Relative Order Of Magnitude Research Articles

Determination of the diffusion coefficient in sodium chloride solution at different concentrations

Phenomena of diffusion are present in several industrial phenomena and therefore need to be properly studied and understood. The study of liquid-liquid diffusion allows to perfect and model several industrial systems. The development of instruments capable of doing this study allows to create methodologies for the development of students of the most diverse engineering. This work employed the study of the diffusion phenomena in a diffusion cell constructed by the authors themselves based on materials found in laboratories, trying to calculate the diffusion coefficient of a solution of sodium chloride in water through the variation of conductivity. The diffusion coefficients obtained presented values in the same order of magnitude in relation to the experimental values reported by other authors and with low experimental error.

Multipath Routing in Elastic Optical Networks with Space-Division Multiplexing

This article introduces four multipath routing, core, and spectrum assignment algorithms, all of which employ image processing techniques for fast identification of allocable slots, since this is less computationally complex and adequate for real-time operation. Numerical results show that multipath routing can decrease the probability of blocking by one order of magnitude in relation to its single-path counterpart, but produce acceptable differential delay values.

Inhibition of Listeria monocytogenes on bologna by a beta acid rich hop extract

Contamination of cold cuts with Listeria monocytogenes pose a risk to human health and frequently cause recalls of affected products. In order to avoid chemical additives for the preservation of ready-to-eat meat products, plant based antimicrobials are currently in demand. Beta acids from the hop plant are known for their strong antimicrobial effects especially against gram-positive bacteria like L. monocytogenes, making them a promising candidate as a functional ingredient. In this study, the antimicrobial activity of a beta acid rich hop extract in combination with sodium nitrite was characterized in vitro, at which the different hurdles of packaged cured boiled sausages were simulated. A complete growth inhibition of L. monocytogenes was found at a minimum inhibitory concentration of 0.2 μg/ml (MIC) when the hop extract was applied in combination with a reduced water activity (aw 0.970), a slightly acidic environment (pH 6) and anaerobic conditions. Under optimal growth conditions (aw 0.995, pH 7, aerobic incubation), the MIC was 16-fold higher (3.2 μg/ml). Sodium nitrite showed a comparably low antimicrobial activity against L. monocytogenes in vitro (MIC > 100 μg/ml). The presence of 1% sunflower oil negatively affected the antimicrobial activity of the hop extract, leading at least to a 32-fold increase of the MIC. The hop extract was subsequently added to a standard recipe of pork bologna at two concentrations. The pork bologna was produced by use of two different cutter processes and then sliced, inoculated on the surface with a two strain mixture of L. monocytogenes and stored at 7 °C under modified gas atmosphere for 28 days. At 0.4 g/kg of hop extract, L. monocytogenes populations were reduced up to 3 orders of magnitude in relation to bologna without hop extract while 0.8 g/kg of hop extract either prevented the growth of L. monocytogenes or resulted in at least 4 orders of magnitude lower final populations. There was no significant sensory deviation of hop bologna according to performed triangle tests (α = 0.05) and the product color remained unaffected. Based on the presented results, the use of beta acid rich hop extracts can be proposed as an additional hurdle to inhibit the propagation of L. monocytogenes on packaged ready-to-eat cold cuts like bologna.

Energy differences of ground state and γ1 bands as a hallmark of collective behavior

The systematics of experimental energy differences between the levels of the ground state band and the even levels of the γ1 band in even-even nuclei are studied as a function of the angular momentum L. Three clearly different trends are seen. In deformed nuclei a decrease of the energy differences with increasing L is found. In γ-unstable and triaxial nuclei the energy differences are increasing with increasing L, but the rate of increase is larger in the triaxial case by an order of magnitude in relation to the γ-unstable case. This observation is corroborated by numerical results and analytic expressions in the framework of several special solutions of the Bohr Hamiltonian.

IBUN2755 Bacillus strain controls seedling root and bacterial panicle blight caused by Burkholderia glumae

Burkholderia glumae is the causal agent of seedling rot and bacterial panicle blight in rice. It has a worldwide distribution in most rice producer countries generating crop losses of up to 75%. Currently, there is no known effective control for this pathogen. In this study 74 Bacillus strains isolated from the rhizosphere of different plants were evaluated under in vitro conditions against three strains of B. glumae. Twenty-six strains of Bacillus were selected for their antagonistic activity and then were evaluated in plantae under the two different inoculation sources of B. glumae: the seeds, and the substrate, since these are the two main reservoirs of the pathogen in the field. Inoculated seeds with the selected Bacillus strains were planted in a previously inoculated substrate with B. glumae, finding that 11 strains showed a reduction of the infection up to 63.5%. When evaluating the biological control activity of those 11 Bacillus strains in B. glumae infested seeds, four strains (IBUN12A04, IBUN16A08, IBUN2755 and IBUN15A09), showed disease reduction of up to 62.4%. These four strains were again evaluated under greenhouse conditions with seeds infested with B. glumae to determine the presence of the pathogen in asymptomatic plants 10 and 30 days after germination. In this case, Bacillus strains reduced the population of B. glumae in the plant up to two orders of magnitude in relation to disease control, and some even promoted plant growth in relation to an uninoculated control. Finally, the IBUN 2755 strain, which showed the highest biocontrol activity in the greenhouse, was evaluated under field conditions, showing a significant reduction in the symptoms of the disease and an increase in crop yield of up to two tons per hectare with relation to the uninoculated control.

The surface roughness effect on electrochemical properties of La0.5Sr0.5Fe0.7Ga0.3O3-δ perovskite for oxygen transport membranes

The effect of the membrane surface on the oxygen permeation performances is not studied to sufficient detail in the literature. However, this paper shows that the roughness, and the surface physico-chemistry can have a large effect on the oxygen semi-performances of the membrane, in particular on the kinetics of oxygen exchanges at the surface of the mixed electronic and ionic conductors. For instance, the kinetic coefficient of oxygen surface exchanges can increase by more than one order of magnitude in relation with the surface roughness for La0.5Sr0.5Fe0.7Ga0.3O3-δ perovskite-type membrane. Then, the best oxygen fluxes obtained in this work, i.e. 3.9 10−3 mol m−2 s−1, are close to the best performances reported in the literature for a dense 1 mm in thick membrane. Finally, some assumptions are discussed and argued in detail to explain the effect of the surface of the La0.5Sr0.5Fe0.7Ga0.3O3-δ perovskite membrane on their oxygen semi-permeation performances.

Near-critical turbulent open-channel flows over bumps and ramps

Steady two-dimensional turbulent free-surface flow in a channel with a slightly uneven bottom is considered. The shape of the unevenness of the bottom can be in the form of a bump or a ramp of very small height. The slope of the channel bottom is assumed to be small, and the bottom roughness is assumed to be constant. Asymptotic expansions for very large Reynolds numbers and Froude numbers close to the critical value {Fr} = 1, respectively, are performed. The relative order of magnitude of two small parameters, i.e. the bottom slope and ({Fr}-1), is defined such that no turbulence modelling is required. The result is a steady-state version of an extended Korteweg–de Vries equation for the surface elevation. Other flow quantities, such as pressure, flow velocity components, and bottom shear stress, are expressed in terms of the surface elevation. An exact solution describing stationary solitary waves of the classical shape is obtained for a bottom of a particular shape. For more general shapes of ramps and bumps, stationary solitary waves of the classical shape are also obtained as a first approximation in the limit of small, but nonzero, dissipation. With the exception of an eigensolution for a ramp, an outer region has to be introduced. The outer solution describes a ’tail’ that is attached to the stationary solitary wave. In addition to the solutions of the solitary-wave type, solutions of smaller amplitudes are obtained both numerically and analytically. Experiments in a water channel confirm the existence of both types of stationary single waves.

Vector Autoregressions and Macroeconomic Modeling: An Error Taxonomy

In this article, we investigate the theoretical behavior of finite lag models fitted to time series that in truth come from an infinite-order data-generating mechanism. We show that the overall error can be broken down into two basic components, an estimation error that stems from the difference between the parameter estimates and their population ensemble counterparts, and an approximation error that stems from the difference between the and the true . The two sources of error are shown to be present in other performance indicators previously employed in the literature to characterize, so-called, truncation effects. Our theoretical analysis indicates that the magnitude of the estimation error exceeds that of the approximation error, but experimental results based upon a prototypical real business cycle model and a practical example indicate that the approximation error approaches its asymptotic position far more slowly than does the estimation error, their relative orders of magnitude notwithstanding. The experimental results suggest that with sample sizes and lag lengths like those commonly employed in practice models are likely to exhibit serious errors of both types when attempting to replicate the dynamics of the true underlying process and that inferences based on models can be very untrustworthy.

Synthesis and characterization of silver phosphate/calcium phosphate mixed particles capable of silver nanoparticle formation by photoreduction

Silver phosphate is a semi-conductor sensitive to UV-Vis radiation (<530nm). Exposure to radiation removes electrons from the oxygen valence shell, which are scavenged by silver cations (Ag+), forming metallic silver (Ag0) nanoparticles. The possibility of silver nanoparticle formation in situ by a photoreduction process was the basis for the application of mixed calcium phosphate/silver phosphate particles as remineralizing and antibacterial fillers in resin-based dental materials. Mixed phosphate particles were synthesized, characterized and added to a dimethacrylate resin in 20% or 30% mass fractions to investigate their efficacy as ion-releasing fillers for dental remineralization and antibacterial activity. The formation of metallic silver nanoparticles after exposure to visible radiation from a dental curing unit (peak emission: 470nm) was demonstrated by particle X-ray diffraction and scanning electron microscopy analysis of the composite fractured surface. Calcium and phosphate release from materials containing the mixed particles were similar to those containing pure CaP particles, whereas Streptococcus mutans colonies were reduced by three orders of magnitude in relation to the control, which can be attributed to silver release. As expected, the optical properties of the materials containing mixed phosphate particles were compromised by the presence of silver. Nevertheless, materials containing mixed phosphate particles presented higher fracture strength and elastic modulus than those with pure CaP particles.

DUST IN CLUSTERS: SEPARATING THE CONTRIBUTION OF GALAXIES AND INTRACLUSTER MEDIA

ABSTRACT We have analyzed a sample of 327 clusters of galaxies, spanning the range of 0.06–0.70 in redshift. Strong constraints on their mean intracluster emission of dust have been obtained using maps and catalogs from the Herschel MerMES project; within a radius of 5 arcmin centered in each cluster, the 95% C.L. limits obtained are 86.6, 48.2, and 30.9 mJy at the observed frequencies of 250, 350, and 500 μm. From these restrictions, and assuming physical parameters typical of interstellar media in the Milky Way, we have obtained tight upper limits on the visual extinction of background galaxies due to the intracluster media (ICM): A V (95% C.L.) ≲ 10−3 mag. Strong constraints are also obtained for the mass of such dust; for instance, using the data at 350 μm we establish a 95% upper limit of &lt;109 M ⊙ within a circle with a radius of 5 arcmin centered in the clusters. This corresponds to a fraction of the total mass of the clusters of 9.5 × 10−6, and indicates a deficiency in the gas-to-dust ratio in the ICM by about three orders of magnitude in relation to the value found in the Milky Way. Computing the total infrared luminosity of the clusters in three ranges of redshift (0.05–0.24, 0.24–0.42, and 0.42–0.71) and two ranges of mass (&lt;1014 and &gt;1014 M ⊙), respectively, a strong evolution of luminosity in redshift (L ∼ z 1.5) for both ranges of masses is found. The results indicate a strong declining in star formation rate with time in the last ∼6 Gyr.

TRANSPORT AND MIXING OF r-PROCESS ELEMENTS IN NEUTRON STAR BINARY MERGER BLAST WAVES

ABSTRACT The r-process nuclei are robustly synthesized in the material ejected during neutron star binary mergers (NSBMs). If NSBMs are indeed solely responsible for the solar system r-process abundances, a galaxy like our own would be required to host a few NSBMs per million years, with each event ejecting, on average, about 5 × 10−2 M ⊙ of r-process material. Because the ejecta velocities in the tidal tail are significantly larger than those in ordinary supernovae, NSBMs deposit a comparable amount of energy into the ISM. In contrast to extensive efforts studying spherical models for supernova remnant evolution, calculations quantifying the impact of NSBM ejecta in the ISM have been lacking. To better understand their evolution, we perform a suite of three-dimensional hydrodynamic simulations of isolated NSBM ejecta expanding in environments with conditions adopted from Milky-Way-like galaxy simulations. Although the remnant morphology is highly complex at early times, the subsequent radiative evolution is remarkably similar to that of a standard supernova. This implies that sub-resolution supernova feedback models can be used in galaxy-scale simulations that are unable to resolve the key evolutionary phases of NSBMs. Among other quantities, we examine the radius, mass, and kinetic energy content of the remnant at shell formation. We find that the shell formation epoch is attained when the swept-up mass is about 103(n H/1 cm−3)−2/7 M ⊙; at this point, the mass fraction of r-process material is enhanced up to two orders of magnitude in relation to a solar metallicity ISM.

Relative Effects at Work

Assessing the relative importance of predictors has been of historical importance in a variety of disciplines including management, medicine, economics, and psychology. When approaching hypotheses on the relative ordering of the magnitude of predicted effects (e.g., the effects of discrimination from managers and coworkers are larger than that from clients), one quickly runs into problems within a traditional frequentist framework. Null hypothesis significance testing does not allow researchers to directly map research hypotheses on to results and suffers from a multiple testing problem that leads to low statistical power. Furthermore, all traditional structural equation modeling fit indices lose much of their suitability for model comparison, because order hypotheses are not countable in terms of degrees of freedom. To adequately tackle order hypotheses, we advocate a Bayesian method that provides a single internally consistent solution for estimation and inference. The key element in the proposed model comparison approach is the use of the Bayes factor and the incorporation of order constraints by means of a smart formulation of prior distributions. An easy-to-use software package BIEMS (Bayesian inequality and equality constrained model selection) is introduced and two empirical examples in the organizational behavior area are provided to showcase the method, both offering new findings that have implications for theory: the first on the differential impact of discrimination in the workplace from insiders and outsiders to the organization on employees’ well-being, and the second on Karasek’s stressor–strain theory about how the relative order of magnitude of the effects of job control and demands depends on the specific well-being outcome dimension.

Evaporating momentum force and shear force on meniscuses of elongated bubble in microchannel flow boiling

The evaporating momentum force and the shear force acting on the meniscus of an evaporating and elongating bubble in flow boiling in microchannel have been investigated theoretically and numerically. The concept of the effective evaporation region and the theory of the liquid layer supplement between elongated bubble and microchannel are proposed, and the analytical expressions of the evaporating momentum force and shear force have been obtained. The relative importance of both forces has been determined by the method of magnitude analysis and numerical simulation. It has been found that the evaporating momentum force can always be neglected in analyzing the bubble elongation process and the motion law of meniscus of elongated bubble in microchannel flow boiling, but whether the shear force should be considered or not is determined by its relative order of magnitude and the particular conditions such as channel dimension and the operating conditions.

CO2 mass transfer and conversion to biomass in a horizontal gas–liquid photobioreactor

This study deals with CO2 mass transfers and biomass conversion in an industrial horizontal tubular photobioreactor. An analytical approach is used to determine an expression modeling the influence of CO2 mass transfers on the overall biomass conversion efficiency for a given culture broth, heat and light conditions. Fluid mechanics and mass transfer are predicted with a classical two-phase flow approach (Taitel and Dukler, 1976) combined with a dissolution correlation developed and tested in the laboratory (Valiorgue et al., 2011). The influence of the stripping gas, removing the excess of oxygen in the liquid, on the conversion to biomass efficiency is shown to be not negligible. The expression is used to evaluate how the photobioreactor's design and process parameters can be tuned in order to improve biomass conversion efficiency. The biomass conversion efficiency evolution with the photobioreactor's length was found to behave asymptotically and it was explained by the relative orders of magnitude of gas dissolution and gas stripping. It has been shown that the gas flow rate for stripping and therefore the oxygen removal will be limited when further increasing the industrial photobioreactor's length for a given objective of CO2 conversion to biomass efficiency.

A theoretical study on surface modification of a nanosized BC3 tube using C2H4 and its derivatives

Chemical functionalization of a BC3 nanotube (BC3NT) with C2X4 (X = –H, –F, –CH2F, –CN, –NH2, –NO2, –CH3, and –OCH3) was investigated by density functional theory calculations. It was found that C2H4 prefers to be added to a B–C bond of the tube wall. The interaction energies are calculated to be ranging from −0.03 to −40.32 kcal/mol, and their relative magnitude order is found to be as follows: C2F4 > C2(NH2)4 > C2H4 > C2(NO2)4 > C2(OCH3)4 > C2(CN4)2 > C2(CH3)4 > C2(CH2F)4. For chemically modified BC3NTs with various functional groups, the functionalization energy can be correlated with the trend of relative electron-withdrawing or electron-donating capability of the adsorbates. The calculated density of states shows that the functionalization of BC3NT with these functional groups (except C2(NO2)4) can be generally classified as a certain type of “electronically harmless modification”. We believe that the preservation of electronic properties of BC3NTs coupled with the enhancement of solubility may render the chemical modification to be an effective way for the purification of BC3NTs. The insight provided by this theoretical study may also assist future development of BC3NTs with targeted chemoselectivity through chemical functionalization.

Asymptotic solutions of glass temperature profiles during steady optical fibre drawing

In this paper we derive realistic simplified models for the high-speed drawing of glass optical fibres via the downdraw method that capture the fluid dynamics and heat transport in the fibre via conduction, convection and radiative heating. We exploit the small aspect ratio of the fibre and the relative orders of magnitude of the dimensionless parameters that characterize the heat transfer to reduce the problem to one- or two-dimensional systems via asymptotic analysis. The resulting equations may be readily solved numerically and in many cases admit exact analytic solutions. The systematic asymptotic breakdown presented is used to elucidate the relative importance of furnace temperature profile, convection, surface radiation and conduction in each portion of the furnace and the role of each in controlling the glass temperature. The models derived predict many of the qualitative features observed in real industrial processes, such as the glass temperature profile within the furnace and the sharp transition in fibre thickness. The models thus offer a desirable route to quick scenario testing, providing valuable practical information about the dependencies of the solution on the parameters and the dominant heat-transport mechanism.

Further analysis of Kahan’s algorithm for the accurate computation of $2\times 2$ determinants

We provide a detailed analysis of Kahan’s algorithm for the accurate computation of the determinant of a $2 \times 2$ matrix. This algorithm requires the availability of a fused multiply-add instruction. Assuming radix-$\beta$, precision-$p$ floating-point arithmetic with $\beta$ even, $p \geq 2$, and barring overflow or underflow we show that the absolute error of Kahan’s algorithm is bounded by $(\beta +1)/2$ ulps of the exact result and that the relative error is bounded by $2u$ with $u=\frac {1}{2}\beta ^{1-p}$ the unit roundoff. Furthermore, we provide input values showing that i) when $\beta /2$ is odd—which holds for $2$ and $10$, the two radices that matter in practice—the absolute error bound is optimal; ii) the relative error bound is asymptotically optimal, that is, for such input the ratio (relative error)/$2u$ has the form $1-O(\beta ^{-p})$. We also give relative error bounds parametrized by the relative order of magnitude of the two products in the determinant, and we investigate whether the error bounds can be improved when adding constraints: When the products in the determinant have opposite signs, which covers the computation of a sum of squares, or when Kahan’s algorithm is used for computing the discriminant of a quadratic equation.

Theoretical study on the functionalization of BC2N nanotube with amino groups

Using density functional theory calculations, we investigated properties of a functionalized BC₂N nanotube with NH₃ and five other NH₂-X molecules in which one of the hydrogen atoms of NH₃ is substituted by X = -CH₃, -CH₂CH₃, -COOH, -CH₂COOH and -CH₂CN functional groups. It was found that NH₃ can be preferentially adsorbed on top of the boron atom, with adsorption energy of -12.0 kcal mol(-1). The trend of adsorption-energy change can be correlated with the trend of relative electron-withdrawing or -donating capability of the functional groups. The adsorption energies are calculated to be in the range of -1.8 to -14.2 kcal mol(-1), and their relative magnitude order is found as follows: H₂N(CH₂CH₃) > H₂N(CH₃) > NH₃ > H2N(CH₂COOH) > H2N(CH₂CN) > H₂N(COOH). Overall, the functionalization of BC₂N nanotube with the amino groups results in little change in its electronic properties. The preservation of electronic properties of BC₂N coupled with the enhancement of solubility renders their chemical modification with either NH₃ or amino functional groups to be a way for the purification of BC₂N nanotubes.

Thin-walled beams with a cross-section of arbitrary geometry: Derivation of linear theories starting from 3D nonlinear elasticity

The subject of this paper is the rigorous derivation of lower dimensional models for a nonlinearly elastic thin-walled beam whose cross-section is given by a thin tubular neighbourhood of a smooth curve. Denoting by h and , respectively, the diameter and the thickness of the cross-section, we analyse the case where the scaling factor of the elastic energy is of order , with . Different linearized models are deduced according to the relative order of magnitude of with respect to h.

A DFT study on the functionalization of a BN nanosheet with PC[sbnd]X, (PC = phenyl carbamate, X = OCH3, CH3, NH2, NO2 and CN)

By using density functional theory calculations, we investigated the chemical functionalization of a BN nanosheet with different organo-azo derivatives including PCX, (PC=phenyl carbamate, X=OCH3, CH3, NH2, NO2 and CN) in terms of geometric, energetic, and electronic properties. Reaction energies have been calculated to be in the range of 0.19 to 0.35eV which is augmented by increasing the electron withdrawing characteristic of the functional groups so that the relative magnitude order is NO2>CN>OCH3>CH3>NH2. The chemical functionalization leads to a decrease in HOMO/LUMO energy gap of BN sheet especially after adsorption of PCNO2 by about 1.88eV. Conduction level and Fermi level of the BN sheet are shifted to lower energies upon the functionalization of the sheet with PCNO2 and PCCN, thus, it leads to an increment in work function of the sheet, impeding the field electron emission.