Organized) avatar teaches the importance of the aggregates on the soil system and how to determine their stability

    NASA Astrophysics Data System (ADS)

    Mataix-Solera, Jorge; Cerdà, Artemi; Jordán, Antonio; Úbeda, Xavier; Pereira, Paulo

    2015-04-01

    Soil structure is the key factor that determine the soil quality as control the organic matter turnnover, soil biology and soil erodibility (Cerdà, 1996; 1998; Wick et al., 2014; Gelaw, 2015). There is a need to understand better the factors and the processes that act on the soil aggregation and the dynamics of the soil aggregation, which will make easier to understand the soil system functioning (Jordán et al., 2011; Jordán et al., 2012; Pulido Moncada et al., 2013). Fire, mines, grazing and agricultura (Cerdà, 2000; Mataix Solera et al., 2011; Cerdà et al., 2012; Hallett et al., 2014; Lozano et al., 2013) determines how the soil structure is highly affected by the humankind. And this determines the sustainability of the land managements (García Orenes et al., 2012; K¨ropfl et al., 2013; Mekuria and Aynekulu, 2013; Taguas et al., 2013; Zhao et al., 2013). Aggregates are Small And Well Organized (SAWO) structures that allow the water to flow, the air fill the porous and the life to be diverse and abundant in the soil. The SAWO avatar will teach the importance of the functions and the services of the aggregates to students and other scientists, but also to any audience. This means that the experiments and the vocabulary to be used by SAWO will be very wide and rich. The Avatar SAWO will use different strategies and skills to teach the soil aggregation properties and characteristics. And also, how to measure. Easy to carry out experiments will be shown by SAWO to measure the aggregate stability in the field and in the laboratory, and the soil sampling in the field. The SAWO avatar will play a special attention to the impact of forest fires on aggregate stability changes and how to measure. The SAWO avatar will teach how to take samples in the field, how to transport and manage in the laboratory, and finally which measurements and test can be done to determine the aggregate stability. Acknowledgements To the "Ministerio de Economía and Competitividad" of

  8. An alternative method for determining particle-size distribution of forest road aggregate and soil with large-sized particles

    Treesearch

    Hakjun Rhee; Randy B. Foltz; James L. Fridley; Finn Krogstad; Deborah S. Page-Dumroese

    2014-01-01

    Measurement of particle-size distribution (PSD) of soil with large-sized particles (e.g., 25.4 mm diameter) requires a large sample and numerous particle-size analyses (PSAs). A new method is needed that would reduce time, effort, and cost for PSAs of the soil and aggregate material with large-sized particles. We evaluated a nested method for sampling and PSA by...

  9. Comparing four non-invasive methods to determine the ventilatory anaerobic threshold during cardiopulmonary exercise testing in children with congenital heart or lung disease.

    PubMed

    Visschers, Naomi C A; Hulzebos, Erik H; van Brussel, Marco; Takken, Tim

    2015-11-01

    The ventilatory anaerobic threshold (VAT) is an important method to assess the aerobic fitness in patients with cardiopulmonary disease. Several methods exist to determine the VAT; however, there is no consensus which of these methods is the most accurate. To compare four different non-invasive methods for the determination of the VAT via respiratory gas exchange analysis during a cardiopulmonary exercise test (CPET). A secondary objective is to determine the interobserver reliability of the VAT. CPET data of 30 children diagnosed with either cystic fibrosis (CF; N = 15) or with a surgically corrected dextro-transposition of the great arteries (asoTGA; N = 15) were included. No significant differences were found between conditions or among testers. The RER = 1 method differed the most compared to the other methods, showing significant higher results in all six variables. The PET-O2 method differed significantly on five of six and four of six exercise variables with the V-slope method and the VentEq method, respectively. The V-slope and the VentEq method differed significantly on one of six exercise variables. Ten of thirteen ICCs that were >0.80 had a 95% CI > 0.70. The RER = 1 method and the V-slope method had the highest number of significant ICCs and 95% CIs. The V-slope method, the ventilatory equivalent method and the PET-O2 method are comparable and reliable methods to determine the VAT during CPET in children with CF or asoTGA. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  10. Batch Tests To Determine Activity Distribution and Kinetic Parameters for Acetate Utilization in Expanded-Bed Anaerobic Reactors

    PubMed Central

    Fox, Peter; Suidan, Makram T.

    1990-01-01

    Batch tests to measure maximum acetate utilization rates were used to determine the distribution of acetate utilizers in expanded-bed sand and expanded-bed granular activated carbon (GAC) reactors. The reactors were fed a mixture of acetate and 3-ethylphenol, and they contained the same predominant aceticlastic methanogen, Methanothrix sp. Batch tests were performed both on the entire reactor contents and with media removed from the reactors. Results indicated that activity was evenly distributed within the GAC reactors, whereas in the sand reactor a sludge blanket on top of the sand bed contained approximately 50% of the activity. The Monod half-velocity constant (Ks) for the acetate-utilizing methanogens in two expanded-bed GAC reactors was searched for by combining steady-state results with batch test data. All parameters necessary to develop a model with Monod kinetics were experimentally determined except for Ks. However, Ks was a function of the effluent 3-ethylphenol concentration, and batch test results demonstrated that maximum acetate utilization rates were not a function of the effluent 3-ethylphenol concentration. Addition of a competitive inhibition term into the Monod expression predicted the dependence of Ks on the effluent 3-ethylphenol concentration. A two-parameter search determined a Ks of 8.99 mg of acetate per liter and a Ki of 2.41 mg of 3-ethylphenol per liter. Model predictions were in agreement with experimental observations for all effluent 3-ethylphenol concentrations. Batch tests measured the activity for a specific substrate and determined the distribution of activity in the reactor. The use of steady-state data in conjunction with batch test results reduced the number of unknown kinetic parameters and thereby reduced the uncertainty in the results and the assumptions made. PMID:16348175

  11. Livestock Anaerobic Digester Database

    EPA Pesticide Factsheets

    The Anaerobic Digester Database provides basic information about anaerobic digesters on livestock farms in the United States, organized in Excel spreadsheets. It includes projects that are under construction, operating, or shut down.

  12. Molecular microbial diversity of an anaerobic digestor as determined by small-subunit rDNA sequence analysis.

    PubMed Central

    Godon, J J; Zumstein, E; Dabert, P; Habouzit, F; Moletta, R

    1997-01-01

    The bacterial community structure of a fluidized-bed reactor fed by vinasses (wine distillation waste) was analyzed. After PCR amplification, four small-subunit (SSU) rDNA clone libraries of Bacteria, Archaea, Procarya, and Eucarya populations were established. The community structure was determined by operational taxonomic unit (OTU) phylogenetic analyses of 579 partial rDNA sequences (about 500 bp long). A total of 146 OTUs were found, comprising 133, 6, and 7 from the Bacteria, Archaea, and Eucarya domains, respectively. A total of 117 bacterial OTU were affiliated with major phyla: low-G+C gram-positive bacteria, Cytophaga-Flexibacter-Bacteroides, Proteobacteria, high-G+C gram-positive bacteria, and Spirochaetes, where the clone distribution was 34, 26, 17, 6, and 4%, respectively. The other 16 bacterial OTUs represent 13% of the clones. They were either affiliated with narrow phyla such as Planctomyces-Chlamydia, green nonsulfur bacteria, or Synergistes, or deeply branched on the phylogenetic tree. A large number of bacterial OTUs are not closely related to any other hitherto determined sequences. The most frequent bacterial OTUs represents less than 5% of the total bacterial SSU rDNA sequences. However, the 20 more frequent bacterial OTUs describe at least 50% of these sequences. Three of the six Archaea OTUs correspond to 95% of the Archaea population and are very similar to already known methanogenic species: Methanosarcina barkeri, Methanosarcina frisius, and Methanobacterium formicicum. In contrast, the three other Archaea OTUs are unusual and are related to thermophilic microorganisms such as Crenarchaea or Thermoplasma spp. Five percent of the sequences analyzed were chimeras and were removed from the analysis. PMID:9212428

  13. Molecular microbial diversity of an anaerobic digestor as determined by small-subunit rDNA sequence analysis.

    PubMed

    Godon, J J; Zumstein, E; Dabert, P; Habouzit, F; Moletta, R

    1997-07-01

    The bacterial community structure of a fluidized-bed reactor fed by vinasses (wine distillation waste) was analyzed. After PCR amplification, four small-subunit (SSU) rDNA clone libraries of Bacteria, Archaea, Procarya, and Eucarya populations were established. The community structure was determined by operational taxonomic unit (OTU) phylogenetic analyses of 579 partial rDNA sequences (about 500 bp long). A total of 146 OTUs were found, comprising 133, 6, and 7 from the Bacteria, Archaea, and Eucarya domains, respectively. A total of 117 bacterial OTU were affiliated with major phyla: low-G+C gram-positive bacteria, Cytophaga-Flexibacter-Bacteroides, Proteobacteria, high-G+C gram-positive bacteria, and Spirochaetes, where the clone distribution was 34, 26, 17, 6, and 4%, respectively. The other 16 bacterial OTUs represent 13% of the clones. They were either affiliated with narrow phyla such as Planctomyces-Chlamydia, green nonsulfur bacteria, or Synergistes, or deeply branched on the phylogenetic tree. A large number of bacterial OTUs are not closely related to any other hitherto determined sequences. The most frequent bacterial OTUs represents less than 5% of the total bacterial SSU rDNA sequences. However, the 20 more frequent bacterial OTUs describe at least 50% of these sequences. Three of the six Archaea OTUs correspond to 95% of the Archaea population and are very similar to already known methanogenic species: Methanosarcina barkeri, Methanosarcina frisius, and Methanobacterium formicicum. In contrast, the three other Archaea OTUs are unusual and are related to thermophilic microorganisms such as Crenarchaea or Thermoplasma spp. Five percent of the sequences analyzed were chimeras and were removed from the analysis.

  14. Biotic and abiotic interactions in aquatic microcosms determine fate and toxicity of Ag nanoparticles. Part 1. Aggregation and dissolution.

    PubMed

    Unrine, Jason M; Colman, Benjamin P; Bone, Audrey J; Gondikas, Andreas P; Matson, Cole W

    2012-07-03

    To better understand their fate and toxicity in aquatic environments, we compared the aggregation and dissolution behavior of gum arabic (GA) and polyvinylpyrrolidone (PVP) coated Ag nanoparticles (NPs) in aquatic microcosms. There were four microcosm types: surface water; water and sediment; water and aquatic plants; or water, sediment, and aquatic plants. Dissolution and aggregation behavior of AgNPs were examined using ultracentrifugation, ultrafiltration, and asymmetrical flow field flow fractionation coupled to ultraviolet-visible spectroscopy, dynamic and static laser light scattering, and inductively coupled plasma mass spectrometry. Plants released dissolved organic matter (DOM) into the water column either through active or passive processes in response to Ag exposure. This organic matter fraction readily bound Ag ions. The plant-derived DOM had the effect of stabilizing PVP-AgNPs as primary particles, but caused GA-AgNPs to be removed from the water column, likely by dissolution and binding of released Ag ions on sediment and plant surfaces. The destabilization of the GA-AgNPs also corresponded with X-ray absorption near edge spectroscopy results which suggest that 22-28% of the particulate Ag was associated with thiols and 5-14% was present as oxides. The results highlight the potential complexities of nanomaterial behavior in response to biotic and abiotic modifications in ecosystems, and may help to explain differences in toxicity of Ag observed in realistic exposure media compared to simplified laboratory exposures.

  15. An aggregation-removal model for the formation and size determination of post-synaptic scaffold domains.

    PubMed

    Ranft, Jonas; Almeida, Leandro G; Rodriguez, Pamela C; Triller, Antoine; Hakim, Vincent

    2017-04-01

    The formation and stability of synapses are key questions in neuroscience. Post-synaptic domains have been classically conceived as resulting from local insertion and turnover of proteins at the synapse. However, insertion is likely to occur outside the post-synaptic domains and advances in single-molecule imaging have shown that proteins diffuse in the plane of the membrane prior to their accumulation at synapses. We quantitatively investigated this scenario using computer simulations and mathematical analysis, taking for definiteness the specific case of inhibitory synapse components, i.e., the glycine receptor (GlyR) and the associated gephyrin scaffolding protein. The observed domain sizes of scaffold clusters can be explained by a dynamic balance between the aggregation of gephyrin proteins diffusing while bound to GlyR and their turnover at the neuron membrane. We also predict the existence of extrasynaptic clusters with a characteristic size distribution that significantly contribute to the size fluctuations of synaptic domains. New super-resolution data for gephyrin proteins established the existence of extrasynaptic clusters the sizes of which are consistent with the model predictions in a range of model parameters. At a general level, our results highlight aggregation with removal as a non-equilibrium phase separation which produces structures of tunable size.

  16. Bioassay-Guided Isolation and HPLC Determination of Bioactive Compound That Relate to the Antiplatelet Activity (Adhesion, Secretion, and Aggregation) from Solanum lycopersicum

    PubMed Central

    Fuentes, Eduardo; Castro, Ricardo; Astudillo, Luis; Carrasco, Gilda; Alarcón, Marcelo; Gutiérrez, Margarita; Palomo, Iván

    2012-01-01

    In seeking the functionality of foodstuff applicable to medicine, ripe tomato fruits were found to show an antiplatelet activity. Therefore, the bioactive compound was isolated, structurally identified, and studied for an inhibitory effects on platelet adhesion, secretion, and aggregation. The concentration of adenosine in ripe tomato fruits (pulp and skin extracts) and its processing by-products (paste and pomace) was determined by reversed-phase high-performance liquid chromatography (HPLC). According to platelet aggregation inhibition induced by ADP, the total extract residual was fractionated by liquid-liquid separation, obtaining aqueous, ethyl acetate and petroleum ether extracts. The aqueous extract was subjected to repeated permeation over sephadex LH-20 and semipreparative TLC. The isolate finally obtained was identified as adenosine on the basis of ESI-MS, 1H NMR, HPLC, and UV spectra. Adenosine concentration dependently (2.3–457 μM) platelet aggregation inhibited induced by ADP. Also, adenosine present inhibition of platelet secretion and thrombus formation under flow conditions. The quantitative HPLC analysis revealed significant amounts of adenosine in ripe tomato fruits and its processing by-products. From these results, extracts/fractions of ripe tomato fruits and their processing by-products may be referred to as functional food and functional ingredients containing a compound that inhibits platelet function with a potent preventive effect on thrombus formation, as those that occur in stroke. PMID:23227097

  17. Bioassay-Guided Isolation and HPLC Determination of Bioactive Compound That Relate to the Antiplatelet Activity (Adhesion, Secretion, and Aggregation) from Solanum lycopersicum.

    PubMed

    Fuentes, Eduardo; Castro, Ricardo; Astudillo, Luis; Carrasco, Gilda; Alarcón, Marcelo; Gutiérrez, Margarita; Palomo, Iván

    2012-01-01

    In seeking the functionality of foodstuff applicable to medicine, ripe tomato fruits were found to show an antiplatelet activity. Therefore, the bioactive compound was isolated, structurally identified, and studied for an inhibitory effects on platelet adhesion, secretion, and aggregation. The concentration of adenosine in ripe tomato fruits (pulp and skin extracts) and its processing by-products (paste and pomace) was determined by reversed-phase high-performance liquid chromatography (HPLC). According to platelet aggregation inhibition induced by ADP, the total extract residual was fractionated by liquid-liquid separation, obtaining aqueous, ethyl acetate and petroleum ether extracts. The aqueous extract was subjected to repeated permeation over sephadex LH-20 and semipreparative TLC. The isolate finally obtained was identified as adenosine on the basis of ESI-MS, (1)H NMR, HPLC, and UV spectra. Adenosine concentration dependently (2.3-457 μM) platelet aggregation inhibited induced by ADP. Also, adenosine present inhibition of platelet secretion and thrombus formation under flow conditions. The quantitative HPLC analysis revealed significant amounts of adenosine in ripe tomato fruits and its processing by-products. From these results, extracts/fractions of ripe tomato fruits and their processing by-products may be referred to as functional food and functional ingredients containing a compound that inhibits platelet function with a potent preventive effect on thrombus formation, as those that occur in stroke.

  18. Construction aggregates

    USGS Publications Warehouse

    Tepordei, V.V.

    1994-01-01

    Part of a special section on industrial minerals in 1993. The 1993 production of construction aggregates increased 6.3 percent over the 1992 figure, to reach 2.01 Gt. This represents the highest estimated annual production of combined crushed stone and construction sand and gravel ever recorded in the U.S. The outlook for construction aggregates and the issues facing the industry are discussed.

  19. Stereochemical determination of chlorophyll-d molecule from Acaryochloris marina and its modification to a self-aggregative chlorophyll as a model of green photosynthetic bacterial antennae.

    PubMed

    Mizoguchi, Tadashi; Shoji, Ayumi; Kunieda, Michio; Miyashita, Hideaki; Tsuchiya, Tohru; Mimuro, Mamoru; Tamiaki, Hitoshi

    2006-03-01

    Acaryochloris marina is a unique photosynthetic prokaryote containing chlorophyll(Chl)-d as a major photoactive pigment (over 95%). The molecular structure of Chl-d is proposed as the 3-formyl analog of Chl-a. However, the stereochemistry of Chl-d at the 13(2)-, 17- and 18-positions has not yet been established unambiguously. In the first part of this paper, we describe the determination of their stereochemistries to be 13(2)-(R)-, 17-(S)- and 18-(S)-configurations by using 1H-1H NOE correlations in 1H-NMR and circular dichroism spectra as well as chemical modification of Chl-a to produce stereochemically defined Chl derivatives. In the second part of the paper, we report a facile synthesis of a self-aggregative Chl by modifying isolated Chl-d. Since Chl-d was characterized by its reactive 3-formyl group, the formyl group was reduced with t-BuNH2BH3 to afford the desirable Chl, 3-deformyl-3-hydroxymethyl-pyrochlorophyll-d (3(1)-OH-pyroChl-d). The synthetic 3(1)-OH-pyroChl-d molecules spontaneously self-organized to form well-ordered aggregates in a non-polar organic solvent. The self-aggregates are a good model of major light-harvesting antenna systems of green photosynthetic bacteria, chlorosomes, in terms of the following three findings. (1) Both the red-shifted electronic absorption band above 750 nm and its induced reverse S-shape CD signal around 750 nm were observed in 0.5% (v/v) THF-cyclohexane. (2) The stretching mode of the 13-carbonyl group was downshifted by about 35 cm(-1) from the wavenumber of its free carbonyl. (3) The self-aggregates were quite stable on titration of pyridine to the suspension, in comparison with those of natural chlorosomal bacteriochlorophyll-d possessing the 3-(1-hydroxyethyl) group.

  20. Determination of preferred pH for root-knot nematode aggregation using pluronic F-127 gel.

    PubMed

    Wang, Congli; Bruening, George; Williamson, Valerie M

    2009-10-01

    Root-knot nematodes (Meloidogyne spp.) are obligate endoparasites of a wide range of plant species. The infective stage is attracted strongly to and enters host roots at the zone of elongation, but the compounds responsible for this attraction have not been identified. We developed a simple assay to investigate nematode response to chemical gradients that uses Pluronic F-127, a synthetic block copolymer that, as a 23% aqueous solution, forms a liquid at low temperature and a gel at room temperature. Test chemicals are put into a modified pipette tip, or 'chemical dispenser,' and dispensers are inserted into the gel in which nematodes have been dispersed. Meloidogyne hapla is attracted to pH gradients formed by acetic acid and several other Brønsted acids and aggregates between pH 4.5 and 5.4. While this pH range was attractive to all tested root-knot nematode strains and species, the level of aggregation depended on the species/strain assessed. For actively growing roots, the pH at the root surface is most acidic at the zone of elongation. This observation is consistent with the idea that low pH is an attractant for nematodes. Root-knot nematodes have been reported to be attracted to carbon dioxide, but our experiments suggest that the observed attraction may be due to acidification of solutions by dissolved CO(2) rather than to CO(2) itself. These results suggest that Pluronic F-127 gel will be broadly applicable for examining responses of a range of organisms to chemical gradients or to each other.

  1. Quinolone activity against anaerobes.

    PubMed

    Appelbaum, P C

    1999-01-01

    The first generation of fluoroquinolones such as ciprofloxacin and ofloxacin are inactive against most anaerobic bacteria. However, some broad-spectrum quinolones, which have recently become clinically available or are under active development, have significant antianaerobic activity. This review summarises the in vitro activity of currently available, as well as experimental, quinolones against clinically significant anaerobic bacteria. Quinolones with low activity against anaerobes include ciprofloxacin, ofloxacin, levofloxacin, fleroxacin, pefloxacin, enoxacin and lomefloxacin. Compounds with intermediate antianaerobic activity include sparfloxacin and grepafloxacin. Trovafloxacin, gatifloxacin and moxifloxacin yield low MICs against most groups of anaerobes. Quinolones with the greatest in vitro activity against anaerobes include clinafloxacin and sitafloxacin (DU-6859a).

  2. Proteins aggregation and human diseases

    NASA Astrophysics Data System (ADS)

    Hu, Chin-Kun

    2015-04-01

    Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

  3. Marine aggregate dynamics

    NASA Astrophysics Data System (ADS)

    The direction and scope of the Office of Naval Research's Marine Aggregate Dynamics Accelerated Research Initiative will be the topic of an open-house style meeting February 14, 7:30-10:00 P.M. in Ballroom D of the Hyatt Regency New Orleans at the Louisiana Superdome. This meeting is scheduled during the AGU/American Society of Limnology and Oceanography Ocean Sciences Meeting February 12-16 in New Orleans.The critical focus of the ARI is the measurement and modeling of the dynamics of the biological, physical, chemical and molecular processes that drive aggregation and produce aggregates. This new ARI will provide funding in Fiscal Years 1991-1995 to identify and quantify mechanisms that determine the distribution, abundance and size spectrum of aggregated particulate matter in the ocean.

  4. A zeta potential value determines the aggregate's size of penta-substituted [60]fullerene derivatives in aqueous suspension whereas positive charge is required for toxicity against bacterial cells.

    PubMed

    Deryabin, Dmitry G; Efremova, Ludmila V; Vasilchenko, Alexey S; Saidakova, Evgeniya V; Sizova, Elena A; Troshin, Pavel A; Zhilenkov, Alexander V; Khakina, Ekaterina A; Khakina, Ekaterina E

    2015-08-08

    The cause-effect relationships between physicochemical properties of amphiphilic [60]fullerene derivatives and their toxicity against bacterial cells have not yet been clarified. In this study, we report how the differences in the chemical structure of organic addends in 10 originally synthesized penta-substituted [60]fullerene derivatives modulate their zeta potential and aggregate's size in salt-free and salt-added aqueous suspensions as well as how these physicochemical characteristics affect the bioenergetics of freshwater Escherichia coli and marine Photobacterium phosphoreum bacteria. Dynamic light scattering, laser Doppler micro-electrophoresis, agarose gel electrophoresis, atomic force microscopy, and bioluminescence inhibition assay were used to characterize the fullerene aggregation behavior in aqueous solution and their interaction with the bacterial cell surface, following zeta potential changes and toxic effects. Dynamic light scattering results indicated the formation of self-assembled [60]fullerene aggregates in aqueous suspensions. The measurement of the zeta potential of the particles revealed that they have different surface charges. The relationship between these physicochemical characteristics was presented as an exponential regression that correctly described the dependence of the aggregate's size of penta-substituted [60]fullerene derivatives in salt-free aqueous suspension from zeta potential value. The prevalence of DLVO-related effects was shown in salt-added aqueous suspension that decreased zeta potential values and affected the aggregation of [60]fullerene derivatives expressed differently for individual compounds. A bioluminescence inhibition assay demonstrated that the toxic effect of [60]fullerene derivatives against E. coli cells was strictly determined by their positive zeta potential charge value being weakened against P. phosphoreum cells in an aquatic system of high salinity. Atomic force microscopy data suggested that the

  5. Comparison of aerobic and anaerobic [3H]leucine incorporation assays for determining pollution-induced bacterial community tolerance in copper-polluted, irrigated soils.

    PubMed

    Aaen, Karoline Nolsø; Holm, Peter E; Priemé, Anders; Hung, Ngoc Ngo; Brandt, Kristian Koefoed

    2011-03-01

    Pollution-induced community tolerance (PICT) constitutes a sensitive and ecologically relevant impact parameter in ecotoxicology. We report the development and application of a novel anaerobic [(3) H]leucine incorporation assay and its comparison with the conventional aerobic [(3) H]leucine incorporation assay for PICT detection in soil bacterial communities. Selection of bacterial communities was performed over 42 d in bulk soil microcosms (no plants) and in rice (Oryza sativa) rhizosphere soil mesocosms. The following experimental treatments were imposed using a full factorial design: two soil types, two soil water regimes, and four Cu application rates (0, 30, 120, or 280 µg g(-1)). Bacterial communities in bulk soil microcosms exhibited similar Cu tolerance patterns when assessed by aerobic and anaerobic PICT assays, whereas aerobic microorganisms tended to be more strongly selected for Cu tolerance than anaerobic microorganisms in rhizosphere soil. Despite similar levels of water-extractable Cu, bacterial Cu tolerance was significantly higher in acid sulfate soil than in alluvial soil. Copper amendment selected for significant PICT development in soils subjected to alternate wetting and drying, but not in continuously flooded soils. Our results demonstrate that soil bacterial communities subjected to alternate wetting and drying may be more affected by Cu than bacterial communities subjected to continuous flooding. We conclude that the parallel use of anaerobic and aerobic [(3) H]leucine PICT assays constitutes a valuable improvement over existing procedures for PICT detection in irrigated soils and other redox gradient environments such as sediments and wetlands. Copyright © 2010 SETAC.

  6. Influence of soot aggregate size and internal multiple scattering on LII signal and the absorption function variation with wavelength determined by the TEW-LII method

    NASA Astrophysics Data System (ADS)

    Yon, J.; Therssen, E.; Liu, F.; Bejaoui, S.; Hebert, D.

    2015-05-01

    Laser-induced incandescence (LII) is a powerful and robust optical method for in situ determination of soot volume fraction and/or soot absorption/emission properties in flames and engine exhaust. The laser-induced signal is interpreted as thermal emission based on the Planck law. Up to now, the evaluation and interpretation of LII signal have been largely based on contributions from isolated primary particles that are assumed much smaller than wavelengths. In the present paper, the morphology, wavelength, and aggregate size-dependent effects of multiple scattering within fractal soot aggregates on their absorption and emission cross sections are taken into account in the evaluation of LII signal by proposing correction terms to the traditional model. The impact of accounting for the correction to soot aggregate emission due to multiple scattering on LII signal and on the two excitation wavelength-induced incandescence method for inferring the soot absorption function, E(m), is discussed. For wavelengths shorter than 532 nm, E(m, λ)/E(m, 1064 nm) increases more significantly with decreasing wavelength. For wavelengths longer than 532 nm, the wavelength dependence of E(m, λ)/E(m, 1064 nm) becomes very small and can be neglected. The proposed corrections, along with the soot morphology, are applied to re-analyze the experimental data of Bejaoui et al. (Appl Phys B Lasers Opt, 116:313, 2014) for deriving the relative soot absorption function variation with wavelength at different locations in a rich premixed methane flat flame at atmospheric pressure. The present analysis showed that the soot absorption function varies with the height above the burner exit and can be correlated with the degree of soot maturation.

  7. Anaerobic exercise in pediatric cystic fibrosis.

    PubMed

    Klijn, Peter H; Terheggen-Lagro, Suzanne W; Van Der Ent, Cornelis K; Van Der Net, Janjaap; Kimpen, Jan L; Helders, Paul J

    2003-09-01

    Anaerobic fitness is important for daily functioning of children with cystic fibrosis (CF). The aim of this study was to assess the determinants of anaerobic performance in CF. Anaerobic performance was measured in 39 children with CF (mean age, 13.2 +/- 1.8 (SD) years, forced expired volume in 1 sec (FEV(1)) 81.6 +/- 22.1% predicted), using a Wingate anaerobic test. Significant associations were found for peak power (PP) and mean power (MP) with fat-free mass (FFM) body weight, body mass index, maximal isometric muscle force, and aerobic capacity. Pulmonary function was correlated with anaerobic indices when controlled for FFM. Multiple regression analysis indicated that FFM and FEV(1) accounted for 82% and 86% of the variability in PP and MP, respectively. Patients with moderate CF (FEV(1) < 80%), as compared to mild CF (FEV(1) >/= 80%), had higher PP (difference = 85 W, 95% CI = 27-144 W) and MP (difference = 53 W, 95% CI = 42-63 W) at equivalent FFM. Our results indicate that FFM and pulmonary function are important determinants of anaerobic exercise performance in children with CF. With progression of pulmonary disease, anaerobic performance may be enhanced. Copyright 2003 Wiley-Liss, Inc.

  8. Molecular ecology of anaerobic reactor systems.

    PubMed

    Hofman-Bang, J; Zheng, D; Westermann, P; Ahring, B K; Raskin, L

    2003-01-01

    Anaerobic reactor systems are essential for the treatment of solid and liquid wastes and constitute a core facility in many waste treatment plants. Although much is known about the basic metabolism in different types of anaerobic reactors, little is known about the microbes responsible for these processes. Only a few percent of Bacteria and Archaea have so far been isolated, and almost nothing is known about the dynamics and interactions between these and other microorganisms. This lack of knowledge is most clearly exemplified by the sometimes unpredictable and unexplainable failures and malfunctions of anaerobic digesters occasionally experienced, leading to sub-optimal methane production and wastewater treatment. Using a variety of molecular techniques, we are able to determine which microorganisms are active, where they are active, and when they are active, but we still need to determine why and what they are doing. As genetic manipulations of anaerobes have been shown in only a few species permitting in-situ gene expression studies, the only way to elucidate the function of different microbes is to correlate the metabolic capabilities of isolated microbes in pure culture to the abundance of each microbe in anaerobic reactor systems by rRNA probing. This chapter focuses on various molecular techniques employed and problems encountered when elucidating the microbial ecology of anaerobic reactor systems. Methods such as quantitative dot blot/fluorescence in-situ probing using various specific nucleic acid probes are discussed and exemplified by studies of anaerobic granular sludge, biofilm and digester systems.

  9. Perception of Lay People Regarding Determinants of Health and Factors Affecting It: An Aggregated Analysis from 29 Countries

    PubMed Central

    ZAHRA, Aqeela; LEE, Eun-Whan; SUN, Li-Yuan; PARK, Jae-Hyun

    2015-01-01

    Background: This study aimed to evaluate the perception of lay people regarding determinants of health at global level and factors affecting it. Methods: Data was collected from International Social Survey Program (ISSP) and World Bank website. Multilevel regression analysis was done and lay people’s perception regarding health behavior, environment, poverty and genes as health determinants was assessed. Various socio demographic factors were used as independent variables. Results: The highest percentage of people agreed environment as determinant of health. An inverse relationship was observed between GNI quartiles and an individual’s agreement with poverty, health behavior, and environment as health determinant. There was a significant negative association of females with health damaging behavior (P<0.05) and positive association with environment and genes (P<0.05) as health determinants. Elderly people agreed with poverty as determinant of health (P<0.05). GNI was negatively related to environment (P<0.05) and poverty (P<0.05) as health determinant. Conclusion: The common public is now becoming aware of a broadened concept of health and people belonging to different backgrounds have different perceptions regarding determinants of health. Our results show that highest percentage of people agreed with environment as determinant of health, which is consistent with scientific view of increased burden of disease, caused by environmental factors. Thus, tailored health programs and policies that address an individual’s specific problems are likely to induce a change in behavior and attitude, hence decreasing the disease burden. PMID:26811813

  10. A quantitative method for determining the antiwashout characteristics of cement-based dental materials including mineral trioxide aggregate.

    PubMed

    Formosa, L M; Mallia, B; Camilleri, J

    2013-02-01

    To introduce and assess a novel method for measuring washout resistance of cement-based dental materials, including mineral trioxide aggregate (MTA), to qualitatively verify the results with a clinical simulation and to evaluate the washout resistance of a new root-end filling material. A method for assessment of washout resistance of root-end filling materials was developed by adapting the CRD-C 661-06 (a method for evaluating the resistance of freshly mixed concrete to washout in water), to permit testing of dental cements. White Portland cement (PC), MTA-Plus mixed with either water or a polymer-based antiwashout gel (MTA-AW), MTA-Angelus, IRM and amalgam were tested with either distilled water or HBSS as washout media. Additionally, the washout resistance was tested qualitatively by spraying the test materials at the terminus of simulated canals with a metered jet of water. A mass loss of 2-7% for PC, 0.4-4% for MTA-Plus, -0.9% for MTA-AW, 5-10% for MTA-Angelus and 0% for IRM and amalgam was recorded with the modified CRD-C 661-06 method. No significant difference was found between using water and HBSS as washout media for the same material. The results of the modified CRD-C 661-06 method were similar to those obtained on the simulated canals. The modified CRD-C 661-06 method provided repeatable results that were comparable to the simulated clinical method. The antiwashout gel used with MTA-Plus reduced the material washout and was similar to IRM and amalgam. © 2012 International Endodontic Journal.

  11. Customer Aggregation: An Opportunity for Green Power?

    SciTech Connect

    Holt, E.; Bird, L.

    2001-02-26

    We undertook research into the experience of aggregation groups to determine whether customer aggregation offers an opportunity to bring green power choices to more customers. The objectives of this report, therefore, are to (1) identify the different types of aggregation that are occurring today, (2) learn whether aggregation offers an opportunity to advance sales of green power, and (3) share these concepts and approaches with potential aggregators and green power advocates.

  12. How anaerobic is the Wingate Anaerobic Test for humans?

    PubMed

    Beneke, R; Pollmann, C; Bleif, I; Leithäuser, R M; Hütler, M

    2002-08-01

    The Wingate Anaerobic Test (WAnT) is generally used to evaluate anaerobic cycling performance, but knowledge of the metabolic profile of WAnT is limited. Therefore the energetics of WAnT was analysed with respect to working efficiency and performance. A group of 11 male subjects [mean (SD), age 21.6 (3.8) years, height 178.6 (6.6) cm, body mass 82.2 (12.1) kg] performed a maximal incremental exercise test and a WAnT. Lactic and alactic anaerobic energy outputs were calculated from net lactate production and the fast component of the kinetics of post-exercise oxygen uptake. Aerobic metabolism was determined from oxygen uptake during exercise. The WAnT mean power of 683 (96.0) W resulted from a total energy output above the value at rest of 128.1 (23.2) kJ x 30 s(-1) [mean metabolic power=4.3 (0.8) kW] corresponding to a working efficiency of 16.2 (1.6)%. The WAnT working efficiency was lower (P < 0.01) than the corresponding value of 24.1 (1.7)% at 362 (41) W at the end of an incremental exercise test. During WAnT the fractions of the energy from aerobic, anaerobic alactic and lactic acid metabolism were 18.6 (2.5)%, 31.1 (4.6)%, and 50.3 (5.1)%, respectively. Energy from metabolism of anaerobic lactic acid explained 83% and 81% of the variance of WAnT peak and mean power, respectively. The results indicate firstly that WAnT requires the use of more anaerobically derived energy than previously estimated, secondly that anaerobic metabolism is dominated by glycolysis, thirdly that WAnT mechanical efficiency is lower than that found in aerobic exercise tests, and fourthly that the latter finding partly explains discrepancies between previously published and the present data about the metabolic profile of WAnT.

  13. Fractal structure of asphaltene aggregates.

    PubMed

    Rahmani, Nazmul H G; Dabros, Tadeusz; Masliyah, Jacob H

    2005-05-15

    A photographic technique coupled with image analysis was used to measure the size and fractal dimension of asphaltene aggregates formed in toluene-heptane solvent mixtures. First, asphaltene aggregates were examined in a Couette device and the fractal-like aggregate structures were quantified using boundary fractal dimension. The evolution of the floc structure with time was monitored. The relative rates of shear-induced aggregation and fragmentation/restructuring determine the steady-state floc structure. The average floc structure became more compact or more organized as the floc size distribution attained steady state. Moreover, the higher the shear rate is, the more compact the floc structure is at steady state. Second, the fractal dimensions of asphaltene aggregates were also determined in a free-settling test. The experimentally determined terminal settling velocities and characteristic lengths of the aggregates were utilized to estimate the 2D and 3D fractal dimensions. The size-density fractal dimension (D(3)) of the asphaltene aggregates was estimated to be in the range from 1.06 to 1.41. This relatively low fractal dimension suggests that the asphaltene aggregates are highly porous and very tenuous. The aggregates have a structure with extremely low space-filling capacity.

  14. Construction aggregates

    USGS Publications Warehouse

    Tepordei, V.V.

    1996-01-01

    Part of the Annual Commodities Review 1995. Production of construction aggregates such as crushed stone and construction sand and gravel showed a marginal increase in 1995. Most of the 1995 increases were due to funding for highway construction work. The major areas of concern to the industry included issues relating to wetlands classification and the classification of crystalline silica as a probable human carcinogen. Despite this, an increase in demand is anticipated for 1996.

  15. Construction aggregates

    USGS Publications Warehouse

    Nelson, T.I.; Bolen, W.P.

    2007-01-01

    Construction aggregates, primarily stone, sand and gravel, are recovered from widespread naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size and sold loose or combined with portland cement or asphaltic cement to make concrete products to build roads, houses, buildings, and other structures. Much smaller quantities are used in agriculture, cement manufacture, chemical and metallurgical processes, glass production and many other products.

  16. Construction aggregates

    USGS Publications Warehouse

    Tepordei, V.V.

    1993-01-01

    Part of a special section on the market performance of industrial minerals in 1992. Production of construction aggregates increased by 4.6 percent in 1992. This increase was due, in part, to the increased funding for transportation and infrastructure projects. The U.S. produced about 1.05 Gt of crushed stone and an estimated 734 Mt of construction sand and gravel in 1992. Demand is expected to increase by about 5 percent in 1993.

  17. Determination of methanogenic pathways through carbon isotope (δ13C) analysis for the two-stage anaerobic digestion of high-solids substrates.

    PubMed

    Gehring, Tito; Klang, Johanna; Niedermayr, Andrea; Berzio, Stephan; Immenhauser, Adrian; Klocke, Michael; Wichern, Marc; Lübken, Manfred

    2015-04-07

    This study used carbon isotope (δ(13)C)-based calculations to quantify the specific methanogenic pathways in a two-stage experimental biogas plant composed of three thermophilic leach bed reactors (51-56 °C) followed by a mesophilic (36.5 °C) anaerobic filter. Despite the continuous dominance of the acetoclastic Methanosaeta in the anaerobic filter, the methane (CH4) fraction derived from carbon dioxide reduction (CO2), fmc, varied significantly over the investigation period of 200 days. At organic loading rates (OLRs) below 6.0 gCOD L(-1) d(-1), the average fmc value was 33%, whereas at higher OLRs, with a maximum level of 17.0 gCOD L(-1) d(-1), the fmc values reached 47%. The experiments allowed for a clear differentiation of the isotope fractionation related to the formation and consumption of acetate in both stages of the plant. Our data indicate constant carbon isotope fractionation for acetate formation at different OLRs within the thermophilic leach bed reactors as well as a negligible contribution of homoacetogenesis. These results present the first quantification of methanogenic pathway (fmc values) dynamics for a continually operated mesophilic bioreactor and highlight the enormous potential of δ(13)C analysis for a more comprehensive understanding of the anaerobic degradation processes in CH4-producing biogas plants.

  18. Aggregates, broccoli and cauliflower

    NASA Astrophysics Data System (ADS)

    Grey, Francois; Kjems, Jørgen K.

    1989-09-01

    Naturally grown structures with fractal characters like broccoli and cauliflower are discussed and compared with DLA-type aggregates. It is suggested that the branching density can be used to characterize the growth process and an experimental method to determine this parameter is proposed.

  19. Analyzing Data in a Repeated Measures Design: A Procedure Used To Determine If the Aggregate Data Should Be Analyzed.

    ERIC Educational Resources Information Center

    Fraas, John W.; And Others

    Researchers frequently deal with data that are cyclical in nature. This paper presents a methodological procedure that can be used to determine if a roller-coaster effect exists in repeated measures data. The procedure incorporates three key components. First, the researcher may find it necessary to analyze each participant's data set separately…

  20. 34 CFR 222.23 - How does a local educational agency determine the aggregate assessed value of its eligible...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... tax-exempt uses, such as public open space, schools, churches, and roads. The local official bases... as roads, parks, churches, and schools. The local official multiplies that proportion (.20) by the... determines base values on a three-year cycle, as follows: (i) The local official allocates expected uses to...

  1. 34 CFR 222.23 - How does a local educational agency determine the aggregate assessed value of its eligible...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... tax-exempt uses, such as public open space, schools, churches, and roads. The local official bases... as roads, parks, churches, and schools. The local official multiplies that proportion (.20) by the... determines base values on a three-year cycle, as follows: (i) The local official allocates expected uses to...

  2. 34 CFR 222.23 - How does a local educational agency determine the aggregate assessed value of its eligible...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... tax-exempt uses, such as public open space, schools, churches, and roads. The local official bases... as roads, parks, churches, and schools. The local official multiplies that proportion (.20) by the... determines base values on a three-year cycle, as follows: (i) The local official allocates expected uses to...

  3. 34 CFR 222.23 - How does a local educational agency determine the aggregate assessed value of its eligible...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... tax-exempt uses, such as public open space, schools, churches, and roads. The local official bases... as roads, parks, churches, and schools. The local official multiplies that proportion (.20) by the... determines base values on a three-year cycle, as follows: (i) The local official allocates expected uses to...

  4. 34 CFR 222.23 - How does a local educational agency determine the aggregate assessed value of its eligible...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... tax-exempt uses, such as public open space, schools, churches, and roads. The local official bases... as roads, parks, churches, and schools. The local official multiplies that proportion (.20) by the... determines base values on a three-year cycle, as follows: (i) The local official allocates expected uses to...

  5. Analyzing Data in a Repeated Measures Design: A Procedure Used To Determine If the Aggregate Data Should Be Analyzed.

    ERIC Educational Resources Information Center

    Fraas, John W.; And Others

    Researchers frequently deal with data that are cyclical in nature. This paper presents a methodological procedure that can be used to determine if a roller-coaster effect exists in repeated measures data. The procedure incorporates three key components. First, the researcher may find it necessary to analyze each participant's data set separately…

  6. Anaerobic thermophilic culture

    DOEpatents

    Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

    1981-01-01

    A newly discovered thermophilic anaerobe is described that was isolated in a biologically pure culture and designated Thermoanaerobacter ethanolicus ATCC 3/550. T. Ethanolicus is cultured in aqueous nutrient medium under anaerobic, thermophilic conditions and is used in a novel process for producing ethanol by subjecting carbohydrates, particularly the saccharides, to fermentation action of the new microorganism in a biologically pure culture.

  7. Anaerobic bag culture method.

    PubMed Central

    Rosenblatt, J E; Stewart, P R

    1975-01-01

    In a new method of anaerobic culture, a transparent, gas-impermeable bag is used and the anaerobic environment is established with copper sulfate-saturated steel wool. An Alka-Seltzer tablet generates carbon dioxide. The agar plate surface can be inspected through the bag at any time without interrupting the anaerobic atmosphere or disturbing other specimens. Methylene blue indicator strips are completely reduced by 4 h after the bag is set up and have remained reduced for as long as 3 weeks. Growth of 16 different stock culture anaerobes was generally equivalent by the bag and GasPak jar methods. Yield and growth of anaerobic isolates also were equivalent with 7 of 10 clinical specimens; from the other 3 specimens, 13 isolates were recovered, 5 by both the bag and jar methods and the rest by one method or the other. No consistent differences were found between the anaerobic bag and GasPak jar methods in the yield of anaerobes from clinical specimens. Early growth (24 h of incubation) of anaerobes from one specimen was detected with the bag method. Images PMID:1100671

  8. Anaerobic bag culture method.

    PubMed

    Rosenblatt, J E; Stewart, P R

    1975-06-01

    In a new method of anaerobic culture, a transparent, gas-impermeable bag is used and the anaerobic environment is established with copper sulfate-saturated steel wool. An Alka-Seltzer tablet generates carbon dioxide. The agar plate surface can be inspected through the bag at any time without interrupting the anaerobic atmosphere or disturbing other specimens. Methylene blue indicator strips are completely reduced by 4 h after the bag is set up and have remained reduced for as long as 3 weeks. Growth of 16 different stock culture anaerobes was generally equivalent by the bag and GasPak jar methods. Yield and growth of anaerobic isolates also were equivalent with 7 of 10 clinical specimens; from the other 3 specimens, 13 isolates were recovered, 5 by both the bag and jar methods and the rest by one method or the other. No consistent differences were found between the anaerobic bag and GasPak jar methods in the yield of anaerobes from clinical specimens. Early growth (24 h of incubation) of anaerobes from one specimen was detected with the bag method.

  9. The self-assemble of natural cyclodextrins in aqueous solutions: Application of miniature permeation studies for critical aggregation concentration (cac) determinations.

    PubMed

    Saokham, Phennapha; Sá Couto, André; Ryzhakov, Alexey; Loftsson, Thorsteinn

    2016-05-30

    Permeation techniques can be applied to determine the critical aggregation concentration (cac) of natural cyclodextrins (CDs) in aqueous solutions although the method is both laborious and time consuming. In the present study, the permeation technique was modified and the influence of osmotic pressure, sampling time, CD concentration and molecular weight-cut off (MWCO) of the membrane were investigated in two different permeation units, that is Franz diffusion cells and Slide-A-Lyzer™ MINI Dialysis. While both the osmotic pressure and CD concentration affect the steady state flux in both permeation units, effects of sampling time and the MWCO of the mounted membrane were only observed in the Franz diffusion cells. The osmotic effect was negligible in the Slide-A-Lyzer™ MINI Dialysis units. The modified permeation technique using Slide-A-Lyzer™ MINI Dialysis units was then used to determine the cac of natural CDs in water. The cac of αCD, βCD and γCD was 1.19±0.17, 0.69±0.05 and 0.93±0.04% (w/v), respectively. The results indicated that the cac values depended on their intrinsic solubility. Moreover, the cac value of γCD in aqueous hydrocortisone/γCD inclusion complex solution was identical to the γCD cac value determined in pure water. Copyright © 2016 Elsevier B.V. All rights reserved.

  10. Aggregation dynamics of rigid polyelectrolytes

    NASA Astrophysics Data System (ADS)

    Tom, Anvy Moly; Rajesh, R.; Vemparala, Satyavani

    2016-01-01

    Similarly charged polyelectrolytes are known to attract each other and aggregate into bundles when the charge density of the polymers exceeds a critical value that depends on the valency of the counterions. The dynamics of aggregation of such rigid polyelectrolytes are studied using large scale molecular dynamics simulations. We find that the morphology of the aggregates depends on the value of the charge density of the polymers. For values close to the critical value, the shape of the aggregates is cylindrical with height equal to the length of a single polyelectrolyte chain. However, for larger values of charge, the linear extent of the aggregates increases as more and more polymers aggregate. In both the cases, we show that the number of aggregates decrease with time as power laws with exponents that are not numerically distinguishable from each other and are independent of charge density of the polymers, valency of the counterions, density, and length of the polyelectrolyte chain. We model the aggregation dynamics using the Smoluchowski coagulation equation with kernels determined from the molecular dynamics simulations and justify the numerically obtained value of the exponent. Our results suggest that once counterions condense, effective interactions between polyelectrolyte chains short-ranged and the aggregation of polyelectrolytes are diffusion-limited.

  11. Sequence-dependent internalization of aggregating peptides.

    PubMed

    Couceiro, José R; Gallardo, Rodrigo; De Smet, Frederik; De Baets, Greet; Baatsen, Pieter; Annaert, Wim; Roose, Kenny; Saelens, Xavier; Schymkowitz, Joost; Rousseau, Frederic

    2015-01-02

    Recently, a number of aggregation disease polypeptides have been shown to spread from cell to cell, thereby displaying prionoid behavior. Studying aggregate internalization, however, is often hampered by the complex kinetics of the aggregation process, resulting in the concomitant uptake of aggregates of different sizes by competing mechanisms, which makes it difficult to isolate pathway-specific responses to aggregates. We designed synthetic aggregating peptides bearing different aggregation propensities with the aim of producing modes of uptake that are sufficiently distinct to differentially analyze the cellular response to internalization. We found that small acidic aggregates (≤500 nm in diameter) were taken up by nonspecific endocytosis as part of the fluid phase and traveled through the endosomal compartment to lysosomes. By contrast, bigger basic aggregates (>1 μm) were taken up through a mechanism dependent on cytoskeletal reorganization and membrane remodeling with the morphological hallmarks of phagocytosis. Importantly, the properties of these aggregates determined not only the mechanism of internalization but also the involvement of the proteostatic machinery (the assembly of interconnected networks that control the biogenesis, folding, trafficking, and degradation of proteins) in the process; whereas the internalization of small acidic aggregates is HSF1-independent, the uptake of larger basic aggregates was HSF1-dependent, requiring Hsp70. Our results show that the biophysical properties of aggregates determine both their mechanism of internalization and proteostatic response. It remains to be seen whether these differences in cellular response contribute to the particular role of specific aggregated proteins in disease.

  12. Anaerobic Digestion and its Applications

    EPA Science Inventory

    Anaerobic digestion is a natural biological process. The initials "AD" may refer to the process of anaerobic digestion, or the built systems of anaerobic digesters. While there are many kinds of digesters, the biology is basically the same for all. Anaerobic digesters are built...

  13. Anaerobic Digestion and its Applications

    EPA Science Inventory

    Anaerobic digestion is a natural biological process. The initials "AD" may refer to the process of anaerobic digestion, or the built systems of anaerobic digesters. While there are many kinds of digesters, the biology is basically the same for all. Anaerobic digesters are built...

  14. Molecular-level insights of early-stage prion protein aggregation on mica and gold surface determined by AFM imaging and molecular simulation.

    PubMed

    Lou, Zhichao; Wang, Bin; Guo, Cunlan; Wang, Kun; Zhang, Haiqian; Xu, Bingqian

    2015-11-01

    By in situ time-lapse AFM, we investigated early-stage aggregates of PrP formed at low concentration (100 ng/mL) on mica and Au(111) surfaces in acetate buffer (pH 4.5). Remarkably different PrP assemblies were observed. Oligomeric structures of PrP aggregates were observed on mica surface, which was in sharp contrast to the multi-layer PrP aggregates yielding parallel linear patterns observed Au(111) surface. Combining molecular dynamics and docking simulations, PrP monomers, dimers and trimers were revealed as the basic units of the observed aggregates. Besides, the mechanisms of the observed PrP aggregations and the corresponding molecular-substrate and intermolecular interactions were suggested. These interactions involved gold-sulfur interaction, electrostatic interaction, hydrophobic interaction, and hydrogen binding interaction. In contrast, the PrP aggregates observed in pH 7.2 PBS buffer demonstrated similar large ball-like structures on both mica and Au(111) surfaces. The results indicate that the pH of a solution and the surface of the system can have strong effects on supramolecular assemblies of prion proteins. This study provides in-depth understanding on the structural and mechanistic nature of PrP aggregation, and can be used to study the aggregation mechanisms of other proteins with similar misfolding properties.

  15. Modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction combined with spectrofluorimetry for trace determination of ofloxacin in pharmaceutical and biological samples

    PubMed Central

    Zeeb, M.; Ganjali, M.R.; Norouzi, P.

    2011-01-01

    Background and the purpose of the study Ofloxacin is a quinolone synthetic antibiotic, which acts against resistant mutants of bacteria by inhibiting DNA gyrase. This antibacterial agent is widely used in the treatment of respiratory tract, urinary tract and tissue-based infections, which are caused by Gram-positive and Gram-negative bacteria. In this work, an efficient modified ionic liquid cold-induced aggregation dispersive liquid-liquid microextraction (M-IL-CIA-DLLME) was combined with spectrofluorimetry for trace determination of ofloxacin in real samples. Methods In this microextraction method, hydrophobic 1-hexyl-3-methylimidazolium hexafluorophosphate ([Hmim] [PF6]) ionic liquid (IL) as a microextraction solvent was dispersed into a heated sample solution containing sodium hexafluorophosphate (NaPF6) (as a common ion) and the analyte of interest. Afterwards, the resultant solution was cooled in an ice-water bath and a cloudy condition was formed due to a considerable decrease of IL solubility. After centrifuging, the enriched phase was introduced to the spectrofluorimeter for the determination of ofloxacin. Results and major conclusion In this technique, the performance of the microextraction method was not influenced by variations in the ionic strength of the sample solution (up to 30% w/v). Furthermore, [Hmim][PF6] IL was chosen as a green microextraction phase and an alternative to traditional toxic organic solvents. Different parameters affecting the analytical performance were studied and optimized. At optimum conditions, a relatively broad linear dynamic range of 0.15-125 µg l-1 and a limit of detection (LOD) of 0.029 µg l-1 were obtained. The relative standard deviation (R.S.D.) obtained for the determination of five replicates of the 10 ml solution containing 50 µg l-1 ofloxacin was 2.7%. Finally, the combined methodology was successfully applied to ofloxacin determination in actual pharmaceutical formulations and biological samples. PMID

  16. Measurement of anaerobic work capacities in humans.

    PubMed

    Green, S

    1995-01-01

    The development of simple, noninvasive tests of work capacities, underpinned primarily by anaerobic metabolism, proliferated in the early 1970s. A 30-second maximal cycle test developed at the Wingate Institute initiated efforts to develop work tests of anaerobic capacities. Such tests can be developed using any ergometer which simulates competitive conditions and enables an accurate determination of mechanical work output. A 10-second all-out test is commonly used to measure maximal work output generated primarily via the hydrolysis of high-energy phosphagens (i.e. the alactic work capacity). In contrast, a variety of constant-load and all-out tests of anaerobic (alactic plus lactic) work capacity have been proposed. It has been suggested that all-out tests provide more information about physiological capabilities and are easier to apply than constant-load tests. The optimal duration for an all-out test of anaerobic work capacity is proposed at 30 seconds, a duration which may also provide the basis for the development of accurate field tests of anaerobic capacity. There is evidence that the y-intercept of the maximal work-derivation regression is a valid work estimate of anaerobic capacity in athletes, although its utility is undermined by the number of tests required for its derivation.

  17. Anaerobic brain abscess

    PubMed Central

    Sudhaharan, Sukanya; Chavali, Padmasri

    2016-01-01

    Background and Objectives: Brain abscess remains a potentially fatal central nervous system (CNS) disease, especially in developing countries. Anaerobic abscess is difficult to diagnose because of cumbersome procedures associated with the isolation of anaerobes. Materials and Methods: This is a hospital-based retrospective microbiological analysis of 430 brain abscess materials (purulent aspirates and/or tissue), for anaerobic organisms, that were received between 1987–2014, by the Microbiology Laboratory in our Institute. Results: Culture showed growth of bacteria 116/430 (27%) of the cases of which anaerobes were isolated in 48/116 (41.1%) of the cases. Peptostreptococcus (51.4 %), was the predominant organism isolated in four cases followed by Bacteroides and Peptococcus species. Conclusion: Early diagnosis and detection of these organisms would help in the appropriate management of these patients. PMID:27307977

  18. Anaerobic protocol for assessing industrial waste treatability

    SciTech Connect

    Young, J.C.; Khandaker, N.R.

    1996-11-01

    Recent promulgation of strict standards for industrial waste pretreatment has greatly increased the number of wastewaters that are candidates for anaerobic treatment. The challenge with industrial wastes is to determine the potential for anaerobic biodegradation prior to investing large amounts of time and expense in design and field investigation. Various methods have been used to assess the treatability of industrial wastewaters, but the methodology has varied significantly. In response to the need for a consistent procedure for determining the treatability of different industrial wastewaters by anaerobic processes, Young developed an anaerobic treatability screening protocol. The purpose of this paper is to describe the protocol and to report a number of case studies in which the test protocol was used to determine the feasibility of using anaerobic processes for treating specific industrial wastes. Specific examples include food processing wastes, chemical production wastes, petroleum wastes, and landfill leachate. Treatability was based on assessment of the rate and extent of biodegradation, identification of the presence of toxic substances, and dilution effects.

  19. Can common exercise indices determine peak exercise oxygen consumption and anaerobic threshold during stress testing in patients with chronic congestive heart failure?

    PubMed

    Chandrashekhar, Y; Anand, I S

    1993-01-01

    Maximal oxygen consumption (VO2 max) is one of the most important predictors of prognosis in chronic heart failure and is now used to define degree of heart failure. While most centres can routinely do treadmill exercise testing (TMT), VO2 max measurements are not widely available. We, therefore, analysed the ability to predict VO2 max from common TMT variables: Peak exercise heart rate, exercise time, and METS achieved in 26 patients with chronic congestive heart failure (NYHA II-III, ejection fraction 43 +/- 2%) in whom exercise VO2 studies were simultaneously done by breath to breath expiratory gas analysis using a metabolic cart. METS achieved during exercise and exercise time correlated reasonably well although not perfectly (r = 0.78 & 0.73 respectively, tail critical value +/-0.41). Resting ejection fraction did not correlate at all (r = 0.0004). The regression equation (2.7) (METS) + 5.8 defined VO2 max with SE of 0.47. Although in unvariate analysis, exercise time, METS achieved & peak heart rate predicted VO2 max, only METS achieved was predictive in step wise regression. None of the parameters predicted the anaerobic threshold accurately although there was a modest relation between AT and peak exercise VO2. We conclude that most exercise variables do not accurately predict VO2 max in patients with chronic congestive heart failure. METS achieved is the best predictor and the VO2 max can be predicted using a regression equation. Anaerobic threshold cannot be predicted without tests involving expiratory gas analysis.

  20. Hydrogen-bonding recognition-induced aggregation of gold nanoparticles for the determination of the migration of melamine monomers using dynamic light scattering.

    PubMed

    Wu, Long; Chen, Kun; Lu, Zhicheng; Li, Tingting; Shao, Kang; Shao, Feng; Han, Heyou

    2014-10-03

    The migration of melamine monomers from food contact materials has aroused particular attention since the 2008 melamine-tainted milk scandal in China. However, the determination of melamine monomer's migratory quantity (MMMQ) has remained an open question because of the complex sample pretreatment and the low sensitivity. Based on the hydrogen bonding interaction between DNA thymine and melamine, this paper described a simple and rapid method focusing on the measurement of MMMQ from melamine tableware by gold nanoparticles (GNPs) and dynamic light scattering (DLS). With the presence of probe DNA (p-DNA), the GNPs were stable in NaCl solution (0.06 M), whereas they became aggregated when the p-DNA hybridized with melamine. The change in the hydrodynamic diameter of GNPs could be detected by DLS technology. Under the optimal conditions, the average diameter increased linearly with the concentration of melamine over the range from 5.0 to 320.0 μg L(-1), and showed a detection limit of 2.0 μg L(-1) (3σ/slope). The MMMQ was investigated within a range from 6.00×10(-4) to 2.58×10(-1) mg dm(-2) (n≥3) in four different food simulants at different temperatures and time points. The results suggest that the DLS method has great potential in the analysis of the migration of melamine monomers. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Field response of Colorado potato beetle to the (R)-enantiomer of the male-produced aggregation pheromone CPB I and determination of activity of blends of the (S)- and (R)-enantiomers of the pheromone

    USDA-ARS?s Scientific Manuscript database

    Adult Colorado potato beetles (CPB) are attracted to (S)-3,7-dimethyl-2-oxo-oct-6-ene-1,3-diol [(S)-CPB I], a male-produced aggregation pheromone. Studies were conducted to determine if the opposite enantiomer of the pheromone, (R)-CPB I had an effect on CPB in the field. Results revealed no differe...

  2. Protein Aggregation/Folding: The Role of Deterministic Singularities of Sequence Hydrophobicity as Determined by Nonlinear Signal Analysis of Acylphosphatase and Aβ(1–40)

    PubMed Central

    Zbilut, Joseph P.; Colosimo, Alfredo; Conti, Filippo; Colafranceschi, Mauro; Manetti, Cesare; Valerio, MariaCristina; Webber, Charles L.; Giuliani, Alessandro

    2003-01-01

    The problem of protein folding vs. aggregation was investigated in acylphosphatase and the amyloid protein Aβ(1–40) by means of nonlinear signal analysis of their chain hydrophobicity. Numerical descriptors of recurrence patterns provided the basis for statistical evaluation of folding/aggregation distinctive features. Static and dynamic approaches were used to elucidate conditions coincident with folding vs. aggregation using comparisons with known protein secondary structure classifications, site-directed mutagenesis studies of acylphosphatase, and molecular dynamics simulations of amyloid protein, Aβ(1–40). The results suggest that a feature derived from principal component space characterized by the smoothness of singular, deterministic hydrophobicity patches plays a significant role in the conditions governing protein aggregation. PMID:14645049

  3. Grain size determination in nano-scale polycrystalline aggregates by precession illumination-hollow cone dark field imaging in the transmission electron microscope

    SciTech Connect

    Kulovits, A.K. Facco, G.; Wiezorek, J.M.K.

    2012-01-15

    Precession illumination hollow cone dark field (PI-HCDF) transmission electron microscopy (TEM) provides high contrast multi-beam dark field images, which are suitable for effective and robust grain size measurements in nano-scale polycrystalline aggregates. Precession illumination with slightly converged electron beam probes and precession angles up to 3 Degree-Sign has been produced using a computer-controlled system using a JEOL JEM 2000FX TEM instrument. Theoretical and practical aspects of the experimental technique are discussed using example precession illumination hollow cone diffraction patterns from single crystalline NiAl and the importance of selecting the appropriate precession angle for PI-HCDF image formation and interpretation is described. Results obtained for precession illumination are compared with those of conventional parallel beam illumination experiments. Nanocrystalline Al has been used to evaluate the influence of the precession angle on PI-HCDF image contrast with a focus on grain size analysis. PI-HCDF imaging has been applied for grain size measurements in regions of a nanocrystalline Al thin film adjacent to the edge of a pulsed laser melted and rapidly solidified region and determined the dimensions of a heat-affected zone. - Highlights: Black-Right-Pointing-Pointer New TEM method for grain size measurements combines TEM resolution with obtainability of statistically significant data sets. Black-Right-Pointing-Pointer We use precession illumination to produce time precession illumination hollow cone diffraction patterns PI-HCDP. Black-Right-Pointing-Pointer Contrast in dark field images (PI-HCDF) formed from PI-HCDP is easy to interpret as dynamical effects are reduced. Black-Right-Pointing-Pointer PI-HCDFs use several time-averaged g-rings simultaneously and contain more information than conventional DF-images. Black-Right-Pointing-Pointer Easy contrast interpretation and less dark field images required, allows fast, robust and

  4. Spatial and seasonal factors are key determinants in the aggregation of helminths in their definitive hosts: Pseudamphistomum truncatum in otters (Lutra lutra).

    PubMed

    Sherrard-Smith, E; Perkins, S E; Chadwick, E A; Cable, J

    2015-01-01

    Parasites are typically aggregated within their host populations. The most heavily infected hosts are frequently cited as targets for optimal disease control. Yet a heavily infected individual is not necessarily highly infective and does not automatically contribute a higher proportion of infective parasitic stages than a host with fewer parasites. Here, Pseudamphistomum truncatum (Opisthorchiida) parasitic infection within the definitive otter host (Lutra lutra) is used as a model system. The hypothesis tested is that variation in parasite abundance, aggregation and egg production (fecundity, as a proxy of host infectivity) can be explained by abiotic (season and region) or biotic (host age, sex and body condition) factors. Parasite abundance was affected most strongly by the biotic factors of age and body condition, such that adults and otters with a higher condition index had heavier infections than sub-adults or those with a lower condition index, whilst there were no significant differences in parasite abundance among the seasons, regions (ecological regions defined by river catchment boundaries) or host sexes. Conversely, parasite aggregation was affected most strongly by the abiotic factors of season and region, which were supported by four different measures of parasite aggregation (the corrected moment estimate k, Taylor's Power Law, the Index of Discrepancy D, and Boulinier's J). Pseudamphistomum truncatum was highly aggregated within otters, with aggregation stronger in the Midlands (England) and Wales than in the southwestern region of the United Kingdom. Overall, more parasites were found in fewer hosts during the summer, which coincides with the summer peak in parasite fecundity. Combined, these data suggest that (i) few otters carry the majority of P. truncatum parasites and that there are more infective stages (eggs) produced during summer; and (ii) abiotic factors are most influential when describing parasite aggregation whilst biotic factors have

  5. Oligomeric baroeffect and gas aggregation states

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1992-01-01

    The baroeffect is analyzed to include a gas that aggregates into higher-order polymers or oligomers. The resulting pressure change is found to vary independently of the molecular weight of the gas components and to depend only on the aggregation or oligomeric order of the gas. With increasing aggregation, diffusive slip velocities are found to increase. The calculations are extended to include general counterdiffusion of two distinct aggregation states (k-, j-mer) for the gas, and the pressure change is derived as a function that is independent of both molecular weight and the absolute aggregation. The only parameter that determines the baroeffect is the ratio of aggregated states, beta = k/j. For gases that reversibly aggregate, possible oscillatory behavior and complex dynamics for pressure are discussed. Gas aggregation may play a role for low-temperature crystal-growth conditions in which vapor concentrations of one (or more) species are high.

  6. Distribution of chromium contamination and microbial activity in soil aggregates.

    PubMed

    Tokunaga, Tetsu K; Wan, Jiamin; Hazen, Terry C; Schwartz, Egbert; Firestone, Mary K; Sutton, Stephen R; Newville, Matthew; Olson, Keith R; Lanzirotti, Antonio; Rao, William

    2003-01-01

    Biogeochemical transformations of redox-sensitive chemicals in soils can be strongly transport-controlled and localized. This was tested through experiments on chromium diffusion and reduction in soil aggregates that were exposed to chromate solutions. Reduction of soluble Cr(VI) to insoluble Cr(II) occurred only within the surface layer of aggregates with higher available organic carbon and higher microbial respiration. Sharply terminated Cr diffusion fronts develop when the reduction rate increases rapidly with depth. The final state of such aggregates consists of a Cr-contaminated exterior, and an uncontaminated core, each having different microbial community compositions and activity. Microbial activity was significantly higher in the more reducing soils, while total microbial biomass was similar in all of the soils. The small fraction of Cr(VI) remaining unreduced resides along external surfaces of aggregates, leaving it potentially available to future transport down the soil profile. Using the Thiele modulus, Cr(VI) reduction in soil aggregates is shown to be diffusion rate- and reaction rate-limited in anaerobic and aerobic aggregates, respectively. Thus, spatially resolved chemical and microbiological measurements are necessary within anaerobic soil aggregates to characterize and predict the fate of Cr contamination. Typical methods of soil sampling and analyses that average over redox gradients within aggregates can erase important biogeochemical spatial relations necessary for understanding these environments.

  7. Gender comparisons in anaerobic power and anaerobic capacity tests.

    PubMed Central

    Maud, P J; Shultz, B B

    1986-01-01

    The purpose of the study was to compare anaerobic power and anaerobic capacity test scores between young active men and women. Three performance measures of anaerobic power and two of anaerobic capacity were administered to a sample comprising 52 male and 50 female college students (means age = 21.4 yrs). Results indicated significant differences between men and women in body height, weight and per cent fat, in fat free mass (FFM), anaerobic power, and anaerobic capacity when recorded as gross work completed and relative to body weight. However, these differences are reduced when data is adjusted for body weight and further reduced when corrected for FFM. The study found no significant differences between men and women in either anaerobic power or anaerobic capacity when values were given relative to FFM. PMID:3730753

  8. Carbon Flux Analysis by 13C Nuclear Magnetic Resonance To Determine the Effect of CO2 on Anaerobic Succinate Production by Corynebacterium glutamicum

    PubMed Central

    Radoš, Dušica; Turner, David L.; Fonseca, Luís L.; Carvalho, Ana Lúcia; Blombach, Bastian; Eikmanns, Bernhard J.; Neves, Ana Rute

    2014-01-01

    Wild-type Corynebacterium glutamicum produces a mixture of lactic, succinic, and acetic acids from glucose under oxygen deprivation. We investigated the effect of CO2 on the production of organic acids in a two-stage process: cells were grown aerobically in glucose, and subsequently, organic acid production by nongrowing cells was studied under anaerobic conditions. The presence of CO2 caused up to a 3-fold increase in the succinate yield (1 mol per mol of glucose) and about 2-fold increase in acetate, both at the expense of l-lactate production; moreover, dihydroxyacetone formation was abolished. The redistribution of carbon fluxes in response to CO2 was estimated by using 13C-labeled glucose and 13C nuclear magnetic resonance (NMR) analysis of the labeling patterns in end products. The flux analysis showed that 97% of succinate was produced via the reductive part of the tricarboxylic acid cycle, with the low activity of the oxidative branch being sufficient to provide the reducing equivalents needed for the redox balance. The flux via the pentose phosphate pathway was low (∼5%) regardless of the presence or absence of CO2. Moreover, there was significant channeling of carbon to storage compounds (glycogen and trehalose) and concomitant catabolism of these reserves. The intracellular and extracellular pools of lactate and succinate were measured by in vivo NMR, and the stoichiometry (H+:organic acid) of the respective exporters was calculated. This study shows that it is feasible to take advantage of natural cellular regulation mechanisms to obtain high yields of succinate with C. glutamicum without genetic manipulation. PMID:24610842

  9. Carbon flux analysis by 13C nuclear magnetic resonance to determine the effect of CO2 on anaerobic succinate production by Corynebacterium glutamicum.

    PubMed

    Radoš, Dušica; Turner, David L; Fonseca, Luís L; Carvalho, Ana Lúcia; Blombach, Bastian; Eikmanns, Bernhard J; Neves, Ana Rute; Santos, Helena

    2014-05-01

    Wild-type Corynebacterium glutamicum produces a mixture of lactic, succinic, and acetic acids from glucose under oxygen deprivation. We investigated the effect of CO2 on the production of organic acids in a two-stage process: cells were grown aerobically in glucose, and subsequently, organic acid production by nongrowing cells was studied under anaerobic conditions. The presence of CO2 caused up to a 3-fold increase in the succinate yield (1 mol per mol of glucose) and about 2-fold increase in acetate, both at the expense of l-lactate production; moreover, dihydroxyacetone formation was abolished. The redistribution of carbon fluxes in response to CO2 was estimated by using (13)C-labeled glucose and (13)C nuclear magnetic resonance (NMR) analysis of the labeling patterns in end products. The flux analysis showed that 97% of succinate was produced via the reductive part of the tricarboxylic acid cycle, with the low activity of the oxidative branch being sufficient to provide the reducing equivalents needed for the redox balance. The flux via the pentose phosphate pathway was low (~5%) regardless of the presence or absence of CO2. Moreover, there was significant channeling of carbon to storage compounds (glycogen and trehalose) and concomitant catabolism of these reserves. The intracellular and extracellular pools of lactate and succinate were measured by in vivo NMR, and the stoichiometry (H(+):organic acid) of the respective exporters was calculated. This study shows that it is feasible to take advantage of natural cellular regulation mechanisms to obtain high yields of succinate with C. glutamicum without genetic manipulation.

  10. Anaerobic acidogenesis of dairy manure

    SciTech Connect

    Krones, M.J.

    1989-01-01

    The objective of this research was to determine if high rate acidogenic fermentation of dairy manure was possible, Whole dairy manure was ground and diluted to 4% total solids and fed to a 10 L anaerobic chemostat operating at 35C and with hydraulic retention times varying between 6 and 50 hours. Several physical and organic parameters of the influent and effluent were measured and compared. The results indicated that the manure was too refractory for high rate liquefaction and hydrolysis. A second experiment was conducted using the same techniques and substrate but varying the substrate pH between 5 and 7. The objectives were to further investigate the pH sensitivity of the acidogenic process and to determine if, by introducing a substrate with a low pH, acidogenesis might proceed more efficiently. The primary result of decreasing the pH was a smaller proportion of methane and an increased proportion of hydrogen in the gas. Liquefaction and hydrolysis continued to be rate limiting and appeared to be a major impediment to two phase anaerobic treatment of dairy manure.

  11. ANAEROBIC BIOLOGICAL TREATMENT OF PRODUCED WATER

    SciTech Connect

    John R. Gallagher

    2001-07-31

    During the production of oil and gas, large amounts of water are brought to the surface and must be disposed of in an environmentally sensitive manner. This is an especially difficult problem in offshore production facilities where space is a major constraint. The chief regulatory criterion for produced water is oil and grease. Most facilities have little trouble meeting this criterion using conventional oil-water separation technologies. However, some operations have significant amounts of naphthenic acids in the water that behave as oil and grease but are not well removed by conventional technologies. Aerobic biological treatment of naphthenic acids in simulated-produced water has been demonstrated by others; however, the system was easily overloaded by the large amounts of low-molecular-weight organic acids often found in produced waters. The objective of this research was to determine the ability of an anaerobic biological system to treat these organic acids in a simulated produced water and to examine the potential for biodegradation of the naphthenic acids in the anaerobic environment. A small fixed-film anaerobic biological reactor was constructed and adapted to treat a simulated produced water. The bioreactor was tubular, with a low-density porous glass packing material. The inocula to the reactor was sediment from a produced-water holding pond from a municipal anaerobic digester and two salt-loving methanogenic bacteria. During start-up, the feed to the reactor contained glucose as well as typical produced-water components. When glucose was used, rapid gas production was observed. However, when glucose was eliminated and the major organic component was acetate, little gas was generated. Methane production from acetate may have been inhibited by the high salt concentrations, by sulfide, or because of the lack, despite seeding, of microbes capable of converting acetate to methane. Toluene, a minor component of the produced water (0.1 g/L) was removed in the

  12. Anaerobic thermophilic culture system

    DOEpatents

    Ljungdahl, Lars G.; Wiegel, Jurgen K. W.

    1981-01-01

    A mixed culture system of the newly discovered microorganism Thermoanaerobacter ethanolicus ATCC31550 and the microorganism Clostridium thermocellum ATCC31549 is described. In a mixed nutrient culture medium that contains cellulose, these microorganisms have been coupled and cultivated to efficiently ferment cellulose to produce recoverable quantities of ethanol under anaerobic, thermophilic conditions.

  13. The anaerobic digestion process

    SciTech Connect

    Rivard, C.J.; Boone, D.R.

    1996-01-01

    The microbial process of converting organic matter into methane and carbon dioxide is so complex that anaerobic digesters have long been treated as {open_quotes}black boxes.{close_quotes} Research into this process during the past few decades has gradually unraveled this complexity, but many questions remain. The major biochemical reactions for forming methane by methanogens are largely understood, and evolutionary studies indicate that these microbes are as different from bacteria as they are from plants and animals. In anaerobic digesters, methanogens are at the terminus of a metabolic web, in which the reactions of myriads of other microbes produce a very limited range of compounds - mainly acetate, hydrogen, and formate - on which the methanogens grow and from which they form methane. {open_quotes}Interspecies hydrogen-transfer{close_quotes} and {open_quotes}interspecies formate-transfer{close_quotes} are major mechanisms by which methanogens obtain their substrates and by which volatile fatty acids are degraded. Present understanding of these reactions and other complex interactions among the bacteria involved in anaerobic digestion is only now to the point where anaerobic digesters need no longer be treated as black boxes.

  14. Anaerobic digestion process

    SciTech Connect

    Ishida, M.; Haga, R.; Odawara, Y.

    1984-04-10

    First, the organic waste slurry of sewage sludge and/or kitchen garbage is stored in a stable condition after effecting partially thereto a liquefaction treatment in advance by adding liquefying bacteria, and next this slurry is effectively digested anaerobically by way of a liquefaction/gasification-mixed step or a liquefaction/gasification separated step.

  15. Anaerobic threshold measurements of elite oarsmen.

    PubMed

    Mickelson, T C; Hagerman, F C

    1982-01-01

    Anaerobic threshold (AT) and Vo2max were determined by automated analysis for 25 members of the 1980 U.S. Olympic Rowing Team during a progressive rowing ergometer exercise to exhaustion. Heart rates and power outputs were also measured to gauge severity of the exercise and to compare with metabolic data. Power increments of 27 W each min were achieved by progressively increasing the brake weight resistance on the ergometer while maintaining a stroke rate of 28-32 strokes/min and spinning the ergometer flywheel at 550 rpm. Anaerobic threshold measurements were determined by observing the onset of the non-linear relationship between Vo2 and VE-Vco2; plots of delta FEO2 and FECO2 were also utilized to confirm recorded AT's. A mean AT of 83% of Vo2max attests to the high aerobic capacity of oarsmen and supports previous research conducted with these subjects. Power output data indicated that 72% of total power is generated at AT; this substantiates previous energy cost data recorded during simulated rowing during which work was 70% aerobic and 30% anaerobic. High levels of anaerobic thresholds among oarsmen are attributed to the specific nature of training regimens that increase oxidative capacity of muscle fibers and significantly improve the cardiorespiratory transport system. Measurement of heart rate at AT has provided coaches and athletes an objective method of determining the intensity of training sessions.

  16. Determination of the activation energies of and aggregate rates for exothermic physico-chemical changes in UHMWPE by isothermal heat-conduction microcalorimetry (IHCMC).

    PubMed

    Hardison, Andy; Lewis, Gladius; Daniels, A U Dan; Smith, Richard A

    2003-12-01

    Exothermic heat flow rates (Q=microW=microJ/s), as a function of elapsed time, were measured by isothermal heat-conduction microcalorimetry (IHCMC) in order to study the aggregate rate of physico-chemical change in specimens of unsterilized and sterilized ultra-high-molecular-weight polyethylene (UHMWPE). Standard protocols for performing the IHCMC tests were developed and are described. Use of the standard protocols yielded the desired results-data that were not significantly different among either replicate sets of unsterilized specimens or as a function of which calorimeter test well was used. Heat flow rates measured in air at 20 degrees C, 25 degrees C, 35 degrees C, and 45 degrees C yielded estimates of activation energies of 47, 11, and 41 kJ/mol for unsterilized, gamma-radiation sterilized, and ethylene oxide gas (EtO) sterilized polymer, respectively. These results support the ideas that (a). initial exothermic degradation takes place much more easily in the radiation-sterilized material, due to direct oxidation of readily available free radicals, and (b). the much slower degradation process in EtO-sterilized UHMWPE is not appreciably different than in unsterilized polymer. Comparison with other activation energy data suggests that the rate-limiting process in EtO- or un-sterilized polymer is oxygen diffusion into the polymer. For shelf storage in air, for periods up to 8 months, the mean exothermic heat flow in air, at 25 degrees C (Q(m)) [determined from the Q values averaged over the time period between 15 and 20 h after test start], from UHMWPE gamma-radiation sterilized in air was significantly higher than for unsterilized material (2.91+/-0.11 vs. 0.73+/-0.11 microW). The higher rate can be attributed to oxidation of radiation-induced free radicals in the polymer near its surface. For the gamma-irradiated polymer, the decline in Q(m) with shelf storage time suggests that, eventually, degradation might become oxygen diffusion limited in this case also

  17. Anaerobic Catabolism of Aromatic Compounds: a Genetic and Genomic View

    PubMed Central

    Carmona, Manuel; Zamarro, María Teresa; Blázquez, Blas; Durante-Rodríguez, Gonzalo; Juárez, Javier F.; Valderrama, J. Andrés; Barragán, María J. L.; García, José Luis; Díaz, Eduardo

    2009-01-01

    Summary: Aromatic compounds belong to one of the most widely distributed classes of organic compounds in nature, and a significant number of xenobiotics belong to this family of compounds. Since many habitats containing large amounts of aromatic compounds are often anoxic, the anaerobic catabolism of aromatic compounds by microorganisms becomes crucial in biogeochemical cycles and in the sustainable development of the biosphere. The mineralization of aromatic compounds by facultative or obligate anaerobic bacteria can be coupled to anaerobic respiration with a variety of electron acceptors as well as to fermentation and anoxygenic photosynthesis. Since the redox potential of the electron-accepting system dictates the degradative strategy, there is wide biochemical diversity among anaerobic aromatic degraders. However, the genetic determinants of all these processes and the mechanisms involved in their regulation are much less studied. This review focuses on the recent findings that standard molecular biology approaches together with new high-throughput technologies (e.g., genome sequencing, transcriptomics, proteomics, and metagenomics) have provided regarding the genetics, regulation, ecophysiology, and evolution of anaerobic aromatic degradation pathways. These studies revealed that the anaerobic catabolism of aromatic compounds is more diverse and widespread than previously thought, and the complex metabolic and stress programs associated with the use of aromatic compounds under anaerobic conditions are starting to be unraveled. Anaerobic biotransformation processes based on unprecedented enzymes and pathways with novel metabolic capabilities, as well as the design of novel regulatory circuits and catabolic networks of great biotechnological potential in synthetic biology, are now feasible to approach. PMID:19258534

  18. Anaerobic digestion of alcohol stillage

    SciTech Connect

    Binder, L.K.

    1981-01-01

    In the production of ethanol from grain, the distillation step produces a residue of distillers grains or stillage that contains greater than 90% water and is currently dried and used as a cattle feed supplement. Experimental work was carried out on the anaerobic digestion of the stillage to determine the feasibility of using the CH/sub 4/ produced to supply the energy required in the ethanol distillation step. The fermentation characteristics of the stillage were studied, and the amount of CH/sub 4/ produced was determined. Based on an economic analysis, the value of the pressed solids fraction of the stillage as feed is much greater than the potential return from producing CH/sub 4/.

  19. The effect of biological sulfate reduction on anaerobic color removal in anaerobic-aerobic sequencing batch reactors.

    PubMed

    Cirik, Kevser; Kitis, Mehmet; Cinar, Ozer

    2013-05-01

    Combination of anaerobic-aerobic sequencing processes result in both anaerobic color removal and aerobic aromatic amine removal during the treatment of dye-containing wastewaters. The aim of the present study was to gain more insight into the competitive biochemical reactions between sulfate and azo dye in the presence of glucose as electron donor source. For this aim, anaerobic-aerobic sequencing batch reactor fed with a simulated textile effluent including Remazol Brilliant Violet 5R (RBV 5R) azo dye was operated with a total cycle time of 12 h including anaerobic (6 h) and aerobic cycles (6 h). Microorganism grown under anaerobic phase of the reactor was exposed to different amounts of competitive electron acceptor (sulfate). Performance of the anaerobic phase was determined by monitoring color removal efficiency, oxidation reduction potential, color removal rate, chemical oxygen demand (COD), color, specific anaerobic enzyme (azo reductase) and aerobic enzyme (catechol 1,2-dioxygenase), and formation of aromatic amines. The presence of sulfate was not found to significantly affect dye decolorization. Sulfate and azo dye reductions took place simultaneously in all operational conditions and increase in the sulfate concentration generally stimulated the reduction of RBV 5R. However, sulfate accumulation under anaerobic conditions was observed proportional to increasing sulfate concentration.

  20. Erythrocyte aggregation: basic aspects and clinical importance.

    PubMed

    Baskurt, Oguz K; Meiselman, Herbert J

    2013-01-01

    Red blood cell (RBC) aggregate to form two- and three-dimensional structures when suspended in aqueous solutions containing large plasma proteins or polymers; this aggregation is reversible and shear dependent (i.e., dispersed at high shear and reformed at low or stasis). The extent of aggregation is the main determinant of low shear blood viscosity, thus predicting an inverse relationship between aggregation and in vivo blood flow. However, the effects of aggregation on hemodynamic mechanisms (e.g., plasma skimming, Fåhraeus Effect, microvascular hematocrit) may promote rather than impede vascular blood flow. The impact of enhanced RBC aggregation on endothelial function and hemostatic mechanisms adds further complexity, thereby requiring specific attention to the nature, extent and time course of aggregation when considering its overall influence on tissue perfusion. A detailed understanding of aggregation effects is important from a clinical point of view since it may be enhanced during a variety of pathophysiological processes, including infections, circulatory and metabolic disorders, hematological pathologies and several other disease states. Altered RBC aggregation may be an indicator of disease as well as a factor affecting the course of the clinical condition; the prognostic value of RBC aggregation indices has been demonstrated in various diseases. Currently, RBC aggregation is an easily and accurately measurable parameter, and therefore may be expected to have broader clinical usage in the future.

  1. Anaerobic contribution during maximal anaerobic running test: correlation with maximal accumulated oxygen deficit.

    PubMed

    Zagatto, A; Redkva, P; Loures, J; Kalva Filho, C; Franco, V; Kaminagakura, E; Papoti, M

    2011-12-01

    The aims of this study were: (i) to measure energy system contributions in maximal anaerobic running test (MART); and (ii) to verify any correlation between MART and maximal accumulated oxygen deficit (MAOD). Eleven members of the armed forces were recruited for this study. Participants performed MART and MAOD, both accomplished on a treadmill. MART consisted of intermittent exercise, 20 s effort with 100 s recovery, after each spell of effort exercise. Energy system contributions by MART were also determined by excess post-exercise oxygen consumption, lactate response, and oxygen uptake measurements. MAOD was determined by five submaximal intensities and one supramaximal intensity exercises corresponding to 120% at maximal oxygen uptake intensity. Energy system contributions were 65.4±1.1% to aerobic; 29.5±1.1% to anaerobic a-lactic; and 5.1±0.5% to anaerobic lactic system throughout the whole test, while only during effort periods the anaerobic contribution corresponded to 73.5±1.0%. Maximal power found in MART corresponded to 111.25±1.33 mL/kg/min but did not significantly correlate with MAOD (4.69±0.30 L and 70.85±4.73 mL/kg). We concluded that the anaerobic a-lactic system is the main energy system in MART efforts and this test did not significantly correlate to MAOD.

  2. pH sensitivity of chlorophyll fluorescence quenching is determined by the detergent/protein ratio and the state of LHCII aggregation.

    PubMed

    Petrou, Katherina; Belgio, Erica; Ruban, Alexander V

    2014-09-01

    Here we show how the protein environment in terms of detergent concentration/protein aggregation state, affects the sensitivity to pH of isolated, native LHCII, in terms of chlorophyll fluorescence quenching. Three detergent concentrations (200, 20 and 6μM n-dodecyl β-d-maltoside) have been tested. It was found that at the detergent concentration of 6μM, low pH quenching of LHCII is close to the physiological response to lumen acidification possessing pK of 5.5. The analysis has been conducted both using arbitrary PAM fluorimetry measurements and chlorophyll fluorescence lifetime component analysis. The second led to the conclusion that the 3.5ns component lifetime corresponds to an unnatural state of LHCII, induced by the detergent used for solubilising the protein, whilst the 2ns component is rather the most representative lifetime component of the conformational state of LHCII in the natural thylakoid membrane environment when the non-photochemical quenching (NPQ) was absent. The 2ns component is related to a pre-aggregated LHCII that makes it more sensitive to pH than the trimeric LHCII with the dominating 3.5ns lifetime component. The pre-aggregated LHCII displayed both a faster response to protons and a shift in the pK for quenching to higher values, from 4.2 to 4.9. We concluded that environmental factors like lipids, zeaxanthin and PsbS protein that modulate NPQ in vivo could control the state of LHCII aggregation in the dark that makes it more or less sensitive to the lumen acidification. This article is part of a special issue entitled: photosynthesis research for sustainability: keys to produce clean energy. Copyright © 2013 Elsevier B.V. All rights reserved.

  3. Perspectives for anaerobic digestion.

    PubMed

    Ahring, Birgitte K

    2003-01-01

    The modern society generates large amounts of waste that represent a tremendous threat to the environment and human and animal health. To prevent and control this, a range of different waste treatment and disposal methods are used. The choice of method must always be based on maximum safety, minimum environmental impact and, as far as possible, on valorization of the waste and final recycling of the end products. One of the main trends of today's waste management policies is to reduce the stream of waste going to landfills and to recycle the organic material and the plant nutrients back to the soil. Anaerobic digestion (AD) is one way of achieving this goal and it will furthermore, reduce energy consumption or may even be net energy producing. This chapter aims at provide a basic understanding of the world in which anaerobic digestion is operating today. The newest process developments as well as future perspectives will be discussed.

  4. Anaerobic transformation of TNT

    SciTech Connect

    Kulpa, C.F.; Roopathy, R.

    1995-12-31

    Most studies on the microbial metabolism of nitroaromatic compounds have used aerobic tempts to degrade nitroaromatics under aerobic microorganisms. In many cases attempts to degrade nitroaromatics under aerobic conditions results in no mineralization and only superficial modifications of the structure. However, under anaerobic sulfate-reducing conditions, the nitroaromatic compounds undergo a series of reductions with the formation of amino compounds. Trinitrotoluene under sulfate-reducing conditions is reduced to triaminotoluene presumably by the enzyme nitrite reductase, which is commonly found in many Desulfovibrio spp. The removal of nitrate from trinitrotoluene is achieved by a series of reductive reactions with the production of ammonia and toluene by Desulfovibrio sp. (B strain). Similar metabolic processes could be applied to other nitroaromatic compounds like nitrobenzene, nitrobenzoic acids, nitrophenols, and aniline. This presentation will review the data supporting the anaerobic transformation of TNT and other nitroaromatics.

  5. Stoichiometry and Physical Chemistry of Promiscuous Aggregate-Based Inhibitors

    PubMed Central

    Coan, Kristin E. D.

    2009-01-01

    Many false positives in early drug discovery owe to nonspecific inhibition by colloid-like aggregates of organic molecules. Despite their prevalence, little is known about aggregate concentration, structure, or dynamic equilibrium; the binding mechanism, stoichiometry with, and affinity for enzymes remain uncertain. To investigate the elementary question of concentration, we counted aggregate particles using flow cytometry. For seven aggregate-forming molecules, aggregates were not observed until the concentration of monomer crossed a threshold, indicating a “critical aggregation concentration” (CAC). Above the CAC, aggregate count increased linearly with added organic material, while the particles dispersed when diluted below the CAC. The concentration of monomeric organic molecule is constant above the CAC, as is the size of the aggregate particles. For two compounds that form large aggregates, nicardipine and miconazole, we measured particle numbers directly by flow cytometry, determining that the aggregate concentration just above the CAC ranged from 5 to 30 fM. By correlating inhibition of an enzyme with aggregate count for these two drugs, we determined that the stoichiometry of binding is about 10 000 enzyme molecules per aggregate particle. Using measured volumes for nicardipine and miconazole aggregate particles (2.1 × 1011 and 4.7 × 1010 Å3, respectively), computed monomer volumes, and the observation that past the CAC all additional monomer forms aggregate particles, we find that aggregates are densely packed particles. Finally, given their size and enzyme stoichiometry, all sequestered enzyme can be comfortably accommodated on the surface of the aggregate. PMID:18588298

  6. Anaerobic digestion process

    SciTech Connect

    Ishida, M.; Haga, R.; Odawara, Y.

    1982-10-19

    An algae culture grown on the water from the digested slurry of a biogasification plant serves as a means of removing CO/sub 2/ from the methane stream while purifying the wastewater and providing more biomass for the anaerobic digestion plant. Tested on a sewage-sludge digestion system, the proposed process improved the methane yield by 32% and methane concentration by 53-98 vol % while lowering the concentration of nitrogen and phosphorus in the final water.

  7. Serial coupling of ion-exchange and size-exclusion chromatography to determine aggregation levels in mAbs in the presence of a proteinaceous excipient, recombinant human serum albumin.

    PubMed

    Weisbjerg, Paul Luigi Gargani; Caspersen, Mikael Bjerg; Cook, Ken; Van De Weert, Marco

    2015-02-01

    Aggregation levels of therapeutic proteins may be difficult to determine in mixtures containing other proteinaceous excipients. We performed a feasibility study of using serial coupling of an anion exchange and size exclusion column to determine the aggregation levels of four different model monoclonal antibodies (mAb) mixed with the model proteinaceous excipient recombinant human serum albumin (rHSA). For three of the four mAbs suitable elution conditions could be established. From the limitations imposed by the pI of the rHSA, the pI of the mAb and the nature of the columns used, it was possible to propose a set of general conditions that allows quantification of the aggregation level of a therapeutic protein in the presence of a proteinaceous excipient: The excipient protein and protein of interest should differ in pI by a minimum of 0.5 units, and the pI of the protein of interest should not be higher than ca. 8.5.

  8. Trace metal speciation and bioavailability in anaerobic digestion: A review.

    PubMed

    Thanh, Pham Minh; Ketheesan, Balachandran; Yan, Zhou; Stuckey, David

    2016-01-01

    Trace metals are essential for the growth of anaerobic microorganisms, however, in practice they are often added to anaerobic digesters in excessive amounts, which can lead to inhibition. The concept of bioavailability of metals in anaerobic digestion has been poorly understood in the past, and a lack of deep understanding of the relationship between trace metal speciation and bioavailability can result in ineffective metal dosing strategies for anaerobic digesters. Sequential extraction schemes are useful for fractionating trace metals into their different forms, and metal sulfides can serve as a store and source for trace metals during anaerobic digestion, while natural/synthetic chelating agents (soluble microbial products-SMPs, extracellular polysaccharides-EPS, and EDTA/NTA) are capable of controlling trace metal bioavailability. Nevertheless, more work is needed to: investigate the speciation and bioavailability of Ca, Mg, Mn, W, and Se; compare the bioavailability of different forms of trace metals e.g. carbonates, sulfides, phosphates to different anaerobic trophic groups; determine what factors influence metal sulfide dissolution; investigate whether chelating agents can increase trace metal bioavailability; develop and adapt specialized analytical techniques, and; determine how trace metal dynamics change in an anaerobic membrane bioreactor (AnMBR).

  9. Early anaerobic metabolisms

    PubMed Central

    Canfield, Don E; Rosing, Minik T; Bjerrum, Christian

    2006-01-01

    Before the advent of oxygenic photosynthesis, the biosphere was driven by anaerobic metabolisms. We catalogue and quantify the source strengths of the most probable electron donors and electron acceptors that would have been available to fuel early-Earth ecosystems. The most active ecosystems were probably driven by the cycling of H2 and Fe2+ through primary production conducted by anoxygenic phototrophs. Interesting and dynamic ecosystems would have also been driven by the microbial cycling of sulphur and nitrogen species, but their activity levels were probably not so great. Despite the diversity of potential early ecosystems, rates of primary production in the early-Earth anaerobic biosphere were probably well below those rates observed in the marine environment. We shift our attention to the Earth environment at 3.8 Gyr ago, where the earliest marine sediments are preserved. We calculate, consistent with the carbon isotope record and other considerations of the carbon cycle, that marine rates of primary production at this time were probably an order of magnitude (or more) less than today. We conclude that the flux of reduced species to the Earth surface at this time may have been sufficient to drive anaerobic ecosystems of sufficient activity to be consistent with the carbon isotope record. Conversely, an ecosystem based on oxygenic photosynthesis was also possible with complete removal of the oxygen by reaction with reduced species from the mantle. PMID:17008221

  10. [Randomised comparative study of early versus delayed surgery in hip-fracture patients on concomitant treatment with antiplatelet drugs. Determination of platelet aggregation, perioperative bleeding and a review of annual mortality].

    PubMed

    Mas-Atance, J; Marzo-Alonso, C; Matute-Crespo, M; Trujillano-Cabello, J J; Català-Tello, N; de Miguel-Artal, M; Forcada-Calvet, P; Fernández-Martínez, J J

    2013-01-01

    A review of the perioperative management of patients with hip fractures and concomitant therapy with antiplatelet agents, and to analyse the differences in mortality and perioperative bleeding in early surgery (<48 h) versus delayed surgery (>5 days). Platelet aggregation was measured on admission and immediately before surgery in all patients included in the study A total of 175 patients over 65 years old, with low energy hip fracture were randomised into 3 groups: Patients on antiplatelet therapy undergoing early surgery, patients on antiplatelet therapy undergoing delayed surgery, and patients not on antiplatelet therapy undergoing early surgery. The same clinical and laboratory data were collected prospectively up to 12 months for all the patients. The platelet aggregation was determined by a semi-quantitative computerised system based on impedance aggregometry in whole blood. Bleeding, transfusion requirements and analytical results showed no significant differences between groups. More than half (59.8%) of the patients not taking antiplatelet therapy had normal platelet aggregation on admission, while 13.5% of those taking antiplatelet agents did not. Multivariate analysis showed increased mortality at 12 months for the variables, low Barthel index before hip fracture (OR: 0.9-0.9) and number of transfusions (OR: 1.1-1.5). The average lenth of stay was 4.1 days greater in the delayed surgery group. Early surgery for patients receiving antiplatelet therapy has similar clinical outcomes to the delayed, but improves hospital efficiency by reducing the average length of stay. The antiplatelet drug reported by the patient showed low concordance with the determination of the platelet aggregation. Copyright © 2011 SECOT. Published by Elsevier Espana. All rights reserved.

  11. Experimental investigations on aggregate-aggregate collisions in the early solar nebula

    NASA Astrophysics Data System (ADS)

    Blum, Jürgen; Münch, Michael

    1993-11-01

    An experimental setup has been devised to study the low-velocity aggregate-aggregate collisions that play a role in determining aggregate sizes in the preplanetary nebula; both central and grazing collisions are in this way studied for both ZrSiO4 and Aerosil 200. Fragment-mass distributions for catastrophic collisions between equal-sized aggregates are extrapolated according to several assumptions of the simple fragmentation model chosen. The model predicts a complete disintegration of the ZrSiO4 equal-size aggregates.

  12. Simple Method for Culturing Anaerobes

    PubMed Central

    Davis, C. E.; Hunter, W. J.; Ryan, J. L.; Braude, A. I.

    1973-01-01

    A simple, effective method is needed for growing obligate anaerobes in the clinical laboratory. This report describes a pre-reduced anaerobic bottle that can be taken to the bedside for direct inoculation, provides a flat agar surface for evaluation of number and morphology of colonies, and can be incubated in conventional bacteriological incubators. Each anaerobic culture set consisted of two bottles containing brain heart infusion agar and CO2. Gentamicin sulfate (50 μg/ml) was added to one of these to inhibit facultative enteric bacilli. Comparison of the anaerobic bottles with an identical aerobic bottle which was also routinely inoculated permitted early identification of anaerobic colonies. Representative species of most anaerobic genera of proven pathogenicity for man have been isolated from this system during 10 months of routine use. Images PMID:4571657

  13. Gender differences in anaerobic power tests.

    PubMed

    Mayhew, J L; Salm, P C

    1990-01-01

    The purpose of this study was to determine if the differences in anaerobic power between males and females could be accounted for by differences in body composition, strength, and neuromuscular function. A total of 82 untrained men and 99 women took part in the study. Body composition, somatotype, isometric strength, neuromuscular function were measured, and four anaerobic power tests performed. The men were significantly different from the women on all strength, power, and neuromuscular measurements except reaction time and on all anthropometric and somatotype dimensions except ectomorphy. Strength and anthropometric dimensions were similarly related to anaerobic power values within each sex. Relative fat (%fat) exerted different degrees of influence on sprint and jump performances in each sex. Removing the influence of anthropometric, strength, and neuromuscular differences by analysis of covariance reduced, but did not remove, the significant differences between the sexes. Therefore, factors other than lean body mass, leg strength, and neuromuscular function may be operating in short-term, explosive power performances to account for the differences between the sexes. The task-specific nature of anaerobic power tests and the relatively large influence of anthropometric factors on power production were confirmed.

  14. C and N accumulations in soil aggregates determine nitrous oxide emissions from cover crop treated rice paddy soils during fallow season.

    PubMed

    Pramanik, Prabhat; Haque, Md Mozammel; Kim, Sang Yoon; Kim, Pil Joo

    2014-08-15

    Combination of leguminous and non-leguminous plant residues are preferably applied in rice paddy soils to increase the rate of organic matter mineralization and to improve plant growth. However, organic matter addition facilitates methane (CH4) emission from rice paddy soil. Mineralization of organic nitrogen (N) increases NO3-N concentrations in soil, which are precursors for the formation of nitrous oxide (N2O). However, N2O is a minor greenhouse gas emitted from submerged rice field and hence is not often considered during calculation of total global warming potential (GWP) during rice cultivation. The hypothesis of this study was that fluxes of N2O emissions might be changed after removal of flooded water from rice field and the effect of cover crops on N2O emissions in the fallow season might be interesting. However, the effects of N-rich plant residues on N2O emission rates in the fallow season and its effect on annual GWP were not studied before. In this experiment, combination of barley (non-leguminous) and hairy vetch (leguminous) biomasses were applied at 9 Mg ha(-1) and 27 Mg ha(-1) rates in rice paddy soil. Cover crop application significantly increased CH4 emission flux while decreased N2O emissions during rice cultivation. The lowest N2O emission was observed in 27 Mg ha(-1) cover crop treated plots. Cover crop applications increased N contents in soil aggregates especially in smaller aggregates (<250 μm), and that proportionately increased the N2O emission potentials of these soil aggregates. Fluxes of N2O emissions in the fallow season were influenced by the N2O emission potentials of soil aggregates and followed opposite trends as those observed during rice cultivation. Therefore, it could be concluded that the doses of cover crop applications for rice cultivation should not be optimized considering only CH4, but N2O should also be considered especially for fallow season to calculate total GWP. Copyright © 2014 Elsevier B.V. All rights reserved.

  15. Applications of aggregation theory to sustainability assessment

    DOE PAGES

    Pollesch, N.; Dale, V. H.

    2015-04-01

    In order to aid in transition towards operations that promote sustainability goals, researchers and stakeholders use sustainability assessments. Although assessments take various forms, many utilize diverse sets of indicators that can number anywhere from two to over 2000. Indices, composite indicators, or aggregate values are used to simplify high dimensional and complex data sets and to clarify assessment results. Although the choice of aggregation function is a key component in the development of the assessment, there are few examples to be found in literature to guide appropriate aggregation function selection. This paper develops a connection between the mathematical study ofmore » aggregation functions and sustainability assessment in order to aid in providing criteria for aggregation function selection. Relevant mathematical properties of aggregation functions are presented and interpreted. Lastly, we provide cases of these properties and their relation to previous sustainability assessment research. Examples show that mathematical aggregation properties can be used to address the topics of compensatory behavior and weak versus strong sustainability, aggregation of data under varying units of measurements, multiple site multiple indicator aggregation, and the determination of error bounds in aggregate output for normalized and non-normalized indicator measures.« less

  16. Applications of aggregation theory to sustainability assessment

    SciTech Connect

    Pollesch, N.; Dale, V. H.

    2015-04-01

    In order to aid in transition towards operations that promote sustainability goals, researchers and stakeholders use sustainability assessments. Although assessments take various forms, many utilize diverse sets of indicators that can number anywhere from two to over 2000. Indices, composite indicators, or aggregate values are used to simplify high dimensional and complex data sets and to clarify assessment results. Although the choice of aggregation function is a key component in the development of the assessment, there are few examples to be found in literature to guide appropriate aggregation function selection. This paper develops a connection between the mathematical study of aggregation functions and sustainability assessment in order to aid in providing criteria for aggregation function selection. Relevant mathematical properties of aggregation functions are presented and interpreted. Lastly, we provide cases of these properties and their relation to previous sustainability assessment research. Examples show that mathematical aggregation properties can be used to address the topics of compensatory behavior and weak versus strong sustainability, aggregation of data under varying units of measurements, multiple site multiple indicator aggregation, and the determination of error bounds in aggregate output for normalized and non-normalized indicator measures.

  17. Taurine and platelet aggregation

    SciTech Connect

    Nauss-Karol, C.; VanderWende, C.; Gaut, Z.N.

    1986-03-01

    Taurine is a putative neurotransmitter or neuromodulator. The endogenous taurine concentration in human platelets, determined by amino acid analysis, is 15 ..mu..M/g. In spite of this high level, taurine is actively accumulated. Uptake is saturable, Na/sup +/ and temperature dependent, and suppressed by metabolic inhibitors, structural analogues, and several classes of centrally active substances. High, medium and low affinity transport processes have been characterized, and the platelet may represent a model system for taurine transport in the CNS. When platelets were incubated with /sup 14/C-taurine for 30 minutes, then resuspended in fresh medium and reincubated for one hour, essentially all of the taurine was retained within the cells. Taurine, at concentrations ranging from 10-1000 ..mu..M, had no effect on platelet aggregation induced by ADP or epinephrine. However, taurine may have a role in platelet aggregation since 35-39% of the taurine taken up by human platelets appears to be secreted during the release reaction induced by low concentrations of either epinephrine or ADP, respectively. This release phenomenon would imply that part of the taurine taken up is stored directly in the dense bodies of the platelet.

  18. Aggregate growth in a protoplanetary disk

    NASA Astrophysics Data System (ADS)

    Xiang, Chuchu; Carballido, Augusto; Matthews, Lorin; Hyde, Truell

    2017-01-01

    We present a method to model the growth of neutral and charged dusts in a turbulent protoplanetary disk, and analyze their collision probabilities. Coagulation of dust aggregates plays an important role in the formation of planets and is of key importance to the evolution of protoplanetary disks. In our method, the temporal evolution of the dusts is followed by Monte Carlo algorithm, and the inter-particle interactions are calculated by Aggregate_Builder (AB), which is a code used to model the collision process of aggregates. First an aggregate library is built and all the aggregates are binned according to their sizes. In each iteration, the collision rate for aggregates from any two bins are computed, which determines the time it takes for the next collision to happen and which two aggregates are selected for collision. Then the AB codes are used to calculate the interaction of the two aggregates. The relative velocity between the two aggregates is the vector sum of Brownian velocity and the turbulent velocity. The latter is calculated by ATHENA, which is a grid-based code for astrophysical magnetohydrodynamics. In each iteration, it’s determined whether the two aggregates hit or miss. In the case of hit, it either sticks or bounces as determined by the critical velocity. As a result, the neutral aggregates are more porous than the charged ones. For a certain size of incoming aggregates, the neutral ones have a higher collision probability than the charged ones. Also, similarly-sized aggregates have lower collision probabilities than aggregates with large size dispersions. This research enables us to determine which physical properties have a greater impact on the collision rate. By tracing the dust size distribution, we can identify the stage when they settle out to the mid-plane and how long it takes to develop to that stage. In the hit-stick regime, our results are consistent with the experiments which shows that when the velocity is smaller than the

  19. Multiscale simulation of red blood cell aggregation

    NASA Astrophysics Data System (ADS)

    Bagchi, P.; Popel, A. S.

    2004-11-01

    In humans and other mammals, aggregation of red blood cells (RBC) is a major determinant to blood viscosity in microcirculation under physiological and pathological conditions. Elevated levels of aggregation are often related to cardiovascular diseases, bacterial infection, diabetes, and obesity. Aggregation is a multiscale phenomenon that is governed by the molecular bond formation between adjacent cells, morphological and rheological properties of the cells, and the motion of the extra-cellular fluid in which the cells circulate. We have developed a simulation technique using front tracking methods for multiple fluids that includes the multiscale characteristics of aggregation. We will report the first-ever direct computer simulation of aggregation of deformable cells in shear flows. We will present results on the effect of shear rate, strength of the cross-bridging bonds, and the cell rheological properties on the rolling motion, deformation and subsequent breakage of an aggregate.

  20. Waves and aggregation patterns in myxobacteria

    NASA Astrophysics Data System (ADS)

    Igoshin, Oleg A.; Welch, Roy; Kaiser, Dale; Oster, George

    2004-03-01

    Under starvation conditions, a population of myxobacteria aggregates to build a fruiting body whose shape is species-specific and within which the cells sporulate. Early in this process, cells often pass through a "ripple phase" characterized by traveling linear, concentric, and spiral waves. These waves are different from the waves observed during slime mold aggregation that depend on diffusible morphogens, because myxobacteria communicate by direct contact. The difference is most dramatic when waves collide: rather than annihilating one another, myxobacterial waves appear to pass through one another unchanged. Under certain conditions, the spacing and location of the nascent fruiting bodies is determined by the wavelength and pattern of the waves. Later in fruiting body development, waves are replaced by streams of cells that circulate around small initial aggregates enlarging and rounding them. Still later, pairs of motile aggregates coalesce to form larger aggregates that develop into fruiting bodies. Here we present a mathematical model that quantitatively explains these wave and aggregation phenomena.

  1. On mean type aggregation.

    PubMed

    Yager, R R

    1996-01-01

    We introduce and define the concept of mean aggregation of a collection of n numbers. We point out that the lack of associativity of this operation compounds the problem of the extending mean of n numbers to n+1 numbers. The closely related concepts of self identity and the centering property are introduced as one imperative for extending mean aggregation operators. The problem of weighted mean aggregation is studied. A new concept of prioritized mean aggregation is then introduced. We next show that the technique of selecting an element based upon the performance of a random experiment can be considered as a mean aggregation operation.

  2. The accuracy of the DDA (Discrete Dipole Approximation) method in determining the optical properties of black carbon fractal-like aggregates

    NASA Astrophysics Data System (ADS)

    Skorupski, Krzysztof

    2015-05-01

    Black carbon (BC) particles are a product of incomplete combustion of carbon-based fuels. One of the possibilities of studying the optical properties of BC structures is to use the DDA (Discrete Dipole Approximation) method. The main goal of this work was to investigate its accuracy and to approximate the most reliable simulation parameters. For the light scattering simulations the ADDA code was used and for the reference program the superposition T-Matrix code by Mackowski was selected. The study was divided into three parts. First, DDA simulations for a single particle (sphere) were performed. The results proved that the meshing algorithm can significantly affect the particle shape, and therefore, the extinction diagrams. The volume correction procedure is recommended for sparse or asymmetrical meshes. In the next step large fractal-like aggregates were investigated. When sparse meshes are used, the impact of the volume correction procedure cannot be easily predicted. In some cases it can even lead to more erroneous results. Finally, the optical properties of fractal-like aggregates composed of spheres in point contact were compared to much more realistic structures made up of connected, non-spherical primary particles.

  3. Evaluation of laboratory test method for determining the potential alkali contribution from aggregate and the ASR safety of the Three-Gorges dam concrete

    SciTech Connect

    Lu Duyou . E-mail: duyoulu@njut.edu.cn; Zhou, Xiaoling; Xu Zhongzi; Lan Xianghui; Tang Mingshu; Fournier, Benoit

    2006-06-15

    The releasable alkali from granite, which was used in the Three-Gorges concrete dam project in China, and from gneiss and feldspar was estimated by extraction in distilled water and super-saturated Ca(OH){sub 2} solution. Results show that: i) the finer the particles and the higher the temperature, the greater and faster the release of alkali; ii) compared with extraction by distilled water, super-saturated Ca(OH){sub 2} solution had a stronger activation on feldspar than on granite and gneiss; iii) for the three rocks tested, thermal activation had the largest effect on gneiss and a lower and similar effect on granite and feldspar. For very fine particles, temperature had a similar effect on the release of alkali by all three rocks. Because the aggregate used in the Three-Gorges dam concrete is non-reactive and a low calcium fly ash was used in the concrete, ASR would not be an issue for the dam, despite the release of alkali from the aggregate into the concrete.

  4. Effect of nitrate on anaerobic azo dye reduction.

    PubMed

    Cirik, Kevser; Kitiş, Mehmet; Çinar, Özer

    2013-01-01

    The aim of the study was to investigate the effect of nitrate on anaerobic color removal efficiencies. For this aim, anaerobic-aerobic sequencing batch reactor (SBR) fed with a simulated textile effluent including Remazol Brilliant Violet 5R azo dye was operated with a total cycle time of 12 h, including anaerobic (6 h) and aerobic cycles (6 h). Microorganism grown under anaerobic phase of the reactor was exposed to different amounts of competitive electron acceptor (nitrate) and performance of the system was determined by monitoring color removal efficiency, nitrate removal, nitrite formation and removal, oxidation reduction potential, color removal rate, chemical oxygen demand (COD), specific anaerobic enzyme (azo reductase) and aerobic enzyme (catechol 1,2 dioxygenase), and formation and removal of aromatic amines. Variations of population dynamics of microorganisms exposed to various amount of nitrate were identified by denaturing gradient gel electrophoresis (DGGE). It was found that nitrate has adverse effect on anaerobic color removal efficiency and color removal was achieved after denitrification process was completed. It was found that nitrate stimulates the COD removal efficiency and accelerates the COD removal in the first hour of anaerobic phase. About 90 % total COD removal efficiencies were achieved in which microorganism exposed to increasing amount of nitrate. Population dynamics of microorganisms exposed to various amount of nitrate were changed and diversity was increased.

  5. Role of Multicellular Aggregates in Biofilm Formation

    PubMed Central

    Kragh, Kasper N.; Hutchison, Jaime B.; Melaugh, Gavin; Rodesney, Chris; Roberts, Aled E. L.; Irie, Yasuhiko; Jensen, Peter Ø.; Diggle, Stephen P.; Allen, Rosalind J.

    2016-01-01

    ABSTRACT In traditional models of in vitro biofilm development, individual bacterial cells seed a surface, multiply, and mature into multicellular, three-dimensional structures. Much research has been devoted to elucidating the mechanisms governing the initial attachment of single cells to surfaces. However, in natural environments and during infection, bacterial cells tend to clump as multicellular aggregates, and biofilms can also slough off aggregates as a part of the dispersal process. This makes it likely that biofilms are often seeded by aggregates and single cells, yet how these aggregates impact biofilm initiation and development is not known. Here we use a combination of experimental and computational approaches to determine the relative fitness of single cells and preformed aggregates during early development of Pseudomonas aeruginosa biofilms. We find that the relative fitness of aggregates depends markedly on the density of surrounding single cells, i.e., the level of competition for growth resources. When competition between aggregates and single cells is low, an aggregate has a growth disadvantage because the aggregate interior has poor access to growth resources. However, if competition is high, aggregates exhibit higher fitness, because extending vertically above the surface gives cells at the top of aggregates better access to growth resources. Other advantages of seeding by aggregates, such as earlier switching to a biofilm-like phenotype and enhanced resilience toward antibiotics and immune response, may add to this ecological benefit. Our findings suggest that current models of biofilm formation should be reconsidered to incorporate the role of aggregates in biofilm initiation. PMID:27006463

  6. Molecular Aggregation in Disodium Cromoglycate

    NASA Astrophysics Data System (ADS)

    Singh, Gautam; Agra-Kooijman, D.; Collings, P. J.; Kumar, Satyendra

    2012-02-01

    Details of molecular aggregation in the mesophases of the anti-asthmatic drug disodium cromoglycate (DSCG) have been studied using x-ray synchrotron scattering. The results show two reflections, one at wide angles corresponding to π-π stacking (3.32 å) of molecules, and the other at small angles which is perpendicular to the direction of molecular stacking and corresponds to the distance between the molecular aggregates. The latter varies from 35 - 41 å in the nematic (N) phase and 27 -- 32 å in the columnar (M) phase. The temperature evolution of the stack height, positional order correlations in the lateral direction, and orientation order parameter were determined in the N, M, and biphasic regions. The structure of the N and M phases and the nature of the molecular aggregation, together with their dependence on temperature and concentration, will be presented.

  7. Anaerobic wastewater treatment using anaerobic baffled bioreactor: a review

    NASA Astrophysics Data System (ADS)

    Hassan, Siti Roshayu; Dahlan, Irvan

    2013-09-01

    Anaerobic wastewater treatment is receiving renewed interest because it offers a means to treat wastewater with lower energy investment. Because the microorganisms involved grow more slowly, such systems require clever design so that the microbes have sufficient time with the substrate to complete treatment without requiring enormous reactor volumes. The anaerobic baffled reactor has inherent advantages over single compartment reactors due to its circulation pattern that approaches a plug flow reactor. The physical configuration of the anaerobic baffled reactor enables significant modifications to be made; resulting in a reactor which is proficient of treating complex wastewaters which presently require only one unit, ultimately significant reducing capital costs. This paper also concerns about mechanism, kinetic and hydrodynamic studies of anaerobic digestion for future application of the anaerobic baffled reactor for wastewater treatment.

  8. Diversity Profile of Microbes Associated with Anaerobic Sulfur Oxidation in an Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Sewage

    PubMed Central

    Aida, Azrina A.; Kuroda, Kyohei; Yamamoto, Masamitsu; Nakamura, Akinobu; Hatamoto, Masashi; Yamaguchi, Takashi

    2015-01-01

    We herein analyzed the diversity of microbes involved in anaerobic sulfur oxidation in an upflow anaerobic sludge blanket (UASB) reactor used for treating municipal sewage under low-temperature conditions. Anaerobic sulfur oxidation occurred in the absence of oxygen, with nitrite and nitrate as electron acceptors; however, reactor performance parameters demonstrated that anaerobic conditions were maintained. In order to gain insights into the underlying basis of anaerobic sulfur oxidation, the microbial diversity that exists in the UASB sludge was analyzed comprehensively to determine their identities and contribution to sulfur oxidation. Sludge samples were collected from the UASB reactor over a period of 2 years and used for bacterial 16S rRNA gene-based terminal restriction fragment length polymorphism (T-RFLP) and next-generation sequencing analyses. T-RFLP and sequencing results both showed that microbial community patterns changed markedly from day 537 onwards. Bacteria belonging to the genus Desulforhabdus within the phylum Proteobacteria and uncultured bacteria within the phylum Fusobacteria were the main groups observed during the period of anaerobic sulfur oxidation. Their abundance correlated with temperature, suggesting that these bacterial groups played roles in anaerobic sulfur oxidation in UASB reactors. PMID:25817585

  9. Economic viability of anaerobic digestion

    SciTech Connect

    Wellinger, A.

    1996-01-01

    The industrial application of anaerobic digestion is a relatively new, yet proven waste treatment technology. Anaerobic digestion reduces and upgrades organic waste, and is a good way to control air pollution as it reduces methane and nitrous gas emissions. For environmental and energy considerations, anaerobic digestion is a nearly perfect waste treatment process. However, its economic viability is still in question. A number of parameters - type of waste (solid or liquid), digester system, facility size, product quality and end use, environmental requirements, cost of alternative treatments (including labor), and interest rates - define the investment and operating costs of an anaerobic digestion facility. Therefore, identical facilities that treat the same amount and type of waste may, depending on location, legislation, and end product characteristics, reveal radically different costs. A good approach for evaluating the economics of anaerobic digestion is to compare it to treatment techniques such as aeration or conventional sewage treatment (for industrial wastewater), or composting and incineration (for solid organic waste). For example, the cost (per ton of waste) of in-vessel composting with biofilters is somewhat higher than that of anaerobic digestion, but the investment costs 1 1/2 to 2 times more than either composting or anaerobic digestion. Two distinct advantages of anaerobic digestion are: (1) it requires less land than either composting or incinerating, which translates into lower costs and milder environmental and community impacts (especially in densely populated areas); and (2) it produces net energy, which can be used to operate the facility or sold to nearby industries.

  10. GEOMETRIC CROSS SECTIONS OF DUST AGGREGATES AND A COMPRESSION MODEL FOR AGGREGATE COLLISIONS

    SciTech Connect

    Suyama, Toru; Wada, Koji; Tanaka, Hidekazu; Okuzumi, Satoshi

    2012-07-10

    Geometric cross sections of dust aggregates determine their coupling with disk gas, which governs their motions in protoplanetary disks. Collisional outcomes also depend on geometric cross sections of initial aggregates. In a previous paper, we performed three-dimensional N-body simulations of sequential collisions of aggregates composed of a number of sub-micron-sized icy particles and examined radii of gyration (and bulk densities) of the obtained aggregates. We showed that collisional compression of aggregates is not efficient and that aggregates remain fluffy. In the present study, we examine geometric cross sections of the aggregates. Their cross sections decrease due to compression as well as to their gyration radii. It is found that a relation between the cross section and the gyration radius proposed by Okuzumi et al. is valid for the compressed aggregates. We also refine the compression model proposed in our previous paper. The refined model enables us to calculate the evolution of both gyration radii and cross sections of growing aggregates and reproduces well our numerical results of sequential aggregate collisions. The refined model can describe non-equal-mass collisions as well as equal-mass cases. Although we do not take into account oblique collisions in the present study, oblique collisions would further hinder compression of aggregates.

  11. Hemodynamic effects of red blood cell aggregation.

    PubMed

    Baskurt, Oguz K; Meiselman, Herbert J

    2007-01-01

    The influence of red blood cell (RBC) aggregation on blood flow in vivo has been under debate since early 1900's, yet a full understanding has still has not been reached. Enhanced RBC aggregation is well known to increase blood viscosity measured in rotational viscometers. However, it has been demonstrated that RBC aggregation may decrease flow resistance in cylindrical tubes, due to the formation of a cell-poor zone near the tube wall which results from the enhanced central accumulation of RBC. There is also extensive discussion regarding the effects of RBC aggregation on in vivo blood flow resistance. Several groups have reported increased microcirculatory flow resistance with enhanced RBC aggregation in experiments that utilized intravital microscopy. Alternatively, whole organ studies revealed that flow resistance may be significantly decreased if RBC aggregation is enhanced. Recently, new techniques have been developed to achieve well-controlled, graded alterations in RBC aggregation without influencing suspending phase properties. Studies using this technique revealed that the effects of RBC aggregation are determined by the degree of aggregation changes, and that this relationship can be explained by different hemodynamic mechanisms.

  12. COLLISIONAL GROWTH CONDITIONS FOR DUST AGGREGATES

    SciTech Connect

    Wada, Koji; Tanaka, Hidekazu; Suyama, Toru; Yamamoto, Tetsuo; Kimura, Hiroshi

    2009-09-10

    Collisions between dust aggregates are the key to understand the formation of planetesimals because the collision inevitably takes place in protoplanetary disks. To clarify whether or not dust aggregates can grow through their mutual collisions at relatively high velocities, we carry out more than 4000 runs of three-dimensional numerical simulations of collisions between icy equal-mass clusters formed under ballistic particle-cluster aggregation (BPCA) as well as those of ballistic cluster-cluster aggregation, including offset collisions with various values of the impact parameter. Since our BPCA clusters have a fractal dimension of 3 and a relatively compact structure, their results enable us to determine the criteria for growth and disruption of compressed aggregates at their collisions in protoplanetary disks. The results show that ice dust aggregates are able to grow at collisions with velocities up to 50 m s{sup -1}, in spite of their initial structures and impact parameters. We also find that the mass of ejecta relative to the total mass of colliding aggregates decreases with increasing the size of the aggregates. These results demonstrate the feasibility of growth and survival for dust aggregates through their mutual collisions with relatively high velocities in protoplanetary disks.

  13. A competitive aggregation model for flash nanoprecipitation.

    PubMed

    Cheng, Janine Chungyin; Vigil, R D; Fox, R O

    2010-11-15

    Flash NanoPrecipitation (FNP) is a novel approach for producing functional nanoparticles stabilized by amphiphilic block copolymers. FNP involves the rapid mixing of a hydrophobic active (organic) and an amphiphilic di-block copolymer with a non-solvent (water) and subsequent co-precipitation of nanoparticles composed of both the organic and copolymer. During this process, the particle size distribution (PSD) is frozen and stabilized by the hydrophilic portion of the amphiphilic di-block copolymer residing on the particle surface. That is, the particle growth is kinetically arrested and thus a narrow PSD can be attained. To model the co-precipitation process, a bivariate population balance equation (PBE) has been formulated to account for the competitive aggregation of the organic and copolymer versus pure organic-organic or copolymer-copolymer aggregation. Aggregation rate kernels have been derived to account for the major aggregation events: free coupling, unimer insertion, and aggregate fusion. The resulting PBE is solved both by direct integration and by using the conditional quadrature method of moments (CQMOM). By solving the competitive aggregation model under well-mixed conditions, it is demonstrated that the PSD is controlled primarily by the copolymer-copolymer aggregation process and that the energy barrier to aggregate fusion plays a key role in determining the PSD. It is also shown that the characteristic aggregation times are smaller than the turbulent mixing time so that the FNP process is always mixing limited.

  14. Bouncing behavior of microscopic dust aggregates

    NASA Astrophysics Data System (ADS)

    Seizinger, A.; Kley, W.

    2013-03-01

    Context. Bouncing collisions of dust aggregates within the protoplanetary disk may have a significant impact on the growth process of planetesimals. Yet, the conditions that result in bouncing are not very well understood. Existing simulations studying the bouncing behavior used aggregates with an artificial, very regular internal structure. Aims: Here, we study the bouncing behavior of sub-mm dust aggregates that are constructed applying different sample preparation methods. We analyze how the internal structure of the aggregate alters the collisional outcome and we determine the influence of aggregate size, porosity, collision velocity, and impact parameter. Methods: We use molecular dynamics simulations where the individual aggregates are treated as spheres that are made up of several hundred thousand individual monomers. The simulations are run on graphic cards (GPUs). Results: Statistical bulk properties and thus bouncing behavior of sub-mm dust aggregates depend heavily on the preparation method. In particular, there is no unique relation between the average volume filling factor and the coordination number of the aggregate. Realistic aggregates bounce only if their volume filling factor exceeds 0.5 and collision velocities are below 0.1 ms-1. Conclusions: For dust particles in the protoplanetary nebula we suggest that the bouncing barrier may not be such a strong handicap in the growth phase of dust agglomerates, at least in the size range of ≈100 μm.

  15. An active principle of Nigella sativa L., thymoquinone, showing significant antimicrobial activity against anaerobic bacteria

    PubMed Central

    Randhawa, Mohammad Akram; Alenazy, Awwad Khalaf; Alrowaili, Majed Gorayan; Basha, Jamith

    2017-01-01

    Aim/Background: Thymoquinone (TQ) is the major active principle of Nigella sativa seed (black seed) and is known to control many fungi, bacteria, and some viruses. However, the activity of TQ against anaerobic bacteria is not well demonstrated. Anaerobic bacteria can cause severe infections, including diarrhea, aspiration pneumonia, and brain abscess, particularly in immunodeficient individuals. The present study aimed to investigate the in vitro antimicrobial activity of TQ against some anaerobic pathogens in comparison to metronidazole. Methods: Standard, ATCC, strains of four anaerobic bacteria (Clostridium difficile, Clostridium perfringens, Bacteroides fragilis, and Bacteroides thetaiotaomicron), were initially isolated on special Brucella agar base (with hemin and vitamin K). Then, minimum inhibitory concentrations (MICs) of TQ and metronidazole were determined against these anaerobes when grown in Brucella agar, using serial agar dilution method according to the recommended guidelines for anaerobic organisms instructed by the Clinical and Laboratory Standards Institute. Results: TQ showed a significant antimicrobial activity against anaerobic bacteria although much weaker than metronidazole. MICs of TQ and metronidazole against various anaerobic human pathogens tested were found to be between 10-160 mg/L and 0.19-6.25 mg/L, respectively. Conclusions: TQ controlled the anaerobic human pathogenic bacteria, which supports the use of N. sativa in the treatment of diarrhea in folk medicine. Further investigations are in need for determination of the synergistic effect of TQ in combination with metronidazole and the activity of derivatives of TQ against anaerobic infections. PMID:28163966

  16. Diversity of anaerobic halophilic microorganisms

    NASA Astrophysics Data System (ADS)

    Oren, Aharon; Oremland, Roland S.

    2000-12-01

    Life in the presence of high salt concentrations is compatible with life in the absence of oxygen. Halophilic and halotolerant anaerobic prokaryotes are found both in the archaeal and in the bacterial domain, and they display a great metabolic diversity. Many of the representatives of the Halobacteriales (Archaea), which are generally considered aerobes, have the potential of anaerobic growth. Some can use alternative electron acceptors such as nitrate, fumarate, dimethylsulfoxide or trimethylamine-N-oxide Halobacterium salinarum can also grow fermentatively on L-arginine, and bacteriorhodopsin-containing cells may even grow anaerobically, energized by light. Obligatory anaerobic halophilic methanogenic Archaea also exist. The bacterial domain contains many anaerobic halophiles, including sulfate reducers. There is also a group of specialized obligatory anaerobic Bacteria, phylogenetically clustering in the low G + C branch of the Firmicutes. Most representatives of this group (order Haloanaerobiales, families Haloanaerobiaceae and Halobacteroidaceae) are fermentative, using a variety of carbohydrates and amino acids. One species combines the potential for anaerobic growth at high salt concentrations with a preference for high temperatures. Others are homoacetogens; Acetohalobium arabaticum can grow anaerobically as a chemolithotroph, producing acetate from hydrogen and CO2. The Haloanaerobiales accumulate high concentrations of K+ and Cl- in their cytoplasm, thereby showing a strategy of salt adaptation similar to that used by the Halobacteriales. Recently a new representative of the Haloanaerobiales was isolated from bottom sediments of the Dead Sea (strain DSSe1), which grows anaerobically by oxidation of glycerol to acetate and CO2 while reducing selenate to selenite and elementary selenium. Other electron acceptors supporting anaerobic growth of this strain are nitrate and trimethylamine-N-oxide. The versatility of life at high salt concentrations with respect

  17. Aerobic and anaerobic performances in tethered swimming.

    PubMed

    Papoti, M; da Silva, A S R; Araujo, G G; Santiago, V; Martins, L E B; Cunha, S A; Gobatto, C A

    2013-08-01

    The purpose of this study was to investigate whether the critical force (CritF) and anaerobic impulse capacity (AIC) - estimated by tethered swimming - reflect the aerobic and anaerobic performance of swimmers. 12 swimmers performed incremental test in tethered swimming to determine lactate anaerobic threshold (AnTLAC), maximal oxygen uptake ( ˙VO2MAX) and force associated with the ˙VO2MAX (i ˙VO2MAX). The swimmers performed 4 exhaustive (tlim) exercise bouts (100, 110, 120 and 130% i ˙VO2MAX) to compute the CritF and AIC (F vs. 1/tlim model); a 30-s all-out tethered swimming bout to determine their anaerobic fitness (ANF); 100, 200, and 400-m time-trials to determine the swimming performance. CritF (57.09±11.77 N) did not differ from AnTLAC (53.96±11.52 N, (P>0.05) but was significantly lower than i ˙VO2MAX (71.02±8.36 N). In addition, CritF presented significant correlation with AnTLAC (r=0.76; P<0.05) and i ˙VO2MAX (r=0.74; P<0.05). On the other hand, AIC (286.19±54.91 N.s) and ANF (116.10±13.66 N) were significantly correlated (r=0.81, p<0.05). In addition, CritF and AIC presented significant correlations with all time-trials. In summary, this study demonstrates that CritF and AIC can be used to evaluate AnTLAC and ANF and to predict 100, 200, and 400-m free swimming. © Georg Thieme Verlag KG Stuttgart · New York.

  18. Bacterial ecology of abattoir wastewater treated by an anaerobic digestor

    PubMed Central

    Jabari, Linda; Gannoun, Hana; Khelifi, Eltaief; Cayol, Jean-Luc; Godon, Jean-Jacques; Hamdi, Moktar; Fardeau, Marie-Laure

    2016-01-01

    Wastewater from an anaerobic treatment plant at a slaughterhouse was analysed to determine the bacterial biodiversity present. Molecular analysis of the anaerobic sludge obtained from the treatment plant showed significant diversity, as 27 different phyla were identified. Firmicutes, Proteobacteria, Bacteroidetes, Thermotogae, Euryarchaeota (methanogens), and msbl6 (candidate division) were the dominant phyla of the anaerobic treatment plant and represented 21.7%, 18.5%, 11.5%, 9.4%, 8.9%, and 8.8% of the total bacteria identified, respectively. The dominant bacteria isolated were Clostridium, Bacteroides, Desulfobulbus, Desulfomicrobium, Desulfovibrio and Desulfotomaculum. Our results revealed the presence of new species, genera and families of microorganisms. The most interesting strains were characterised. Three new bacteria involved in anaerobic digestion of abattoir wastewater were published. PMID:26887229

  19. [Anaerobic growth ability and alcohol fermentation activity of microscopic fungi].

    PubMed

    Kurakov, A V; Khidirov, K S; Sadykova, V S; Zviagintsev, D G

    2011-01-01

    The method proposed in this study was used to isolate fungi grown under anaerobic conditions and to reveal distinctions in their abundance and species composition in different habitats. The ability of micromycetes of different taxa to grow under anaerobic conditions and ensure alcohol fermentation was determined for a representative sample (344 strains belonging to more than 60 species). The group of fungi growing under anaerobic conditions included species with high, moderate, and low fermentation activity. The ability for anaerobic growth and fermentation depended on the taxonomic affiliation of fungi. In some cases, the expression of these characteristics depended on the habitat from which the strain was isolated. The maximum level of ethanol accumulation in culture liquid (1.2-4.7%) was detected for Absidia spinosa, Aspergillus sp. of group flavus, Aspergillus terreus, Acremonium sp., Mucor circinelloides, Mucor sp., Fusarium oxysporum, F. solani, F. sambucinum, Rhizopus arrhizus var. Arrhizus, Trichoderma atroviride, and Trichoderma sp.

  20. Retrospective determination of 137Cs specific activity distribution in spruce bark and bark aggregated transfer factor in forests on the scale of the Czech Republic ten years after the Chernobyl accident.

    PubMed

    Suchara, I; Rulík, P; Hůlka, J; Pilátová, H

    2011-04-15

    The (137)Cs specific activities (mean 32Bq kg(-1)) were determined in spruce bark samples that had been collected at 192 sampling plots throughout the Czech Republic in 1995, and were related to the sampling year. The (137)Cs specific activities in spruce bark correlated significantly with the (137)Cs depositions in areas affected by different precipitation sums operating at the time of the Chernobyl fallout in 1986. The ratio of the (137)Cs specific activities in bark and of the (137)Cs deposition levels yielded bark aggregated transfer factor T(ag) about 10.5×10(-3)m(-2)kg(-1). Taking into account the residual specific activities of (137)Cs in bark 20Bq kg(-1) and the available pre-Chernobyl data on the (137)Cs deposition loads on the soil surface in the Czech Republic, the real aggregated transfer factor after and before the Chernobyl fallout proved to be T*(ag)=3.3×10(-3)m(-2)kg(-1) and T**(ag)=4.0×10(-3)m(-2)kg(-1), respectively. The aggregated transfer factors T*(ag) for (137)Cs and spruce bark did not differ significantly in areas unequally affected by the (137)Cs fallout in the Czech Republic in 1986, and the figures for these aggregated transfer factors were very similar to the mean bark T(ag) values published from the extensively affected areas near Chernobyl. The magnitude of the (137)Cs aggregated transfer factors for spruce bark for the pre-Chernobyl and post-Chernobyl period in the Czech Republic was also very similar. The variability in spruce bark acidity caused by the operation of local anthropogenic air pollution sources did not significantly influence the accumulation and retention of (137)Cs in spruce bark. Increasing elevation of the bark sampling plots had a significant effect on raising the remaining (137)Cs specific activities in bark in areas affected by precipitation at the time when the plumes crossed, because the sums of this precipitation increased with elevation (covariable).

  1. Physiologically anaerobic microorganisms of the deep subsurface. Progress report, June 1, 1990--May 30, 1991

    SciTech Connect

    Stevens, S.E. Jr.; Chung, K.T.

    1991-06-01

    This study seeks to determine numbers, diversity, and morphology of anaerobic microorganisms in 15 samples of subsurface material from the Idaho National Engineering Laboratory, in 18 samples from the Hanford Reservation and in 1 rock sample from the Nevada Test Site; set up long term experiments on the chemical activities of anaerobic microorganisms based on these same samples; work to improve methods for the micro-scale determination of in situ anaerobic microbial activity;and to begin to isolate anaerobes from these samples into axenic culture with identification of the axenic isolates.

  2. Decomposition of organic waste products under aerobic and anaerobic conditions

    SciTech Connect

    Gale, P.M.

    1988-01-01

    The objectives of this research were to determine the kinetics of C and N mineralization under aerobic and anaerobic conditions. These parameters were then used to verify the simulation model, DECOMPOSITION, for the anaerobic system. Incubation experiments were conducted to compare the aerobic and anaerobic decomposition of alfalfa (Medicago sativa L.), a substrate with a low C:N ratio. Under anaerobic conditions the net mineralization of N occurred more rapidly than that under aerobic conditions. However, the rate of C mineralization as measured by CO{sub 2} evolution was much lower. For the anaerobic decomposition of alfalfa, C mineralization was best described as the sum of the CO{sub 2} and CH{sub 4} evolved plus the water soluble organic C formed. The kinetics of C mineralization, as determined by this approach, were used to successfully predict the rate and amount of N mineralization from alfalfa undergoing anaerobic decomposition. The decomposition of paper mill sludge, a high C:N ratio substrate, was also evaluated.

  3. Energetics of Anaerobic Sodium Transport by the Fresh Water Turtle Bladder

    PubMed Central

    Klahr, Saulo; Bricker, Neal S.

    1965-01-01

    Certain of the metabolic events associated with anaerobic sodium transport by the isolated bladder of the fresh water turtle have been investigated. The data suggest that energy for this transport arises from glycolysis and that endogenous glycogen was the major and perhaps the sole source of substrate. The rate of anaerobic glycolysis, as determined by lactate formation, correlates well with the rate as determined by glycogen utilization. Using lactate formation as the index of anaerobic glycolysis, a linear relationship was observed between glycolysis and net anaerobic sodium transport. In the absence of sodium transport, glycolysis decreased by approximately 45 per cent. Tissue ATP concentrations were maintained at about the same level under anaerobic as under aerobic conditions. Finally if it is assumed that in the conversion of glycogen to lactate anaerobically, 3 moles of ATP are generated per mole of glucose residue, an average of over 15 equivalents of sodium were transported for every mole of ATP generated. PMID:14324976

  4. Validity and reliability of the Hawaii anaerobic run test.

    PubMed

    Kimura, Iris F; Stickley, Christopher D; Lentz, Melissa A; Wages, Jennifer J; Yanagi, Kazuhiko; Hetzler, Ronald K

    2014-05-01

    This study examined the reliability and validity of the Hawaii anaerobic run test (HART) by comparing anaerobic capacity measures obtained to those during the Wingate Anaerobic Test (WAnT). Ninety-six healthy physically active volunteers (age, 22.0 ± 2.8 years; height, 163.9 ± 9.5 cm; body mass, 70.6 ± 14.7 kg; body fat %, 19.29 ± 5.39%) participated in this study. Each participant performed 2 anaerobic capacity tests: the WAnT and the HART by random assignment on separate days. The reliability of the HART was calculated from 2 separate trials of the test and then determined through intraclass correlation coefficients (ICCs). Blood samples were collected, and lactate was analyzed both pretest and posttest for each of the 2 exercise modes. Heart rate and rate of perceived exertion were also measured pre- and post-exercise. Hawaii anaerobic run test peak and mean momentum were calculated as body mass times highest or average split velocity, respectively. Intraclass correlation coefficients between trials of the HART for peak and mean momentum were 0.98 and 0.99, respectively (SEM = 18.8 and 25.7, respectively). Validity of the HART was established through comparison of momentum on the HART with power on the WAnT. High correlations were found between peak power and peak momentum (r = 0.88), as well as mean power and mean momentum (r = 0.94). The HART was considered to be a reliable test of anaerobic power. The HART was also determined to be a valid test of anaerobic power when compared with the WAnT. When testing healthy college-aged individuals, the HART offers an easy and inexpensive alternative maximal effort anaerobic power test to other established tests.

  5. 24 CFR 55.24 - Aggregation.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... approval under this section is subject to compliance with the decision making process in § 55.20. ... FLOODPLAIN MANAGEMENT Procedures for Making Determinations on Floodplain Management § 55.24 Aggregation...

  6. 24 CFR 55.24 - Aggregation.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... approval under this section is subject to compliance with the decision making process in § 55.20. ... FLOODPLAIN MANAGEMENT Procedures for Making Determinations on Floodplain Management § 55.24 Aggregation...

  7. 24 CFR 55.24 - Aggregation.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... approval under this section is subject to compliance with the decision making process in § 55.20. ... FLOODPLAIN MANAGEMENT Procedures for Making Determinations on Floodplain Management § 55.24 Aggregation...

  8. 24 CFR 55.24 - Aggregation.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... approval under this section is subject to compliance with the decision making process in § 55.20. ... FLOODPLAIN MANAGEMENT Procedures for Making Determinations on Floodplain Management § 55.24 Aggregation...

  9. Anaerobic Metabolism of Indoleacetate

    PubMed Central

    Ebenau-Jehle, Christa; Thomas, Markus; Scharf, Gernot; Kockelkorn, Daniel; Knapp, Bettina; Schühle, Karola; Heider, Johann

    2012-01-01

    The anaerobic metabolism of indoleacetate (indole-3-acetic acid [IAA]) in the denitrifying betaproteobacterium Azoarcus evansii was studied. The strain oxidized IAA completely and grew with a generation time of 10 h. Enzyme activities that transformed IAA were present in the soluble cell fraction of IAA-grown cells but were 10-fold downregulated in cells grown on 2-aminobenzoate or benzoate. The transformation of IAA did not require molecular oxygen but required electron acceptors like NAD+ or artificial dyes. The first products identified were the enol and keto forms of 2-oxo-IAA. Later, polar products were observed, which could not yet be identified. The first steps likely consist of the anaerobic hydroxylation of the N-heterocyclic pyrrole ring to the enol form of 2-oxo-IAA, which is catalyzed by a molybdenum cofactor-containing dehydrogenase. This step is probably followed by the hydrolytic ring opening of the keto form, which is catalyzed by a hydantoinase-like enzyme. A comparison of the proteome of IAA- and benzoate-grown cells identified IAA-induced proteins. Owing to the high similarity of A. evansii with strain EbN1, whose genome is known, we identified a cluster of 14 genes that code for IAA-induced proteins involved in the early steps of IAA metabolism. These genes include a molybdenum cofactor-dependent dehydrogenase of the xanthine oxidase/aldehyde dehydrogenase family, a hydantoinase, a coenzyme A (CoA) ligase, a CoA transferase, a coenzyme B12-dependent mutase, an acyl-CoA dehydrogenase, a fusion protein of an enoyl-CoA hydratase and a 3-hydroxyacyl-CoA dehydrogenase, a beta-ketothiolase, and a periplasmic substrate binding protein for ABC transport as well as a transcriptional regulator of the GntR family. Five predicted enzymes form or act on CoA thioesters, indicating that soon after the initial oxidation of IAA and possibly ring opening, CoA thioesters are formed, and the carbon skeleton is rearranged, followed by a CoA-dependent thiolytic

  10. Arsenic, Anaerobes, and Autotrophy.

    NASA Astrophysics Data System (ADS)

    Oremland, R. S.

    2008-12-01

    That microbes have resistance to the toxic arsenic oxyanions arsenite [As(III)] and arsenate [As(V)] has been recognized for some time. More recently it was shown that certain prokaryotes can demonstrate As- dependent growth by conserving the energy gained from the aerobic oxidation of As(III) to As(V), or from the reduction of As(V) to As(III) under anaerobic conditions. During the course of our field studies of two alkaline, hypersaline soda lakes (Mono Lake and Searles Lake, CA) we have discovered several new anaerobic chemo- and photo-autotrophic bacteria that can center their energy gain around the redox reactions between As(III) and As(V). Alkalilimnicola ehrlichii, isolated from the water column of Mono Lake is a nitrate-respiring, As(III)-oxidizing chemoautotroph of the gamma-proteobacteria that has a highly flexible metabolism. It can function either as a facultative anaerobe or as a chemo-autotroph, or as a heterotroph (Hoeft et al., 2007). In contrast, strain MLMS-1 of the delta-proteobacteria was also isolated from Mono Lake, but to date is the first example of an obligate As(V)-respirer that is also an obligate chemo-autotroph, gaining its energy via the oxidation of sulfide to sulfate (Hoeft et al., 2004). Strain SLAS-1, isolated from salt-saturated Searles Lake is a member of the Halananerobiales, and can either grow as a heterotroph (lactate e-donor) or chemo- autotroph (sulfide e-donor) while respiring As(V). The fact that it can achieve this feat at salt-saturation (~ 340 g/L) makes it a true extremophile (Oremland et. al., 2005). Finally, strain PHS-1 isolated from a hot spring on Paoha island in Mono Lake is the first example of a photosynthetic bacterium of the gamma- proteobacteria able to link its growth to As(III)-dependent anoxygenic photosynthesis (Kulp et al., 2008). These novel microbes give us new insights into the evolution of arsenic-based metabolism and their role in the biogeochemical cycling of this toxic element. Hoeft, S.E., et

  11. A visual assay and spectrophotometric determination of LLM-105 explosive using detection of gold nanoparticle aggregation at two pH values.

    PubMed

    He, Yi; Cheng, Yang

    2016-08-01

    We report a simple, rapid, and sensitive assay for visual and spectrophotometric detection of the 2,6-diamino-3,5-dinitropyrazine-1-oxide (LLM-105) explosive. The assay is based on different interactions between LLM-105 and gold nanoparticle (AuNP) dispersions at two pH values, leading to the formation of dispersed or aggregated AuNPs. Two AuNP dispersions at two pH values were applied to recognize and detect LLM-105 instead of traditional AuNP dispersion under an aptotic pH to improve the anti-interference ability. The developed assay showed excellent sensitivity with a detection limit of 3 ng/mL, and the presence of as low as 0.2 μg/mL LLM-105 can be directly detected with the bare eye. This sensitivity is about six orders of magnitude higher than that of the reported traditional assays. Additionally, the assay exhibited good selectivity toward LLM-105 over other explosives, sulfur-containing compounds, and amines. Graphical abstract A simple, sensitive, and selective assay for LLM-105 was developed based on the pH-dependent interaction between the LLM-105 explosive and gold nanoparticle dispersion.

  12. Contact inhibition of locomotion and mechanical cross-talk between cell–cell and cell–substrate adhesion determine the pattern of junctional tension in epithelial cell aggregates

    PubMed Central

    Coburn, Luke; Lopez, Hender; Caldwell, Benjamin J.; Moussa, Elliott; Yap, Chloe; Priya, Rashmi; Noppe, Adrian; Roberts, Anthony P.; Lobaskin, Vladimir; Yap, Alpha S.; Neufeld, Zoltan; Gomez, Guillermo A.

    2016-01-01

    We used a computational approach to analyze the biomechanics of epithelial cell aggregates—islands, stripes, or entire monolayers—that combines both vertex and contact-inhibition-of-locomotion models to include cell–cell and cell–substrate adhesion. Examination of the distribution of cell protrusions (adhesion to the substrate) in the model predicted high-order profiles of cell organization that agree with those previously seen experimentally. Cells acquired an asymmetric distribution of basal protrusions, traction forces, and apical aspect ratios that decreased when moving from the edge to the island center. Our in silico analysis also showed that tension on cell–cell junctions and apical stress is not homogeneous across the island. Instead, these parameters are higher at the island center and scale up with island size, which we confirmed experimentally using laser ablation assays and immunofluorescence. Without formally being a three-dimensional model, our approach has the minimal elements necessary to reproduce the distribution of cellular forces and mechanical cross-talk, as well as the distribution of principal stress in cells within epithelial cell aggregates. By making experimentally testable predictions, our approach can aid in mechanical analysis of epithelial tissues, especially when local changes in cell–cell and/or cell–substrate adhesion drive collective cell behavior. PMID:27605701

  13. Anaerobic Origin of Ergothioneine.

    PubMed

    Burn, Reto; Misson, Laëtitia; Meury, Marcel; Seebeck, Florian P

    2017-10-02

    Ergothioneine is a sulfur metabolite that occurs in microorganisms, fungi, plants, and animals. The physiological function of ergothioneine is not clear. In recent years broad scientific consensus has formed around the idea that cellular ergothioneine primarily protects against reactive oxygen species. Herein we provide evidence that this focus on oxygen chemistry may be too narrow. We describe two enzymes from the strictly anaerobic green sulfur bacterium Chlorobium limicola that mediate oxygen-independent biosynthesis of ergothioneine. This anoxic origin suggests that ergothioneine is also important for oxygen-independent life. Furthermore, one of the discovered ergothioneine biosynthetic enzymes provides the first example of a rhodanese-like enzyme that transfers sulfur to non-activated carbon. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Marine Snow Aggregates: Size Specific Settling Speeds, Abundance, and Size Specific Ratios of Settling to Total Abundance of Aggregates

    NASA Astrophysics Data System (ADS)

    Diercks, Arne-Roland

    1995-01-01

    Determining in situ settling speeds, vertical profiles of total aggregate abundance, and the amount of settling aggregates as a ratio of the total aggregate abundance were the main objectives of this research. Aggregate abundance was determined with the MAGENUM (Marine AGgregate ENUMerator) camera system (modified after Honjo et al., 1984). Aggregate flux and settling speeds were determined with the MAFIA (Marine Aggregate Flux Investigation Apparatus), a combination of aggregate camera system and sediment trap. In situ settling speed data (MAFIA) of aggregates from the central Black Sea and the northern Gulf of Mexico were analyzed for five size classes of aggregates, showed a wide variation in settling speeds in the individual size classes. Neither environment studied showed a positive correlation of aggregate settling speed to aggregate diameter, indicating that particle density was the more important factor in determining the aggregates settling speed. Marine snow abundance data from the Equatorial Pacific were analyzed using discrete fourier transform analysis to estimate size specific settling speeds of aggregates ranging from 1 to 10 mm spherical diameter. Settling speeds of aggregates followed the exponential function: rm Settling^eed = 22.3 e^ {(0.147 {aggregate diameter [ mm]})} (r^2 of 0.65). The ratio of the abundance of settling aggregates to the total abundance of aggregates, termed S-ratio, was calculated from MAFIA data from the central Black Sea and the northern Gulf of Mexico for six size classes of aggregates. In both locations ratios greater than one were calculated. This suggested that the MAGENUM did not record the total aggregate abundance, as assumed, but only a fraction of the aggregates present in the water column. The abundance of fine particles was compared to profiles of abundance of marine snow aggregates. Interactions were qualitatively discussed between these two size classes. In most profiles aggregates and fine particles showed

  15. A whole soil stability index (WSSI) for evaluating soil aggregation

    USDA-ARS?s Scientific Manuscript database

    Soil aggregate stability is an indicator of soil quality. However, there is no standard methodology for measuring soil aggregation or aggregate stability, particularly for determining a whole soil stability index. A whole soil stability index (WSSI) was developed here which combined data from dry ...

  16. 21 CFR 1303.11 - Aggregate production quotas.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 9 2014-04-01 2014-04-01 false Aggregate production quotas. 1303.11 Section 1303.11 Food and Drugs DRUG ENFORCEMENT ADMINISTRATION, DEPARTMENT OF JUSTICE QUOTAS Aggregate Production and Procurement Quotas § 1303.11 Aggregate production quotas. (a) The Administrator shall determine...

  17. PCB breakdown by anaerobic microorganisms

    SciTech Connect

    Not Available

    1989-03-01

    Recently, altered PCB cogener distribution patterns observed in anaerobic sediment samples from the upper Hudson River are being attributed to biologically mediated reductive dechlorination. The authors report their successful demonstration of biologically mediated reductive dechlorination of an Aroclor mixture. In their investigation, they assessed the ability of microorganisms from PCB-contaminated Hudson River sediments (60-562 ppm PCBs) to dechlorinate Aroclor 1242 under anaerobic conditions by eluting microorganisms from the PCB- contaminated sediments and transferring them to a slurry of reduced anaerobic mineral medium and PCB-free sediments in tightly stoppered bottles. They observed dechlorination to be the most rapid at the highest PCB concentration tried by them.

  18. Ageing and hypoxia cause protein aggregation in mitochondria.

    PubMed

    Kaufman, Daniel M; Wu, Xia; Scott, Barbara A; Itani, Omar A; Van Gilst, Marc R; Bruce, James E; Michael Crowder, C

    2017-10-01

    Aggregation of cytosolic proteins is a pathological finding in disease states, including ageing and neurodegenerative diseases. We have previously reported that hypoxia induces protein misfolding in Caenorhabditis elegans mitochondria, and electron micrographs suggested protein aggregates. Here, we seek to determine whether mitochondrial proteins actually aggregate after hypoxia and other cellular stresses. To enrich for mitochondrial proteins that might aggregate, we performed a proteomics analysis on purified C. elegans mitochondria to identify relatively insoluble proteins under normal conditions (110 proteins identified) or after sublethal hypoxia (65 proteins). A GFP-tagged mitochondrial protein (UCR-11 - a complex III electron transport chain protein) in the normally insoluble set was found to form widespread aggregates in mitochondria after hypoxia. Five other GFP-tagged mitochondrial proteins in the normally insoluble set similarly form hypoxia-induced aggregates. Two GFP-tagged mitochondrial proteins from the soluble set as well as a mitochondrial-targeted GFP did not form aggregates. Ageing also resulted in aggregates. The number of hypoxia-induced aggregates was regulated by the mitochondrial unfolded protein response (UPRmt) master transcriptional regulator ATFS-1, which has been shown to be hypoxia protective. An atfs-1(loss-of-function) mutant and RNAi construct reduced the number of aggregates while an atfs-1(gain-of-function) mutant increased aggregates. Our work demonstrates that mitochondrial protein aggregation occurs with hypoxic injury and ageing in C. elegans. The UPRmt regulates aggregation and may protect from hypoxia by promoting aggregation of misfolded proteins.

  19. Aggregations in Flatworms.

    ERIC Educational Resources Information Center

    Liffen, C. L.; Hunter, M.

    1980-01-01

    Described is a school project to investigate aggregations in flatworms which may be influenced by light intensity, temperature, and some form of chemical stimulus released by already aggregating flatworms. Such investigations could be adopted to suit many educational levels of science laboratory activities. (DS)

  20. Aggregations in Flatworms.

    ERIC Educational Resources Information Center

    Liffen, C. L.; Hunter, M.

    1980-01-01

    Described is a school project to investigate aggregations in flatworms which may be influenced by light intensity, temperature, and some form of chemical stimulus released by already aggregating flatworms. Such investigations could be adopted to suit many educational levels of science laboratory activities. (DS)

  1. Using aggregated single patient (N-of-1) trials to determine the effectiveness of psychostimulants to reduce fatigue in advanced cancer patients: a rationale and protocol

    PubMed Central

    2013-01-01

    Background It is estimated that 29% of deaths in Australia are caused by malignant disease each year and can be expected to increase with population ageing. In advanced cancer, the prevalence of fatigue is high at 70–90%, and can be related to the disease and/or the treatment. The negative impact of fatigue on function (physical, mental, social and spiritual) and quality of life is substantial for many palliative patients as well as their families/carers. Method/design This paper describes the design of single patient trials (n-of-1 s or SPTs) of a psychostimulant, methylphenidate hydrochloride (MPH) (5 mg bd), compared to placebo as a treatment for fatigue, with a population estimate of the benefit by the aggregation of multiple SPTs. Forty patients who have advanced cancer will be enrolled through specialist palliative care services in Australia. Patients will complete up to 3 cycles of treatment. Each cycle is 6 days long and has 3 days treatment and 3 days placebo. The order of treatment and placebo is randomly allocated for each cycle. The primary outcome is a reduction in fatigue severity as measured by the Functional Assessment of Cancer Therapy-fatigue subscale (FACIT-F). Secondary outcomes include adverse events, quality of life, additional fatigue assessments, depression and Australian Karnovsky Performance Scale. Discussion This study will provide high-level evidence using a novel methodological approach about the effectiveness of psychostimulants for cancer-related fatigue. If effective, the findings will guide clinical practice in reducing this prevalent condition to improve function and quality of life. Trial registration Australian New Zealand Clinical Trials Registry ACTRN12609000794202 PMID:23617794

  2. Fungal survival during anaerobic digestion of organic household waste.

    PubMed

    Schnürer, Anna; Schnürer, Johan

    2006-01-01

    Anaerobic digestion of organic waste yields energy rich biogas and retains nutrients (N, P, K, S, etc.) in a stabilised residue. For the residue to be used as a soil fertiliser, it must be free from pollutants and harmful microorganisms. Fungal survival during sanitation and anaerobic treatment of source-separated organic household waste and during aerobic storage of the residue obtained was investigated. Decimal reduction times were determined for inoculated fungi (Aspergillus flavus and Aspergillus fumigatus, Penicillium roqueforti, Rhizomucor pusillus, Thermoascus crustaceus and Thermomyces lanuginosus). Several different fungal species were found after waste sanitation treatment (70 degrees C, 1 h), with Aspergillus species dominating in non-inoculated waste. Anaerobic waste degradation decreased the diversity of fungal species for processes run at both 37 and 55 degrees C, but not total fungal colony forming units. Fungi surviving the mesophilic anaerobic digestion were mainly thermotolerant Talaromyces and Paecilomyces species. T. crustaceus and T. lanuginosus were the only inoculated fungi to survive the thermophilic anaerobic degradation process. Aerobic storage of both types of anaerobic residues for one month significantly decreased fungal counts.

  3. Using contaminated plants involved in phytoremediation for anaerobic digestion.

    PubMed

    Cao, Zewei; Wang, Shengxiao; Wang, Ting; Chang, Zhizhou; Shen, Zhenguo; Chen, Yahua

    2015-01-01

    This study investigated the anaerobic digestion capability of five plants and the effects of copper (Cu) and S,S'-ethylenediaminedisuccinic acid (EDDS, a chelator widely used in chelant-assisted phytoremediation) on biogas production to determine a feasible disposal method for plants used in remediation. The results showed that in addition to Phytolacca americana L., plants such as Zea mays L., Brassica napus L., Elsholtzia splendens Nakai ex F. Maekawa, and Oenothera biennis L. performed well in biogas production. Among these, O. biennis required the shortest period to finish anaerobic digestion. Compared to normal plants with low Cu content, the plants used in remediation with increased Cu levels (100 mg kg(-1)) not only promoted anaerobic digestion and required a shorter anaerobic digestion time, but also increased the methane content in biogas. When the Cu content in plants increased to 500, 1000, and 5000 mg kg(-1), the cumulative biogas production decreased by 12.3%, 14.6%, and 41.2%, respectively. Studies also found that EDDS conspicuously restrained biogas production from anaerobic digestion. The results suggest that anaerobic digestion has great potential for the disposal of contaminated plants and may provide a solution for the resource utilization of plants used in remediation.

  4. Carbon and Hydrogen Isotopic Fractionation during Anaerobic Biodegradation of Benzene

    PubMed Central

    Mancini, Silvia A.; Ulrich, Ania C.; Lacrampe-Couloume, Georges; Sleep, Brent; Edwards, Elizabeth A.; Sherwood Lollar, Barbara

    2003-01-01

    Compound-specific isotope analysis has the potential to distinguish physical from biological attenuation processes in the subsurface. In this study, carbon and hydrogen isotopic fractionation effects during biodegradation of benzene under anaerobic conditions with different terminal-electron-accepting processes are reported for the first time. Different enrichment factors (ɛ) for carbon (range of −1.9 to −3.6‰) and hydrogen (range of −29 to −79‰) fractionation were observed during biodegradation of benzene under nitrate-reducing, sulfate-reducing, and methanogenic conditions. These differences are not related to differences in initial biomass or in rates of biodegradation. Carbon isotopic enrichment factors for anaerobic benzene biodegradation in this study are comparable to those previously published for aerobic benzene biodegradation. In contrast, hydrogen enrichment factors determined for anaerobic benzene biodegradation are significantly larger than those previously published for benzene biodegradation under aerobic conditions. A fundamental difference in the previously proposed initial step of aerobic versus proposed anaerobic biodegradation pathways may account for these differences in hydrogen isotopic fractionation. Potentially, C-H bond breakage in the initial step of the anaerobic benzene biodegradation pathway may account for the large fractionation observed compared to that in aerobic benzene biodegradation. Despite some differences in reported enrichment factors between cultures with different terminal-electron-accepting processes, carbon and hydrogen isotope analysis has the potential to provide direct evidence of anaerobic biodegradation of benzene in the field. PMID:12513995

  5. Contribution of anaerobic energy expenditure to whole body thermogenesis

    PubMed Central

    Scott, Christopher B

    2005-01-01

    Heat production serves as the standard measurement for the determination of energy expenditure and efficiency in animals. Estimations of metabolic heat production have traditionally focused on gas exchange (oxygen uptake and carbon dioxide production) although direct heat measurements may include an anaerobic component particularly when carbohydrate is oxidized. Stoichiometric interpretations of the ratio of carbon dioxide production to oxygen uptake suggest that both anaerobic and aerobic heat production and, by inference, all energy expenditure – can be accounted for with a measurement of oxygen uptake as 21.1 kJ per liter of oxygen. This manuscript incorporates contemporary bioenergetic interpretations of anaerobic and aerobic ATP turnover to promote the independence of these disparate types of metabolic energy transfer: each has different reactants and products, uses dissimilar enzymes, involves different types of biochemical reactions, takes place in separate cellular compartments, exploits different types of gradients and ultimately each operates with distinct efficiency. The 21.1 kJ per liter of oxygen for carbohydrate oxidation includes a small anaerobic heat component as part of anaerobic energy transfer. Faster rates of ATP turnover that exceed mitochondrial respiration and that are supported by rapid glycolytic phosphorylation with lactate production result in heat production that is independent of oxygen uptake. Simultaneous direct and indirect calorimetry has revealed that this anaerobic heat does not disappear when lactate is later oxidized and so oxygen uptake does not adequately measure anaerobic efficiency or energy expenditure (as was suggested by the "oxygen debt" hypothesis). An estimate of anaerobic energy transfer supplements the measurement of oxygen uptake and may improve the interpretation of whole-body energy expenditure. PMID:15958171

  6. Marine Synechococcus Aggregation

    NASA Astrophysics Data System (ADS)

    Neuer, S.; Deng, W.; Cruz, B. N.; Monks, L.

    2016-02-01

    Cyanobacteria are considered to play an important role in the oceanic biological carbon pump, especially in oligotrophic regions. But as single cells are too small to sink, their carbon export has to be mediated by aggregate formation and possible consumption by zooplankton producing sinking fecal pellets. Here we report results on the aggregation of the ubiquitous marine pico-cyanobacterium Synechococcus as a model organism. We first investigated the mechanism behind such aggregation by studying the potential role of transparent exopolymeric particles (TEP) and the effects of nutrient (nitrogen or phosphorus) limitation on the TEP production and aggregate formation of these pico-cyanobacteria. We further studied the aggregation and subsequent settling in roller tanks and investigated the effects of the clays kaolinite and bentonite in a series of concentrations. Our results show that despite of the lowered growth rates, Synechococcus in nutrient limited cultures had larger cell-normalized TEP production, formed a greater volume of aggregates, and resulted in higher settling velocities compared to results from replete cultures. In addition, we found that despite their small size and lack of natural ballasting minerals, Synechococcus cells could still form aggregates and sink at measureable velocities in seawater. Clay minerals increased the number and reduced the size of aggregates, and their ballasting effects increased the sinking velocity and carbon export potential of aggregates. In comparison with the Synechococcus, we will also present results of the aggregation of the pico-cyanobacterium Prochlorococcus in roller tanks. These results contribute to our understanding in the physiology of marine Synechococcus as well as their role in the ecology and biogeochemistry in oligotrophic oceans.

  7. Impact of Particle Aggregation on Nanoparticle Reactivity

    NASA Astrophysics Data System (ADS)

    Jassby, David

    2011-12-01

    nanoparticle that photoluminesces after exposure to UV; TiO2 and ZnO nanoparticles---photocatalytic nanoparticles that generate reactive oxygen species upon UV irradition; and, fullerene nanoparticles used in the filtration experiments, selected for their potential use, small size, and surface chemistry. Our primary methods used to characterize particle and aggregate characteristics include dynamic light scattering used to describe particle size, static light scattering used to characterize aggregate structure (fractal dimension), transmission electron microscopy used to verify primary particle sizes, and electrophoretic mobility measurements to evaluate suspension stability. The reactive property of ZnS that was measured as a function of aggregation was photoluminescence, which was measured using a spectrofluorometer. The reactive property of TiO2 and ZnO that was studied was their ability to generate hydroxyl radicals; these were measured by employing a fluorescent probe that becomes luminescent upon interaction with the hydroxyl radical. To detect the presence of fullerene nanoparticles and calculate removal efficiencies, we used total organic carbon measurements. Additionally, we used UV-vis spectroscopy to approximate the impact of particle shadowing in TiO2 and ZnO aggregates, and Fourier transformed infrared spectroscopy to determine how different electrolytes interact with fullerene surface groups. Our findings indicate that the impact of aggregation on nanoparticle reactivity is material specific. ZnS nanoparticles exhibit a 2-fold increase in band-edge photoluminescence alongside a significant decrease in defect-site photoluminescence. This is attributed to aggregate size-dependent surface tension. Additionally, we used photoluminescence measurements to develop a new method for calculating the critical coagulation concentration of a nanoparticle suspension. The ability of both TiO2 and ZnO to generate hydroxyl radicals was significantly hampered by aggregation. The

  8. Flow Partitioning in Fully Saturated Soil Aggregates

    SciTech Connect

    Yang, Xiaofan; Richmond, Marshall C.; Scheibe, Timothy D.; Perkins, William A.; Resat, Haluk

    2014-03-30

    Microbes play an important role in facilitating organic matter decomposition in soils, which is a major component of the global carbon cycle. Microbial dynamics are intimately coupled to environmental transport processes, which control access to labile organic matter and other nutrients that are needed for the growth and maintenance of microorganisms. Transport of soluble nutrients in the soil system is arguably most strongly impacted by preferential flow pathways in the soil. Since the physical structure of soils can be characterized as being formed from constituent micro aggregates which contain internal porosity, one pressing question is the partitioning of the flow among the “inter-aggregate” and “intra-aggregate” pores and how this may impact overall solute transport within heterogeneous soil structures. The answer to this question is particularly important in evaluating assumptions to be used in developing upscaled simulations based on highly-resolved mechanistic models. We constructed a number of diverse multi-aggregate structures with different packing ratios by stacking micro-aggregates containing internal pores and varying the size and shape of inter-aggregate pore spacing between them. We then performed pore-scale flow simulations using computational fluid dynamics methods to determine the flow patterns in these aggregate-of-aggregates structures and computed the partitioning of the flow through intra- and inter-aggregate pores as a function of the spacing between the aggregates. The results of these numerical experiments demonstrate that soluble nutrients are largely transported via flows through inter-aggregate pores. Although this result is consistent with intuition, we have also been able to quantify the relative flow capacity of the two domains under various conditions. For example, in our simulations, the flow capacity through the aggregates (intra-aggregate flow) was less than 2% of the total flow when the spacing between the aggregates

  9. Oxygen limitation within a bacterial aggregate.

    PubMed

    Wessel, Aimee K; Arshad, Talha A; Fitzpatrick, Mignon; Connell, Jodi L; Bonnecaze, Roger T; Shear, Jason B; Whiteley, Marvin

    2014-04-15

    ABSTRACT Cells within biofilms exhibit physiological heterogeneity, in part because of chemical gradients existing within these spatially structured communities. Previous work has examined how chemical gradients develop in large biofilms containing >10(8) cells. However, many bacterial communities in nature are composed of small, densely packed aggregates of cells (≤ 10(5) bacteria). Using a gelatin-based three-dimensional (3D) printing strategy, we confined the bacterium Pseudomonas aeruginosa within picoliter-sized 3D "microtraps" that are permeable to nutrients, waste products, and other bioactive small molecules. We show that as a single bacterium grows into a maximally dense (10(12) cells ml(-1)) clonal population, a localized depletion of oxygen develops when it reaches a critical aggregate size of ~55 pl. Collectively, these data demonstrate that chemical and phenotypic heterogeneity exists on the micrometer scale within small aggregate populations. IMPORTANCE Before developing into large, complex communities, microbes initially cluster into aggregates, and it is unclear if chemical heterogeneity exists in these ubiquitous micrometer-scale aggregates. We chose to examine oxygen availability within an aggregate since oxygen concentration impacts a number of important bacterial processes, including metabolism, social behaviors, virulence, and antibiotic resistance. By determining that oxygen availability can vary within aggregates containing ≤ 10(5) bacteria, we establish that physiological heterogeneity exists within P. aeruginosa aggregates, suggesting that such heterogeneity frequently exists in many naturally occurring small populations.

  10. Structure and kinetics of shear aggregation in turbulent flows. I. Early stage of aggregation.

    PubMed

    Bäbler, Matthäus U; Moussa, Amgad S; Soos, Miroslav; Morbidelli, Massimo

    2010-08-17

    Aggregation of rigid colloidal particles leads to fractal-like structures that are characterized by a fractal dimension d(f) which is a key parameter for describing aggregation processes. This is particularly true in shear aggregation where d(f) strongly influences aggregation kinetics. Direct measurement of d(f) in the early stages of shear aggregation is however difficult, as the aggregates are small and few in number. An alternative method for determining d(f) is to use an aggregation model that when fitted to the time evolution of the cluster mass distribution allows for estimating d(f). Here, we explore three such models, two of which are based on an effective collision sphere and one which directly incorporates the permeable structure of the aggregates, and we apply them for interpreting the initial aggregate growth measured experimentally in a turbulent stirred tank reactor. For the latter, three polystyrene latexes were used that differed only in the size of the primary particles (d(p) = 420, 600, and 810 nm). It was found that all three models describe initial aggregation kinetics reasonably well using, however, substantially different values for d(f). To discriminate among the models, we therefore also studied the regrowth of preformed aggregates where d(f) was experimentally accessible. It was found that only the model that directly incorporates the permeable structure of the aggregates is able to predict correctly this second type of experiments. Applying this model to the initial aggregation kinetics, we conclude that the actual initial fractal dimension is d(f) = 2.07 +/- 0.04 as found from this model.

  11. Anaerobic Biodegradation of Soybean Biodiesel and Diesel ...

    EPA Pesticide Factsheets

    Biotransformation of soybean biodiesel and the inhibitory effect of petrodiesel were studied under methanogenic conditions. Biodiesel removal efficiency of more than 95% was achieved in a chemostat with influent biodiesel concentrations up to 2.45 g/L. The kinetics of anaerobic biodegradation of soybean biodiesel B100 (biodiesel only) with different petrodiesel loads were studied using biomass pre-acclimated to B100 and B80 (80% biodiesel and 20 petrodiesel). The results indicated that the biodiesel fraction of the blend could be effectively biodegraded, whereas petrodiesel was not biodegraded at all under methanogenic conditions. The presence of petrodiesel in blends with biodiesel had a greater inhibitory effect on the rate of biodegradation than the biodegradation efficiency (defined as the efficiency of methane production). Both the biodegradation rate coefficient and the methane production efficiency increased almost linearly with the increasing fraction of biodiesel. With the increasing fraction of petrodiesel, the biodegradation rate and efficiency were correlated with the concentration of soluble FAMEs in the water. The objective of this study was to investigate the anaerobic biodegradation of soybean biodiesel blends under methanogenic conditions. Biological methane potential (BMP) tests were conducted in serum bottles to determine the anaerobic biodegradation kinetics of biodiesel in the absence and presence of different concentrations of petrod

  12. Dance--Aerobic and Anaerobic.

    ERIC Educational Resources Information Center

    Cohen, Arlette

    1984-01-01

    This article defines and explains aerobic exercise and its effects on the cardiovascular system. Various studies on dancers are cited indicating that dance is an anaerobic activity with some small degree of aerobic benefit. (DF)

  13. Implementing Livestock Anaerobic Digestion Projects

    EPA Pesticide Factsheets

    Page provides information to help make an informed decision about installing an anaerobic digester. Is it a good match for a farm’s organic waste, project financing, development guidelines and permit requirements?

  14. Dance--Aerobic and Anaerobic.

    ERIC Educational Resources Information Center

    Cohen, Arlette

    1984-01-01

    This article defines and explains aerobic exercise and its effects on the cardiovascular system. Various studies on dancers are cited indicating that dance is an anaerobic activity with some small degree of aerobic benefit. (DF)

  15. Manganese Dependent Anaerobic Oxidation of Methane

    NASA Astrophysics Data System (ADS)

    Beal, E.; House, C.

    2007-12-01

    Understanding the anaerobic oxidation is not only important for understanding hydrocarbon degradation but it also important for understanding the global carbon cycle. The anaerobic oxidation of methane (AOM) is a large sink for methane consuming 5-20% of today's methane flux (Valentine and Reeburgh, 2000), yet the requirements for this process are not well understood. It has been suggested that no other electron acceptors other than sulfate can be used in the AOM (Nauhaus, 2005). However, our new data suggests that manganese, in the form of birnessite, can be used as an electron acceptor instead of sulfate (Beal et al., in prep). Methane seep sediment from the Eel River Basin, CA was incubated with methane, 13C-labeled methane, and carbon dioxide. Because the net result of the AOM is the production of carbon dioxide from methane, the rate of the AOM in each of the incubations can be determined by measuring the incorporation of 13C in the carbon dioxide. Using this method, it was found that cultures incubated with nitrate showed inhibition of the AOM, while cultures incubated with iron gave inconclusive results. The only positive results that were found for alternate electron acceptors are the incubations that were given manganese and no sulfate, which showed methane oxidation. Further, when more manganese was injected into these incubations, the rate of AOM increased. Preliminary analysis of the microbial population using terminal restriction fragment length polymorphism (TRFLP) targeting the mcr gene showed an unidentified organism in these cultures. Future work with TRFLP, as well as clone libraries, will help to identify the organisms responsible for this process. Nauhaus, K., 2005, Environmental regulation of the anaerobic oxidation of methane: a comparison of ANME-I and ANME-II communities: Environmental microbiology, v. 7, p. 98. Valentine, D.L., and Reeburgh, W.S., 2000, New perspectives on anaerobic methane oxidation: Environmental Microbiology, v. 2, p

  16. Microbial activity measurements for anaerobic sludge digestion

    SciTech Connect

    Chung, Y.C.

    1988-01-01

    The use of particulate substrate in the anaerobic sludge digestion process makes it difficult to measure the biomass in these reactors. Adenosine triphosphate (ATP) and dehydrogenase activity (DHA) were investigated as indicators of the sludge activity for the anaerobic sludge digestion process. ATP measures the energy pools in the biomass and is therefore a measure of the total sludge activity. DHA measurement relies on the addition of specific substrates to stimulate the metabolic activity of the bacteria. Glucose, starch, propionic acid, butyric acid, acetic acid, and digester feed as added substrates were used to stimulate the metabolic activity for DHA measurements. Laboratory experiments were performed to monitor the microbial activity of anaerobic sludge digesters operated both under steady state and in batch mode. The ATP content responded rapidly to changes in the digester operation, which may be the result of increased non-growth associated biochemical activity, not that of increased numbers of the bacteria. DHA was more sensitive than ATP at both low and high sludge ages and seemed to be correlated with the cell's growth phase. At low sludge ages (less than 10 days) glucose as added substrate showed the highest DHA responses, while the digester food and no added substrated showed the highest response when the sludge age exceeded 20 days. A kinetic model based on the solids balances was developed to determine the microbial mass and activity. Both ATP and DHA on a VSS basis (viability) appeared nearly constant over a wide range of sludge ages for the kinetic model data, indicating that ATP and DHA may be used as a rapid and convenient indicator of microbial mass and activity for anaerobic sludge digestion.

  17. Modified anaerobic digestion elutriated phased treatment for the anaerobic co-digestion of sewage sludge and food wastewater.

    PubMed

    Mo, Kyung; Lee, Wonbae; Kim, Moonil

    2017-02-01

    A modified anaerobic digestion elutriated phased treatment (MADEPT) process was developed for investigating anaerobic co-digestion of sewage sludge and food wastewater. The anaerobic digestion elutriated phased treatment (ADEPT) process is similar to a two-phase system, however, in which the effluent from a methanogenic reactor recycles into an acidogenic reactor to elutriate mainly dissolved organics. Although ADEPT could reduce reactor volume significantly, the unsolubilized solids should be wasted from the system. The MADEPT process combines thermo-alkali solubilization with ADEPT to improve anaerobic performance and to minimize the sludge disposal. It was determined that the optimal volume mixing ratio of sewage sludge and food wastewater was 4 : 1 for the anaerobic co-digestion. The removal efficiencies of total chemical oxygen demand, volatile solids, and volatile suspended solids in the MADEPT process were 73%, 70%, and 64%, respectively. However, those in the ADEPT process were only 48%, 37%, and 40%, respectively, at the same hydraulic retention time (HRT) of 7 days. The gas production of MADEPT was two times higher than that of ADEPT. The thermo-alkali solubilization increased the concentration of dissolved organics so that they could be effectively degraded in a short HRT, implying that MADEPT could improve the performance of ADEPT in anaerobic co-digestion.

  18. Charged Dust Aggregate Interactions

    NASA Astrophysics Data System (ADS)

    Matthews, Lorin; Hyde, Truell

    2015-11-01

    A proper understanding of the behavior of dust particle aggregates immersed in a complex plasma first requires a knowledge of the basic properties of the system. Among the most important of these are the net electrostatic charge and higher multipole moments on the dust aggregate as well as the manner in which the aggregate interacts with the local electrostatic fields. The formation of elongated, fractal-like aggregates levitating in the sheath electric field of a weakly ionized RF generated plasma discharge has recently been observed experimentally. The resulting data has shown that as aggregates approach one another, they can both accelerate and rotate. At equilibrium, aggregates are observed to levitate with regular spacing, rotating about their long axis aligned parallel to the sheath electric field. Since gas drag tends to slow any such rotation, energy must be constantly fed into the system in order to sustain it. A numerical model designed to analyze this motion provides both the electrostatic charge and higher multipole moments of the aggregate while including the forces due to thermophoresis, neutral gas drag, and the ion wakefield. This model will be used to investigate the ambient conditions leading to the observed interactions. This research is funded by NSF Grant 1414523.

  19. Aggregate breakup in a contracting nozzle.

    PubMed

    Soos, Miroslav; Ehrl, Lyonel; Bäbler, Matthäus U; Morbidelli, Massimo

    2010-01-05

    The breakup of dense aggregates in an extensional flow was investigated experimentally. The flow was realized by pumping the suspension containing the aggregates through a contracting nozzle. Variation of the cluster mass distribution during the breakage process was measured by small-angle light scattering. Because of the large size of primary particles and the dense aggregate structure image analysis was used to determine the shape and structure of the produced fragments. It was found, that neither aggregate structure, characterized by a fractal dimension d(f) = 2.7, nor shape, characterized by an average aspect ratio equal to 1.5, was affected by breakage. Several passes through the nozzle were required to reach the steady state. This is explained by the radial variation of the hydrodynamic stresses at the nozzle entrance, characterized through computational fluid dynamics, which implies that only the fraction of aggregates whose strength is smaller than the local hydrodynamic stress is broken during one pass through the nozzle. Scaling of the steady-state aggregate size as a function of the hydrodynamic stress was used to determine the aggregate strength.

  20. Aggregate and the environment

    USGS Publications Warehouse

    Langer, William H.; Drew, Lawrence J.; Sachs, J.S.

    2004-01-01

    This book is designed to help you understand our aggregate resources-their importance, where they come from, how they are processed for our use, the environmental concerns related to their mining and processing, how those concerns are addressed, and the policies and regulations designed to safeguard workers, neighbors, and the environment from the negative impacts of aggregate mining. We hope this understanding will help prepare you to be involved in decisions that need to be made-individually and as a society-to be good stewards of our aggregate resources and our living planet.

  1. Aggregate size distribution of the soil loss

    NASA Astrophysics Data System (ADS)

    Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka; Józsa, Sándor; Szalai, Zoltán; Centeri, Csaba

    2016-04-01

    In agricultural areas the soil erosion and soil loss estimation is vital information in long-term planning. During the initial period of the erosion a part of the soil particles and aggregates get transportable and nutrients and organic matter could be transported due to the effect of water or wind. This preliminary phase was studied with laboratory-scale rainfall simulator. Developed surface crust and aggregate size composition of the runoff was examined in six different slope-roughness-moisture content combination of a Cambisol and a Regosol. The ratio of micro- and macro aggregates in the runoff indicate the stability of the aggregates and determine the transport capacity of the runoff. Both soil samples were taken from field where the water erosion is a potential hazard. During the experiment the whole amount of runoff and sediment was collected through sieve series to a bucket to separate the micro- and macro aggregates. In case of both samples the micro aggregates dominate in the runoff and the runoff rates are similar. Although the runoff of the Regosol - with dominant >1000μm macro aggregate content - contained almost nothing but <50μm sized micro aggregates. Meanwhile the runoff of the Cambisol - with more balanced micro and macro aggregate content - contained dominantly 50-250μm sized micro aggregates and in some case remarkable ratio 250-1000μm sized macro aggregates. This difference occurred because the samples are resistant against drop erosion differently. In case of both sample the selectivity of the erosion and substance matrix redistribution manifested in mineral crusts in the surface where the quartz deposited in place while the lighter organic matter transported with the sediment. The detachment of the aggregates and the redistribution of the particles highly effect on the aggregate composition of the runoff which is connected with the quality of the soil loss. So while the estimation of soil loss quantity is more or less is easy, measuring

  2. Protein Colloidal Aggregation Project

    NASA Technical Reports Server (NTRS)

    Oliva-Buisson, Yvette J. (Compiler)

    2014-01-01

    To investigate the pathways and kinetics of protein aggregation to allow accurate predictive modeling of the process and evaluation of potential inhibitors to prevalent diseases including cataract formation, chronic traumatic encephalopathy, Alzheimer's Disease, Parkinson's Disease and others.

  3. Propagation of Tau aggregates.

    PubMed

    Goedert, Michel; Spillantini, Maria Grazia

    2017-05-30

    Since 2009, evidence has accumulated to suggest that Tau aggregates form first in a small number of brain cells, from where they propagate to other regions, resulting in neurodegeneration and disease. Propagation of Tau aggregates is often called prion-like, which refers to the capacity of an assembled protein to induce the same abnormal conformation in a protein of the same kind, initiating a self-amplifying cascade. In addition, prion-like encompasses the release of protein aggregates from brain cells and their uptake by neighbouring cells. In mice, the intracerebral injection of Tau inclusions induced the ordered assembly of monomeric Tau, followed by its spreading to distant brain regions. Short fibrils constituted the major species of seed-competent Tau. The existence of several human Tauopathies with distinct fibril morphologies has led to the suggestion that different molecular conformers (or strains) of aggregated Tau exist.

  4. Aggregation and Averaging.

    ERIC Educational Resources Information Center

    Siegel, Irving H.

    The arithmetic processes of aggregation and averaging are basic to quantitative investigations of employment, unemployment, and related concepts. In explaining these concepts, this report stresses need for accuracy and consistency in measurements, and describes tools for analyzing alternative measures. (BH)

  5. Aggregation of retail stores

    NASA Astrophysics Data System (ADS)

    Jensen, Pablo; Boisson, Jean; Larralde, Hernán

    2005-06-01

    We propose a simple model to understand the economic factors that induce aggregation of some businesses over small geographical regions. The model incorporates price competition with neighboring stores, transportation costs and the satisfaction probability of finding the desired product. We show that aggregation is more likely for stores selling expensive products and/or stores carrying only a fraction of the business variety. We illustrate our model with empirical data collected in the city of Lyon.

  6. Protein aggregation and prionopathies.

    PubMed

    Renner, M; Melki, R

    2014-06-01

    Prion protein and prion-like proteins share a number of characteristics. From the molecular point of view, they are constitutive proteins that aggregate following conformational changes into insoluble particles. These particles escape the cellular clearance machinery and amplify by recruiting the soluble for of their constituting proteins. The resulting protein aggregates are responsible for a number of neurodegenerative diseases such as Creutzfeldt-Jacob, Alzheimer, Parkinson and Huntington diseases. In addition, there are increasing evidences supporting the inter-cellular trafficking of these aggregates, meaning that they are "transmissible" between cells. There are also evidences that brain homogenates from individuals developing Alzheimer and Parkinson diseases propagate the disease in recipient model animals in a manner similar to brain extracts of patients developing Creutzfeldt-Jacob's disease. Thus, the propagation of protein aggregates from cell to cell may be a generic phenomenon that contributes to the evolution of neurodegenerative diseases, which has important consequences on human health issues. Moreover, although the distribution of protein aggregates is characteristic for each disease, new evidences indicate the possibility of overlaps and crosstalk between the different disorders. Despite the increasing evidences that support prion or prion-like propagation of protein aggregates, there are many unanswered questions regarding the mechanisms of toxicity and this is a field of intensive research nowadays. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  7. Development of Arsenic and Iron Biogeochemical Gradients upon Anaerobiosis at Soil Aggregate Scale

    NASA Astrophysics Data System (ADS)

    Masue-Slowey, Y.; Pallud, C.; Bedore, P.; Tufano, K.; Fendorf, S.

    2008-12-01

    In aerated soils, As release is limited due to the strong interaction between As(V) and soil minerals. However, under anaerobic conditions, As desorption is stimulated by As(V) reduction to As(III) and reductive dissolution/transformation of Fe (hydr)oxides, common hosts of As. The effect of As(V) and Fe(III) reduction on As release has been extensively studied in laboratory batch and column systems; correlation of apparent Fe and As reduction, with concomitant release to pore water, has also been noted under field conditions. What remains unresolved is the coupling of biogeochemical and physical processes that ultimately control As transport within structured media such as soils. Soils are heterogeneous porous media that are comprised of individual aggregates having pores that are dominated by diffusive (aggregate interiors) or advective (aggregate exteriors) transport. As a consequence of physical and chemical differences in the interior and the exterior of aggregates, As(III,V) and Fe(II,III) chemical gradients develop. Here, we examine As release from constructed aggregates exposed to fluctuating redox conditions. Artificial aggregates were made with As(V) adsorbed ferrihydrite-coated sand homogeneously inoculated with Shewanella sp. ANA-3 (model As(V) and Fe(III) reducer) and then fused using an agarose binder into spheres. Aggregates were placed in a flow reactor and saturated flow of aerobic or anaerobic artificial groundwater media was initiated. Redox fluctuated in select systems to examine changes in chemical gradient under changing aeration status. Our results show that within aerated solutions, oxidized aggregate exteriors provide a "gprotective barrier"h against As release despite anoxia within diffusively constrained aggregate interiors. During a transition to anaerobic conditions in advective zones, however, As is released and transport is promoted. Our study illustrates the microscale variation in biogeoechemical processes within soils and the

  8. Genetic, phenotypic and matrix-assisted laser desorption ionization time-of-flight mass spectrometry-based identification of anaerobic bacteria and determination of their antimicrobial susceptibility at a University Hospital in Japan.

    PubMed

    Yunoki, Tomoyuki; Matsumura, Yasufumi; Nakano, Satoshi; Kato, Karin; Hotta, Go; Noguchi, Taro; Yamamoto, Masaki; Nagao, Miki; Takakura, Shunji; Ichiyama, Satoshi

    2016-05-01

    The accuracies of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) and the phenotypic method using VITEK 2 were compared to the accuracy of 16S rRNA sequence analysis for the identification of 170 clinically isolated anaerobes. The antimicrobial susceptibility of the isolates was also evaluated. Genetic analysis identified 21 Gram-positive species in 14 genera and 29 Gram-negative species in 11 genera. The most frequently isolated genera were Prevotella spp. (n = 46), Bacteroides spp. (n = 25) and Clostridium spp. (n = 25). MALDI-TOF MS correctly identified more isolates compared with VITEK 2 at the species (80 vs. 58%, respectively; p < 0.01) and genus (85 vs. 71%, respectively; p < 0.01) levels. More than 90% of the isolates of the three major genera identified (Prevotella, Bacteroides, and Clostridium species other than Clostridium difficile) were susceptible to beta-lactam/beta-lactamase inhibitor combinations, carbapenems, metronidazole and chloramphenicol. MALDI-TOF MS provided better identification results than VITEK2. Commonly used anti-anaerobic agents indicated that the isolates of the three most frequently identified anaerobic genera exhibited good antimicrobial susceptibility.

  9. Distributed microbially- and chemically-mediated redox processes controlling arsenic dynamics within Mn-/Fe-oxide constructed aggregates

    NASA Astrophysics Data System (ADS)

    Ying, Samantha C.; Masue-Slowey, Yoko; Kocar, Benjamin D.; Griffis, Sarah D.; Webb, Samuel; Marcus, Matthew A.; Francis, Christopher A.; Fendorf, Scott

    2013-03-01

    The aggregate-based structure of soils imparts physical heterogeneity that gives rise to variation in microbial and chemical processes which influence the speciation and retention of trace elements such as As. To examine the impact of distributed redox conditions on the fate of As in soils, we imposed various redox treatments upon constructed soil aggregates composed of ferrihydrite- and birnessite-coated sands presorbed with As(V) and inoculation with the dissimilatory metal reducing bacterium Shewanella sp. ANA-3. Aeration of the advecting solution surrounding the aggregates was varied to simulate environmental conditions. We find that diffusion-limited transport within high dissolved organic carbon environments allows reducing conditions to persist in the interior of aggregates despite aerated advecting external solutes, causing As, Mn, and Fe to migrate from the reduced aggregate interiors to the aerated exterior region. Upon transitioning to anoxic conditions in the external solutes, pulses of As, Mn and Fe are released into the advecting solution, while, conversely, a transition to aerated conditions in the exterior resulted in a cessation of As, Mn, and Fe release. Importantly, we find that As(III) oxidation by birnessite is appreciable only in the presence of O2; oxidation of As(III) to As(V) by Mn-oxides ceases under anaerobic conditions apparently as a result of microbially mediated Mn(IV/III) reduction. Our results demonstrate the importance of considering redox conditions and the physical complexity of soils in determining As dynamics, where redox transitions can either enhance or inhibit As release due to speciation shifts in both sorbents (solubilization versus precipitation of Fe and Mn oxides) and sorbates (As).

  10. Oxidation of nanoscale zero-valent iron under sufficient and limited dissolved oxygen: Influences on aggregation behaviors.

    PubMed

    Jiang, Danlie; Hu, Xialin; Wang, Rui; Yin, Daqiang

    2015-03-01

    Oxidations of nanoscale zero-valent iron (nZVI) under aerobic (dissolved oxygen≈8mgL(-1)) and anaerobic (dissolved oxygen <3mgL(-1)) conditions were simulated, and their influences on aggregation behaviors of nZVI were investigated. The two oxidation products were noted as HO-nZVI (nZVI oxidized in highly oxygenated water) and LO-nZVI (nZVI oxidized in lowly oxygenated water) respectively. The metallic iron of the oxidized nZVI was almost exhausted (Fe(0)≈8±5%), thus magnetization mainly depended on magnetite content. Since sufficient dissolved oxygen led to the much less magnetite (∼15%) in HO-nZVI than that in LO-nZVI (>90%), HO-nZVI was far less magnetic (Ms=88kAm(-1)) than LO-nZVI (Ms=365kAm(-1)). Consequently, HO-nZVI formed small agglomerates (228±10nm), while LO-nZVI tended to form chain-like aggregations (>1μm) which precipitated rapidly. Based on the EDLVO theory, we suggested that dissolved oxygen level determined aggregation morphologies by controlling the degree of oxidation and the magnitude of magnetization. Then the chain-like alignment of LO-nZVI would promote further aggregation, but the agglomerate morphology of HO-nZVI would eliminate magnetic forces and inhibit the aggregation while HO-nZVI remained magnetic. Our results indicated the fine colloidal stability of HO-nZVI, which might lead to the great mobility in the environment. Copyright © 2014 Elsevier Ltd. All rights reserved.

  11. Biology of gut anaerobic fungi.

    PubMed

    Bauchop, T

    1989-01-01

    The obligately anaerobic nature of the gut indigenous fungi distinguishes them from other fungi. They are distributed widely in large herbivores, both in the foregut of ruminant-like animals and in the hindgut of hindgut fermenters. Comparative studies indicate that a capacious organ of fermentative digestion is required for their development. These fungi have been assigned to the Neocallimasticaceae, within the chytridiomycete order Spizellomycetales. The anaerobic fungi of domestic ruminants have been studied most extensively. Plant material entering the rumen is rapidly colonized by zoospores that attach and develop into thalli. The anaerobic rumen fungi have been shown to produce active cellulases and xylanases and specifically colonise and grow on plant vascular tissues. Large populations of anaerobic fungi colonise plant fragment in the rumens of cattle and sheep on high-fibre diets. The fungi actively ferment cellulose which results in formation of a mixture of products including acetate, lactate, ethanol, formate, succinate, CO2 and H2. The properties of the anaerobic fungi together with the extent of their populations on plant fragments in animals on high-fibre diets indicates a significant role for the fungi in fibre digestion.

  12. Anaerobic benzene degradation by bacteria

    PubMed Central

    Vogt, Carsten; Kleinsteuber, Sabine; Richnow, Hans‐Hermann

    2011-01-01

    Summary Benzene is a widespread and toxic contaminant. The fate of benzene in contaminated aquifers seems to be primarily controlled by the abundance of oxygen: benzene is aerobically degraded at high rates by ubiquitous microorganisms, and the oxygen‐dependent pathways for its breakdown were elucidated more than 50 years ago. In contrast, benzene was thought to be persistent under anoxic conditions until 25 years ago. Nevertheless, within the last 15 years, several benzene‐degrading cultures have been enriched under varying electron acceptor conditions in laboratories around the world, and organisms involved in anaerobic benzene degradation have been identified, indicating that anaerobic benzene degradation is a relevant environmental process. However, only a few benzene degraders have been isolated in pure culture so far, and they all use nitrate as an electron acceptor. In some highly enriched strictly anaerobic cultures, benzene has been described to be mineralized cooperatively by two or more different organisms. Despite great efforts, the biochemical mechanism by which the aromatic ring of benzene is activated in the absence of oxygen is still not fully elucidated; methylation, hydroxylation and carboxylation are discussed as likely reactions. This review summarizes the current knowledge about the ‘key players’ of anaerobic benzene degradation under different electron acceptor conditions and the possible pathway(s) of anaerobic benzene degradation. PMID:21450012

  13. Determination of the aggregate size in detergent solution of the light-harvesting chlorophyll a/b-protein complex from chloroplast membranes

    PubMed Central

    Butler, P. J. G.; Kühlbrandt, W.

    1988-01-01

    The molecular mass of an oligomeric integral membrane protein, the light-harvesting chlorophyll a/b-protein complex from the photosynthetic membranes of chloroplasts, has been determined in detergent solution by analytical ultracentrifugation and measurement of the density increment at constant chemical potential of all diffusible solutes. The technique used eliminates any problems resulting from detergent binding to the protein, is independent of the particular detergent used (in this case the nonionic n-octyl β-D-glucopyranoside), and gives the apparent weight-average molecular mass at different protein concentrations, allowing extrapolation to zero concentration. It means that the solutions of the complex must be brought to dialysis equilibrium with the solvent detergent solution and also requires a reliable method for measuring the protein concentration, for which amino acid analysis was used. The detergent-solubilized complex was a trimer that dissociated into monomers and dimers at low protein concentration. The accurate concentration determinations also allowed the molar chlorophyll-to-protein ratio to be measured as 15, corresponding to 8 chlorophyll a and 7 chlorophyll b molecules. PMID:16593931

  14. Prevalence and Contribution of Anaerobic Microsites to Carbon Mineralization in Upland Soils

    NASA Astrophysics Data System (ADS)

    Fendorf, S. E.; Keiluweit, M.; Gee, K. E.; Kleber, M.; Wanzek, T.; Nico, P. S.

    2015-12-01

    Soil organic matter (SOM) storage, or residence time, is dominantly controlled by the mineralization (oxidation) rate, which is affected by climatic factors (particularly temperature and rainfall) influencing microbial metabolic rates as well as SOM chemistry, mineral-organic associations, and physical protection. Variation in anaerobic respiratory pathways can further, and dramatically, impact carbon oxidation rates. Within the aggregated structure of soils, steep chemical gradients arise from the supply of oxygen and nutrients along macropores that are rapidly consumed (relative to supply) within the micropore domains of aggregate interiors. As a consequence of demand exceeding oxygen supply within soil aggregates and peds, an appreciable fraction of the soil volume may persist in an anaerobic state within upland, agriculturally productive system. Factors limiting oxygen diffusion and availability such as soil texture, soil moisture content, organic matter input, and aggregate size (soil structure) provide central controls on microbial carbon mineralization rates. Here, we combine laboratory studies with manipulations of field samples and in-field measurements to illustrate how soil structure and carbon availability interact to impose anaerobic conditions and associated respiratory constraints on organic matter mineralization rates and thus storage within soils.

  15. A Novel Method to Quantify Soil Aggregate Stability by Measuring Aggregate Bond Energies

    NASA Astrophysics Data System (ADS)

    Efrat, Rachel; Rawlins, Barry G.; Quinton, John N.; Watts, Chris W.; Whitmore, Andy P.

    2016-04-01

    Soil aggregate stability is a key indicator of soil quality because it controls physical, biological and chemical functions important in cultivated soils. Micro-aggregates are responsible for the long term sequestration of carbon in soil, therefore determine soils role in the carbon cycle. It is thus vital that techniques to measure aggregate stability are accurate, consistent and reliable, in order to appropriately manage and monitor soil quality, and to develop our understanding and estimates of soil as a carbon store to appropriately incorporate in carbon cycle models. Practices used to assess the stability of aggregates vary in sample preparation, operational technique and unit of results. They use proxies and lack quantification. Conflicting results are therefore drawn between projects that do not provide methodological or resultant comparability. Typical modern stability tests suspend aggregates in water and monitor fragmentation upon exposure to an un-quantified amount of ultrasonic energy, utilising a laser granulometer to measure the change in mean weight diameter. In this project a novel approach has been developed based on that of Zhu et al., (2009), to accurately quantify the stability of aggregates by specifically measuring their bond energies. The bond energies are measured operating a combination of calorimetry and a high powered ultrasonic probe, with computable output function. Temperature change during sonication is monitored by an array of probes which enables calculation of the energy spent heating the system (Ph). Our novel technique suspends aggregates in heavy liquid lithium heteropolytungstate, as opposed to water, to avoid exposing aggregates to an immeasurable disruptive energy source, due to cavitation, collisions and clay swelling. Mean weight diameter is measured by a laser granulometer to monitor aggregate breakdown after successive periods of calculated ultrasonic energy input (Pi), until complete dispersion is achieved and bond

  16. Equilibrium studies of protein aggregates and homogeneous nucleation in protein formulation.

    PubMed

    Kiese, Sylvia; Pappenberger, Astrid; Friess, Wolfgang; Mahler, Hanns-Christian

    2010-02-01

    Shaking or heat stress may induce protein aggregates. Aggregation behavior of an IgG1 stressed by shaking or heat following static storage at 5 and 25 degrees C was investigated to determine whether protein aggregates exist in equilibrium. Aggregates were detected using different analytical methods including visual inspection, turbidity, light obscuration, size exclusion chromatography, and dynamic light scattering. Significant differences were evident between shaken and heated samples upon storage. Visible and subvisible particles (insoluble aggregates), turbidity and z-average diameter decreased whilst soluble aggregate content increased in shaken samples over time. Insoluble aggregates were considered to be reversible and dissociate into soluble aggregates and both aggregate types existed in equilibrium. Heat-induced aggregates had a denatured protein structure and upon static storage, no significant change in insoluble aggregates content was shown, whilst changes in soluble aggregates content occurred. This suggested that heat-induced insoluble aggregates were irreversible and not in equilibrium with soluble aggregates. Additionally, the aggregation behavior of unstressed IgG1 after spiking with heavily aggregated material (shaken or heat stressed) was studied. The aggregation behavior was not significantly altered, independent of the spiking concentration over time. Thus, neither mechanically stressed native nor temperature-induced denatured aggregates were involved in nucleating or propagating aggregation.

  17. Fibronectin Aggregation and Assembly

    PubMed Central

    Ohashi, Tomoo; Erickson, Harold P.

    2011-01-01

    The mechanism of fibronectin (FN) assembly and the self-association sites are still unclear and contradictory, although the N-terminal 70-kDa region (I1–9) is commonly accepted as one of the assembly sites. We previously found that I1–9 binds to superfibronectin, which is an artificial FN aggregate induced by anastellin. In the present study, we found that I1–9 bound to the aggregate formed by anastellin and a small FN fragment, III1–2. An engineered disulfide bond in III2, which stabilizes folding, inhibited aggregation, but a disulfide bond in III1 did not. A gelatin precipitation assay showed that I1–9 did not interact with anastellin, III1, III2, III1–2, or several III1–2 mutants including III1–2KADA. (In contrast to previous studies, we found that the III1–2KADA mutant was identical in conformation to wild-type III1–2.) Because I1–9 only bound to the aggregate and the unfolding of III2 played a role in aggregation, we generated a III2 domain that was destabilized by deletion of the G strand. This mutant bound I1–9 as shown by the gelatin precipitation assay and fluorescence resonance energy transfer analysis, and it inhibited FN matrix assembly when added to cell culture. Next, we introduced disulfide mutations into full-length FN. Three disulfide locks in III2, III3, and III11 were required to dramatically reduce anastellin-induced aggregation. When we tested the disulfide mutants in cell culture, only the disulfide bond in III2 reduced the FN matrix. These results suggest that the unfolding of III2 is one of the key factors for FN aggregation and assembly. PMID:21949131

  18. Time resolved study of three ruthenium(II) complexes at micellar surfaces: A new long excited state lifetime probe for determining critical micelle concentration of surfactant nano-aggregates.

    PubMed

    Patra, Digambara; Chaaban, Ahmad H; Darwish, Shaza; Saad, Huda A; Nehme, Ali S; Ghaddar, Tarek H

    2016-02-01

    Three different ruthenium complexes have been synthesized and their luminescence properties in different solvent environments are reported. Luminescence intensities and excited state lifetimes of Ru-I, Ru-II and Ru-III vary with solvent viscosity. The excited state lifetime of Ru-I linearly increases in the viscosity range 1.76-12,100cP. Ru-II shows two linear increases: one in the low and another in the high viscosity ranges, whereas Ru-III illustrates a linear enhancement only in the low viscosity range. Interestingly, luminescence intensities and excited state lifetimes of Ru-I, Ru-II and Ru-III are found to be sensitive to nano-aggregation. However, the surfactant head charge and that of the ruthenium center as well as the hydrophobic tail of the ancillary ligand of the complexes have a great role in deciding the nature of the interaction and on the excited state properties at micellar surfaces. It is proposed that the long lifetime of Ru-III in water could be due to the coiling of the carbon chain of the ancillary ligand around the ruthenium center. At micelle surface, this coiling of the carbon chain is lost due to the parallel alignment with surfactants and thus quenching of the excited state lifetime is seen. Furthermore, it is shown that the variation of the excited state lifetime with respect to the change in surfactant concentration is a result of the formation of micelles from the surfactant monomer, thus, a novel technique for the determination of the critical micelle concentration (cmc) based on the long excited state lifetime of Ru-III located at the micellar nano-aggregates is reported. Copyright © 2015 Elsevier B.V. All rights reserved.

  19. Carbonic anhydrases of anaerobic microbes.

    PubMed

    Ferry, James G

    2013-03-15

    Carbonic anhydrases (CAs) catalyze the reversible hydration of carbon dioxide to bicarbonate and are abundantly distributed in prokaryotes and eukaryotes. There are five classes (α,β,γ,δ,ζ) with no significant sequence or structural identity among them, a remarkable example of convergent evolution. The β and γ classes predominate in anaerobic microbes, living without O2, that comprise a substantial portion of the living protoplasm on Earth. Anaerobes reside in the lower intestinal tract of humans, one of many O2-free environments on Earth, where they convert complex biomass to methane and CO2 contributing an essential link in the global carbon cycle. Carbon dioxide is a universal metabolite of anaerobes necessitating CA for a diversity of proposed functions. Copyright © 2012 Elsevier Ltd. All rights reserved.

  20. Microbial physiology of an anaerobic propionate-degrading consortium

    SciTech Connect

    Xun, L.

    1989-01-01

    A methanogenic propionate-degrading consortium, comprised of a strictly anaerobic chemoheterotroph and two types of methanogenic bacteria, is responsible for the complete conversion of propionate to CH{sub 4} and CO{sub 2} via the intermediate formation of acetate, H{sub 2}, and CO{sub 2}. Propionate oxidation by the heterotroph to acetate, H{sub 2} and CO{sub 2} proceeds only if H{sub 2} is removed through oxidation by CO{sub 2}-reducing methanogens. Acetate may only be catabolized anaerobically by one specific physiological group of bacteria, the aceticlastic methanogens, which produces CH{sub 4} and CO{sub 2} by cleaving acetate. Representatives of all three of these organisms have been studied. The effects of environmental factors such as temperature, pH, and nutrients on anaerobic propionate degradation was studied by enrichment cultures. From the propionate enrichment, the H{sub 2} using methanogen (strain LX1) and the propionate-degrading organism (strain LX2) were isolated. Both organisms have been characterized. In regard to the aceticlastic reaction, Methanosarcina mazei S-6 isolated by Mah (1980), was studied as the third member of the consortium. By changing the culture conditions, the morphology of M. mazei was manipulated from an aggregated to single cell form.

  1. The Transition from Aerobic to Anaerobic Metabolism.

    ERIC Educational Resources Information Center

    Skinner, James S.; McLellan, Thomas H.

    1980-01-01

    The transition from aerobic to anaerobic metabolism is discussed. More research is needed on different kinds of athletes and athletic activities and how they may affect aerobic and anaerobic metabolisms. (CJ)

  2. The Transition from Aerobic to Anaerobic Metabolism.

    ERIC Educational Resources Information Center

    Skinner, James S.; McLellan, Thomas H.

    1980-01-01

    The transition from aerobic to anaerobic metabolism is discussed. More research is needed on different kinds of athletes and athletic activities and how they may affect aerobic and anaerobic metabolisms. (CJ)

  3. Observing Convective Aggregation

    NASA Astrophysics Data System (ADS)

    Holloway, Christopher E.; Wing, Allison A.; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan S.; Turner, David D.; Zuidema, Paquita

    2017-06-01

    Convective self-aggregation, the spontaneous organization of initially scattered convection into isolated convective clusters despite spatially homogeneous boundary conditions and forcing, was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  4. Observing convective aggregation

    NASA Astrophysics Data System (ADS)

    Holloway, Christopher; Wing, Allison; Bony, Sandrine; Muller, Caroline; Masunaga, Hirohiko; L'Ecuyer, Tristan; Turner, David; Zuidema, Paquita

    2017-04-01

    Convective self-aggregation was first recognized and studied in idealized numerical simulations. While there is a rich history of observational work on convective clustering and organization, there have been only a few studies that have analyzed observations to look specifically for processes related to self-aggregation in models. Here we review observational work in both of these categories and motivate the need for more of this work. We acknowledge that self-aggregation may appear to be far-removed from observed convective organization in terms of time scales, initial conditions, initiation processes, and mean state extremes, but we argue that these differences vary greatly across the diverse range of model simulations in the literature and that these comparisons are already offering important insights into real tropical phenomena. Some preliminary new findings are presented, including results showing that a self-aggregation simulation with square geometry has too broad a distribution of humidity and is too dry in the driest regions when compared with radiosonde records from Nauru, while an elongated channel simulation has realistic representations of atmospheric humidity and its variability. We discuss recent work increasing our understanding of how organized convection and climate change may interact, and how model discrepancies related to this question are prompting interest in observational comparisons. We also propose possible future directions for observational work related to convective aggregation, including novel satellite approaches and a ground-based observational network.

  5. Fractal dimension and mechanism of aggregation of apple juice particles.

    PubMed

    Benítez, E I; Lozano, J E; Genovese, D B

    2010-04-01

    Turbidity of freshly squeezed apple juice is produced by a polydisperse suspension of particles coming from the cellular tissue. After precipitation of coarse particles by gravity, only fine-colloidal particles remain in suspension. Aggregation of colloidal particles leads to the formation of fractal structures. The fractal dimension is a measure of the internal density of these aggregates and depends on their mechanism of aggregation. Digitized images of primary particles and aggregates of depectinized, diafiltered cloudy apple juice were obtained by scanning electron microscopy (SEM). Average radius of the primary particles was found to be a = 40 ± 11 nm. Maximum radius of the aggregates, R(L), ranged between 250 and 7750 nm. Fractal dimension of the aggregates was determined by analyzing SEM images with the variogram method, obtaining an average value of D(f) = 2.3 ± 0.1. This value is typical of aggregates formed by rapid flocculation or diffusion limited aggregation. Diafiltration process was found to reduce the average size and polydispersity of the aggregates, determined by photon correlation spectroscopy. Average gyration radius of the aggregates before juice diafiltration was found to be R(g) = 629 ± 87 nm. Average number of primary particles per aggregate was calculated to be N = 1174.

  6. Arsenic, Anaerobes, and Astrobiology

    NASA Astrophysics Data System (ADS)

    Stolz, J. F.; Oremland, R. S.; Switzer Blum, J.; Hoeft, S. E.; Baesman, S. M.; Bennett, S.; Miller, L. G.; Kulp, T. R.; Saltikov, C.

    2013-12-01

    Arsenic is an element best known for its highly poisonous nature, so it is not something one would associate with being a well-spring for life. Yet discoveries made over the past two decades have delineated that not only are some microbes resistant to arsenic, but that this element's primary redox states can be exploited to conserve energy and support prokaryotic growth ('arsenotrophy') in the absence of oxygen. Hence, arsenite [As(III)] can serve as an electron donor for chemo- or photo-autotrophy while arsenate [As(V)] will serve as an electron acceptor for chemo-heterotrophs and chemo-autotrophs. The phylogenetic diversity of these microbes is broad, encompassing many individual species from diverse taxonomic groups in the Domain Bacteria, with fewer representatives in the Domain Archaea. Speculation with regard to the evolutionary origins of the key functional genes in anaerobic arsenic transformations (arrA and arxA) and aerobic oxidation (aioB) has led to a disputation as to which gene and function is the most ancient and whether arsenic metabolism extended back into the Archaean. Regardless of its origin, robust arsenic metabolism has been documented in extreme environments that are rich in their arsenic content, such as hot springs and especially hypersaline soda lakes associated with volcanic regions. Searles Lake, CA is an extreme, salt-saturated end member where vigorous arsenic metabolism occurs, but there is no detectable sulfate-reduction or methanogenesis. The latter processes are too weak bio-energetically to survive as compared with arsenotrophy, and are also highly sensitive to the abundance of borate ions present in these locales. These observations have implications with respect to the search for microbial life elsewhere in the Solar System where volcanic-like processes have been operative. Hence, because of the likelihood of encountering dense brines in the regolith of Mars (formed by evapo-concentration) or beneath the ice layers of Europa

  7. Anaerobic biosynthesis of the lower ligand of vitamin B12

    PubMed Central

    Hazra, Amrita B.; Han, Andrew W.; Mehta, Angad P.; Mok, Kenny C.; Osadchiy, Vadim; Begley, Tadhg P.; Taga, Michiko E.

    2015-01-01

    Vitamin B12 (cobalamin) is required by humans and other organisms for diverse metabolic processes, although only a subset of prokaryotes is capable of synthesizing B12 and other cobamide cofactors. The complete aerobic and anaerobic pathways for the de novo biosynthesis of B12 are known, with the exception of the steps leading to the anaerobic biosynthesis of the lower ligand, 5,6-dimethylbenzimidazole (DMB). Here, we report the identification and characterization of the complete pathway for anaerobic DMB biosynthesis. This pathway, identified in the obligate anaerobic bacterium Eubacterium limosum, is composed of five previously uncharacterized genes, bzaABCDE, that together direct DMB production when expressed in anaerobically cultured Escherichia coli. Expression of different combinations of the bza genes revealed that 5-hydroxybenzimidazole, 5-methoxybenzimidazole, and 5-methoxy-6-methylbenzimidazole, all of which are lower ligands of cobamides produced by other organisms, are intermediates in the pathway. The bza gene content of several bacterial and archaeal genomes is consistent with experimentally determined structures of the benzimidazoles produced by these organisms, indicating that these genes can be used to predict cobamide structure. The identification of the bza genes thus represents the last remaining unknown component of the biosynthetic pathway for not only B12 itself, but also for three other cobamide lower ligands whose biosynthesis was previously unknown. Given the importance of cobamides in environmental, industrial, and human-associated microbial metabolism, the ability to predict cobamide structure may lead to an improved ability to understand and manipulate microbial metabolism. PMID:26246619

  8. Susceptibility testing of anaerobic bacteria: myth, magic, or method?

    PubMed Central

    Wexler, H M

    1991-01-01

    The demand for susceptibility testing of anaerobes has increased, yet consensus as to procedure and interpretation in this area has not been achieved. While routine testing of anaerobic isolates is not needed, certain isolates in specific clinical settings should be tested. Also, laboratories may monitor their local antibiograms by doing periodic surveillance batch testing. The National Committee for Clinical Laboratory Standards has published a protocol of methods approved for susceptibility testing of anaerobic bacteria. Both agar and broth microdilution are included; however, the broth disk elution method is no longer approved by the National Committee for Clinical Laboratory Standards because of method-related interpretive errors. A number of newer methods are undergoing evaluation and seem promising. Clinicians and microbiologists reviewing susceptibility reports should be aware of sources of variability in the test results. Variables in susceptibility testing of anaerobes include the media and methods used, organisms chosen for testing, breakpoints chosen for interpretation, antibiotic, and determination of endpoint. Clustering of MICs around the breakpoint may lead to significant variability in test results. Adherence of testing laboratories to approved methods and careful descriptions of the method and the breakpoints used for interpretation would facilitate interlaboratory comparisons and allow problems of emerging resistance to be noted. A variety of resistance mechanisms occurs in anaerobic bacteria, including the production of beta-lactamase and other drug-inactivating enzymes, alteration of target proteins, and inability of the drug to penetrate the bacterial wall. Antimicrobial resistance patterns in the United States and abroad are described. PMID:1747863

  9. Anaerobic biosynthesis of the lower ligand of vitamin B12.

    PubMed

    Hazra, Amrita B; Han, Andrew W; Mehta, Angad P; Mok, Kenny C; Osadchiy, Vadim; Begley, Tadhg P; Taga, Michiko E

    2015-08-25

    Vitamin B12 (cobalamin) is required by humans and other organisms for diverse metabolic processes, although only a subset of prokaryotes is capable of synthesizing B12 and other cobamide cofactors. The complete aerobic and anaerobic pathways for the de novo biosynthesis of B12 are known, with the exception of the steps leading to the anaerobic biosynthesis of the lower ligand, 5,6-dimethylbenzimidazole (DMB). Here, we report the identification and characterization of the complete pathway for anaerobic DMB biosynthesis. This pathway, identified in the obligate anaerobic bacterium Eubacterium limosum, is composed of five previously uncharacterized genes, bzaABCDE, that together direct DMB production when expressed in anaerobically cultured Escherichia coli. Expression of different combinations of the bza genes revealed that 5-hydroxybenzimidazole, 5-methoxybenzimidazole, and 5-methoxy-6-methylbenzimidazole, all of which are lower ligands of cobamides produced by other organisms, are intermediates in the pathway. The bza gene content of several bacterial and archaeal genomes is consistent with experimentally determined structures of the benzimidazoles produced by these organisms, indicating that these genes can be used to predict cobamide structure. The identification of the bza genes thus represents the last remaining unknown component of the biosynthetic pathway for not only B12 itself, but also for three other cobamide lower ligands whose biosynthesis was previously unknown. Given the importance of cobamides in environmental, industrial, and human-associated microbial metabolism, the ability to predict cobamide structure may lead to an improved ability to understand and manipulate microbial metabolism.

  10. Potential nanosilver impact on anaerobic digestion at moderate silver concentrations.

    PubMed

    Yang, Yu; Chen, Qian; Wall, Judy D; Hu, Zhiqiang

    2012-03-15

    Silver nanoparticles (AgNPs, nanosilver) entering the sewers and wastewater treatment plants (WWTPs) are mostly accumulated in the sludge. In this study, we determined the impact of AgNPs on anaerobic glucose degradation, sludge digestion and methanogenic assemblages. At ambient (22 °C) and mesophilic temperatures (37 °C), there was no significant difference in biogas and methane production between the sludge treated with AgNPs at the concentrations up to 40 mg Ag/L (13.2 g silver/Kg biomass COD) and the control. In these anaerobic digestion samples, acetate and propionic acid were the only detectable volatile fatty acids (VFAs) and they were depleted in 3 days. On the other hand, more than 90% of AgNPs was removed from the liquid phase and associated with the sludge while almost no silver ions were released from AgNPs under anaerobic conditions. Quantitative PCR results indicated that Methanosaeta and Methanomicrobiales were the dominant methanogens, and the methanogenic diversity and population remained largely unchanged after nanosilver exposure and anaerobic digestion. The results suggest that AgNPs at moderate concentrations (e.g., ≤40 mg/L) have negligible impact on anaerobic digestion and methanogenic assemblages because of little to no silver ion release.

  11. Anaerobic treatment of food wastes

    SciTech Connect

    Criner, G. )

    1991-04-01

    This article describes a research project at the University of Maine in which food wastes from the University cafeteria salad bar are processed in the anaerobic facility which normally treats only animal wastes. The project has benefited the University in several ways: avoidance of waste disposal fees; increased electricity co-generated from the biogas process; and use of the residual as fertilizer. An economic analysis indicated that the estimated cost of anaerobic treatment of the salad bar wastes was $4520/yr and benefits were $4793/yr. Since the digester was already in use, this cost was not factored into the analysis. Further studies are being planned.

  12. Aggregation of Montmorillonite and Organic Matter in Aqueous Media Containing Artificial Seawater

    DTIC Science & Technology

    2009-01-23

    laboratory kaolinite and montmorillonite aggregation in which the dispersion-aggregation properties of pure clay suspensions were found to be primarily...Article 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Aggregation of montmorillonite and organic matter in aqueous media containing...properties of suspended colloids and aggregates) were determined for systems containing suspended montmorillonite , humic acid, and/or chitin at the

  13. Microbiology and physiology of anaerobic fermentations of cellulose

    SciTech Connect

    Wiegel, J.

    1991-05-01

    The biochemistry and physiology of four major groups of anaerobic bacteria involved in the conversion of cellulose to methane or chemical feedstocks are examined. Aspects of metabolism which are relevant to the interactions and bioenergetics of consortia are being studied. Properties of the cellulolytic enzyme cluster of Clostridium thermocellum are investigated. Five different hydrogenases have been characterized in detail from anaerobic bacteria. Genes for different hydrogenases are being cloned and sequenced to determine their structural relationships. The role of metal clusters in activation of H{sub 2} is being investigated, as is the structure and role of metal clusters in formate metabolism. The function of formate in the total synthesis of acetate from CO{sub 2} and the role of this primary in anaerobes will be examined as well. Finally, these enzyme studies will be performed on thermophilic bacteria and new, pertinent species will be isolated. 50 refs., 3 figs., 1 tab.

  14. Defining Anaerobic Digestion Stability-Full Scale Study

    NASA Astrophysics Data System (ADS)

    Demitry, M. E., Sr.

    2014-12-01

    A full-scale anaerobic digester receiving a mixture of primary and secondary sludge was monitored for one hundred days. A chemical oxygen demand, COD, and a volatile solids, VS, mass balance was conducted to evaluate the stability of the digester and its capability of producing methane gas. The COD mass balance could account for nearly 90% of the methane gas produced while the VS mass balance showed that 91% of the organic matter removed resulted in biogas formation. Other parameters monitored included: pH, alkalinity, VFA, and propionic acid. The values of these parameters showed that steady state had occurred. Finally, at mesophilic temperature and at steady state performance, the anaerobic digester stability was defined as a constant ratio of methane produced per substrate of ΔVS (average ratio=0.404 l/g). This ratio can be used as universal metric to determine the anaerobic digester stability in an easy and inexpensive way.

  15. Anaerobic Digestion Analysis. Training Module 5.120.2.77.

    ERIC Educational Resources Information Center

    Kirkwood Community Coll., Cedar Rapids, IA.

    This document is an instructional module package prepared in objective form for use by an instructor familiar with alkalinity, volatile acids and carbon dioxide determinations for an anaerobic sludge digester. Included are objectives, instructor guides, student handouts and transparency masters. This module considers total and bicarbonate…

  16. INCREASE OF INDICATOR ORGANISMS FOLLOWING ANAEROBIC DIGESTION AND CENTRIFUGE DEWATERING.

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled “Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges”. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bac...

  17. INCREASE OF INDICATOR ORGANISMS FOLLOWING ANAEROBIC DIGESTION AND CENTRIFUGE DEWATERING.

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled “Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges”. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bac...

  18. Aerobic and anaerobic cecal bacterial flora of commercially processed broilers

    USDA-ARS?s Scientific Manuscript database

    Differences in the bacterial flora of aerobic and anaerobic cultures of broiler ceca collected from a commercial poultry processing facility were determined. Bacterial isolates from cecal cultures were selected based on the ability of the bacteria to grow in media supplemented with lactate and succ...

  19. Technology meets aggregate

    SciTech Connect

    Wilson, C.; Swan, C.

    2007-07-01

    New technology carried out at Tufts University and the University of Massachusetts on synthetic lightweight aggregate has created material from various qualities of fly ash from coal-fired power plants for use in different engineered applications. In pilot scale manufacturing tests an 'SLA' containing 80% fly ash and 20% mixed plastic waste from packaging was produced by 'dry blending' mixed plastic with high carbon fly ash. A trial run was completed to produce concrete masonry unit (CMU) blocks at a full-scale facility. It has been shown that SLA can be used as a partial substitution of a traditional stone aggregate in hot asphalt mix. 1 fig., 2 photos.

  20. Impact of virus aggregation on inactivation by peracetic acid and implications for other disinfectants.

    PubMed

    Mattle, Michael J; Crouzy, Benoit; Brennecke, Moritz; Wigginton, Krista R; Perona, Paolo; Kohn, Tamar

    2011-09-15

    Viruses in wastewater and natural environments are often present as aggregates. The disinfectant dose required for their inactivation, however, is typically determined with dispersed viruses. This study investigates how aggregation affects virus inactivation by chemical disinfectants. Bacteriophage MS2 was aggregated by lowering the solution pH, and aggregates were inactivated by peracetic acid (PAA). Aggregates were redispersed before enumeration to obtain the residual number of individual infectious viruses. In contrast to enumerating whole aggregates, this approach allowed an assessment of disinfection efficiency which remains applicable even if the aggregates disperse in post-treatment environments. Inactivation kinetics were determined as a function of aggregate size (dispersed, 0.55 and 0.90 μm radius) and PAA concentration (5-103 mg/L). Aggregation reduced the apparent inactivation rate constants 2-6 fold. The larger the aggregate and the higher the PAA concentration, the more pronounced the inhibitory effect of aggregation on disinfection. A reaction-diffusion based model was developed to interpret the experimental results, and to predict inactivation rates for additional aggregate sizes and disinfectants. The model showed that the inhibitory effect of aggregation arises from consumption of the disinfectant within the aggregate, but that diffusion of the disinfectant into the aggregates is not a rate-limiting factor. Aggregation therefore has a large inhibitory effect if highly reactive disinfectants are used, whereas inactivation by mild disinfectants is less affected. Our results suggest that mild disinfectants should be used for the treatment of water containing viral aggregates.

  1. Dynamics of soil GHG emissions shaped by hydration state, aggregate size distribution and carbon placement: Column experiments using artificial soil aggregates

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Ali; Or, Dani

    2017-04-01

    Dynamics of soil hydration affect microbial community dynamics and various biogeochemical processes (soil respiration, denitrification, methane production). Evidence suggests that anoxic conditions may persist in soil aggregates (long after bulk soil is aerated) thereby providing niches for anaerobic microbial communities (hot spots). Despite their recognized role in mediating soil biogeochemical fluxes, systematic studies of the impact of different environmental conditions on CO2, N2O and CH4 emissions from soil aggregates remain rare. We constructed artificial aggregates using a silt loam soil of different sizes and different carbon configurations (mixed, core, no addition) to study effects of hydration, aggregate size and carbon source configuration on GHG emissions. An assembly of aggregates of three sizes (18, 12, and 6 mm aggregates) was embedded in sand columns at four distinct layers (3 replicates for each aggregate-carbon source, 9 columns) and the water level was varied periodically to quantify effects of wetting/drying and submersion on GHG fluxes. Several gas samples were taken from the headspaces of each column (after closure) and analyzed using GC with the proper detectors to resolve fluxes. Results illustrate the critical role of hydration states on GHG emission, for example, lowering the water table (unsaturated conditions) decreases CH4 emissions while increasing N2O flux. We observe links between aerobic processes (e.g., nitrification) and anaerobic denitrification presumably by promoting alternative pathways (e.g., ammonia and nitrite oxidation). Methane production was activated under highly anoxic conditions (prolonged inundation). N2O production was highest form aggregates with carbon placed in the (anoxic) core whereas CO2 production rates were comparable from mixed and centered carbon sources (at rates that fluctuated with hydration conditions). Experimental results of artificial soil aggregates are of interest for improvement of physically

  2. Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

    NASA Astrophysics Data System (ADS)

    Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

    2015-04-01

    intensity of WR in aggregates of different sizes. [ii] the intra-aggregate distribution of OC and the intensity of WR and [iii] the structural stability of soil aggregates relative to the OC content and the intensity of WR in soils under different crops (apricot, citrus and wheat) and different treatments (conventional tilling and mulching). Soil samples were collected from an experimental area (Luvic Calcisols and Calcic Luvisols) in the province of Sevilla (Southern Spain) under different crops (apricot, citrus and wheat) and different management types (conventional tillage with moldboard plow) and mulching (no-tilling and addition of wheat residues at rates varying between 5 and 8 Mg/ha/year). At each sampling site, soil blocks (50 cm long × 50 cm wide × 10 cm deep) were carefully collected to avoid disturbance of aggregates as much as possible and transported to the laboratory. At field moist condition, undisturbed soil aggregates were separated by hand. In order to avoid possible interferences due to disturbance by handling, aggregates broken during this process were discarded. Individual aggregates were arranged in paper trays and air-dried during 7 days under laboratory standard conditions. After air-drying, part of each sample was carefully divided for different analyses: [i] part of the original samples was sieved (2 mm) to eliminate coarse soil particles and homogenized for characterization of OC and N contents, C/N ratio and texture; [ii] part of the aggregates were dry-sieved (0.25-0.5, 0.5-1 and 1-2 mm) or measured with a caliper (2-5, 5-10 and 10-15 mm) and separated in different sieve-size classes for determination of WR and OC content; [iii] aggregates 10-15 mm in size were selected for obtaining aggregate layers using a soil aggregate erosion (SAE) apparatus and WR and OC content were determined at each layer; finally, [iv] in order to study the relation between stability to slaking, WR and OC, these properties were determined in 90 air-dried aggregates

  3. INT-dehydrogenase activity test for assessing anaerobic biodegradability of organic compounds.

    PubMed

    Hongwei, Yang; Zhanpeng, Jiang; Shaoqi, Shi; Tang, W Z

    2002-11-01

    This study assessed anaerobic biodegradability of organic compounds from microorganism activity. Dehydrogenase activity can be a good parameter characterizing the microorganism activity. A modified method of 2-(p-iodophenyl-3-(p-nitrophenyl)-5-pheny tetrazolium chloride-dehydrogenase activity determination was proposed in anaerobic biodegradability assessment. Cubic spline curves were adopted to link the data points. This curve was integrated twice to calculate areas. The microorganism activity index in anaerobic biodegradability assessment was calculated by standardizing the integral. According to the results of the activity index, 14 kinds of organic compounds were classified into readily, partially, and poorly biodegradable under anaerobic conditions, respectively. As a result, some conclusions for anaerobic biodegradability of organic compounds were reached, based on the activity index value.

  4. Thermodynamics of Micellization of Surfactants of Low Aggregation Number: The Aggregation of Propranolol Hydrochloride.

    PubMed

    Mosquera; Ruso; Attwood; Jones; Prieto; Sarmiento

    1999-02-01

    The self-association of propranolol hydrochloride in aqueous solution has been studied as a function of temperature. The critical concentration (C*) and the degree of ionization (alpha) were determined by conductivity measurements at temperatures over the range 298.15 to 313.15 K. The enthalpy change on aggregation in water was measured by microcalorimetry. To calculate changes in the thermodynamic properties of aggregation the mass action model for high and low aggregation numbers was applied, the latter model giving better agreement between experimental and theoretical enthalpy changes. Copyright 1999 Academic Press.

  5. Partitioning of red blood cell aggregates in bifurcating microscale flows

    NASA Astrophysics Data System (ADS)

    Kaliviotis, E.; Sherwood, J. M.; Balabani, S.

    2017-03-01

    Microvascular flows are often considered to be free of red blood cell aggregates, however, recent studies have demonstrated that aggregates are present throughout the microvasculature, affecting cell distribution and blood perfusion. This work reports on the spatial distribution of red blood cell aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance.

  6. Partitioning of red blood cell aggregates in bifurcating microscale flows

    PubMed Central

    Kaliviotis, E.; Sherwood, J. M.; Balabani, S.

    2017-01-01

    Microvascular flows are often considered to be free of red blood cell aggregates, however, recent studies have demonstrated that aggregates are present throughout the microvasculature, affecting cell distribution and blood perfusion. This work reports on the spatial distribution of red blood cell aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance. PMID:28303921

  7. Antibiotic Susceptibility Pattern of Aerobic and Anaerobic Bacteria Isolated From Surgical Site Infection of Hospitalized Patients

    PubMed Central

    Akhi, Mohammad Taghi; Ghotaslou, Reza; Beheshtirouy, Samad; Asgharzadeh, Mohammad; Pirzadeh, Tahereh; Asghari, Babak; Alizadeh, Naser; Toloue Ostadgavahi, Ali; Sorayaei Somesaraei, Vida; Memar, Mohammad Yousef

    2015-01-01

    Background: Surgical Site Infections (SSIs) are infections of incision or deep tissue at operation sites. These infections prolong hospitalization, delay wound healing, and increase the overall cost and morbidity. Objectives: This study aimed to investigate anaerobic and aerobic bacteria prevalence in surgical site infections and determinate antibiotic susceptibility pattern in these isolates. Materials and Methods: One hundred SSIs specimens were obtained by needle aspiration from purulent material in depth of infected site. These specimens were cultured and incubated in both aerobic and anaerobic condition. For detection of antibiotic susceptibility pattern in aerobic and anaerobic bacteria, we used disk diffusion, agar dilution, and E-test methods. Results: A total of 194 bacterial strains were isolated from 100 samples of surgical sites. Predominant aerobic and facultative anaerobic bacteria isolated from these specimens were the members of Enterobacteriaceae family (66, 34.03%) followed by Pseudomonas aeruginosa (26, 13.4%), Staphylococcus aureus (24, 12.37%), Acinetobacter spp. (18, 9.28%), Enterococcus spp. (16, 8.24%), coagulase negative Staphylococcus spp. (14, 7.22%) and nonhemolytic streptococci (2, 1.03%). Bacteroides fragilis (26, 13.4%), and Clostridium perfringens (2, 1.03%) were isolated as anaerobic bacteria. The most resistant bacteria among anaerobic isolates were B. fragilis. All Gram-positive isolates were susceptible to vancomycin and linezolid while most of Enterobacteriaceae showed sensitivity to imipenem. Conclusions: Most SSIs specimens were polymicrobial and predominant anaerobic isolate was B. fragilis. Isolated aerobic and anaerobic strains showed high level of resistance to antibiotics. PMID:26421133

  8. In vitro canine platelet aggregation caused by Dirofilaria immitis extract

    PubMed Central

    TAKASHIMA, Yasuhiro; ONODA, Isako; CHIOU, Shin-Pin; KITOH, Katsuya

    2016-01-01

    Platelet function hyper-activity has been reported in Dirofilaria immitis (heartworm, HW)-infected dogs. Although the mechanism of increased platelet hyper-activity has not yet been elucidated, it is suggested to be mediated by unknown factors, which may be related to adult HW components. This study aims to determine whether adult male HW whole body extract induces canine platelet aggregation in vitro. The results indicate that HW extract caused an aggregation of canine platelets in a concentration-dependent manner. This aggregation ability of the HW extract was not mediated by the adenosine diphosphate receptor. In addition, the mechanisms of aggregation did not require cyclooxygenase-dependent pathways, and the aggregating activity of substances contained in the HW extract was heat stable; therefore, the active substances may be different from collagen. Furthermore, the platelet aggregating activity remained within the molecular weight (MW)≥100,000 fraction obtained by ultrafiltrating the HW extract. In contrast, the MW <100,000 fraction also had a platelet aggregation ability, but the aggregation pattern was reversible and the maximum extent decreased, compared with the MW≥100,000 fraction response. Our experiments have been conducted using a whole body extract from adult HWs to determine with certainty the aggregating activity of HW elements on canine platelets. More studies are necessary to evaluate the effects of the metabolic products released from live adult worms in pulmonary arteries and the symbiont bacterium Wolbachia-derived antigens on canine platelet aggregation. PMID:28049921

  9. In vitro canine platelet aggregation caused by Dirofilaria immitis extract.

    PubMed

    Takashima, Yasuhiro; Onoda, Isako; Chiou, Shin-Pin; Kitoh, Katsuya

    2017-02-28

    Platelet function hyper-activity has been reported in Dirofilaria immitis (heartworm, HW)-infected dogs. Although the mechanism of increased platelet hyper-activity has not yet been elucidated, it is suggested to be mediated by unknown factors, which may be related to adult HW components. This study aims to determine whether adult male HW whole body extract induces canine platelet aggregation in vitro. The results indicate that HW extract caused an aggregation of canine platelets in a concentration-dependent manner. This aggregation ability of the HW extract was not mediated by the adenosine diphosphate receptor. In addition, the mechanisms of aggregation did not require cyclooxygenase-dependent pathways, and the aggregating activity of substances contained in the HW extract was heat stable; therefore, the active substances may be different from collagen. Furthermore, the platelet aggregating activity remained within the molecular weight (MW)≥100,000 fraction obtained by ultrafiltrating the HW extract. In contrast, the MW <100,000 fraction also had a platelet aggregation ability, but the aggregation pattern was reversible and the maximum extent decreased, compared with the MW≥100,000 fraction response. Our experiments have been conducted using a whole body extract from adult HWs to determine with certainty the aggregating activity of HW elements on canine platelets. More studies are necessary to evaluate the effects of the metabolic products released from live adult worms in pulmonary arteries and the symbiont bacterium Wolbachia-derived antigens on canine platelet aggregation.

  10. Asphaltene aggregation in organic solvents.

    PubMed

    Oh, Kyeongseok; Ring, Terry A; Deo, Milind D

    2004-03-01

    Asphaltenic solids formed in the Rangely field in the course of a carbon dioxide flood and heptane insolubles in the oil from the same field were used in this study. Four different solvents were used to dissolve the asphaltenes. Near-infrared (NIR) spectroscopy was used to determine the onset of asphaltene precipitation by heptane titration. When the onset values were plotted versus asphaltene concentrations, distinct break points (called critical aggregation concentrations (CAC) in this paper) were observed. CACs for the field asphaltenes dissolved in toluene, trichloroethylene, tetrahydrofuran, and pyridine occurred at concentrations of 3.0, 3.7, 5.0, and 8.2 g/l, respectively. CACs are observed at similar concentrations as critical micelle concentrations (CMC) for the asphaltenes in the solvents employed and can be interpreted to be the points at which rates of asphaltene aggregations change. CMC values of asphaltenes determined from surface tension measurements (in pyridine and TCE) were slightly higher than the CAC values measured by NIR onset measurements. The CAC for heptane-insoluble asphaltenes in toluene was 3.1 g/l. Thermal gravimetric analysis (TGA) and elemental compositions of the two asphaltenes showed that the H/C ratio of the heptane-insoluble asphaltenes was higher and molecular weight (measured by vapor pressure osmometry) was lower.

  11. The aerobic activity of metronidazole against anaerobic bacteria.

    PubMed

    Dione, Niokhor; Khelaifia, Saber; Lagier, Jean-Christophe; Raoult, Didier

    2015-05-01

    Recently, the aerobic growth of strictly anaerobic bacteria was demonstrated using antioxidants. Metronidazole is frequently used to treat infections caused by anaerobic bacteria; however, to date its antibacterial activity was only tested in anaerobic conditions. Here we aerobically tested using antioxidants the in vitro activities of metronidazole, gentamicin, doxycycline and imipenem against 10 common anaerobic and aerobic bacteria. In vitro susceptibility testing was performed by the disk diffusion method, and minimum inhibitory concentrations (MICs) were determined by Etest. Aerobic culture of the bacteria was performed at 37°C using Schaedler agar medium supplemented with 1mg/mL ascorbic acid and 0.1mg/mL glutathione; the pH was adjusted to 7.2 by 10M KOH. Growth of anaerobic bacteria cultured aerobically using antioxidants was inhibited by metronidazole after 72h of incubation at 37°C, with a mean inhibition diameter of 37.76mm and an MIC of 1μg/mL; however, strains remained non-sensitive to gentamicin. No growth inhibition of aerobic bacteria was observed after 24h of incubation at 37°C with metronidazole; however, inhibition was observed with doxycycline and imipenem used as controls. These results indicate that bacterial sensitivity to metronidazole is not related to the oxygen tension but is a result of the sensitivity of the micro-organism. In future, both culture and antibiotic susceptibility testing of strictly anaerobic bacteria will be performed in an aerobic atmosphere using antioxidants in clinical microbiology laboratories. Copyright © 2015 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

  12. Adaptation and Antibiotic Tolerance of Anaerobic Burkholderia pseudomallei ▿ †

    PubMed Central

    Hamad, Mohamad A.; Austin, Chad R.; Stewart, Amanda L.; Higgins, Mike; Vázquez-Torres, Andrés; Voskuil, Martin I.

    2011-01-01

    The Gram-negative bacterium Burkholderia pseudomallei is the etiological agent of melioidosis and is remarkably resistant to most classes of antibacterials. Even after months of treatment with antibacterials that are relatively effective in vitro, there is a high rate of treatment failure, indicating that this pathogen alters its patterns of antibacterial susceptibility in response to cues encountered in the host. The pathology of melioidosis indicates that B. pseudomallei encounters host microenvironments that limit aerobic respiration, including the lack of oxygen found in abscesses and in the presence of nitric oxide produced by macrophages. We investigated whether B. pseudomallei could survive in a nonreplicating, oxygen-deprived state and determined if this physiological state was tolerant of conventional antibacterials. B. pseudomallei survived initial anaerobiosis, especially under moderately acidic conditions similar to those found in abscesses. Microarray expression profiling indicated a major shift in the physiological state of hypoxic B. pseudomallei, including induction of a variety of typical anaerobic-environment-responsive genes and genes that appear specific to anaerobic B. pseudomallei. Interestingly, anaerobic B. pseudomallei was unaffected by antibacterials typically used in therapy. However, it was exquisitely sensitive to drugs used against anaerobic pathogens. After several weeks of anaerobic culture, a significant loss of viability was observed. However, a stable subpopulation that maintained complete viability for at least 1 year was established. Thus, during the course of human infection, if a minor subpopulation of bacteria inhabited an oxygen-restricted environment, it might be indifferent to traditional therapy but susceptible to antibiotics frequently used to treat anaerobic infections. PMID:21537012

  13. Expert system for control of anaerobic digesters

    SciTech Connect

    Pullammanappallil, P.C.; Svoronos, S.A.; Chynoweth, D.P.; Lyberatos, G.

    1998-04-05

    Anaerobic digestion is a biochemical process that converts organic matter into methane and carbon dioxide along with the production of bacterial matter. It is primarily used for waste and wastewater treatment but can also be used for energy production. Continuous anaerobic digesters are systems that present challenging control problems including the possibility that an unmeasured disturbance can change the sign of the steady-state process gain. An expert system is developed that recognizes changes in the sign of process gain and implements appropriate control laws. The sole on-line measured variable is the methane production rate, and the manipulated input is the dilution rate. The expert system changes the dilution rate according to one of four possible strategies: a constrained conventional set-point control law, a constant yield control law (CYCL) that is nearly optimal for the most common cause of change in the sign of the process gain, batch operation, or constant dilution rate. The algorithm uses a t test for determining when to switch to the CYCL and returns to the conventional set-point control law with bumpless transfer. The expert system has proved successful in several experimental tests: severe overload; mild, moderate, and severe underload; and addition of phenol in low and high levels. Phenol is an inhibitor that in high concentrations changes the sign of the process gain.

  14. Tolerance of anaerobic bacteria to chlorinated solvents.

    PubMed

    Koenig, Joanna C; Groissmeier, Kathrin D; Manefield, Mike J

    2014-01-01

    The aim of this research was to evaluate the effects of four chlorinated aliphatic hydrocarbons (CAHs), perchloroethene (PCE), carbon tetrachloride (CT), chloroform (CF) and 1,2-dichloroethane (1,2-DCA), on the growth of eight anaerobic bacteria: four fermentative species (Escherichia coli, Klebsiella sp., Clostridium sp. and Paenibacillus sp.) and four respiring species (Pseudomonas aeruginosa, Geobacter sulfurreducens, Shewanella oneidensis and Desulfovibrio vulgaris). Effective concentrations of solvents which inhibited growth rates by 50% (EC50) were determined. The octanol-water partition coefficient or log Po/w of a CAH proved a generally satisfactory measure of its toxicity. Most species tolerated approximately 3-fold and 10-fold higher concentrations of the two relatively more polar CAHs CF and 1,2-DCA, respectively, than the two relatively less polar compounds PCE and CT. EC50 values correlated well with growth rates observed in solvent-free cultures, with fast-growing organisms displaying higher tolerance levels. Overall, fermentative bacteria were more tolerant to CAHs than respiring species, with iron- and sulfate-reducing bacteria in particular appearing highly sensitive to CAHs. These data extend the current understanding of the impact of CAHs on a range of anaerobic bacteria, which will benefit the field of bioremediation.

  15. Processing anaerobic sludge for extended storage as anaerobic digester inoculum.

    PubMed

    Li, Jiajia; Zicari, Steven M; Cui, Zongjun; Zhang, Ruihong

    2014-08-01

    Thermophilic anaerobic sludge was processed to reduce the volume and moisture content in order to reduce costs for storing and transporting the sludge as microbial inoculum for anaerobic digester startup. The moisture content of the sludge was reduced from 98.7% to 82.0% via centrifugation and further to 71.5% via vacuum evaporation. The processed sludge was stored for 2 and 4 months and compared with the fresh sludge for the biogas and methane production using food waste and non-fat dry milk as substrates. It was found that fresh unprocessed sludge had the highest methane yield and the yields of both unprocessed and processed sludges decreased during storage by 1-34%, however processed sludges seemed to regain some activity after 4 months of storage as compared to samples stored for only 2 months. Maximum methane production rates obtained from modified Gompertz model application also increased between the 2-month and 4-month processed samples.

  16. Do anaerobic digestates promote dispersion, acidification and water repellency in soils?

    NASA Astrophysics Data System (ADS)

    Voelkner, Amrei; Holthusen, Dörthe; Horn, Rainer

    2014-05-01

    Digestates are used as organic fertilizer on agricultural land due to their high amounts of nutrients (e.g. potassium, sodium). It is commonly expected that the application of sludge derived from anaerobic digestion can influence the soil structure and soil stability. Due to the fact that digestates contain large quantities of monovalent salts and long-chained fatty acids, the consequence of sludge amendment can be soil degradation caused by acidification, dispersion and increased water-repellency. Thus, water infiltration can be impeded which results in a preservation of stable soil aggregates. However, a diminished water infiltration can support water erosion and preferential flow of easy soluble nutrients into the groundwater. Our research was conducted with different digestates derived from maize, wheat and sugar beet to examine occurring processes in soils of two different textures after the application of anaerobic sludges. Particularly, we focused on the wetting properties of the soil. For this purpose, the wetting behavior was investigated by determining the sorptivity-based Repellency Index with moist samples and the contact angle with homogenized, air-dried soil material. Further surveys were carried out to assess the flow behavior of digestates application and the deformation of the particle-to-particle association by microscaled shearing. Additionally, the acidification process in the soil as a result of sludge application was investigated. To account for the dispersive impact of digestates, the turbidity of soil suspensions was ascertained. We summarize from the results that the digestates have a clear impact on the water repellency of the soil. We recognized a shift to more hydrophobic conditions. Partially, the pH remains on a high level due to the alkaline digestate, but several samples show a decline of pH, depending on the soil texture, respectively. However, soil structure was weakened as was shown by an increase of turbidity. As a conclusion, we

  17. Effect of lightweight fly ash aggregate microstructure on the strength of concretes

    SciTech Connect

    Wasserman, R.; Bentur, A.

    1997-04-01

    The structure and properties of sintered fly ash lightweight aggregate was modified by heat and polymer treatments to obtain aggregates different in their strength, absorption and pozzolanic activity. These properties of the aggregates were accounted for by changes in their microstructure. The strength of concretes of equal effective water/cement ratio prepared from these aggregates was determined at different ages to resolve the influence of the aggregate properties. It was shown that the strength of the concrete could not be accounted for by the strength of the aggregates only, and it is suggested that the absorption and pozzolanic activity of the aggregates can have an influence on the strength developed.

  18. Anaerobic digestate from biogas production as a resource for improving soil fertility: effects on crop yield and soil properties

    NASA Astrophysics Data System (ADS)

    Pastorelli, Roberta; Lagomarsino, Alessandra; Vignozzi, Nadia; Valboa, Giuseppe; Papini, Rossella; Fabiani, Arturo; Simoncini, Stefania; Mocali, Stefano; Piccolo, Raimondo

    2013-04-01

    Soil fertility is fundamental in determining crops productivity in all farming systems. Production of biogas through anaerobic digestion of energy crops generates residues that can represent a valuable resource to sustain and improve soil fertility and to increase soil organic matter content. Residues from anaerobic digestion contain organic fractions and available nutrients, that can thus be returned to the cultivation soil as fertilizer and soil conditioner. However, some unknown aspects of digested residues utilization remain to explore: i) the nutrient supply and the real potential for mineral fertilization substitution, ii) the impact on the structure and functioning of soil microbial communities, iii) the direct and indirect effects on soil structure, organic matter and C mineralization. The aim of the present research was to gain a better understanding of these aspects, evaluating the effects of anaerobic digestate application on soil properties and maize yield. With the main focus of comparing mineral fertilization (250 Kg N ha-1) with digested residues addition (at the dose of 25 % and 50 % of mineral fertilizer), a triplicate sets of plots were designed in a field experiment on a silty-clay loam soil in the southern Po Valley (Italy). The amount of applied residues was calculated according to its N content in order to fertilizer each plots with the same amount of total nitrogen. Residues from digestion showed a N content of 0.4 % (60 % as N-NH4) and a C/N ratio of 3. Changes in soil quality after residues application were studied with a holistic approach, involving microbiological, physical and chemical aspects of soil fertility. In particular, we determined: the abundance and diversity of bacterial and fungal soil communities; the soil organic matter content, its distribution within soil aggregates and the C mineralization potential; cation exchange capacity; the main macro and micro nutrients; bulk density; aggregate stability. No significant

  19. Anaerobic and aerobic fitness profiling of competitive surfers.

    PubMed

    Farley, Oliver; Harris, Nigel K; Kilding, Andrew E

    2012-08-01

    Despite widespread popularity of competitive surfing internationally, very little research has investigated the physiological profile of surf athletes and attempted to identify the relationships between physiological measures and surfing performance. This study determined the peak oxygen uptake (V(O2)peak) from an incremental ramp test and anaerobic power (watts) during a 10-second maximal-paddling burst using a surf paddle-specific modified kayak ergometer, customized with a surfboard and hand paddles. Twenty nationally ranked surf athletes volunteered to participate in the VV(O2)peak test, and 8 also participated in the anaerobic power test. The interrelationships between these components of athletic performance and surfing performance, as assessed by season rank, were determined using Pearsons correlations. We found a significant relationship between anaerobic power and season rank (r = 0.55, p = 0.05). No significant relationship between VV(O2)peak and season rank was found (r = -0.02, p = 0.97). Although correlations do not imply cause and effect, such a finding provides theoretical support for the importance of including anaerobic paddling power in assessment batteries and conditioning practice for surf athletes.

  20. Transient shear viscosity of weakly aggregating polystyrene latex dispersions

    NASA Astrophysics Data System (ADS)

    de Rooij, R.; Potanin, A. A.; van den Ende, D.; Mellema, J.

    1994-04-01

    The transient behavior of the viscosity (stress growth) of a weakly aggregating polystyrene latex dispersion after a step from a high shear rate to a lower shear rate has been measured and modeled. Single particles cluster together into spherical fractal aggregates. The steady state size of these aggregates is determined by the shear stresses exerted on the latter by the flow field. The restructuring process taking place when going from a starting situation with monodisperse spherical aggregates to larger monodisperse spherical aggregates is described by the capture of primary fractal aggregates by growing aggregates until a new steady state is reached. It is assumed that the aggregation mechanism is diffusion limited. The model is valid if the radii of primary aggregates Rprim are much smaller than the radii of the growing aggregates. Fitting the model to experimental data at two volume fractions and a number of step sizes in shear rate yielded physically reasonable values of Rprim at fractal dimensions 2.1≤df≤2.2. The latter range is in good agreement with the range 2.0≤df≤2.3 obtained from steady shear results. The experimental data have also been fitted to a numerical solution of the diffusion equation for primary aggregates for a cell model with moving boundary, also yielding 2.1≤df≤2.2. The range for df found from both approaches agrees well with the range df≊2.1-2.2 determined from computer simulations on diffusion-limited aggregation including restructuring or thermal breakup after formation of bonds. Thus a simple model has been put forward which may capture the basic features of the aggregating model dispersion on a microstructural level and leads to physically acceptable parameter values.

  1. Decolorization of azo dyes under batch anaerobic and sequential anaerobic/aerobic conditions.

    PubMed

    Işik, Mustafa; Sponza, Delia Teresa

    2004-01-01

    Batch anaerobic and sequential anaerobic upflow anaerobic sludge blanket (UASB)/aerobic continuous stirred tank reactor (CSTR) were used to determine the color and COD removals under anaerobic/aerobic conditions. Two azo dyes namely "Reactive Black 5 (RB 5)," "Congo Red (CR)," and glucose as a carbon source were used for synthetic wastewater. The course of the decolorization process approximates to first order and zero order kinetics with respect to dye concentration for RB 5 and Congo Red azo dyes, respectively, in batch conditions. The decolorization kinetic constant (K0) values increased from 3.6 to 11.8 mg(L h)(-1) as increases in dye concentrations from 200 to 3200 mg L(-1) for CR. Increases in dye concentrations from 0 to 3200 mg L(-1) reduce the decolorization rate constant (k1) values from 0.0141 to 0.0019 h(-1) in batch studies performed with RB 5. Decolorization was achieved effectively under test conditions but ultimate decolorization of azo dyes was not observed at all dye concentrations in batch assay conditions. Dye concentrations of 100 mg L(-1) and 3000 mg L(-1) of glucose-COD containing basal medium were used for continuous studies. The effect of organic loadings and HRT, on the color removal efficiencies and methane gas productions were monitored. 94.1-45.4% COD and 79-73% color removal efficiencies were obtained at an organic system during decolorization of Reactive Black 5. 92.3-77.0% COD and 95.3-92.2% decolorization efficiencies were achieved at a organic loading rate of 1.03-6.65 kg (m3 day)(-1) and a HRT of 3.54-0.49 for Congo Red treatment. The results of this study showed that, although decolorization continued, COD removal efficiencies and methane gas production were depressed at high organic loadings under anaerobic conditions. Furthermore, VFA accumulation, alkalinity consumption, and methane gas percentage were monitored at organic loading as high as 2.49-4.74 kg (m3 day)(-1) and 24.60-30.62 kg (m3 day)(-1), respectively, through the

  2. The effect of music during warm-up on consecutive anaerobic performance in elite adolescent volleyball players.

    PubMed

    Eliakim, M; Meckel, Y; Nemet, D; Eliakim, A

    2007-04-01

    Music is believed to improve athletic performance. The aim of the present study was to determine the effect of arousing music during warm-up on anaerobic performance in elite national level adolescent volleyball players. Twenty-four players (12 males and 12 females) performed the Wingate Anaerobic Test following a 10-minute warm-up with and without music (two separate occasions, random order). During warm-up with music, mean heart rate was significantly higher. Following the warm-up with music, peak anaerobic power was significantly higher in all volleyball players (10.7 +/- 0.3 vs. 11.1 +/- 0.3 Watts/kg, p < 0.05, without and with music, respectively). Gender did not influence the effect of music on peak anaerobic power. Music had no significant effect on mean anaerobic output or fatigue index in both genders. Music affects warm-up and may have a transient beneficial effect on anaerobic performance.

  3. Reversible Aggregation of Albumin

    NASA Astrophysics Data System (ADS)

    Colby, Ralph H.; Oates, Katherine M. N.; Krause, Wendy E.; Jones, Ronald L.

    2004-03-01

    We explore the interactions in synovial fluid involving the polyelectrolyte sodium hyaluronate (NaHA) and plasma proteins in their native state (albumin and globulins). Rheological measurements on synovial fluid show it to be highly viscoelastic and also rheopectic (stress increases with time in steady shear). Equilibrium dialysis confirms the findings of Ogston and Dubin that there is no association between NaHA and albumin at physiological pH and salt. What we find instead is a reversible aggregation of albumin, with an association energy of order 3kT and commensurate association lifetime of order microseconds. Certain anti-inflammatory drugs are shown to prevent this reversible aggregation. The implications of these findings for synovial fluid and blood rheology are discussed.

  4. Tracking protein aggregate interactions

    PubMed Central

    Bartz, Jason C; Nilsson, K Peter R

    2011-01-01

    Amyloid fibrils share a structural motif consisting of highly ordered β-sheets aligned perpendicular to the fibril axis.1, 2 At each fibril end, β-sheets provide a template for recruiting and converting monomers.3 Different amyloid fibrils often co-occur in the same individual, yet whether a protein aggregate aids or inhibits the assembly of a heterologous protein is unclear. In prion disease, diverse prion aggregate structures, known as strains, are thought to be the basis of disparate disease phenotypes in the same species expressing identical prion protein sequences.4–7 Here we explore the interactions reported to occur when two distinct prion strains occur together in the central nervous system. PMID:21597336

  5. Zooplankton Aggregations Near Sills

    DTIC Science & Technology

    2003-09-30

    frequency echo-sounder system. This data were supplemented with multi-net (BIONESS) trawls, bongo nets, and otter trawls (operated by D. Mackas and group...side. The general composition of the zooplankton aggregations can be deduced from the relative levels of the three echo-sounder frequencies; krill ...Nov. 20th, 2002. Krill layer is evident at 66 – 90 m, coincident with BIONESS trawl through the region. 3 Figure 2 shows a comparison between

  6. Aggregates: Waste and recycled materials; new rapid evaluation technology. Soils, geology, and foundations; materials and construction. Transportation research record

    SciTech Connect

    Not Available

    1994-01-01

    ;Contents: Engineering Properties of Shredded Tires in Lightweight Fill Applications; Using Recovered Glass as Construction Aggregate Feedstock; Utilization of Phosphogypsum-Based Slag Aggregate in Portland Cement Concrete Mixtures; Waste Foundry Sand in Asphalt Concrete; Toward Automating Size-Gradation Analysis of Mineral Aggregate; Evaluation of Fine Aggregate Angularity Using National Aggregate Association Flow Test; Siliceous Content Determination of Sands Using Automatic Image Analysis; and Methodology for Improvement of Oxide Residue Models for Estimation of Aggregate Performance Using Stoichiometric Analysis.

  7. Endocarditis caused by anaerobic bacteria.

    PubMed

    Kestler, M; Muñoz, P; Marín, M; Goenaga, M A; Idígoras Viedma, P; de Alarcón, A; Lepe, J A; Sousa Regueiro, D; Bravo-Ferrer, J M; Pajarón, M; Costas, C; García-López, M V; Hidalgo-Tenorio, C; Moreno, M; Bouza, E

    2017-04-05

    Infective endocarditis (IE) caused by anaerobic bacteria is a rare and poorly characterized disease. Most data reported in the literature are from case reports [1-3]. Therefore, we assessed the situation of anaerobic IE (AIE) in Spain using the database of the Spanish Collaboration on Endocarditis (GAMES). We performed a prospective study from 2008 to 2016 in 26 Spanish centers. We included 2491 consecutive cases of definite IE (Duke criteria). Anaerobic bacteria caused 22 cases (0.9%) of definite IE. Median age was 66 years (IQR, 56-73), and 19 (86.4%) patients were men. Most patients (14 [63.6%]) had prosthetic valve IE and all episodes were left-sided: aortic valves, 12 (54.5%); and mitral valves, 8 (36.4%). The most common pathogens were Propionibacterium acnes (14 [63.6%]), Lactobacillus spp (3 [13.63%]), and Clostridium spp. (2 [9.0%]), and the infection was mainly odontogenic. Fifteen of the 22 patients (68.2%) underwent cardiac surgery. Mortality was 18.2% during admission and 5.5% after 1 year of follow-up. When patients with AIE were compared with the rest of the cohort, we found that although those with AIE had a similar age and Charlson comorbidity index, they were more likely to have community-acquired IE (86.4% vs. 60.9%, p = 0.01), have undergone cardiac surgery (68.2% vs 48.7% p = 0.06), and have had lower mortality rates during admission (18.2% vs. 27.3%). IE due to anaerobic bacteria is an uncommon disease that affects mainly prosthetic valves and frequently requires surgery. Otherwise, there are no major differences between AIE and IE caused by other microorganisms. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Surfactant effects on soil aggregate tensile strength

    USDA-ARS?s Scientific Manuscript database

    Little is known regarding a soil aggregate's tensile strength response to surfactants that may be applied to alleviate soil water repellency. Two laboratory investigations were performed to determine surfactant effects on the tensile strength of 1) Ap horizons of nine wettable, agricultural soils co...

  9. Phosphorus recovery from wastewater by struvite crystallization: property of aggregates.

    PubMed

    Ye, Zhilong; Shen, Yin; Ye, Xin; Zhang, Zhaoji; Chen, Shaohua; Shi, Jianwen

    2014-05-01

    Struvite crystallization is a promising method to remove and recover phosphorus from wastewater to ease both the scarcity of phosphorus rock resources and water eutrophication worldwide. To date, although various kinds of reactor systems have been developed, supporting methods are required to control the struvite fines flushing out of the reactors. As an intrinsic property, aggregation is normally disregarded in the struvite crystallization process, although it is the key factor in final particle size and therefore guarantees phosphorus recovery efficiency. The present study developed a method to analyze the characteristics of struvite aggregates using fractal geometry, and the influence of operational parameters on struvite aggregation was evaluated. Due to its typical orthorhombic molecular structure, struvite particles are prone to crystallize into needle or rod shapes, and aggregate at the corners or edges of crystals. The determined fractal dimension (Dpf) of struvite aggregates was 1.52-1.31, with the corresponding range of equivalent diameter (d0.5) at 295.9-85.4 μm. Aggregates formed in relatively low phosphorus concentrations (3.0-5.0 mmol/L) and mildly alkaline conditions (pH 9.0-9.5) displayed relatively compact structures, large aggregate sizes and high aggregation strength. Increasing pH values led to continuous decrease of aggregate sizes, while the variation of Dpf was insignificant. As to the aggregate evolution, fast growth in a short time followed by a long steady stage was observed.

  10. Optimal policies for aggregate recycling from decommissioned forest roads.

    PubMed

    Thompson, Matthew; Sessions, John

    2008-08-01

    To mitigate the adverse environmental impact of forest roads, especially degradation of endangered salmonid habitat, many public and private land managers in the western United States are actively decommissioning roads where practical and affordable. Road decommissioning is associated with reduced long-term environmental impact. When decommissioning a road, it may be possible to recover some aggregate (crushed rock) from the road surface. Aggregate is used on many low volume forest roads to reduce wheel stresses transferred to the subgrade, reduce erosion, reduce maintenance costs, and improve driver comfort. Previous studies have demonstrated the potential for aggregate to be recovered and used elsewhere on the road network, at a reduced cost compared to purchasing aggregate from a quarry. This article investigates the potential for aggregate recycling to provide an economic incentive to decommission additional roads by reducing transport distance and aggregate procurement costs for other actively used roads. Decommissioning additional roads may, in turn, result in improved aquatic habitat. We present real-world examples of aggregate recycling and discuss the advantages of doing so. Further, we present mixed integer formulations to determine optimal levels of aggregate recycling under economic and environmental objectives. Tested on an example road network, incorporation of aggregate recycling demonstrates substantial cost-savings relative to a baseline scenario without recycling, increasing the likelihood of road decommissioning and reduced habitat degradation. We find that aggregate recycling can result in up to 24% in cost savings (economic objective) and up to 890% in additional length of roads decommissioned (environmental objective).

  11. Anaerobic digestion of aliphatic polyesters.

    PubMed

    Šmejkalová, Pavla; Kužníková, Veronika; Merna, Jan; Hermanová, Soňa

    2016-01-01

    Anaerobic processes for the treatment of plastic materials waste represent versatile and effective approach in environmental protection and solid waste management. In this work, anaerobic biodegradability of model aliphatic polyesters, poly(L-lactic acid) (PLA), and poly(ɛ-caprolactone) (PCL), in the form of powder and melt-pressed films with varying molar mass, was studied. Biogas production was explored in batch laboratory trials at 55 ± 1°C under a nitrogen atmosphere. The inoculum used was thermophilic digested sludge (total solids concentration of 2.9%) from operating digesters at the Central Waste Water Treatment Plant in Prague, Czech Republic. Methanogenic biodegradation of PCLs typically yielded from 54 to 60% of the theoretical biogas yield. The biodegradability of PLAs achieved from 56 to 84% of the theoretical value. High biogas yield (up to 677 mL/g TS) with high methane content (more than 60%), comparable with conventionally processed materials, confirmed the potential of polyester samples for anaerobic treatment in the case of their exploitation in agriculture or as a packaging material in the food industry.

  12. Pyridine Aggregation in Helium Nanodroplets

    NASA Astrophysics Data System (ADS)

    Nieto, Pablo; Poerschke, Torsten; Habig, Daniel; Schwaab, Gerhard; Havenith, Martina

    2012-06-01

    Pyridine crystals show the unusual property of isotopic polymorphism. Experimentally it has been observed that deuterated pyridine crystals exist in two phases while non-deuterated pyridine does not show a phase transition. Therefore, although isotopic substitution is the smallest possible modification of a molecule it greatly affects the stability of pyridine crystals. A possible experimental approach in order to understand this striking effect might be the study of pyridine aggregation for small clusters. By embedding the clusters in helium nanodroplets the aggregates can be stabilized and studied by means of Infrared Depletion Spectroscopy. Pyridine oligomers were investigated in the C-H asymmetric vibration region (2980-3100 cm-1) using this experimental technique. The number of molecules for the clusters responsibles for each band were determined by means of pick-up curves as well as mass sensitive depletion spectra. Furthermore, the intensity dependence of the different bands on applying a dc electric field was studied. The assignment of the different structures for pyridine clusters on the basis of these measurements were also carried out. S. Crawford et al., Angew. Chem. Int. Ed., 48, 755 (2009).

  13. Monitoring Insulin Aggregation via Capillary Electrophoresis

    PubMed Central

    Pryor, Elizabeth; Kotarek, Joseph A.; Moss, Melissa A.; Hestekin, Christa N.

    2011-01-01

    Early stages of insulin aggregation, which involve the transient formation of oligomeric aggregates, are an important aspect in the progression of Type II diabetes and in the quality control of pharmaceutical insulin production. This study is the first to utilize capillary electrophoresis (CE) with ultraviolet (UV) detection to monitor insulin oligomer formation at pH 8.0 and physiological ionic strength. The lag time to formation of the first detected species in the aggregation process was evaluated by UV-CE and thioflavin T (ThT) binding for salt concentrations from 100 mM to 250 mM. UV-CE had a significantly shorter (5–8 h) lag time than ThT binding (15–19 h). In addition, the lag time to detection of the first aggregated species via UV-CE was unaffected by salt concentration, while a trend toward an increased lag time with increased salt concentration was observed with ThT binding. This result indicates that solution ionic strength impacts early stages of aggregation and β-sheet aggregate formation differently. To observe whether CE may be applied for the analysis of biological samples containing low insulin concentrations, the limit of detection using UV and laser induced fluorescence (LIF) detection modes was determined. The limit of detection using LIF-CE, 48.4 pM, was lower than the physiological insulin concentration, verifying the utility of this technique for monitoring biological samples. LIF-CE was subsequently used to analyze the time course for fluorescein isothiocyanate (FITC)-labeled insulin oligomer formation. This study is the first to report that the FITC label prevented incorporation of insulin into oligomers, cautioning against the use of this fluorescent label as a tag for following early stages of insulin aggregation. PMID:22272138

  14. Characterization of Ovine Dermal Papilla Cell Aggregation

    PubMed Central

    Sari, Agnes Rosarina Prita; Rufaut, Nicholas Wolfgang; Jones, Leslie Norman; Sinclair, Rodney Daniel

    2016-01-01

    Context: The dermal papilla (DP) is a condensation of mesenchymal cells at the proximal end of the hair follicle, which determines hair shaft size and regulates matrix cell proliferation and differentiation. DP cells have the ability to regenerate new hair follicles. These cells tend to aggregate both in vitro and in vivo. This tendency is associated with the ability of papilla cells to induce hair growth. However, human papilla cells lose their hair-inducing activity in later passage number. Ovine DP cells are different from human DP cells since they do not lose their aggregative behavior or hair-inducing activity in culture. Nonetheless, our understanding of ovine DP cells is still limited. Aim: The aim of this study was to observe the expression of established DP markers in ovine cells and their association with aggregation. Subjects and Methods: Ovine DP cells from three different sheep were compared. Histochemistry, immunoflourescence, and polymerase chain reaction experiments were done to analyze the DP markers. Results: We found that ovine DP aggregates expressed all the 16 markers evaluated, including alkaline phosphatase and versican. Expression of the versican V0 and V3 isoforms, neural cell adhesion molecule, and corin was increased significantly with aggregation, while hey-1 expression was significantly decreased. Conclusions: Overall, the stable expression of numerous markers suggests that aggregating ovine DP cells have a similar phenotype to papillae in vivo. The stability of their molecular phenotype is consistent with their robust aggregative behavior and retained follicle-inducing activity after prolonged culture. Their phenotypic stability in culture contrasts with DP cells from other species, and suggests that a better understanding of ovine DP cells might provide opportunities to improve the hair-inducing activity and therapeutic potential of human cells. PMID:27625564

  15. Age-Dependent Protein Aggregation Initiates Amyloid-β Aggregation

    PubMed Central

    Groh, Nicole; Bühler, Anika; Huang, Chaolie; Li, Ka Wan; van Nierop, Pim; Smit, August B.; Fändrich, Marcus; Baumann, Frank; David, Della C.

    2017-01-01

    Aging is the most important risk factor for neurodegenerative diseases associated with pathological protein aggregation such as Alzheimer’s disease. Although aging is an important player, it remains unknown which molecular changes are relevant for disease initiation. Recently, it has become apparent that widespread protein aggregation is a common feature of aging. Indeed, several studies demonstrate that 100s of proteins become highly insoluble with age, in the absence of obvious disease processes. Yet it remains unclear how these misfolded proteins aggregating with age affect neurodegenerative diseases. Importantly, several of these aggregation-prone proteins are found as minor components in disease-associated hallmark aggregates such as amyloid-β plaques or neurofibrillary tangles. This co-localization raises the possibility that age-dependent protein aggregation directly contributes to pathological aggregation. Here, we show for the first time that highly insoluble proteins from aged Caenorhabditis elegans or aged mouse brains, but not from young individuals, can initiate amyloid-β aggregation in vitro. We tested the seeding potential at four different ages across the adult lifespan of C. elegans. Significantly, protein aggregates formed during the early stages of aging did not act as seeds for amyloid-β aggregation. Instead, we found that changes in protein aggregation occurring during middle-age initiated amyloid-β aggregation. Mass spectrometry analysis revealed several late-aggregating proteins that were previously identified as minor components of amyloid-β plaques and neurofibrillary tangles such as 14-3-3, Ubiquitin-like modifier-activating enzyme 1 and Lamin A/C, highlighting these as strong candidates for cross-seeding. Overall, we demonstrate that widespread protein misfolding and aggregation with age could be critical for the initiation of pathogenesis, and thus should be targeted by therapeutic strategies to alleviate neurodegenerative

  16. Aggregation Rates in Montmorillonite Clay Measured by Light Extinction

    NASA Astrophysics Data System (ADS)

    Katz, A.; Xu, M.; Trusiak, A.; Gottlieb, P.; Alimova, A.; Steiner, J. C.; Block, K. A.

    2012-12-01

    The aggregation rate and configuration of colloidal clay aggregates are important factors in soil clotting and marine-estuary sedimentation. Colloidal aggregation occurs in either of two regimes: 1) reaction limited colloidal aggregation (RLCA) or slow aggregation, in which particles must overcome a potential barrier to adhere, and aggregation rates are determined by the height of the barrier which determines the average number of collisions before adhesion; and 2) diffusion limited colloidal aggregation (DLCA) or fast aggregation, in which there is no barrier to adhesion, and aggregation is limited by the time between collisions. The universality principle dictates that the fractal dimension in the DLCA and RLCA are 1.7-1.9 and 2.1-2.3, respectively. We employ turbidity measurements to determine the aggregation rates and fractal dimension of homoionic smectite suspended in electrolyte solutions over a range of cation concentrations. Early stage aggregation rates (proportional to the time rate of change of the turbidity) and the stability ratio were determined as a function of cation concentration (Ca2+, Mg2+ and K+) from turbidity measurements. At low cation concentrations, the aggregation rates increased with cation concentration until a saturation concentration was reached. The "saturation" concentration, or critical coagulation concentration (CCC), is 3 mM for CaCl2, 4 mM for MgCl2, and 70 mM for KCl. The stability ratio exhibits a z-1 dependence (z is cation valence) rather than the widely accepted z-2 relationship predicted by Reerink and Overbeek. The analysis of turbidity results shows that RLCA occurs at very low concentrations while DLCA extends for a range of concentrations below the CCC. The fractal dimension of the Ca2+ and Mg2+ induced aggregates are 1.65 and 1.75, respectively for concentrations near and above the CCC. The fractal dimension of the K+ induced aggregates varies from 1.35-1.95 as the concentration is elevated, indicating that more

  17. Role of Carbonyl Modifications on Aging-Associated Protein Aggregation

    NASA Astrophysics Data System (ADS)

    Tanase, Maya; Urbanska, Aleksandra M.; Zolla, Valerio; Clement, Cristina C.; Huang, Liling; Morozova, Kateryna; Follo, Carlo; Goldberg, Michael; Roda, Barbara; Reschiglian, Pierluigi; Santambrogio, Laura

    2016-01-01

    Protein aggregation is a common biological phenomenon, observed in different physiological and pathological conditions. Decreased protein solubility and a tendency to aggregate is also observed during physiological aging but the causes are currently unknown. Herein we performed a biophysical separation of aging-related high molecular weight aggregates, isolated from the bone marrow and splenic cells of aging mice and followed by biochemical and mass spectrometric analysis. The analysis indicated that compared to younger mice an increase in protein post-translational carbonylation was observed. The causative role of these modifications in inducing protein misfolding and aggregation was determined by inducing carbonyl stress in young mice, which recapitulated the increased protein aggregation observed in old mice. Altogether our analysis indicates that oxidative stress-related post-translational modifications accumulate in the aging proteome and are responsible for increased protein aggregation and altered cell proteostasis.

  18. Specific methanogenic activity test for anaerobic degradation of influents

    NASA Astrophysics Data System (ADS)

    Hussain, Athar; Dubey, Shashi Kant

    2017-05-01

    Specific methanogenic activity (SMA) determines the methane-producing capability of the sludge for a specific substrate. Methanogenic activity test can be used to delineate the operating conditions for anaerobic systems and a parameter to assess the system performance by giving a better perceptive of the system and its stability. At the beginning of the start-up period of a new digester, the SMA is of great importance for the determination of proper initial organic loading rate. In different phases, a regular determination of SMA also ascertains the development stages of the sludge. Also, a change in SMA indicates an inhibition or an accumulation of slow degradable or even non-biodegradable organic matter from the influents. This paper reviews the SMA of anaerobic sludge under different operating conditions using different substrates.

  19. H- and J-aggregation of fluorene-based chromophores.

    PubMed

    Deng, Yonghong; Yuan, Wen; Jia, Zhe; Liu, Gao

    2014-12-11

    Understanding of H- and J-aggregation behaviors in fluorene-based polymers is significant both for determining the origin of various red-shifted emissions occurring in blue-emitting polyfluorenes and for developing polyfluorene-based device performance. In this contribution, we demonstrate a new theory of the H- and J-aggregation of polyfluorenes and oligofluorenes, and understand the influence of chromosphere aggregation on their photoluminescent properties. H- and J-aggregates are induced by a continuous increasing concentration of the oligofluorene or polyfluorene solution. A relaxed molecular configuration is simulated to illustrate the spatial arrangement of the bonding of fluorenes. It is indicated that the relaxed state adopts a 21 helical backbone conformation with a torsion angle of 18° between two connected repeat units. This configuration makes the formation of H- and J-aggregates through the strong π-π interaction between the backbone rings. A critical aggregation concentration is observed to form H- and J-aggregates for both polyfluorenes and oligofluorenes. These aggregates show large spectral shifts and distinct shape changes in photoluminescent excitation (PLE) and emission (PL) spectroscopy. Compared with "isolated" chromophores, H-aggregates induce absorption spectral blue-shift and fluorescence spectral red-shift but largely reduce fluorescence efficiency. "Isolated" chromophores not only refer to "isolated molecules" but also include those associated molecules if their conjugated backbones are not compact enough to exhibit perturbed absorption and emission. J-aggregates induce absorption spectral red-shift and fluorescence spectral red-shift but largely enhance fluorescence efficiency. The PLE and PL spectra also show that J-aggregates dominate in concentrated solutions. Different from the excimers, the H- and J-aggregate formation changes the ground-state absorption of fluorene-based chromophores. H- and J-aggregates show changeable

  20. Extraction of TNT from aggregate soil fractions.

    PubMed

    Williford, C W; Mark Bricka, R

    1999-04-23

    Past explosives manufacture, disposal, and training activities have contaminated soil at many military facilities, posing health and environmental risks through contact, potential detonation, and leaching into ground water. While methods have been confirmed for extraction and measuring explosives concentration in soil, no work has addressed aggregate size material (the >2 mm gravel and cobbles) that often occurs with the smaller soil fractions. This paper describes methods and results for extraction and measurement of TNT (2,4,6-trinitrotoluene) in aggregate material from 1/2 to 2-1/1 from a WWII era ammunition plant. TNT was extracted into acetonitrile by both Soxhlet and ultrasonic extraction methods. High pressure liquid chromatography analyses of extracts showed expected variation among samples. Also effective extraction and determination of TNT concentration for each aggregate size fraction was achieved.

  1. A unified kinetic model for particle aggregation

    SciTech Connect

    Gardner, K.H.; Theis, T.L.

    1996-06-01

    Aggregation of submicrometer particles is a process with significant implications for the fate and transport of contaminants and major nutrients in many coastal, estuarine, and freshwater bodies as well as groundwater systems. A unified model has been developed that describes the kinetics of particle aggregation. The model is unique in the incorporation of surface chemical phenomena along with solution chemistry in the determination of the stability of a colloidal dispersion. The aggregation process is treated in a truly kinetic fashion, the main output from the model being the evolution of complete particle size distributions over time. The model was developed to interpret laboratory data and, as such, has the capacity to estimate a (variable) set of system parameters by fitting the size distribution over time data to that measured. It was found that the attachment distance, a parameter frequently approximated in practice, has a profound influence on the predicted aggregation kinetics as does the choice of a solid/solution interfacial model. Furthermore, simulation of relatively long-term aggregation, which was the principal focus of this work, indicates that values of the collision efficiency factor should be much smaller than those reported elsewhere in the literature.

  2. Rotating Bacteria Aggregate into Active Crystals

    NASA Astrophysics Data System (ADS)

    Petroff, A. P.; Wu, X. L.; Libchaber, A.

    2014-12-01

    The dynamics of many microbial ecosystems are determined not only by the response of individual bacteria to their chemical and physical environments but also the dynamics that emerge from interactions between cells. Here we investigate collective dynamics displayed by communities of Thiovulum majus, one of the fastest known bacteria. We observe that when these bacteria swim close to a microscope cover slip, the cells spontaneously aggregate into a visually-striking, two-dimensional hexagonal lattice of rotating cells. Each cell in an aggregate rotates its flagella, exerting a force that pushes the cell into the cover slip and a torque that causes the cell to rotate. As cells rotate against their neighbors, they exert forces and torques on the aggregate that cause the crystal to move and cells to hop to new positions in the lattice. We show how these dynamics arise from hydrodynamic and surface forces between cells. We derive the equations of motion for an aggregate, show that this model reproduces many aspects of the observed dynamics, and discuss the stability of these and similar active crystals. Finally, we discuss the ecological significance of this behavior to understand how the ability to aggregate into these communities may have evolved.

  3. Rotating bacteria aggregate into active crystals

    NASA Astrophysics Data System (ADS)

    Petroff, Alexander; Wu, Xiao-Lun; Libchaber, Albert

    2014-11-01

    The dynamics of many microbial ecosystems are determined not only by the response of individual bacteria to their chemical and physical environments but also the dynamics that emerge from interactions between cells. Here we investigate the collective dynamics displayed by communities of Thiovulum majus, one of the fastest known bacteria. We observe that when these bacteria swim close to a microscope cover slip, the cells spontaneously aggregate into a visually-striking two-dimensional hexagonal lattice of rotating cells. Each cell in an aggregate rotates its flagella, exerting a force that pushes the cell into the cover slip and a torque that causes the cell to rotate. As cells rotate against their neighbors, they exert forces and torques on the aggregate that cause the crystal to move and cells to hop to new positions in the lattice. We show how these dynamics arises from hydrodynamic and surface forces between cells. We derive the equations of motion for an aggregate, show that this model reproduces many aspects of the observed dynamics, and discuss the stability of these and similar active crystals. Finally, we discuss the ecological significance of this behavior to understand how the ability to aggregate into these communities may have evolved.

  4. Aggregation kinetics and structure of cryoimmunoglobulins clusters

    NASA Astrophysics Data System (ADS)

    Spirito, M. De; Chiappini, R.; Bassi, F. Andreasi; Stasio, E. Di; Giardina, B.; Arcovito, G.

    2002-02-01

    Cryoimmunoglobulins are pathological antibodies characterized by a temperature-dependent reversible insolubility. Rheumatoid factors (RF) are immunoglobulins possessing anti-immunoglobulin activity and usually consist of an IgM antibody that recognizes IgG as antigen. These proteins are present in sera of patients affected by a large variety of different pathologies, such as HCV infection, neoplastic and autoimmune diseases. Aggregation and precipitation of cryoimmunoglobulins, leading to vasculiti, are physical phenomena behind such pathologies. A deep knowledge of the physico-chemical mechanisms regulating such phenomena plays a fundamental role in biological and clinical applications. In this work, a preliminary investigation of the aggregation kinetics and of the final macromolecular structure of the aggregates is presented. Through static light scattering techniques, the gyration radius Rg and the fractal dimension Dm of the growing clusters have been determined. However, while the initial aggregation mechanism could be described using the universal reaction-limited cluster-cluster aggregation (RLCCA) theory, at longest times from the beginning of the process, the RLCCA theory fails and a restructuring of clusters is observed together with an increase of the cluster fractal dimension Dm up to a value Dm∼3. The time tn, at which the restructuring takes place, and the final cluster size can be modulated by varying the quenching temperature.

  5. Modelling sodium inhibition on the anaerobic digestion process.

    PubMed

    Hierholtzer, A; Akunna, J C

    2012-01-01

    Sodium is a known process inhibitor in anaerobic systems and impacts on methanogens through an increase of osmotic pressure or complete dehydration of microorganisms. In this study, a combination of experimental and modelling approaches has been employed to determine and simulate sodium inhibition on the anaerobic digestion process. The ADM1, which has been successfully used in modelling anaerobic processes, has been modified to include an extra inhibition function that considers the effect of sodium on acetoclastic methanogens and the impact on biogas production and composition. A non-competitive inhibition function was added to the rate of acetate uptake for the model to take into account sodium toxicity. Experimental studies consisted of both batch and reactor tests to obtain parameters for model calibration and validation. The calibrated model was used to predict the effect of ammonia nitrogen on sodium toxicity. It was found that relatively low sodium levels can bring about significant levels of process inhibition in the presence of high levels of ammonia. On the other hand, where the concentration of ammonia is relatively low, the tolerance threshold for sodium ions increases. Hence, care must be taken in the use of sodium hydroxide for pH adjustment during anaerobic digestion of protein-rich substrates.

  6. The Relationship Between Aerobic and Anaerobic Performance in Recreational Runners

    PubMed Central

    GILLEN, ZACHARY M.; WYATT, FRANK B.; WINCHESTER, JASON B.; SMITH, DALTON A.; GHETIA, VIDHI

    2016-01-01

    Research has indicated that combined aerobic and anaerobic training (concurrent training) may improve aerobic performance greater than aerobic training alone. The purpose of this investigation was to establish any associations between aerobic and anaerobic performance. Eleven participants (n = 11, age = 34.1 ± 13 years, VO2max = 58.4 ± 7.8) volunteered for this study. Participants were asked for endurance training experience (4.7 ± 3.7 years) and resistance training experience (4.1 ± 4.6 years). To meet training status, participants were to have a VO2max in the 80th percentile as per ACSM guidelines. The Bruce treadmill test was used to measure aerobic performance. In order to measure anaerobic performance, several tests were completed utilizing a force platform. A Pearson Product R Correlation Coefficient was calculated to determine correlations between variables. The results show significant correlation between VO2max and RFD (r = 0.68). Further analyses utilizing Cohen’s effect size indicated a strong association between VO2max and peak force, as well as running efficiency and peak power, relative peak power, and power endurance. These results indicate an existing possibility that anaerobic performance measures such as RFD may have a positive relationship with aerobic performance measures such as VO2max. Therefore, it may be beneficial to integrate specific training components which focus on improving RFD as a method of improving running performance. PMID:27990224

  7. Kinetics of biogas production in Anaerobic Filters.

    PubMed

    Krümpel, Johannes; Schäufele, Friedrich; Schneider, Johannes; Jungbluth, Thomas; Zielonka, Simon; Lemmer, Andreas

    2016-01-01

    This study investigates methane production kinetics from individual volatile fatty acids (VFA) in an Upflow Anaerobic Filter (AF). 1gCOD in the form of acetic (HAc), propionic (HPr) or butyric acid (HBu) was injected into the AF while operating at an organic loading rate (OLRCOD) of 3.5gL(-1)d(-1). A new method is introduced to separate gas production of the baseload from the product formation of VFA degradation after the injection. The lag phase, fractional rate of gas production and half-life has been determined for the methane production of the three VFAs. The half-lives were in the order HAc

  8. CFD simulation of mixing in anaerobic digesters.

    PubMed

    Terashima, Mitsuharu; Goel, Rajeev; Komatsu, Kazuya; Yasui, Hidenari; Takahashi, Hiroshi; Li, Y Y; Noike, Tatsuya

    2009-04-01

    A three-dimensional CFD model incorporating the rheological properties of sludge was developed and applied to quantify mixing in a full-scale anaerobic digester. The results of the model were found to be in good agreement with experimental tracer response curve. In order to predict the dynamics of mixing, a new parameter, UI (uniformity index) was defined. The visual patterns of tracer mixing in simulation were well reflected in the dynamic variation in the value of UI. The developed model and methods were applied to determine the required time for complete mixing in a full-scale digester at different solid concentrations. This information on mixing time is considered to be useful in optimizing the feeding cycles for better digester performance.

  9. Non-Arrhenius protein aggregation.

    PubMed

    Wang, Wei; Roberts, Christopher J

    2013-07-01

    Protein aggregation presents one of the key challenges in the development of protein biotherapeutics. It affects not only product quality but also potentially impacts safety, as protein aggregates have been shown to be linked with cytotoxicity and patient immunogenicity. Therefore, investigations of protein aggregation remain a major focus in pharmaceutical companies and academic institutions. Due to the complexity of the aggregation process and temperature-dependent conformational stability, temperature-induced protein aggregation is often non-Arrhenius over even relatively small temperature windows relevant for product development, and this makes low-temperature extrapolation difficult based simply on accelerated stability studies at high temperatures. This review discusses the non-Arrhenius nature of the temperature dependence of protein aggregation, explores possible causes, and considers inherent hurdles for accurately extrapolating aggregation rates from conventional industrial approaches for selecting accelerated conditions and from conventional or more advanced methods of analyzing the resulting rate data.

  10. Theoretical and experimental analysis of the sedimentation kinetics of concentrated red cell suspensions in a centrifugal field: determination of the aggregation and deformation of RBC by flux density and viscosity functions.

    PubMed

    Lerche, D; Frömer, D

    2001-01-01

    The flow properties of blood are mostly determined using various viscometric approaches, and described in terms of a shear rate or shear stress dependent apparent viscosity. The interpretation of results are rather difficult, especially at low shear rates when particle sedimentation and migration within the viscometer gap are significant. By contrast, analysing the separation process in concentrated RBC suspensions in a centrifugal field also yields information about the viscosity function, including particle-particle interaction and deformation parameters. In this paper, the sedimentation process is approached by means of the theory of kinematic waves and theoretically described by solving the corresponding one-dimensional quasi-linear partial differential equation based on viscosity/flow function as a function of volume concentration. The sedimentation kinetics of rigid spherical RBC suspended in saline and normal RBC suspended in Dx-saline solutions were investigated by means of a separation analyser (LUMiFuge 114). The instrument detects the light transmission over the total length of the cell containing the suspension. During centrifugation the analyser automatically determines the position of the particle free fluid/suspension interface or the sediment by means of a special algorithm. The data obtained with sedimentation of rigid spherical RBC at different volume concentrations demonstrate that, in the case of suspensions rotated in containers of constant cross section, there is good agreement between the theory of kinematic waves developed by Anestis and Schneider (1983) and the results of the experiments. Such good agreement was obtained even though a restrictive one-dimensional model was used to obtain the theoretically derived sedimentation time course. In addition, we describe an algorithm enabling the experimental determination of the viscosity and related flux density function to be made for any suspension. Through this approach, we investigated in

  11. Anaerobic Biotransformation and Mobility of Pu and Pu-EDTA

    SciTech Connect

    Bolton, H., Jr.; Bailey, V.L.; Plymale, A.E.; Rai, D.; Xun, L.

    2006-04-05

    begun to enrich and isolate bacteria capable of aerobic and anaerobic degradation of EDTA. Environmental samples (e.g., sludges, river sediments) were incubated aerobically and anaerobically with EDTA or NTA as the sole carbon and energy source. Aerobic enrichment with EDTA has not resulted in any cultures, but NTA has provided several isolates. Partial 16S rRNA gene sequence and sequence comparison identified four separate strains closely related to Microbacterium oxydans, Aminobacter sp., Achromobacter sp., Aminobacter sp., respectively. Anaerobic enrichments with either EDTA or NTA are still in progress since metabolism and growth is relatively slow. In addition to the biotransformation experiments, studies are underway to determine/validate complexation constants of Pu(III) with EDTA and the influence of competing ions on Pu(III)-EDTA complexes. These data are being obtained through solubility studies of PuPO{sub 4}(s) and Pu(OH){sub 3}(s) as a function of time, pH, and EDTA and competing ion concentrations. These results have begun to fill-in knowledge gaps of how anaerobic conditions will influence Pu and Pu-EDTA fate and transport to assess, model, and design approaches to stop Pu transport in groundwater at DOE sites.

  12. Ultrastructure of acetylcholine receptor aggregates parallels mechanisms of aggregation

    PubMed Central

    Kunkel, Dennis D; Lee, Lara K; Stollberg, Jes

    2001-01-01

    Background Acetylcholine receptors become aggregated at the developing neuromuscular synapse shortly after contact by a motorneuron in one of the earliest manifestations of synaptic development. While a major physiological signal for receptor aggregation (agrin) is known, the mechanism(s) by which muscle cells respond to this and other stimuli have yet to be worked out in detail. The question of mechanism is addressed in the present study via a quantitative examination of ultrastructural receptor arrangement within aggregates. Results In receptor rich cell membranes resulting from stimulation by agrin or laminin, or in control membrane showing spontaneous receptor aggregation, receptors were found to be closer to neighboring receptors than would be expected at random. This indicates that aggregation proceeds heterogeneously: nanoaggregates, too small for detection in the light microscope, underlie developing microaggregates of receptors in all three cases. In contrast, the structural arrangement of receptors within nanoaggregates was found to depend on the aggregation stimulus. In laminin induced nanoaggregates receptors were found to be arranged in an unstructured manner, in contrast to the hexagonal array of about 10 nm spacing found for agrin induced nanoaggregates. Spontaneous aggregates displayed an intermediate amount of order, and this was found to be due to two distinct population of nanoaggregates. Conclusions The observations support earlier studies indicating that mechanisms by which agrin and laminin-1 induced receptor aggregates form are distinct and, for the first time, relate mechanisms underlying spontaneous aggregate formation to aggregate structure. PMID:11749670

  13. The influence of erythrocyte aggregation on induced platelet aggregation.

    PubMed

    Ott, C; Lardi, E; Schulzki, T; Reinhart, W H

    2010-01-01

    Red blood cells (RBCs) affect platelet aggregation in flowing blood (primary hemostasis). We tested the hypothesis that RBC aggregation could influence platelet aggregation. RBC aggregation was altered in vitro by: (i) changing plasma aggregatory properties with 3.7 g% dextran 40 (D40), 3.0 g% dextran 70 (D70) or 1.55 g% dextran 500 (D500); (ii) changing RBC aggregatory properties by incubating RBCs in 50 mU/ml neuraminidase for 60 min (reduction of the surface sialic acid content, thus reducing electrostatic repulsion) and subsequent RBC resuspension in platelet rich plasma (PRP) containing 1 g% dextran 70. RBC aggregation was assessed with the sedimentation rate (ESR). Platelet aggregation was measured: (i) in flowing whole blood with a platelet function analyzer PFA-100(R), which simulates in vivo conditions with RBCs flowing in the center and platelets along the wall, where they adhere to collagen and aggregate; and (ii) in a Chrono-log 700 Aggregometer, which measures changes of impedance by platelet aggregation in whole blood or changes in light transmission in PRP. We found that RBC aggregation increased with increasing molecular weight of dextran (ESR: 4 +/- 3 mm/h, 34 +/- 14 mm/h and 89 +/- 23 mm/hfor D40, D70 and D500, respectively, p < 0.0001) and with neuraminidase-treated RBCs (76 +/- 27 mm/h vs 27 +/- 8 mm/h, respectively, p < 0.0001). Platelet aggregation measured in whole blood under flow conditions (PFA-100) and without flow (Chronolog Aggregometer) was not affected by RBC aggregation. Our data suggest that RBC aggregation does not affect platelet aggregation in vitro and plays no role in primary hemostasis.

  14. Infected Pneumatocele Following Anaerobic Pneumonia in Adult

    PubMed Central

    Chung, Yeon Tae; Lee, Kyung Duk; Seon, Kyoung Youn; Lee, Jong Hyun; Lee, Sung Ho; Choi, Se Ho

    2005-01-01

    We report a case of an infected pneumatocele in the course of anaerobic pneumonia in an adult. To the best of our knowledge, anaerobic pneumonia complicated by a pneumatocele in an adult has not previously been described. The pneumatocele occurred on the fifth day of hospitalization, and rapidly increased in size, with the development of a subsequent mixed anaerobe infection. A pig-tail catheter was inserted and the pus drained. The bacterial culture from the pus was positive for three anaerobes: Bacteroid species, Peptostreptococcus asaccharolyticus and Fusobacterium species. Intravenous antibiotics and percutaneous catheter drainage resulted in a successful treatment. PMID:16491835

  15. Making Graphene Resist Aggregation

    NASA Astrophysics Data System (ADS)

    Luo, Jiayan

    Graphene-based sheets have stimulated great interest in many scientific disciplines and shown promise for wide potential applications. Among various ways of creating single atomic layer carbon sheets, a promising route for bulk production is to first chemically exfoliate graphite powders to graphene oxide (GO) sheets, followed by reduction to form chemically modified graphene (CMG). Due to the strong van der Waals attraction between graphene sheets, CMG tends to aggregate. The restacking of sheets is largely uncontrollable and irreversible, thus it reduces their processability and compromises properties such as accessible surface area. Strategies based on colloidal chemistry have been applied to keep CMG dispersed in solvents by introducing electrostatic repulsion to overcome the van der Waals attraction or adding spacers to increase the inter-sheet spacing. In this dissertation, two very different ideas that can prevent CMG aggregation without extensively modifying the material or introducing foreign spacer materials are introduced. The van der Waals potential decreases with reduced overlapping area between sheets. For CMG, reducing the lateral dimension from micrometer to nanometer scale should greatly enhance their colloidal stability with additional advantages of increased charge density and decreased probability to interact. The enhanced colloidal stability of GO and CMG nanocolloids makes them especially promising for spectroscopy based bio-sensing applications. For potential applications in a compact bulk solid form, the sheets were converted into paper-ball like structure using capillary compression in evaporating aerosol droplets. The crumpled graphene balls are stabilized by locally folded pi-pi stacked ridges, and do not unfold or collapse during common processing steps. They can tightly pack without greatly reducing the surface area. This form of graphene leads to scalable performance in energy storage. For example, planer sheets tend to aggregate and

  16. Structure of Viral Aggregates

    NASA Astrophysics Data System (ADS)

    Barr, Stephen; Luijten, Erik

    2010-03-01

    The aggregation of virus particles is a particular form of colloidal self-assembly, since viruses of a give type are monodisperse and have identical, anisotropic surface charge distributions. In small-angle X-ray scattering experiments, the Qbeta virus was found to organize in different crystal structures in the presence of divalent salt and non-adsorbing polymer. Since a simple isotropic potential cannot explain the occurrence of all observed phases, we employ computer simulations to investigate how the surface charge distribution affects the virus interactions. Using a detailed model of the virus particle, we find an asymmetric ion distribution around the virus which gives rise to the different phases observed.

  17. Synergistic effects of the chitosan addition and polysaccharides-EPS on the formation of anaerobic granules.

    PubMed

    Hudayah, N; Suraraksa, B; Chaiprasert, P

    2016-11-01

    Concomitant early granulation with chitosan addition under a syntroph-specific substrate and enhancement of extracellular polymeric substances (EPS) production were aimed at to build anaerobic granules with high syntrophic activities in a short period. Two laboratory-scale upflow anaerobic sludge blanket reactors were operated as control (R1) and chitosan addition (R2) reactors during early granulation (phase 1). Chitosan decreased the negativity of microbial surface charges (zeta potential) to -10.5 mV on day 58 which led to increases in average diameter sizes, nuclei and granule ratio of approximately 115 µm, 55.1% and 8.2%, respectively. While zeta potential in R1 slightly changed, this resulted in less microbial aggregation. Although microbial aggregation in R2 was rapidly triggered by chitosan addition during phase 1, its structure was clumpy with rough surface due to lack of EPS. Substrate switching to glucose increased polysaccharides-EPS during phase 2 which was synergistically improved on the structural characteristics of microbial aggregate in R2, that is, more spherical and compact, with a smoother surface. Rapid-growth microorganism was also boosted, which then dominated the outer layer of the aggregate. The Archaea clumps were observed at a deeper layer and were surrounded by Eubacteria, presumably acetogens, indicating a syntrophic relationship due to substrate association between these microbial groups.

  18. Multicenter Study of Antimicrobial Susceptibility of Anaerobic Bacteria in Korea in 2012

    PubMed Central

    Lee, Yangsoon; Park, Yeon-Joon; Kim, Mi-Na; Uh, Young; Kim, Myung Sook

    2015-01-01

    Background Periodic monitoring of regional or institutional resistance trends of clinically important anaerobic bacteria is recommended, because the resistance of anaerobic pathogens to antimicrobial drugs and inappropriate therapy are associated with poor clinical outcomes. There has been no multicenter study of clinical anaerobic isolates in Korea. We aimed to determine the antimicrobial resistance patterns of clinically important anaerobes at multiple centers in Korea. Methods A total of 268 non-duplicated clinical isolates of anaerobic bacteria were collected from four large medical centers in Korea in 2012. Antimicrobial susceptibility was tested by the agar dilution method according to the CLSI guidelines. The following antimicrobials were tested: piperacillin, piperacillin-tazobactam, cefoxitin, cefotetan, imipenem, meropenem, clindamycin, moxifloxacin, chloramphenicol, metronidazole, and tigecycline. Results Organisms of the Bacteroides fragilis group were highly susceptible to piperacillin-tazobactam, imipenem, and meropenem, as their resistance rates to these three antimicrobials were lower than 6%. For B. fragilis group isolates and anaerobic gram-positive cocci, the resistance rates to moxifloxacin were 12-25% and 11-13%, respectively. Among B. fragilis group organisms, the resistance rates to tigecycline were 16-17%. Two isolates of Finegoldia magna were non-susceptible to chloramphenicol (minimum inhibitory concentrations of 16-32 mg/L). Resistance patterns were different among the different hospitals. Conclusions Piperacillin-tazobactam, cefoxitin, and carbapemems are highly active β-lactam agents against most of the anaerobes. The resistance rates to moxifloxacin and tigecycline are slightly higher than those in the previous study. PMID:26206683

  19. The influence of alloy composition on anaerobic adhesives in dental bonding.

    PubMed

    Ireland, A J; Sherriff, M

    1998-11-01

    Single-component anaerobic adhesives are in common use in the electronics and engineering industries. They are generally diacrylate monomers which do not require conventional sources of heat, light or chemicals for activation. Their advantages include activation by the bonding substrate, as well as inhibition of polymerisation until the necessary anaerobic environment is created. The aim of this experiment was to determine whether metal attachments could be successfully bonded to enamel in vitro by such adhesives. Metal attachments capable of providing an anaerobic environment were fabricated from one of three alloys: stainless steel, copper or cobalt-chromium. They were bonded to prepared human enamel with one of four adhesives: Orthodontic Concise, as a control, and three anaerobic adhesives, Perma Metal, Permabond A134 and Loctite 326. The specimens were then bond tested in shear to failure after bench curing for one of four time periods. The results were analysed in terms of mean force to debond (N) and 95% confidence intervals. Kaplan-Meier survival probabilities and log-rank tests were performed for the 10 min test times. Both Orthodontic Concise and the three anaerobic adhesives displayed a specificity towards different attachment alloys. Whereas Orthodontic Concise displayed the highest force to debond with stainless steel attachments, for the anaerobic adhesives this was true of the copper attachments. With stainless steel attachments, however, the force to debond with the anaerobic adhesives was similar to that observed with Orthodontic Concise and steel, at least after the relatively short 10 min bench curing time.

  20. Biofilm formation and granule properties in anaerobic digestion at high salinity.

    PubMed

    Gagliano, M C; Ismail, S B; Stams, A J M; Plugge, C M; Temmink, H; Van Lier, J B

    2017-09-15

    For the anaerobic biological treatment of saline wastewater, Anaerobic Digestion (AD) is currently a possibility, even though elevated salt concentrations can be a major obstacle. Anaerobic consortia and especially methanogenic archaea are very sensitive to fluctuations in salinity. When working with Upflow Sludge Blanket Reactor (UASB) technology, in which the microorganisms are aggregated and retained in the system as a granular biofilm, high sodium concentration negatively affects aggregation and consequently process performances. In this research, we analysed the structure of the biofilm and granules formed during the anaerobic treatment of high salinity (at 10 and 20 g/L of sodium) synthetic wastewater at lab scale. The acclimated inoculum was able to accomplish high rates of organics removal at all the salinity levels tested. 16S rRNA gene clonal analysis and Fluorescence In Situ Hybridization (FISH) analyses identified the acetoclastic Methanosaeta harundinacea as the key player involved acetate degradation and microbial attachment/granulation. When additional calcium (1 g/L) was added to overcome the negative effect of sodium on microbial aggregation, during the biofilm formation process microbial attachment and acetate degradation decreased. The same result was observed on granules formation: while calcium had a positive effect on granules strength when added to UASB reactors, Methanosaeta filaments were not present and the degradation of the partially acidified substrate was negatively influenced. This research demonstrated the possibility to get granulation at high salinity, bringing to the forefront the importance of a selection towards Methanosaeta cells growing in filamentous form to obtain strong and healthy granules. Copyright © 2017 The Authors. Published by Elsevier Ltd.. All rights reserved.

  1. Maximal anaerobic power: relationship to anthropometric characteristics during growth.

    PubMed

    Mercier, B; Mercier, J; Granier, P; Le Gallais, D; Préfaut, C

    1992-01-01

    The purpose of this study was to determine the effects of age in relation to anthropometric characteristics upon maximal anaerobic power of legs in sixty-nine young boys aged 11 to 19 years. Maximal anaerobic power (Wmax) was measured by the force-velocity test. Lean body mass (LBM) was determined from all four skin-fold thickness measurements, leg volume (LV) was estimated by anthropometric method, and anthropometric measurements were used to determine total muscular mass (TMM). Wmax increased significantly (F = 44.1, p less than 0.001) between 11 and 19 years and was correlated with LV (r = 0.84) and TMM (r = 0.88). It was most highly correlated with LBM (r = 0.94), which best explained the percentage of the total variance of Wmax (88%). Normalized Wmax (Wmax/LBM) also increased significantly between 11 and 19 years (F = 21.9, p less than 0.001). In conclusion, Wmax determined by the force-velocity test was closely related to anthropometric characteristics, especially LBM, during the growth period. Furthermore, even when corrected for lean body mass, maximal anaerobic power was always found to increase. This suggests that other undetermined factors, in addition to the amount of lean tissue mass, may explain the increase of Wmax during the force-velocity test.

  2. Naphthalecin, a novel antibiotic produced by the anaerobic bacterium, Sporotalea colonica sp. nov.

    PubMed

    Ezaki, Masami; Muramatsu, Hideyuki; Takase, Shigehiro; Hashimoto, Michizane; Nagai, Koji

    2008-04-01

    A novel antibiotic naphthalecin was purified and isolated from the cells of an anaerobic bacterium isolated from a soil sample. This antibiotic contained a naphthalene moiety, so named as naphthalecin, and showed antibacterial activity against gram positive species. The producing strain, an obligate anaerobe, was identified as a new species of the genus Sporotalea. Identification of the bacterium, cultivation, purification, structure determination, and antibacterial activity are shown.

  3. Analysis and behavior of colistin during anaerobic fermentation.

    PubMed

    Riemenschneider, C; Zerr, W; Vater, N; Brunn, H; Mohring, S A I; Hamscher, G

    2014-10-01

    A new analytical method for the determination of colistin in fermenter samples was developed followed by a study on the behavior of this substance during anaerobic fermentation. Analysis of colistin A and B was carried out by liquid chromatography-tandem mass spectrometry. Separation of the analytes was performed on a Security Guard column (4×3mm). Fourteen fermentation tests in batch as well as in continuous reactors were carried out. After 44days of anaerobic digestion of cattle manure, initially spiked with 500mg/kg of colistin sulfate, a considerable decrease of the colistin concentration to less than 1mg/kg could be observed. Furthermore, the daily production of biogas and methane was measured. A correlation between gas production and colistin concentration could not be determined. However, an increase of 10% of the cumulative methane production was observed in those fermenters spiked with an initial bolus of 500mg/kg colistin.

  4. Studies on upflow anaerobic filter

    NASA Astrophysics Data System (ADS)

    Varandani, Nanik Sobhraj

    The thesis presents a critical review of the available literature on the various studies carried out on various aspects of Upflow Anaerobic Filter (UAF) throughout the world. Young and McCarty (1969) did the pioneering work in developing UAF in 1969, since then several studies have been carried out by different researchers using different substrates under different operating conditions and variety of supporting media. However, the most significant modification of the original reactor developed by Young and McCarty (1968), has been the development and use of high porosity media. The use of high porosity media, in fact, has changed the character of the reactor, from basically a fixed film reactor to a fixed film reactor in which the contribution by the suspended bio-solids, entrapped in the numerous media pores, in the substrate removal is quite significant that is to say that the reactor no longer remains a biological reactor which can be modeled and designed on the basis of biofilm kinetics only. The thesis presents an attempt to validate the developed mathematical model(s) by using the laboratory scale reactor performance data and the calculated values of reaction kinetic and bio-kinetic constants. To simplify the verification process, computer programmes have been prepared using the "EXCELL" software and C language. The results of the "EXCELL" computer program runs are tabulated at table no. 7.1 to 7.5. The verification of various mathematical models indicate that the model III B, i.e. Non ideal plug flow model assumed to consist of Complete Mix Reactors in series based on reaction kinetics, gives results with least deviation from the real situation. An interesting observation being that the model offers least deviation or nearly satisfies the real situation for a particular COD removal efficiency, for a particular OLR, eg. the least deviations are obtained at COD removal efficiency of 89% for OLR 2, 81.5% for OLR 4, 78.5% for OLR 6 . However, the use of the

  5. Anaerobic bacteria from hypersaline environments.

    PubMed Central

    Ollivier, B; Caumette, P; Garcia, J L; Mah, R A

    1994-01-01

    Strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. To date, six anaerobic fermentative genera, containing nine species, have been described. Two of them are homoacetogens. Six species belong to the family Haloanaerobiaceae, as indicated by their unique 16S rRNA oligonucleotide sequences. Desulfohalobium retbaense and Desulfovibrio halophilus represent the only two moderately halophilic sulfate reducers so far reported. Among anoxygenic phototrophic anaerobes, a few purple bacteria with optimal growth at salinities between 6 and 11% NaCl have been isolated from hypersaline habitats. They belong to the genera Rhodospirillum, Chromatium, Thiocapsa, and Ectothiorhodospira. The commonest organisms isolated so far are Chromatium salexigens, Thiocapsa halophila, and Rhodospirillum salinarum. Extremely halophilic purple bacteria have most commonly been isolated from alkaline brines and require about 20 to 25% NaCl for optimal growth. They belong to the family Ectothiorodhospiraceae. Their osmoregulation involves synthesis or uptake of compatible solutes such as glycine-betaine that accumulate in their cytoplasm. The existence of methanogens in hypersaline environments is related to the presence of noncompetitive substrates such as methylamines, which originate mainly from the breakdown of osmoregulatory amines. Methanogenesis probably does not contribute to the mineralization of carbohydrates at NaCl concentrations higher than 15%. Above this concentration, sulfate reduction is probably the main way to oxidize H2 (although at rates too low to use up all the H2 formed) and occupies a terminal function kn the degradation of carbohydrates. Three genera and five species of halophilic methylotrophic methanogens have been reported. A bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the

  6. Anaerobic bacteria from hypersaline environments.

    PubMed

    Ollivier, B; Caumette, P; Garcia, J L; Mah, R A

    1994-03-01

    Strictly anaerobic halophiles, namely fermentative, sulfate-reducing, homoacetogenic, phototrophic, and methanogenic bacteria are involved in the oxidation of organic carbon in hypersaline environments. To date, six anaerobic fermentative genera, containing nine species, have been described. Two of them are homoacetogens. Six species belong to the family Haloanaerobiaceae, as indicated by their unique 16S rRNA oligonucleotide sequences. Desulfohalobium retbaense and Desulfovibrio halophilus represent the only two moderately halophilic sulfate reducers so far reported. Among anoxygenic phototrophic anaerobes, a few purple bacteria with optimal growth at salinities between 6 and 11% NaCl have been isolated from hypersaline habitats. They belong to the genera Rhodospirillum, Chromatium, Thiocapsa, and Ectothiorhodospira. The commonest organisms isolated so far are Chromatium salexigens, Thiocapsa halophila, and Rhodospirillum salinarum. Extremely halophilic purple bacteria have most commonly been isolated from alkaline brines and require about 20 to 25% NaCl for optimal growth. They belong to the family Ectothiorodhospiraceae. Their osmoregulation involves synthesis or uptake of compatible solutes such as glycine-betaine that accumulate in their cytoplasm. The existence of methanogens in hypersaline environments is related to the presence of noncompetitive substrates such as methylamines, which originate mainly from the breakdown of osmoregulatory amines. Methanogenesis probably does not contribute to the mineralization of carbohydrates at NaCl concentrations higher than 15%. Above this concentration, sulfate reduction is probably the main way to oxidize H2 (although at rates too low to use up all the H2 formed) and occupies a terminal function kn the degradation of carbohydrates. Three genera and five species of halophilic methylotrophic methanogens have been reported. A bloom of phototrophic bacteria in the marine salterns of Salins-de-Giraud, located on the

  7. Orthogonal cross-seeding: an approach to explore protein aggregates in living cells.

    PubMed

    Hinz, Justyna; Gierasch, Lila M; Ignatova, Zoya

    2008-04-08

    Protein aggregation is associated with the pathology of many diseases, especially neurodegenerative diseases. A variety of structurally polymorphic aggregates or preaggregates including amyloid fibrils is accessible to any aggregating protein. Preaggregates are now believed to be the toxic culprits in pathologies rather than mature aggregates. Although clearly valuable, understanding the mechanism of formation and the structural characteristics of these prefibrillar species is currently lacking. We report here a simple new approach to map the nature of the aggregate core of transient aggregated species directly in the cell. The method is conceptually based on the highly discriminating ability of aggregates to recruit new monomeric species with equivalent molecular structure. Different soluble segments comprising parts of an amyloidogenic protein were transiently pulse-expressed in a tightly controlled, time-dependent manner along with the parent aggregating full-length protein, and their recruitment into the insoluble aggregate was monitored immunochemically. We used this approach to determine the nature of the aggregate core of the metastable aggregate species formed during the course of aggregation of a chimera containing a long polyglutamine repeat tract in a bacterial host. Strikingly, we found that different segments of the full-length protein dominated the aggregate core at different times during the course of aggregation. In its simplicity, the approach is also potentially amenable to screen also for compounds that can reshape the aggregate core and induce the formation of alternative nonamyloidogenic species.

  8. Transition metal salt solutions and anaerobic adhesives in dental bonding.

    PubMed

    Ireland, A J; Sherriff, M

    1999-07-01

    The objectives of this experiment were twofold. Firstly to determine whether an anaerobic adhesive could be used to bond steel attachments to etched human enamel, following treatment of this surface with various concentrations of copper (II) sulphate solution. Secondly, to determine the effect of 0.05 M solutions of other transition metal sulphates and chlorides on the same bonding process. Stainless steel attachments were bonded to human enamel using an anaerobic adhesive. In each case the enamel, which had been ground flat, was etched with 37% o-phosphoric acid and then treated with copper (II) sulphate solution prior to bonding. After bench curing for one hour, the specimens were shear tested to failure, and the load at bebond recorded in each case. The effect of varying the concentration of copper (II) sulphate solution was determined. Following determination of the optimal copper (II) sulphate concentration, the experiment was repeated using the same concentration of various other transition metal sulphates and chlorides. The results were analysed using mean force to debond (N) and 95% confidence intervals. Kaplan-Meier survival probabilities and log-rank tests were also performed. Under the conditions of this experiment the optimal concentration of copper (II) sulphate solution was found to be 0.05 M. Of the various transition metal sulphates and chlorides under test, the sulphates appeared to provide a more active surface for the polymerisation of the anaerobic adhesive than the chlorides. Of the sulphate solutions, the most effective was that of copper. Anaerobic adhesives show promise as dental bonding agents capable of bonding metal attachments to enamel following enamel pretreatment with 0.05 M copper (II) sulphate solution.

  9. Anaerobic fermentation of beef cattle manure and crop residues

    NASA Astrophysics Data System (ADS)

    Hashimoto, A. G.; Chen, Y. R.; Varel, V. H.; Robinson, S.

    1981-05-01

    Research on the feasibility of fermenting manure crop residue mixtures to methane, and on factors affecting the rate and extent of methane production is summarized. Experiments were conducted to evaluate effects of temperature, pH, substrate concentration, and alkaline pretreatment on the rate and extent of hydrolysis of manure straw mixtures. The effects of mixing duration and vacuum fermenters on methane production rates from anaerobically fermented beef cattle wastes were also determined.

  10. [Maximal anaerobic capacity of man in a modified Wingate test].

    PubMed

    Ushakov, B B; Chelnokova, E V

    1992-01-01

    We studied the possibility of using a 380B Siemens-Elema (Sweden) bicycle ergometer to determine the maximal anaerobic capacity of healthy subjects during a modified Wingate test. Exercise was performed under stable moment conditions, with calculation of braking resistance on the basis of the subjects lean body mass. The values of total work performed and maximal power may be used for comparative evaluation of physical work capacity in participants of training and rehabilitation programs.

  11. Natural attenuation of xenobiotic compounds: Anaerobic field injection experiment

    SciTech Connect

    Ruegge, K.; Bjerg, P.L.; Mosbaek, H.; Christensen, T.H.

    1995-12-31

    Currently, a continuous field injection experiment is being performed in the anaerobic part of a pollution plume downgradient of the Grindsted Landfill in Denmark. This natural gradient experiment includes an injection of 18 different xenobiotic compounds with bromide as a tracer. The injection is taking place under methanogenic/sulfate-reducing conditions and the compounds will, as they migrate with the groundwater, pass through a zone where the redox conditions have been determined as iron-reducing.

  12. Holographic characterization of protein aggregates

    NASA Astrophysics Data System (ADS)

    Wang, Chen; Zhong, Xiao; Ruffner, David; Stutt, Alexandra; Philips, Laura; Ward, Michael; Grier, David

    Holographic characterization directly measures the size distribution of subvisible protein aggregates in suspension and offers insights into their morphology. Based on holographic video microscopy, this analytical technique records and interprets holograms of individual aggregates in protein solutions as they flow down a microfluidic channel, without requiring labeling or other exceptional sample preparation. The hologram of an individual protein aggregate is analyzed in real time with the Lorenz-Mie theory of light scattering to measure that aggregate's size and optical properties. Detecting, counting and characterizing subvisible aggregates proceeds fast enough for time-resolved studies, and lends itself to tracking trends in protein aggregation arising from changing environmental factors. No other analytical technique provides such a wealth of particle-resolved characterization data in situ. Holographic characterization promises accelerated development of therapeutic protein formulations, improved process control during manufacturing, and streamlined quality assurance during storage and at the point of use. Mrsec and MRI program of the NSF, Spheryx Inc.

  13. Prognostic factors and impact of antibiotherapy in 117 cases of anaerobic bacteraemia.

    PubMed

    Robert, R; Deraignac, A; Le Moal, G; Ragot, S; Grollier, G

    2008-08-01

    Bacteraemia due to anaerobic bacteria occurs infrequently, making the systematic use of an anaerobic blood sample bottle in patients with sepsis controversial. We retrospectively reviewed the clinical and microbiological data from all cases of anaerobic bacteraemia in a teaching hospital over 2 years and determined the prognostic factors and antibiotic management. With the goal of evaluating the morbidity and mortality of bacteraemia due to anaerobic bacteria, a case-control study was also performed. One hundred eighty-four blood cultures from 125 patients grew at least one anaerobic bacterium, representing 0.5% of all and 7.0% of the positive blood cultures. One hundred seventeen patients were studied. In 24 cases, anaerobic blood cultures were associated with concomitant aerobic bacteria isolation. The most frequently isolated anaerobic species were Bacteroides sp. (n = 62), Clostridium sp. (n = 25), and Fusobacterium sp. (n = 12). The most frequent site of origin was the digestive tract (n = 61). In 51 cases, patients did not receive adequate empirical antianaerobic therapy. The mortality rate was 27%. Age [odds ratio (OR) 1.059; 95% confidence interval (CI) 1.021-1.100], cancer history (OR 3.21, 95% CI 1.126-9.156), and ineffective definitive antibiotherapy (OR 19.292, 95% CI 5.330-69.832) were independently associated with increased hospital mortality. The 72 patients that could be matched with patients without anaerobic bacteria according to their primary diagnosis had a longer hospitalisation and a trend toward increased mortality (P = 0.08). Anaerobic bacteraemia contributed significantly to the morbidity of the patients, and adequate empirical antibiotherapy may play an important role in the clinical outcomes.

  14. Vocal Fold Mucus Aggregation in Persons with Voice Disorders

    PubMed Central

    Bonilha, Heather Shaw; White, Lisa; Kuckhahn, Kelsey; Gerlach, Terri Treman; Deliyski, Dimitar D.

    2012-01-01

    Mucus aggregation on the vocal folds is a common finding from laryngeal endoscopy. Patients with voice disorders report the presence of mucus aggregation. Patients also report that mucus aggregation causes them to clear their throat, a behavior believed to be harmful to vocal fold mucosa. Even though clinicians and patients report and discuss mucus aggregation, we have a limited understanding of mucus aggregation in persons with voice disorders. The primary goal of this study was to provide an initial assessment of the presence and features of mucus aggregation in persons with voice disorders. The secondary goal of this study was to determine if there are differences in mucus aggregation between persons with and without voice disorders. To address these goals, four features of mucus aggregation were judged from laryngeal endoscopy recordings from 54 speakers with voice disorders and compared to judgments of these same features in persons without voice disorders. The results from this study showed: (1) 100% of dysphonic speakers had visible mucus aggregation on their vocal folds. (2) Persons with hyperfunctional voice disorders had different mucus characteristics than persons with hypofunctional voice disorders (p=0.002). (3) Dysphonic speakers did not differ in frequency of mucus identified on the vocal folds than non-dysphonic speakers. However, the two groups had different mucus characteristics (p=0.001). Future studies are warranted to determine if these differences in mucus aggregation between persons with and without voice disorders relate to specific aspects of laryngeal pathology or patient characteristics, such as age and gender. Once we understand these relationships, we may be able to use this information to improve our diagnosis and treatment of patients with atypical laryngeal mucus aggregation. PMID:22510352

  15. Peripheral-type benzodiazepine receptor (PBR) aggregation and absence of steroidogenic acute regulatory protein (StAR)/PBR association in the mitochondrial membrane as determined by bioluminescence resonance energy transfer (BRET).

    PubMed

    Bogan, Randy L; Davis, Tracy L; Niswender, Gordon D

    2007-04-01

    The steroidogenic acute regulatory protein (StAR) is responsible for acute control of cholesterol transport across the mitochondrial membrane, however the mechanism of StAR-associated cholesterol transport is unknown and may involve the peripheral-type benzodiazepine receptor (PBR)/endozepine system. Several molecules of PBR may associate to form a channel through which cholesterol passes to the inner mitochondrial membrane, and endozepine is the natural ligand for PBR. Bioluminescence resonance energy transfer (BRET) was used to test StAR/PBR/endozepine interactions, PBR aggregation, and the effect of second messengers on interactions. There was no evidence of StAR/PBR, StAR/endozepine, or PBR/endozepine interactions. The StAR and PBR fusion proteins were trafficking to the mitochondria as expected, but the endozepine fusion protein was not localized to the mitochondria indicating that it was not biologically active. Data were obtained indicating that PBR forms aggregates in the mitochondrial membrane. Energy transfer between PBR fusion proteins was dose and time dependent, but there was no effect induced by PK11195 ligand binding or pharmacologic activation of PKA or PKC second messenger pathways. It appears that PBR aggregates in the mitochondrial membrane, however there was no evidence that PBR aggregation is regulated in the acute control of steroidogenesis, or that PBR and StAR interact.

  16. Solving Transportation Problems via Aggregation,

    DTIC Science & Technology

    1984-07-01

    AD-A144 219 SOLVING TRANSPORTATION PROBLEMS VIA AGGREGATION (U) i/l GEORGIA INST OF TECH ATLANTA PRODUCTION AND DISTRIBUTION RESEARCH CENTER R W...10 July 1984 SOLVING TRANSPORTATION PROBLEMS VIA AGGREGATION by" 4 Richard W. Taylort C. M. Shettytt PDRC 84-10 DTIC E L - TE~ School of Business...c UoaOO48--17 Rpouto spritein whol or pr for ny prpos of he U S. overment Abstract Solving Transportation Problems Via Aggregation 0

  17. Anaerobic Toxicity of Cationic Silver Nanoparticles

    EPA Pesticide Factsheets

    Toxicity data for the impact of nano-silver on anaerobic degradation.This dataset is associated with the following publication:Gitipour, A., S. Thiel, K. Scheckel, and T. Tolaymat. Anaerobic Toxicity of Cationic Silver Nanoparticles. D. Barcelo Culleres, and J. Gan SCIENCE OF THE TOTAL ENVIRONMENT. Elsevier BV, AMSTERDAM, NETHERLANDS, 557: 363-368, (2016).

  18. Factor Analysis of Various Anaerobic Power Tests.

    ERIC Educational Resources Information Center

    Manning, James M.; And Others

    A study investigated the relationship between selected anthropometric variables and of numerous anaerobic power tests with measures obtained on an isokinetic dynamometer. Thirty-one male college students performed several anaerobic power tests, including: the vertical jump using the Lewis formula; the Margaria-Kalamen stair climb test; the Wingate…

  19. 21 CFR 866.2120 - Anaerobic chamber.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

  20. 21 CFR 866.2120 - Anaerobic chamber.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

  1. 21 CFR 866.2120 - Anaerobic chamber.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

  2. Factor Analysis of Various Anaerobic Power Tests.

    ERIC Educational Resources Information Center

    Manning, James M.; And Others

    A study investigated the relationship between selected anthropometric variables and of numerous anaerobic power tests with measures obtained on an isokinetic dynamometer. Thirty-one male college students performed several anaerobic power tests, including: the vertical jump using the Lewis formula; the Margaria-Kalamen stair climb test; the Wingate…

  3. Anaerobic Infections in Children with Neurological Impairments.

    ERIC Educational Resources Information Center

    Brook, Itzhak

    1995-01-01

    Children with neurological impairments are prone to develop serious infection with anaerobic bacteria. The most common anaerobic infections are decubitus ulcers; gastrostomy site wound infections; pulmonary infections (aspiration pneumonia, lung abscesses, and tracheitis); and chronic suppurative otitis media. The unique microbiology of each of…

  4. 21 CFR 866.2120 - Anaerobic chamber.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

  5. 21 CFR 866.2120 - Anaerobic chamber.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Anaerobic chamber. 866.2120 Section 866.2120 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Microbiology Devices § 866.2120 Anaerobic chamber. (a...

  6. Anaerobic Infections in Children with Neurological Impairments.

    ERIC Educational Resources Information Center

    Brook, Itzhak

    1995-01-01

    Children with neurological impairments are prone to develop serious infection with anaerobic bacteria. The most common anaerobic infections are decubitus ulcers; gastrostomy site wound infections; pulmonary infections (aspiration pneumonia, lung abscesses, and tracheitis); and chronic suppurative otitis media. The unique microbiology of each of…

  7. Deep sequencing-based analysis of the anaerobic stimulon in Neisseria gonorrhoeae

    PubMed Central

    2011-01-01

    Background Maintenance of an anaerobic denitrification system in the obligate human pathogen, Neisseria gonorrhoeae, suggests that an anaerobic lifestyle may be important during the course of infection. Furthermore, mounting evidence suggests that reduction of host-produced nitric oxide has several immunomodulary effects on the host. However, at this point there have been no studies analyzing the complete gonococcal transcriptome response to anaerobiosis. Here we performed deep sequencing to compare the gonococcal transcriptomes of aerobically and anaerobically grown cells. Using the information derived from this sequencing, we discuss the implications of the robust transcriptional response to anaerobic growth. Results We determined that 198 chromosomal genes were differentially expressed (~10% of the genome) in response to anaerobic conditions. We also observed a large induction of genes encoded within the cryptic plasmid, pJD1. Validation of RNA-seq data using translational-lacZ fusions or RT-PCR demonstrated the RNA-seq results to be very reproducible. Surprisingly, many genes of prophage origin were induced anaerobically, as well as several transcriptional regulators previously unknown to be involved in anaerobic growth. We also confirmed expression and regulation of a small RNA, likely a functional equivalent of fnrS in the Enterobacteriaceae family. We also determined that many genes found to be responsive to anaerobiosis have also been shown to be responsive to iron and/or oxidative stress. Conclusions Gonococci will be subject to many forms of environmental stress, including oxygen-limitation, during the course of infection. Here we determined that the anaerobic stimulon in gonococci was larger than previous studies would suggest. Many new targets for future research have been uncovered, and the results derived from this study may have helped to elucidate factors or mechanisms of virulence that may have otherwise been overlooked. PMID:21251255

  8. Deep sequencing-based analysis of the anaerobic stimulon in Neisseria gonorrhoeae.

    PubMed

    Isabella, Vincent M; Clark, Virginia L

    2011-01-20

    Maintenance of an anaerobic denitrification system in the obligate human pathogen, Neisseria gonorrhoeae, suggests that an anaerobic lifestyle may be important during the course of infection. Furthermore, mounting evidence suggests that reduction of host-produced nitric oxide has several immunomodulary effects on the host. However, at this point there have been no studies analyzing the complete gonococcal transcriptome response to anaerobiosis. Here we performed deep sequencing to compare the gonococcal transcriptomes of aerobically and anaerobically grown cells. Using the information derived from this sequencing, we discuss the implications of the robust transcriptional response to anaerobic growth. We determined that 198 chromosomal genes were differentially expressed (~10% of the genome) in response to anaerobic conditions. We also observed a large induction of genes encoded within the cryptic plasmid, pJD1. Validation of RNA-seq data using translational-lacZ fusions or RT-PCR demonstrated the RNA-seq results to be very reproducible. Surprisingly, many genes of prophage origin were induced anaerobically, as well as several transcriptional regulators previously unknown to be involved in anaerobic growth. We also confirmed expression and regulation of a small RNA, likely a functional equivalent of fnrS in the Enterobacteriaceae family. We also determined that many genes found to be responsive to anaerobiosis have also been shown to be responsive to iron and/or oxidative stress. Gonococci will be subject to many forms of environmental stress, including oxygen-limitation, during the course of infection. Here we determined that the anaerobic stimulon in gonococci was larger than previous studies would suggest. Many new targets for future research have been uncovered, and the results derived from this study may have helped to elucidate factors or mechanisms of virulence that may have otherwise been overlooked.

  9. Peptide Aggregation in Finite Systems

    PubMed Central

    Singh, Gurpreet; Brovchenko, Ivan; Oleinikova, Alla; Winter, Roland

    2008-01-01

    Universal features of the peptide aggregation process suggest a common mechanism, with a first-order phase transition in aqueous solutions of the peptides being the driving force. Small system sizes strongly affect the stability of the minor phase in the two-phase region. We show manifestations of this effect in aqueous solutions of fragments of the islet amyloid polypeptide, using computer simulation methods and invoking various approaches in characterizing clustering and aggregate formation. These systems with peptide concentrations deeply inside the immiscibility region show two distinct stable states, which interchange with time: one state contains a peptide aggregate; and the other state has an aggregate that is noticeably dissolved. The first state is relevant for macroscopic systems, whereas the second one is artificial. At a fixed concentration, the occurrence probability of the aggregate state vanishes upon decreasing the system size, thus indicating the necessity to apply a finite size-scaling for meaningful studies of peptide aggregation by simulations. The effect observed may be one of the factors responsible for the difference between intracellular and extracellular aggregation and fibrillization of polypeptides. The finite size of biological cells or their compartments may be playing a decisive role in hampering intracellular aggregation of highly insoluble amyloidogenic proteins, whereas aggregation is unavoidable in the extracellular space at the same peptide concentration. PMID:18621830

  10. Molecular Aggregates in Cryogenic Solutions.

    DTIC Science & Technology

    1981-07-07

    of aggregates from solutions of monomers. Rapid deposition into a precooled sample cell is required to generate an aggregate solution. Such a solution...U AU-A11b 490 COLORAO0 STATE UNIV FORT COLLINS DEPT OF CHEMISTRY F/G 20/8 MOLECULAR AGGREGATES IN CRYOGENIC SOLUTIONS.CU) JUL 81 M W SCHAUER- J LEE...MOLECULAR AGGREGATES IN CRYOGENIC SOLUTIONS by M.W. Schauer, J. Lee, and E.R. Bernstein Prepared for Publication in The Journal of Chemical Physics

  11. Strain-dependent profile of misfolded prion protein aggregates

    PubMed Central

    Morales, Rodrigo; Hu, Ping Ping; Duran-Aniotz, Claudia; Moda, Fabio; Diaz-Espinoza, Rodrigo; Chen, Baian; Bravo-Alegria, Javiera; Makarava, Natallia; Baskakov, Ilia V.; Soto, Claudio

    2016-01-01

    Prions are composed of the misfolded prion protein (PrPSc) organized in a variety of aggregates. An important question in the prion field has been to determine the identity of functional PrPSc aggregates. In this study, we used equilibrium sedimentation in sucrose density gradients to separate PrPSc aggregates from three hamster prion strains (Hyper, Drowsy, SSLOW) subjected to minimal manipulations. We show that PrPSc aggregates distribute in a wide range of arrangements and the relative proportion of each species depends on the prion strain. We observed a direct correlation between the density of the predominant PrPSc aggregates and the incubation periods for the strains studied. The relative presence of PrPSc in fractions of different sucrose densities was indicative of the protein deposits present in the brain as analyzed by histology. Interestingly, no association was found between sensitivity to proteolytic degradation and aggregation profiles. Therefore, the organization of PrP molecules in terms of the density of aggregates generated may determine some of the particular strain properties, whereas others are independent from it. Our findings may contribute to understand the mechanisms of strain variation and the role of PrPSc aggregates in prion-induced neurodegeneration. PMID:26877167

  12. Strain-dependent profile of misfolded prion protein aggregates.

    PubMed

    Morales, Rodrigo; Hu, Ping Ping; Duran-Aniotz, Claudia; Moda, Fabio; Diaz-Espinoza, Rodrigo; Chen, Baian; Bravo-Alegria, Javiera; Makarava, Natallia; Baskakov, Ilia V; Soto, Claudio

    2016-02-15

    Prions are composed of the misfolded prion protein (PrP(Sc)) organized in a variety of aggregates. An important question in the prion field has been to determine the identity of functional PrP(Sc) aggregates. In this study, we used equilibrium sedimentation in sucrose density gradients to separate PrP(Sc) aggregates from three hamster prion strains (Hyper, Drowsy, SSLOW) subjected to minimal manipulations. We show that PrP(Sc) aggregates distribute in a wide range of arrangements and the relative proportion of each species depends on the prion strain. We observed a direct correlation between the density of the predominant PrP(Sc) aggregates and the incubation periods for the strains studied. The relative presence of PrP(Sc) in fractions of different sucrose densities was indicative of the protein deposits present in the brain as analyzed by histology. Interestingly, no association was found between sensitivity to proteolytic degradation and aggregation profiles. Therefore, the organization of PrP molecules in terms of the density of aggregates generated may determine some of the particular strain properties, whereas others are independent from it. Our findings may contribute to understand the mechanisms of strain variation and the role of PrP(Sc) aggregates in prion-induced neurodegeneration.

  13. Anaerobic digestion for household organics

    SciTech Connect

    Sinclair, R.; Kelleher, M.

    1995-04-01

    Considerable success in using anaerobic technology for processing household organics is being reported by several recently constructed facilities in Europe. Organic residuals collected separately in a Belgian town are processed to produce biogas and a compost-like material in less than one month. The dry anaerobic conversion process (DRANCO) was developed by Organic Waste Systems (OWS) in the 1980s, with the collaboration of Professor Willy Verstraete at the University of Ghent`s Laboratory of Applied Microbial Ecology. The patented process converts solid and semisolid organic residuals into biogas (for energy recovery) and a stable humus like product. The plant has competing odor sources such as the active landfill and the surrounding farmland - in fact, the smell of livestock manure is quite prevalent in this heavily agricultural area. Addition of the nonrecyclable paper fraction to the feedstock improves the carbon/nitrogen ratio, soaks up moisture, and absorbs odor. The entire Brecht facility does not occupy much space and total material retention time at the site is one month, compared to a number of months for aerobic systems. It also has a low staffing requirement, provides energy self-sufficiency, and the final soil enhancement product meets established quality standards.

  14. Anaerobic digestion in rural China

    SciTech Connect

    Henderson, J.P.

    1997-01-01

    The People`s Republic of China has been promoting underground, individual, anaerobic digesters to process rural organic materials. This strategy has resulted in approximately five million household anaerobic digesters installed in China today. Simple reactors provide energy and fertilizer for Chinese farms and villages. Another benefit includes improved household sanitation. Reactor design has evolved over time. In the standard modern design, effluent is removed from the reactor at the top of the water column, meaning that supernatant is collected rather than sludge. Additionally, no mixing of the system occurs when effluent is removed. In some systems, a vertical cylindrical pull-rod port is added to the base of the effluent port. Effluent is removed by moving the pull-rod - simply a wooden shaft with a metal disk on the bottom - up and down in the port. A bucket can be placed directly under the pull-rod port, simplifying effluent removal, while the movement of the wooden shaft provides some mixing in the reactor. The gas primarily is used for cooking and lighting. A digester can provide approximately 60 percent of a family`s energy needs. Effluent from the reactors is an odorless, dark colored slurry, primarily used as an agricultural fertilizer. 3 figs.

  15. Investigation of Usability as Aggregate of Different Originated Rocks

    NASA Astrophysics Data System (ADS)

    Başpinar Tuncay, Ebru; Kilinçarslan, Şemsettin; Yağmurlu, Fuzuli

    2016-10-01

    The general properties of aggregate can determine the performance and durability of the concrete. In this study, mineralogical, petrographic, mechanical, physical and chemical properties of the rock samples of different origin (limestone, recrystallized limestone, dolomite, sand and gravel, tephra-phonolite, trachybasalt) were determined. Samples were obtained from different origin rocks units and they have been classified in three different sizes of aggregate with crushing and screening method. Grading, classification of particle, loose bulk density, water absorption ratio, flakiness index, coefficient of Los Angeles, resistance to freeze-loosening and alkali-silica reaction of aggregates and organic matter determination has been determined. The rocks have been investigated in compliance with the relevant standards. Trachybasalt and dolomite have higher particle density than other rocks. In addition, strength and flexural strength of these rocks are higher than other rocks. Tephra-phonolite has the lowest water absorption rate. At the same time resistance to freeze loosening of Tephra- phonolite is lower than the other rocks. Resistance to fragmentation and the resistance to wear of all of rocks are quite high. Sand and gravel, tephra-phonolite and trachybasalt are evaluated in terms of alkali-silica reaction. Sand and gravel are more reactive than the other aggregates. Organic matter content of the aggregates is low for the quality of aggregate. Also high correlation between some properties of aggregates was observed. For example, high correlation between compressive strength and flexural strength, water absorption and porosity, resistance to fragmentation and the resistance to ware (Micro-Deval).

  16. Toxicants inhibiting anaerobic digestion: a review.

    PubMed

    Chen, Jian Lin; Ortiz, Raphael; Steele, Terry W J; Stuckey, David C

    2014-12-01

    Anaerobic digestion is increasingly being used to treat wastes from many sources because of its manifold advantages over aerobic treatment, e.g. low sludge production and low energy requirements. However, anaerobic digestion is sensitive to toxicants, and a wide range of compounds can inhibit the process and cause upset or failure. Substantial research has been carried out over the years to identify specific inhibitors/toxicants, and their mechanism of toxicity in anaerobic digestion. In this review we present a detailed and critical summary of research on the inhibition of anaerobic processes by specific organic toxicants (e.g., chlorophenols, halogenated aliphatics and long chain fatty acids), inorganic toxicants (e.g., ammonia, sulfide and heavy metals) and in particular, nanomaterials, focusing on the mechanism of their inhibition/toxicity. A better understanding of the fundamental mechanisms behind inhibition/toxicity will enhance the wider application of anaerobic digestion.

  17. Anaerobic biorefinery: Current status, challenges, and opportunities.

    PubMed

    Sawatdeenarunat, Chayanon; Nguyen, Duc; Surendra, K C; Shrestha, Shilva; Rajendran, Karthik; Oechsner, Hans; Xie, Li; Khanal, Samir Kumar

    2016-09-01

    Anaerobic digestion (AD) has been in use for many decades. To date, it has been primarily aimed at treating organic wastes, mainly manures and wastewater sludge, and industrial wastewaters. However, with the current advancements, a more open mind is required to look beyond these somewhat restricted original applications of AD. Biorefineries are such concepts, where multiple products including chemicals, fuels, polymers etc. are produced from organic feedstocks. The anaerobic biorefinery concept is now gaining increased attention, utilizing AD as the final disposal step. This review aims at evaluating the potential significance of anaerobic biorefineries, including types of feedstocks, uses for the produced energy, as well as sustainable applications of the generated residual digestate. A comprehensive analysis of various types of anaerobic biorefineries has been developed, including both large-scale and household level applications. Finally, future directives are highlighted showing how anaerobic biorefinery concept could impact the bioeconomy in the near future. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. Potential for Direct Interspecies Electron Transfer in Methanogenic Wastewater Digester Aggregates

    PubMed Central

    Morita, Masahiko; Malvankar, Nikhil S.; Franks, Ashley E.; Summers, Zarath M.; Giloteaux, Ludovic; Rotaru, Amelia E.; Rotaru, Camelia; Lovley, Derek R.

    2011-01-01

    ABSTRACT Mechanisms for electron transfer within microbial aggregates derived from an upflow anaerobic sludge blanket reactor converting brewery waste to methane were investigated in order to better understand the function of methanogenic consortia. The aggregates were electrically conductive, with conductivities 3-fold higher than the conductivities previously reported for dual-species aggregates of Geobacter species in which the two species appeared to exchange electrons via interspecies electron transfer. The temperature dependence response of the aggregate conductance was characteristic of the organic metallic-like conductance previously described for the conductive pili of Geobacter sulfurreducens and was inconsistent with electron conduction through minerals. Studies in which aggregates were incubated with high concentrations of potential electron donors demonstrated that the aggregates had no significant capacity for conversion of hydrogen to methane. The aggregates converted formate to methane but at rates too low to account for the rates at which that the aggregates syntrophically metabolized ethanol, an important component of the reactor influent. Geobacter species comprised 25% of 16S rRNA gene sequences recovered from the aggregates, suggesting that Geobacter species may have contributed to some but probably not all of the aggregate conductivity. Microorganisms most closely related to the acetate-utilizing Methanosaeta concilii accounted for more than 90% of the sequences that could be assigned to methane producers, consistent with the poor capacity for hydrogen and formate utilization. These results demonstrate for the first time that methanogenic wastewater aggregates can be electrically conductive and suggest that direct interspecies electron transfer could be an important mechanism for electron exchange in some methanogenic systems. PMID:21862629

  19. Hydrophobically modified polyelectrolytes: Characterization, aggregation and adsorption

    NASA Astrophysics Data System (ADS)

    Islam, Mohammad Ferdous

    The focus of our work was to experimentally study the aggregation and adsorption behavior of model HM polyelectrolytes. Hydrophobically modified alkali soluble emulsions (HASE), the model HM polyelectrolytes, were chosen because they had complex architecture yet possessed key variables for systematic study. The HASE polymers have methacrylic acid (MAA) and ethyl acrylate (EA) in the backbone with pendent hydrophobic groups. Characterization of a single molecule is an important first step in understanding the aggregation and adsorption of these polymers. However, characterizations of the HASE polymers using conventional techniques such as gel permeation chromatography or static light scattering were difficult because of the hydrophobic association. In this study, two different approaches have been taken to prevent the hydrophobic association in aqueous solution: (1) hydrolyze the polymer to cleave the hydrophobic constituents, and (2) use methyl beta-cyclodextrin that has a hydrophobic cavity and a hydrophilic outer shell, to shield the hydrophobes from associating. By taking these two approaches and using gel permeation chromatography (GPC), dynamic (DLS) and static (SLS) light scattering techniques, the molecular weight, hydrodynamic radius and radius of gyration of a single molecule were determined. Except for one chemical site, we were able to determine that branching or grafting did not occur in the polymer chain during synthesis. Our aggregation studies showed that, in aqueous solutions, the HASE polymers formed small aggregates (presumably single micelles of single or a few chains) and large aggregates (presumably formed by bridging between micelles). The radii and masses of the larger aggregates, measured using DLS and SLS, were found to increase with an increase in the polymer concentration, indicating an open association process for the HASE polymers. Our SLS results also showed that, at high salt concentration, the aggregates of the HASE polymer with

  20. Rapid start-up of thermophilic anaerobic digestion with the turf fraction of MSW as inoculum.

    PubMed

    Suwannoppadol, Suwat; Ho, Goen; Cord-Ruwisch, Ralf

    2011-09-01

    This study aims to determine suitable start-up conditions and inoculum sources for thermophilic anaerobic digestion. Within days of incubation MSW at 55°C, methane was produced at a high rate. In an attempt to narrow down which components of typical MSW contained the thermophilic methanogens, vacuum cleaner dust, banana peel, kitchen waste, and garden waste were tested as inoculum for thermophilic methanogenesis with acetate as the substrate. Results singled out grass turf as the key source of thermophilic acetate degrading methanogenic consortia. Within 4 days of anaerobic incubation (55°C), anaerobically incubated grass turf samples produced methane accompanied by acetate degradation enabling successful start-up of thermophilic anaerobic digestion. Other essential start-up conditions are specified. Stirring of the culture was not conducive for successful start-up as it resulted specifically in propionate accumulation. Copyright © 2011 Elsevier Ltd. All rights reserved.

  1. Dechlorination of polychlorinated biphenyl-contaminated soil via anaerobic composting with pig manure.

    PubMed

    Zhang, Chi; Du, Yao; Tao, Xiao-Qing; Zhang, Kun; Shen, Dong-Sheng; Long, Yu-Yang

    2013-10-15

    Anaerobic dechlorination is an effective degradation pathway of higher chlorinated polychlorinated biphenyls (PCBs). The efficiency of anaerobic composting remediation of PCB-contaminated soil using pig manure was determined. The results show that the dechlorination of PCB-contaminated soil via anaerobic composting with pig manure is feasible. PCB concentration is the most critical factor. Elevated PCB concentrations can inhibit dechlorination but does not disrupt the anaerobic fermentation process. At 1 mg kg(-1) PCBs, the degradation rate of five or more chlorinated biphenyls is 43.8%. The highest dechlorination performance in this experiment was obtained when the soil-to-organic waste ratio, carbon-to-nitrogen ratio, moisture content, and PCB concentration were 2:3, 20, 60%, and 1 mg kg(-1), respectively.

  2. Aggregation of nucleosomes by divalent cations.

    PubMed Central

    de Frutos, M; Raspaud, E; Leforestier, A; Livolant, F

    2001-01-01

    Conditions of precipitation of nucleosome core particles (NCP) by divalent cations (Ca(2+) and Mg(2+)) have been explored over a large range of nucleosome and cation concentrations. Precipitation of NCP occurs for a threshold of divalent cation concentration, and redissolution is observed for further addition of salt. The phase diagram looks similar to those obtained with DNA and synthetic polyelectrolytes in the presence of multivalent cations, which supports the idea that NCP/NCP interactions are driven by cation condensation. In the phase separation domain the effective charge of the aggregates was determined by measurements of their electrophoretic mobility. Aggregates formed in the presence of divalent cations (Mg(2+)) remain negatively charged over the whole concentration range. They turn positively charged when aggregation is induced by trivalent (spermidine) or tetravalent (spermine) cations. The higher the valency of the counterions, the more significant is the reversal of the effective charge of the aggregates. The sign of the effective charge has no influence on the aspect of the phase diagram. We discuss the possible reasons for this charge reversal in the light of actual theoretical approaches. PMID:11463653

  3. Comparison of three optical methods to study erythrocyte aggregation.

    PubMed

    Zhao, H; Wang, X; Stoltz, J F

    1999-01-01

    The aim of this work was to evaluate three optical methods designed to determine erythrocyte aggregation: Erythroaggregometer (EA; Regulest, France), Laser-assisted Optical Rotational Cell Analyzer (LORCA; Mechatronics, Netherlands) and Fully Automatic Erythrocyte Aggregometer (FAEA; Myrenne, GmbH, Germany). Blood samples were taken from fifty donors (26 males and 24 females). The aggregation of normal red blood cell (RBC) and RBCs suspended in three normo- and hyperaggregating suspending media was studied. The results revealed some significant correlations between parameters measured by these instruments, in particular, between the indexes of aggregation of EA and LORCA. Further, RBC aggregation of multiple myeloma patients was also studied and a hyper erythrocyte aggregation state was found by EA and LORCA.

  4. H- and J-aggregate behavior in polymeric semiconductors.

    PubMed

    Spano, Frank C; Silva, Carlos

    2014-01-01

    Aggregates of conjugated polymers exhibit two classes of fundamental electronic interactions: those occurring within a given chain and those occurring between chains. The impact of such excitonic interactions on the photophysics of polymer films can be understood using concepts of J- and H-aggregation originally developed by Kasha and coworkers to treat aggregates of small molecules. In polymer assemblies, intrachain through-bond interactions lead to J-aggregate behavior, whereas interchain Coulombic interactions lead to H-aggregate behavior. The photophysics of common emissive conjugated polymer films are determined by a competition between intrachain, J-favoring interactions and interchain, H-favoring interactions. We review formalisms describing absorption and photoluminescence lineshapes, based on intra- and intermolecular excitonic coupling, electron-vibrational coupling, and correlated energetic disorder. Examples include regioregular polythiophenes, pheneylene-vinylenes, and polydiacetylene.

  5. Diatom-associated bacteria are required for aggregation of Thalassiosira weissflogii

    PubMed Central

    Gärdes, Astrid; Iversen, Morten H; Grossart, Hans-Peter; Passow, Uta; Ullrich, Matthias S

    2011-01-01

    Aggregation of algae, mainly diatoms, is an important process in marine systems leading to the settling of particulate organic carbon predominantly in the form of marine snow. Exudation products of phytoplankton form transparent exopolymer particles (TEP), which acts as the glue for particle aggregation. Heterotrophic bacteria interacting with phytoplankton may influence TEP formation and phytoplankton aggregation. This bacterial impact has not been explored in detail. We hypothesized that bacteria attaching to Thalassiosira weissflogii might interact in a yet-to-be determined manner, which could impact TEP formation and aggregate abundance. The role of individual T. weissflogii-attaching and free-living new bacterial isolates for TEP production and diatom aggregation was investigated in vitro. T. weissflogii did not aggregate in axenic culture, and striking differences in aggregation dynamics and TEP abundance were observed when diatom cultures were inoculated with either diatom-attaching or free-living bacteria. The data indicated that free-living bacteria might not influence aggregation whereas bacteria attaching to diatom cells may increase aggregate formation. Interestingly, photosynthetically inactivated T. weissflogii cells did not aggregate regardless of the presence of bacteria. Comparison of aggregate formation, TEP production, aggregate sinking velocity and solid hydrated density revealed remarkable differences. Both, photosynthetically active T. weissflogii and specific diatom-attaching bacteria were required for aggregation. It was concluded that interactions between heterotrophic bacteria and diatoms increased aggregate formation and particle sinking and thus may enhance the efficiency of the biological pump. PMID:20827289

  6. Aggregation in ecosystem models and model stability

    NASA Astrophysics Data System (ADS)

    Giricheva, Evgeniya

    2015-05-01

    Using a multimodal approach to research ecosystems improves usage of available information on an object. This study presents several models of the Bering Sea ecosystem. The ecosystem is considered as a closed object, that is, the influence of the environment is not provided. We then add the links with the external medium in the models. The models differ in terms of the degree and method of grouping components. Our method is based on the differences in habitat and food source of groups, which allows us to determine the grouping of species with a greater effect on system dynamics. In particular, we determine whether benthic fish aggregation or pelagic fish aggregation can change the consumption structure of some groups of species, and consequently, the behavior of the entire model system.

  7. Scaling and shadowing effects in ballistic aggregation

    NASA Astrophysics Data System (ADS)

    Joag, P. S.; Limaye, A. V.; Amritkar, R. E.

    1987-10-01

    We have studied the scaling and shadowing properties of two-dimensional off-lattice ballistic aggregation on a seed. The computer simulations show that the limiting semivertical cone angle is about 15.5°. The density as a function of distance from the seed tends to a constant value showing a basic two-dimensional nature of the aggregates and has a correction with a metadimension of about 0.56. The density as a function of angle near the edges of the cone is found to obey a scaling relation similar to the on-lattice case. The probabilities for the fingers of different lengths which shadow the particle near the edge are determined in the computer experiment and also determined analytically.

  8. Topics in Probabilistic Judgment Aggregation

    ERIC Educational Resources Information Center

    Wang, Guanchun

    2011-01-01

    This dissertation is a compilation of several studies that are united by their relevance to probabilistic judgment aggregation. In the face of complex and uncertain events, panels of judges are frequently consulted to provide probabilistic forecasts, and aggregation of such estimates in groups often yield better results than could have been made…

  9. Topics in Probabilistic Judgment Aggregation

    ERIC Educational Resources Information Center

    Wang, Guanchun

    2011-01-01

    This dissertation is a compilation of several studies that are united by their relevance to probabilistic judgment aggregation. In the face of complex and uncertain events, panels of judges are frequently consulted to provide probabilistic forecasts, and aggregation of such estimates in groups often yield better results than could have been made…

  10. Mineral of the month: aggregates

    USGS Publications Warehouse

    Tepordei, Valentin V.

    2005-01-01

    Natural aggregates, consisting of crushed stone, and sand and gravel, are a major contributor to economic health, and have an amazing variety of uses. Aggregates are among the most abundant mineral resources and are major basic raw materials used by construction, agriculture and other industries that employ complex chemical and metallurgical processes.

  11. Light-induced aggregation of microbial exopolymeric substances.

    PubMed

    Sun, Luni; Xu, Chen; Zhang, Saijin; Lin, Peng; Schwehr, Kathleen A; Quigg, Antonietta; Chiu, Meng-Hsuen; Chin, Wei-Chun; Santschi, Peter H

    2017-08-01

    Sunlight can inhibit or disrupt the aggregation process of marine colloids via cleavage of high molecular weight compounds into smaller, less stable fragments. In contrast, some biomolecules, such as proteins excreted from bacteria can form aggregates via cross-linking due to photo-oxidation. To examine whether light-induced aggregation can occur in the marine environment, we conducted irradiation experiments on a well-characterized protein-containing exopolymeric substance (EPS) from the marine bacterium Sagitulla stellata. Our results show that after 1 h sunlight irradiation, the turbidity level of soluble EPS was 60% higher than in the dark control. Flow cytometry also confirmed that more particles of larger sized were formed by sunlight. In addition, we determined a higher mass of aggregates collected on filter in the irradiated samples. This suggests light can induce aggregation of this bacterial EPS. Reactive oxygen species hydroxyl radical and peroxide played critical roles in the photo-oxidation process, and salts assisted the aggregation process. The observation that Sagitulla stellata EPS with relatively high protein content promoted aggregation, was in contrast to the case where no significant differences were found in the aggregation of a non-protein containing phytoplankton EPS between the dark and light conditions. This, together with the evidence that protein-to-carbohydrate ratio of aggregates formed under light condition is significantly higher than that formed under dark condition suggest that proteins are likely the important component for aggregate formation. Light-induced aggregation provides new insights into polymer assembly, marine snow formation, and the fate/transport of organic carbon and nitrogen in the ocean. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Gender difference in anaerobic capacity: role of aerobic contribution.

    PubMed

    Hill, D W; Smith, J C

    1993-03-01

    The purpose of this study was to evaluate effects of gender on anaerobic and aerobic contributions to high-intensity exercise. A group of 38 subjects (22 women, 16 men) performed modified Wingate tests against resistances of 0.086 kg kg-1 body mass (0.844 N kg-1) for women and 0.095 kg kg-1 body mass (0.932 N kg-1) for men. The aerobic contribution to total work performed was determined from breath-by-breath analyses of expired gases during each test. Total work in 30 s was 30% lower (Student's t test; P < 0.01) in women than men (211 +/- 5 J kg-1 versus 299 +/- 14 J kg-1). Aerobic contribution was only 7% lower (P = 0.12) in women than men (53 +/- 1 J kg-1 versus 57 +/- 2 J kg-1). The anaerobic component of the work performed, determined by subtraction of the aerobic component from total work in 30 s, was 35% lower (P < 0.01) in women than men (158 +/- 5 J kg-1 versus 242 +/- 15 J kg-1). It is concluded that, because women provide a relatively higher (P < 0.01) portion of the energy for a 30-s test aerobically than men (25% versus 20%), total work during a Wingate test actually underestimates the gender difference in anaerobic capacity between women and men.

  13. Effect of long term anaerobic and intermittent anaerobic/aerobic starvation on aerobic granules.

    PubMed

    Pijuan, Maite; Werner, Ursula; Yuan, Zhiguo

    2009-08-01

    The effect of long term anaerobic and intermittent anaerobic/aerobic starvation on the structure and activity of aerobic granules was studied. Aerobic granular sludge treating abattoir wastewater and achieving high levels of nutrient removal was subjected to 4-5 week starvation under anaerobic and intermittent anaerobic/aerobic conditions. Microscopic pictures of granules at the beginning of the starvation period presented a round and compact surface morphology with a much defined external perimeter. Under both starvation conditions, the morphology changed at the end of starvation with the external border of the granules surrounded by floppy materials. The loss of granular compactness was faster and more pronounced under anaerobic/aerobic starvation conditions. The release of Ca(2+) at the onset of anaerobic/aerobic starvation suggests a degradation of extracellular polymeric substances. The activity of ammonia oxidizing bacteria was reduced by 20 and 36% during anaerobic and intermittent anaerobic/aerobic starvation, respectively. When fresh wastewater was reintroduced, the granules recovered their initial morphology within 1 week of normal operation and the nutrient removal activity recovered fully in 3 weeks. The results show that both anaerobic and intermittent anaerobic/aerobic conditions are suitable for maintaining granule structure and activity during starvation.

  14. Microelectrode Measurements of the Activity Distribution in Nitrifying Bacterial Aggregates

    PubMed Central

    de Beer, D.; van den Heuvel, J. C.; Ottengraf, S. P. P.

    1993-01-01

    Microelectrodes for ammonium, oxygen, nitrate, and pH were used to study nitrifying aggregates grown in a fluidized-bed reactor. Local reactant fluxes and distribution of microbial activity could be determined from the microprofiles. The interfacial fluxes of the reactants closely reflected the stoichiometry of bacterial nitrification. Both ammonium consumption and nitrate production were localized in the outer shells, with a thickness of approximately 100 to 120 μm, of the aggregates. Under conditions in which ammonium and oxygen penetrated the whole aggregate, nitrification was restricted to this zone; oxygen was consumed in the central parts of the aggregates as well, probably because of oxidation of dead biomass. A sudden increase of the oxygen concentration to saturation (pure oxygen) was inhibitory to nitrification. The pH profiles showed acidification in the aggregates, but not to an inhibitory level. The distribution of activity was determined by the penetration depth of oxygen during aggregate development in the reactor. Mass transfer was significantly limited by the boundary layer surrounding the aggregates. Microelectrode measurements showed that the thickness of this layer was correlated with the diffusion coefficient of the species. Determination of the distribution of nitrifying activity required the use of ammonium or nitrate microelectrodes, whereas the use of oxygen microelectrodes alone would lead to erroneous results. Images PMID:16348875

  15. Hydration and diffusion processes shape microbial community organization and function in model soil aggregates

    NASA Astrophysics Data System (ADS)

    Ebrahimi, Ali; Or, Dani

    2015-12-01

    The constantly changing soil hydration status affects gas and nutrient diffusion through soil pores and thus the functioning of soil microbial communities. The conditions within soil aggregates are of particular interest due to limitations to oxygen diffusion into their core, and the presence of organic carbon often acting as binding agent. We developed a model for microbial life in simulated soil aggregates comprising of 3-D angular pore network model (APNM) that mimics soil hydraulic and transport properties. Within these APNM, we introduced individual motile (flagellated) microbial cells with different physiological traits that grow, disperse, and respond to local nutrients and oxygen concentrations. The model quantifies the dynamics and spatial extent of anoxic regions that vary with hydration conditions, and their role in shaping microbial community size and activity and the spatial (self) segregation of anaerobes and aerobes. Internal carbon source and opposing diffusion directions of oxygen and carbon within an aggregate were essential to emergence of stable coexistence of aerobic and anaerobic communities (anaerobes become extinct when carbon sources are external). The model illustrates a range of hydration conditions that promote or suppress denitrification or decomposition of organic matter and thus affect soil GHG emissions. Model predictions of CO2 and N2O production rates were in good agreement with limited experimental data. These limited tests support the dynamic modeling approach whereby microbial community size, composition, and spatial arrangement emerge from internal interactions within soil aggregates. The upscaling of the results to a population of aggregates of different sizes embedded in a soil profile is underway.

  16. Molecular aggregation of humic substances

    USGS Publications Warehouse

    Wershaw, R. L.

    1999-01-01

    Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into amphiphilic molecules, that is, molecules that consist of separate hydrophobic (nonpolar) and hydrophilic (polar) parts. The nonpolar parts of the molecules are composed of relatively unaltered segments of plant polymers and the polar parts of carboxylic acid groups. These amphiphiles form membrane-like aggregates on mineral surfaces and micelle-like aggregates in solution. The exterior surfaces of these aggregates are hydrophilic, and the interiors constitute separate hydrophobic liquid-like phases.

  17. Imbibition kinetics of spherical aggregates

    NASA Astrophysics Data System (ADS)

    Hébraud, Pascal; Lootens, Didier; Debacker, Alban

    The imbibition kinetics of a millimeter-sized aggregate of 300 nm diameter colloidal particles by a wetting pure solvent is studied. Three successive regimes are observed : in the first one, the imbibition proceeds by compressing the air inside the aggregate. Then, the solvent stops when the pressure of the compressed air is equal to the Laplace pressure at the meniscus of the wetting solvent in the porous aggregate. The interface is pinned and the aggregate slowly degases, up to a point where the pressure of the entrapped air stops decreasing and is controlled by the Laplace pressure of small bubbles. Depending on the curvature of the bubble, the system may then be in an unstable state. The imbibition then starts again, but with an inner pressure in equilibrium with these bubbles. This last stage leads to the complete infiltration of the aggregate.

  18. Influence of aggregated particles on biodegradation activities for dimethylarsinic acid (DMA) in Lake Kahokugata.

    PubMed

    Maki, Teruya; Hirota, Wakana; Motojima, Hiroyuki; Hasegawa, Hiroshi; Rahman, Mohammad Azizur

    2011-06-01

    Aquatic arsenic cycles mainly depend on microbial activities that change the arsenic chemical forms and influence human health and organism activities. The microbial aggregates degrading organic matter are significantly related to the turnover between inorganic arsenic and organoarsenic compounds. We investigated the effects of microbial aggregates on organoarsenic mineralization in Lake Kahokugata using lake water samples spiked with dimethylarsinic acid (DMA). The lake water samples converted 1 μmol L(-1) of DMA to inorganic arsenic for 28d only under anaerobic and dark conditions in the presence of microbial activities. During the DMA mineralization process, organic aggregates >5.0 μm with bacterial colonization increased the densities. When the organic aggregates >5.0 μm were eliminated from the lake water samples using filters, the degradation activities were reduced. DMA in the lake water would be mineralized by the microbial aggregates under anaerobic and dark conditions. Moreover, DMA amendment enhanced the degradation activities in the lake water samples, which mineralized 50 μmol L(-1) of DMA. The DMA-amended aggregates >5.0 μm completely degraded 1 μmol L(-1) of DMA with a shorter incubation time of 7d. The supplement of KNO(3) and NaHCO(3) to lake water samples also shortened the DMA-degradation period. Presumably, the bacterial aggregates involved in the chemical heterotrophic process would contribute to the DMA-biodegradation process in Lake Kahokugata, which is induced by the DMA amendment. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. EFFECT OF MUSIC ON ANAEROBIC EXERCISE PERFORMANCE

    PubMed Central

    2013-01-01

    For years, mostly the effects of music on cardiorespiratory exercise performance have been studied, but a few studies have examined the effect of music on anaerobic exercise. The purpose of this study was to assess the effect of listening to music and its rhythm on anaerobic exercise: on power output, heart rate and the concentration of blood lactate. 28 male subjects were required to visit the laboratory on 6 occasions, each separated by 48 hours. Firstly, each subject performed the Running-based Anaerobic Sprint Test (RAST) under 3 conditions on separate days: while listening to “slow rhythm music”, “fast rhythm music” or “no music”. 48 hours after the subjects completed RAST under 3 conditions, Wingate Anaerobic Power (WAN) tests were performed under 3 music conditions. The order of the 3 conditions (slow music, fast music and no music) was selected randomly to prevent an order effect. Results showed no significant differences between 3 conditions in anaerobic power assessments, heart rate or blood lactate (p > 0.05). On the basis of these results it can be said that music cannot improve anaerobic performance. The type of music had no impact on power outputs during RAST and WAN exercise. As a conclusion, listening to music and its rhythm cannot enhance anaerobic performance and cannot change the physiological response to supramaximal exercise. PMID:24744463

  20. Premature red blood cells have decreased aggregation and enhanced aggregability.

    PubMed

    Arbell, D; Orkin, B; Bar-Oz, B; Barshtein, G; Yedgar, S

    2008-06-01

    Preterm infants are highly susceptible to ischemic damage. This damage is most obvious in the brain, retina, and gastrointestinal tract. Studies focusing on the rheological properties of premature red blood cells (pRBCs) have consistently shown minimal or no RBC aggregation. Previously, measurements of pRBC aggregation kinetics indicated that specific plasma properties are responsible for the decreased RBC aggregation observed in the neonates, but that their specific RBC properties do not affect it. However, the strength of interaction in the pRBC aggregates as a function of medium composition has not been tested. In our previous research, we described clinically relevant parameters, that is, the aggregate resistance to disaggregation by flow. With the help of a cell flow property analyzer (CFA), we can monitor RBC aggregation by direct visualization of its dynamics during flow. We used the CFA to examine pRBC (from 9 premature babies) in the natural plasma and in PBS buffer supplemented with dextran (500 kDa) to distinguish between RBC intrinsic-cellular and plasma factors. pRBCs suspended in the native plasma showed minimal or no aggregation in comparison to normal adult RBC. When we transferred pRBCs from the same sample to the dextran solution, enhanced resistance to disaggregation by flow was apparent.

  1. Anaerobic filter for biogas production

    NASA Astrophysics Data System (ADS)

    Chavadej, S.

    1980-01-01

    A laboratory study evaluated the performance of an anaerobic filter in producing biogas from pig waste with 30,000 mg/l of COD. The filter packing was bamboo rings of 1 and 1/2 in. diameter, 1 in. long; the bamboo-bed filter operated satisfactorily in a wide COD loading range of 3.74-15.65 kg/cu m/d which corresponds to the hydraulic retention of 8.47 to 1.68 days. At the optimum loading of 7.299 kg COD/cu m/d, the largest gas rate of 0.212 cu m/kg of COD was produced. The required volume of the digester for 1.2 cu m/d of gas production would be only 1.5 cu m; in practical applications, consideration should be given to the gas collecting system and clogging problems.

  2. Shaping the Growth Behaviour of Biofilms Initiated from Bacterial Aggregates

    PubMed Central

    Melaugh, Gavin; Hutchison, Jaime; Kragh, Kasper Nørskov; Irie, Yasuhiko; Roberts, Aled; Bjarnsholt, Thomas; Diggle, Stephen P.; Gordon, Vernita D.; Allen, Rosalind J.

    2016-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the initial shape the aggregate forms on the surface, we find that the degree of spreading of an aggregate on a surface can play an important role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding unaggregated bacterial cells is low, while initially rounded aggregates perform better when competition with surrounding unaggregated cells is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the social evolution of biofilm communities. PMID:26934187

  3. Aggregation and vertical migration behavior of Euphausia superba

    NASA Astrophysics Data System (ADS)

    Zhou, Meng; Dorland, Ryan D.

    2004-08-01

    Aggregation and vertical migration behavior of Euphausia superba were studied in Marguerite Bay and its vicinity west of the Antarctic Peninsula using a vessel-mounted, Acoustic Doppler Current Profiler, and a Multiple Opening and Closing Nets and Environmental Sensing System, during the 2001 and 2002 fall US Southern Ocean GLOBEC project cruises. The kinematics of aggregation behavior of E. superba associated with diel migration is studied using observations of their abundance and swimming velocities: during the day, E. superba reduce their swimming at a depth of 250 m; and at night, they swim randomly at their cruising speed in the upper part of an aggregation near the surface, and coherently as schooling in the lower part of an aggregation. The causes for the aggregation behavior and vertical migration of krill are explored by examining the relationship with ice coverage and presence of predators. The motion of euphausiids is further analyzed in terms of kinetic energy and force balance, leading to new considerations of mathematical theories and models of aggregation behavior. The results show a diel variation of the energy demand for maintaining their locomotion. The horizontal scale of an aggregation is studied in conjunction with horizontal gradients of currents. Results indicate that the swimming capability of euphausiids determines the maintenance of an aggregation in the mesoscale circulation field.

  4. Population balance modeling of the conidial aggregation of Aspergillus niger.

    PubMed

    Lin, P-J; Grimm, L H; Wulkow, M; Hempel, D C; Krull, R

    2008-02-01

    Numerous biotechnological production processes are based on the submerse cultivation of filamentous fungi. Process design, however, is often hampered by the complex growth pattern of these organisms. In the morphologic development of coagulating filamentous fungi, like Aspergillus niger, conidial aggregation is the first step of filamentous morphogenesis. For a proper description of this phenomenon it is necessary to characterize conidial populations. Kinetic studies performed with an in-line particle size analyzer suggested that two distinct aggregation steps have to be considered. The first step of conidial aggregation starts immediately after inoculation. Both the rate constants of formation and disintegration of aggregates have been determined by measuring the concentration of conidia at the beginning of the cultivation and the concentration of particles at steady state during the first hours of cultivation. In contrast to the first aggregation step, where the collision of conidia is presumed to be responsible for the process, the second aggregation step is thought to be initiated by germination of conidia. Growing hyphae provide additional surface for the attachment of non- germinated conidia, which leads to a strong decrease in particle concentration. The specific hyphal length growth rate and the ratio of particle concentration to the growing adhesion hyphal surface are decisive matters of the second aggregation step. Both aggregation steps can be described by population dynamics and simulated using the program package PARSIVAL (PARticle SIze eVALution) for the treatment of general particle population balances.

  5. Evolution of unsaturated hydraulic conductivity of aggregated soils during compression

    NASA Astrophysics Data System (ADS)

    Berli, M.; Carminati, A.; Ghezzehei, T. A.; Or, D.

    2007-12-01

    Prediction of water flow and transport processes in soils susceptible to structural alteration such as compaction of tilled agricultural lands, or newly constructed landfills rely on accurate description of changes in soil unsaturated hydraulic conductivity. Recent studies have documented the critical impact of aggregate contact characteristics on water flow rates and pathways in unsaturated aggregated soils. We developed an analytical model for aggregate contact size evolution as a basis for quantifying effects of compression on unsaturated hydraulic conductivity of aggregated soil. Relating confined one-dimensional sample strain with aggregate deformation facilitates prediction of the increase in inter-aggregate contact area and concurrent decrease in macro-pore size with degree of sample compression. The hydrologic component of the model predicts unsaturated hydraulic conductivity of a pack of idealized aggregates (spheres) based on contact size and saturation conditions under prescribed sample deformation. Calculated contact areas and hydraulic conductivity for pairs of aggregates agreed surprisingly well with measured values, determined from compaction experiments employing Neutron- as well as X-ray-radiography and image analysis.

  6. Shaping the Growth Behaviour of Biofilms Initiated from Bacterial Aggregates.

    PubMed

    Melaugh, Gavin; Hutchison, Jaime; Kragh, Kasper Nørskov; Irie, Yasuhiko; Roberts, Aled; Bjarnsholt, Thomas; Diggle, Stephen P; Gordon, Vernita D; Allen, Rosalind J

    2016-01-01

    Bacterial biofilms are usually assumed to originate from individual cells deposited on a surface. However, many biofilm-forming bacteria tend to aggregate in the planktonic phase so that it is possible that many natural and infectious biofilms originate wholly or partially from pre-formed cell aggregates. Here, we use agent-based computer simulations to investigate the role of pre-formed aggregates in biofilm development. Focusing on the initial shape the aggregate forms on the surface, we find that the degree of spreading of an aggregate on a surface can play an important role in determining its eventual fate during biofilm development. Specifically, initially spread aggregates perform better when competition with surrounding unaggregated bacterial cells is low, while initially rounded aggregates perform better when competition with surrounding unaggregated cells is high. These contrasting outcomes are governed by a trade-off between aggregate surface area and height. Our results provide new insight into biofilm formation and development, and reveal new factors that may be at play in the social evolution of biofilm communities.

  7. Orthogonal flexible Rydberg aggregates

    NASA Astrophysics Data System (ADS)

    Leonhardt, K.; Wüster, S.; Rost, J. M.

    2016-02-01

    We study the link between atomic motion and exciton transport in flexible Rydberg aggregates, assemblies of highly excited light alkali-metal atoms, for which motion due to dipole-dipole interaction becomes relevant. In two one-dimensional atom chains crossing at a right angle adiabatic exciton transport is affected by a conical intersection of excitonic energy surfaces, which induces controllable nonadiabatic effects. A joint exciton-motion pulse that is initially governed by a single energy surface is coherently split into two modes after crossing the intersection. The modes induce strongly different atomic motion, leading to clear signatures of nonadiabatic effects in atomic density profiles. We have shown how this scenario can be exploited as an exciton switch, controlling direction and coherence properties of the joint pulse on the second of the chains [K. Leonhardt et al., Phys. Rev. Lett. 113, 223001 (2014), 10.1103/PhysRevLett.113.223001]. In this article we discuss the underlying complex dynamics in detail, characterize the switch, and derive our isotropic interaction model from a realistic anisotropic one with the addition of a magnetic bias field.

  8. Analysis of topsoil aggregation with linkage to dust emission potential

    NASA Astrophysics Data System (ADS)

    Swet, Nitzan; Katra, Itzhak

    2015-04-01

    Dust emission by soil erosion has environmental and socioeconomic significances due to loss of a natural resource and air pollution. Topsoil resistance to erosion depends on its physicochemical properties, especially on the soil aggregation. Aggregate size distribution of soil samples is commonly used for the assessment of soil stability and fertility. It is suggested that aggregates larger than 840 µm in their effective diameter are stable to aeolian (wind) soil erosion. However the physicochemical properties of aggregates should be considered in determining the dust emission potential from soils. This study focuses on quantitative analyses of physical and chemical properties of aggregates in order to develop a soil stability index for dust emission. The study integrates laboratory analyses of soil samples and aeolian experiments of dust emission. Soil samples were taken from different land uses in a semi-arid loess soil that is subjected to aeolian erosion and dust emission. Laboratory tests include particle size distribution (PSD), soil organic carbon (SOC), inorganic carbon (CaCO3), water content (WC), and elemental composition by XRF technique. The size analysis shows significant differences in aggregation between natural-soil plots (N) and grazing-soil plots (G). The MWD index was higher in N (1204 µm) than that of G (400 µm). Basic aeolain experiments with a boundary layer wind tunnel showed dust emission of particulate matter (PM10) from both soils, although the concentrations were significantly lower in N plots. Aggregates at specific size fractions are characterized by different content of cementing agents. The content of fine particles (< 20 µm) and SOM were higher in macro-aggregates (500-2000 µm), while the CaCO3 content was higher in aggregate fraction of 63-250 µm. WC values were highest in micro-aggregates (< 63 µm). However the lowest content of these cementing agents were mostly found in the aggregate size fraction of 1000 µm. Differences

  9. Gram-Positive Anaerobic Cocci

    PubMed Central

    Murdoch, D. A.

    1998-01-01

    Gram-positive anaerobic cocci (GPAC) are a heterogeneous group of organisms defined by their morphological appearance and their inability to grow in the presence of oxygen; most clinical isolates are identified to species in the genus Peptostreptococcus. GPAC are part of the normal flora of all mucocutaneous surfaces and are often isolated from infections such as deep organ abscesses, obstetric and gynecological sepsis, and intraoral infections. They have been little studied for several reasons, which include an inadequate classification, difficulties with laboratory identification, and the mixed nature of the infections from which they are usually isolated. Nucleic acid studies indicate that the classification is in need of radical revision at the genus level. Several species of Peptostreptococcus have recently been described, but others still await formal recognition. Identification has been based on carbohydrate fermentation tests, but most GPAC are asaccharolytic and use the products of protein degradation for their metabolism; the introduction of commercially available preformed enzyme kits affords a physiologically more appropriate method of identification, which is simple and relatively rapid and can be used in routine diagnostic laboratories. Recent reports have documented the isolation in pure culture of several species, notably Peptostreptococcus magnus, from serious infections. Studies of P. magnus have elucidated several virulence factors which correlate with the site of infection, and reveal some similarities to Staphylococcus aureus. P. micros is a strongly proteolytic species; it is increasingly recognized as an important pathogen in intraoral infections, particularly periodontitis, and mixed anaerobic deep-organ abscesses. Comparison of antibiotic susceptibility patterns reveals major differences between species. Penicillins are the antibiotics of choice, although some strains of P. anaerobius show broad-spectrum β-lactam resistance. PMID:9457430

  10. Sleep deprivation induced anxiety and anaerobic performance.

    PubMed

    Vardar, Selma Arzu; Oztürk, Levent; Kurt, Cem; Bulut, Erdogan; Sut, Necdet; Vardar, Erdal

    2007-01-01

    The aim of this study was to investigate the effects of sleep deprivation induced anxiety on anaerobic performance. Thirteen volunteer male physical education students completed the Turkish version of State Anxiety Inventory and performed Wingate anaerobic test for three times: (1) following a full-night of habitual sleep (baseline measurements), (2) following 30 hours of sleep deprivation, and (3) following partial-night sleep deprivation. Baseline measurements were performed the day before total sleep deprivation. Measurements following partial sleep deprivation were made 2 weeks later than total sleep deprivation measurements. State anxiety was measured prior to each Wingate test. The mean state anxiety following total sleep deprivation was higher than the baseline measurement (44.9 ± 12.9 vs. 27.6 ± 4.2, respectively, p = 0.02) whereas anaerobic performance parameters remained unchanged. Neither anaerobic parameters nor state anxiety levels were affected by one night partial sleep deprivation. Our results suggest that 30 hours continuous wakefulness may increase anxiety level without impairing anaerobic performance, whereas one night of partial sleep deprivation was ineffective on both state anxiety and anaerobic performance. Key pointsShort time total sleep deprivation (30 hours) increases state anxiety without any competition stress.Anaerobic performance parameters such as peak power, mean power and minimum power may not show a distinctive difference from anaerobic performance in a normal sleep day despite the high anxiety level induced by short time sleep deprivation.Partial sleep deprivation does not affect anxiety level and anaerobic performance of the next day.

  11. REACTIVATION AND REGROWTH OF INDICATOR ORGANISMS ASSOCIATED WITH ANAEROBICALLY DIGESTED AND DEWATERED BIOSOLIDS: EPA’S PERSPECTIVE

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bacte...

  12. REACTIVATION AND REGROWTH OF INDICATOR ORGANISMS ASSOCIATED WITH ANAEROBICALLY DIGESTED AND DEWATERED BIOSOLIDS: EPA’S PERSPECTIVE

    EPA Science Inventory

    The Water Environment Research Foundation (WERF) recently published a report titled Examination of Reactivation and Regrowth of Fecal Coliforms in Anaerobically Digested Sludges. Seven full-scale publicly owned treatment facilities were sampled several times to determine if bacte...

  13. Mechanical and Physical Properties of Hydrophobized Lightweight Aggregate Concrete with Sewage Sludge

    PubMed Central

    Suchorab, Zbigniew; Barnat-Hunek, Danuta; Franus, Małgorzata; Łagód, Grzegorz

    2016-01-01

    This article is focused on lightweight aggregate-concrete modified by municipal sewage sludge and lightweight aggregate-concrete obtained from light aggregates. The article presents laboratory examinations of material physical parameters. Water absorptivity of the examined material was decreased by the admixture of water emulsion of reactive polysiloxanes. Water transport properties were determined using Time Domain Reflectometry, an indirect technique for moisture detection in porous media. Together with basic physical parameters, the heat conductivity coefficient λ was determined for both types of lightweight aggregate-concrete. Analysis of moisture and heat properties of the examined materials confirmed the usefulness of light aggregates supplemented with sewage sludge for prospective production. PMID:28773442

  14. Mechanical and Physical Properties of Hydrophobized Lightweight Aggregate Concrete with Sewage Sludge.

    PubMed

    Suchorab, Zbigniew; Barnat-Hunek, Danuta; Franus, Małgorzata; Łagód, Grzegorz

    2016-04-27

    This article is focused on lightweight aggregate-concrete modified by municipal sewage sludge and lightweight aggregate-concrete obtained from light aggregates. The article presents laboratory examinations of material physical parameters. Water absorptivity of the examined material was decreased by the admixture of water emulsion of reactive polysiloxanes. Water transport properties were determined using Time Domain Reflectometry, an indirect technique for moisture detection in porous media. Together with basic physical parameters, the heat conductivity coefficient λ was determined for both types of lightweight aggregate-concrete. Analysis of moisture and heat properties of the examined materials confirmed the usefulness of light aggregates supplemented with sewage sludge for prospective production.

  15. Energy from anaerobic methane production. [Sweden

    SciTech Connect

    Not Available

    1982-02-01

    Since 1970 Swedish researchers have been testing the ANAMET (anaerobic-aerobic-methane) process, which involves converting industrial wastewaters via an initial anaerobic microbiological step followed by an aerobic one. Recycling the biomass material in each step allows shorter hydraulic retention times without decreasing stability or solids reduction. Since the first ANAMET plants began operating at a Swedish sugar factory in 1972, 17 more plants have started up or are under construction. Moreover, the ANAMET process has engendered to offshoot BIOMET (biomass-methane) process, a thermophilic anaerobic scheme that can handle sugar-beet pulp as well as grass and other soft, fast-growing biomasses.

  16. Fate of Trace Metals in Anaerobic Digestion.

    PubMed

    Fermoso, F G; van Hullebusch, E D; Guibaud, G; Collins, G; Svensson, B H; Carliell-Marquet, C; Vink, J P M; Esposito, G; Frunzo, L

    2015-01-01

    A challenging, and largely uncharted, area of research in the field of anaerobic digestion science and technology is in understanding the roles of trace metals in enabling biogas production. This is a major knowledge gap and a multifaceted problem involving metal chemistry; physical interactions of metal and solids; microbiology; and technology optimization. Moreover, the fate of trace metals, and the chemical speciation and transport of trace metals in environments--often agricultural lands receiving discharge waters from anaerobic digestion processes--simultaneously represents challenges for environmental protection and opportunities to close process loops in anaerobic digestion.

  17. Microbial properties of soil aggregates created by earthworms and other factors: spherical and prismatic soil aggregates from unreclaimed post-mining sites.

    PubMed

    Frouz, J; Krištůfek, V; Livečková, M; van Loo, D; Jacobs, P; Van Hoorebeke, L

    2011-01-01

    Soil aggregates between 2 and 5 mm from 35- and 45-year-old unreclaimed post-mining sites near Sokolov (Czech Republic) were divided into two groups: spherical and prismatic. X-ray tomography indicated that prismatic aggregates consisted of fragments of claystone bonded together by amorphous clay and roots while spherical aggregates consisted of a clay matrix and organic fragments of various sizes. Prismatic aggregates were presumed to be formed by plant roots and physical processes during weathering of Tertiary mudstone, while earthworms were presumed to contribute to the formation of spherical aggregates. The effects of drying and rewetting and glucose addition on microbial respiration, microbial biomass, and counts of bacteria in these aggregates were determined. Spherical aggregates contained a greater percentage of C and N and a higher C-to-N ratio than prismatic ones. The C content of the particulate organic matter was also higher in the spherical than in the prismatic aggregates. Although spherical aggregates had a higher microbial respiration and biomass, the growth of microbial biomass in spherical aggregates was negatively correlated with initial microbial biomass, indicating competition between bacteria. Specific respiration was negatively correlated with microbial biomass. Direct counts of bacteria were higher in spherical than in prismatic aggregates. Bacterial numbers were more stable in the center than in the surface layers of the aggregates. Transmission electron microscopy indicated that bacteria often occurred as individual cells in prismatic aggregates but as small clusters of cells in spherical aggregates. Ratios of colony forming units (cultivatable bacteria) to direct counts were higher in spherical than in prismatic aggregates. Spherical aggregates also contained faster growing bacteria.

  18. Anaerobic Codigestion of Sludge: Addition of Butcher's Fat Waste as a Cosubstrate for Increasing Biogas Production.

    PubMed

    Martínez, E J; Gil, M V; Fernandez, C; Rosas, J G; Gómez, X

    2016-01-01

    Fat waste discarded from butcheries was used as a cosubstrate in the anaerobic codigestion of sewage sludge (SS). The process was evaluated under mesophilic and thermophilic conditions. The codigestion was successfully attained despite some inhibitory stages initially present that had their origin in the accumulation of volatile fatty acids (VFA) and adsorption of long-chain fatty acids (LCFA). The addition of a fat waste improved digestion stability and increased biogas yields thanks to the higher organic loading rate (OLR) applied to the reactors. However, thermophilic digestion was characterized by an effluent of poor quality and high VFA content. Results from spectroscopic analysis suggested the adsorption of lipid components onto the anaerobic biomass, thus disturbing the complete degradation of substrate during the treatment. The formation of fatty aggregates in the thermophilic reactor prevented process failure by avoiding the exposure of biomass to the toxic effect of high LCFA concentrations.

  19. Reversibility of the structure and dewaterability of anaerobic digested sludge.

    PubMed

    Sheng, Yiqi; Wang, Yili; Hu, Wei; Qian, Xu; Zheng, Huaili; Lun, Xiaoxiu

    2016-04-01

    The reversibility of the structure and dewaterability of broken anaerobic digested sludge (ADS) is important to ensure the efficiency of sludge treatment or management processes. This study investigated the effect of continuous strong shear (CSS) and multipulse shear (MPS) on the zeta potential, size (median size, d50), mass fractal dimension (D(F)), and capillary suction time (CST) of ADS aggregates. Moreover, the self-regrowth (SR) of broken ADS aggregates during slow mixing was also analyzed. The results show that raw ADS with d50 of 56.5 μm was insensitive to CSS-SR or MPS-SR, though the size slightly decreased after the breakage phase. For conditioned ADS with d50 larger than 600 μm, the breakage in small-scale surface erosion changed to large-scale fragmentation as the CSS strength increased. In most cases, after CSS or MPS, the broken ADS had a relatively more compact structure than before and d50 is at least 200 μm. The CST of the broken fragments from optimally dosed ADS increased, whereas that corresponding to overdosed ADS decreased. MPS treatment resulted in larger and more compact broken ADS fragments with a lower CST value than CSS. During the subsequent slow mixing, the broken ADS aggregates did not recover their charge, size, and dewaterability to the initial values before breakage. In addition, less than 15% self-regrowth in terms of percentage of the regrowth factor was observed in broken ADS after CSS at average velocity gradient no less than 1905.6 sec(-1).

  20. Evaluation of a classification method for biodegradable solid wastes using anaerobic degradation parameters.

    PubMed

    Zheng, Wei; Phoungthong, Khamphe; Lü, Fan; Shao, Li-Ming; He, Pin-Jing

    2013-12-01

    We studied the biochemical and anaerobic degradation characteristics of 29 types of materials to evaluate the effects of a physical composition classification method for degradable solid waste on the computation of anaerobic degradation parameters, including the methane yield potential (L0), anaerobic decay rate (k), and carbon sequestration factor (CSF). Biochemical methane potential tests were conducted to determine the anaerobic degradation parameters of each material. The results indicated that the anaerobic degradation parameters of nut waste were quite different from those of other food waste and nut waste was classified separately. Paper was subdivided into two categories according to its lignin content: degradable paper with lignin content of <0.05 g g VS(-1), and refractory paper with lignin content >0.15 g g VS(-1). The L0, k, and CSF parameters of leaves, a type of garden waste, were similar to those of grass. This classification method for degradable solid waste may provide a theoretical basis that facilitates the more accurate calculation of anaerobic degradation parameters.

  1. Positional Role Differences in the Aerobic and Anaerobic Power of Elite Basketball Players

    PubMed Central

    Pojskić, Haris; Šeparović, Vlatko; Užičanin, Edin; Muratović, Melika; Mačković, Samir

    2015-01-01

    The aim of the present study was to compare the aerobic and anaerobic power and capacity of elite male basketball players who played multiple positions. Fifty-five healthy players were divided into the following three different subsamples according to their positional role: guards (n = 22), forwards (n = 19) and centers (n = 14). The following three tests were applied to estimate their aerobic and anaerobic power and capacities: the countermovement jump (CMJ), a multistage shuttle run test and the Running-based Anaerobic Sprint Test (RAST). The obtained data were used to calculate the players’ aerobic and anaerobic power and capacities. To determine the possible differences between the subjects considering their different positions on the court, one-way analysis of variance (ANOVA) with the Bonferroni post-hoc test for multiple comparisons was used. The results showed that there was a significant difference between the different groups of players in eleven out of sixteen measured variables. Guards and forwards exhibited greater aerobic and relative values of anaerobic power, allowing shorter recovery times and the ability to repeat high intensity, basketball-specific activities. Centers presented greater values of absolute anaerobic power and capacities, permitting greater force production during discrete tasks. Coaches can use these data to create more individualized