Assessment of antimicrobial effect of Biosilicate (R) against anaerobic, microaerophilic and facultative anaerobic microorganisms

This study assessed the antimicrobial activity of a new bioactive glass-ceramic (Biosilicate (R)) against anaerobic, microaerophilic, and facultative anaerobic microorganisms. Evaluation of the antimicrobial activity was carried out by three methods, namely agar diffusion, direct contact, and minimal inhibitory concentration (MIC). For the agar diffusion technique, bio glass-ceramic activity was observed against various microorganisms, with inhibition haloes ranging from 9.0 +/- 1.0 to 22.3 +/- 2.1 mm. For the direct contact technique, Biosilicate (R) displayed activity against all the microorganisms, except for S. aureus. In the first 10 min of contact between the microorganisms and Biosilicate (R), there was a drastic reduction in the number of viable cells. Confirming the latter results, MIC showed that the Biosilicate (R) inhibited the growth of microorganisms, with variations between <= 2.5 and 20 mg/ml. The lowest MIC values (7.5 to <= 2.5 mg/ml) were obtained for oral microorganisms. In conclusion, Biosilicate (R) exhibits a wide spectrum of antimicrobial properties, including anaerobic bacteria.

Effect of agitation on the performance of an anaerobic sequencing batch biofilm reactor in the treatment of dairy effluents

Agitation rate is an important parameter in the operation of Anaerobic Sequencing Biofilm Batch Reactors (ASBBRs), and a proper agitation rate guarantees good mixing, improves mass transfer, and enhances the solubility of the particulate organic matter. Dairy effluents have a high amount of particulate organic matter, and their anaerobic digestion presents inhibitory intermediates (e. g., long-chain fatty acids). The importance of studying agitation in such batch systems is clear. The present study aimed to evaluate how agitation frequency influences the anaerobic treatment of dairy effluents. The ASBBR was fed with wastewater from milk pasteurisation process and cheese manufacture with no whey segregation. The organic matter concentration, measured as chemical oxygen demand (COD), was maintained at approximately 8,000 mg/L. The reactor was operated with four agitation frequencies: 500 rpm, 350 rpm, 200 rpm, and no agitation. In terms of COD removal efficiency, similar results were observed for 500 rpm and 350 rpm (around 90%) and for 200 rpm and no agitation (around 80%). Increasing the system`s agitation thus not only improved the global efficiency of organic matter removal but also influenced volatile acid production and consumption and clearly modified this balance in each experimental condition.

A comparison of two bench-scale anaerobic systems used for the treatment of dairy effluents

The objective of this work was to compare two anaerobic reactor conflgurations, a hybrid upflow anaerobic sludge blanket (UASBh) reactor and an anaerobic sequencing batch reactor with immobilised biomass (ASBBR) treating dairy effluents. The reactors were fed with effluent from the milk pasteurisation process (effluent 1-E1) and later with effluent from the same process combined with the one from the cheese manufacturing (effluent 2-E2). The ASBBR reactor showed average organic matter removal efficiency of 95.2% for E1 and 93.5% for E2, while the hybrid UASB reactor showed removal efficiencies of 90.3% and 80.1% respectively.

Critical discontinuous phase transition in the threshold contact process

We analyze a threshold contact process on a square lattice in which particles are created on empty sites with at least two neighboring particles and are annihilated spontaneously. We show by means of Monte Carlo simulations that the process undergoes a discontinuous phase transition at a definite value of the annihilation parameter, in accordance with the Gibbs phase rule, and that the discontinuous transition exhibits critical behavior. The simulations were performed by using boundary conditions in which the sites of the border of the lattice are permanently occupied by particles.

CRITICAL BEHAVIOR AND THRESHOLD OF COEXISTENCE OF A PREDATOR-PREY STOCHASTIC MODEL IN A 2D LATTICE

We investigate the critical behavior of a stochastic lattice model describing a predator-prey system. By means of Monte Carlo procedure we simulate the model defined on a regular square lattice and determine the threshold of species coexistence, that is, the critical phase boundaries related to the transition between an active state, where both species coexist and an absorbing state where one of the species is extinct. A finite size scaling analysis is employed to determine the order parameter, order parameter fluctuations, correlation length and the critical exponents. Our numerical results for the critical exponents agree with those of the directed percolation universality class. We also check the validity of the hyperscaling relation and present the data collapse curves.

Disentangling static and dynamic effects of low breakup threshold in fusion reactions

A new technique to analyze fusion data is developed. From experimental cross sections and results of coupled-channel calculations a dimensionless function is constructed. In collisions of strongly bound nuclei this quantity is very close to a universal function of a variable related to the collision energy, whereas for weakly bound projectiles the effects of breakup coupling are measured by the deviations with respect to this universal function. This technique is applied to collisions of stable and unstable weakly bound isotopes.

Near threshold vibrational excitation of molecules by positron impact: A projection operator approach

We report vibrational excitation (v(i) = 0 -> v(f) = 1) cross-sections for positron scattering by H(2) and model calculations for the (v(i) = 0 -> v(f) = 1) excitation of the C-C symmetric stretch mode of C(2)H(2). The Feshbach projection operator formalism was employed to vibrationally resolve the fixed-nuclei phase shifts obtained with the Schwinger multichannel method. The near threshold behavior of H(2) and C(2)H(2) significantly differ in the sense that no low lying singularity (either virtual or bound state) was found for the former, while a e(+)-acetylene virtual state was found at the equilibrium geometry (this virtual state becomes a bound state upon stretching the molecule). For C(2)H(2), we also performed model calculations comparing excitation cross-sections arising from virtual (-i kappa(0)) and bound (+i kappa(0)) states symmetrically located around the origin of the complex momentum plane (i.e. having the same kappa(0)). The virtual state is seen to significantly couple to vibrations, and similar cross-sections were obtained for shallow bound and virtual states. (c) 2007 Elsevier B.V. All rights reserved.

Assessing Threshold Concepts for Information Literacy

This presentation was offered as part of the CUNY Library Assessment Conference, Reinventing Libraries: Reinventing Assessment, held at the City University of New York in June 2014.

Cycling at 120 when compared to 80 rev/min increases the accumulated oxygen deficit but does not affect the precision of its calculation

The aim of the present study was to determine the influence of pedal rate on the precision and quantification of the accumulated oxygen deficit (AOD). Eight trained male triathletes completed a lactate threshold test, VO2 peak test, 10 x 3 min submaximal exercise bouts and a high-intensity exercise bout, all performed at 80 and 120 rev/min. For both pedal rates the intensities for the sub-maximal and high-intensity tests were relative to the lactate threshold and VO2 peak work rates. The VO2-power regressions were calculated using 5 intensities from above the lactate threshold combined with a y intercept value with VO2 measured after 3 min of exercise. For the 120 compared to the 80 rev/min tests, the lactate threshold work rate (255±13 versus 276±47 Watts) (p<0.01) and VO2 peak work rate (352±17 versus 382±20, Watts) (p<0.05) were lower at 120 rev/m. Conversely, the VO2 peak and the VO2 measured during the exhaustive exercise were the same for both pedal rates (p>0.05). Using linear regression modelling the slope of the VO2-power regression (0.0112 versus 0.010 L/Watt) (p<0.01), the estimated total energy demand (ETED) (5.13±0.75 versus 4.89±0.88 L/min) and the AOD (4.27±0.94 versus 3.66±1.25 L) (p<0.05) were greater at 120 rev/m. However, the 95% confidence interval for the ETED and the standard error of the predicted value were the same for both pedal rates (p>0.05). Our results demonstrate that pedal rate effects the size but not the precision of the calculated AOD and should therefore be considered when developing an AOD protocol.

Anaerobic treatment of juice and fruit-processing effluents

Effluents from the juice and fruit processing industries have high organic matter content. Discharge of these effluents without appropriate treatment would therefore have a negative impact on the environment. High organic contents and low contamination levels make such effluents suitable for biological treatment, especially anaerobic digestion. In the latter process, significant amounts of digester gas can be produced, turning a waste stream into a source of renewable energy that can be used for electricity and heat production, leading to financial benefits.This paper investigates the feasibility of anaerobic digestion and the gas generation potential of five different effluents from the carrot-juice, orange-juice and sultana processing industries. Benefits are assessed in terms of digester gas production and organic matter reduction. The results show that the specific gas production ranges between 665 and 860 m3 per tonne of effluent treated (as organic dry matter). Furthermore, nearly 100% of the organic matter is converted into gas in the case of the carrot- and orange-juice processing residues, while a 84.5% reduction of the organic matter was found to be achievable in the case of the sultana wastes. While these results are promising, further testing will be required to validate them in a larger scale.

Anaerobic degradation of organic materials - significance of the substrate surface area

In anaerobic degradation of substrates containing mainly particulate organic matter, solids hydrolysis is rate-limiting. In these investigations, the particle size of various substrates was reduced by comminution to support hydrolysis. Two positive effects of comminution were observed. For substrates with high fibre content, which are particularly resistant to biodegradation, a significant improvement of the degradation degree was observed as a result of comminution. Secondly, for all substrates tested, and particularly for those rich in fibres, the degradation rate of comminuted samples was significantly higher. The first reason for both effects is an increase of the sample surface area. Several methods for measuring the specific surface area of organic materials, including particle size analysis, Nitrogen-adsorption and enzyme adsorption, were used and compared for the purpose of this study, where the surface area accessible to microbial enzymes is critical. The significance of the surface area in anaerobic degradation of particulate substrates was investigated through a kinetic model where the hydrolysis rate was based on the sample surface area. Good agreements were obtained between model and experiments carried out with samples of various specific surface areas. These results reinforced the significance of the sample surface area in anaerobic degradation processes. However, other effects of comminution responsible for the increased degradation degree and degradation rate were identified and discussed. These include: the increase of dissolved compounds due to cell rupture, exposition of surface areas previously inaccessible for microbial degradation, and alteration of the sample structure such as the lignin-cellulose arrangements.

The need for a higher custody threshold for indigenous offenders in Victoria

Over-representation of indigenous persons in the criminal justice system has changed little since the Royal Commission into Aboriginal Deaths in Custody (RCIADIC) - claim by the Victorian Department of Justice that a key recommendation of RCIADIC had been implemented, namely that imprisonment should be a sentence of last resort for indigenous offenders - how to ensure that imprisonment is a sanction of last resort when indigenous prisoners present for sentence.