Properties Of Excess Research Articles

Effects of microbubble pretreatment on physiochemical and microbial properties of excess activated sludge.

Fast increased amount of excess activated sludge (EAS) from wastewater treatment plants has aroused universal concerns on its environmental risks and demands for appropriate treatments, while effective treatment is dependent upon proper pretreatment. In this study, air-supplied microbubbles (air-MBs) with generated size of 25.18 to 28.25 μm were used for EAS pretreatment. Different durations (30, 60, 90, and 120 s) yielded sludge with varied physiochemical conditions, and 60 s decreased sludge oxidation status and significantly increased adenosine triphosphate (ATP) content. Soluble, loosely-bound, and tightly-bound extracellular polymeric substances (SEPS, LB-EPS, and TB-EPS) were extracted from the sludge through a stepwise approach and examined through three-dimensional excitation-emission matrix (3D-EEM) and quantitative analysis. The results showed that 60- and 120-s treatments generated stronger fluorescence intensities on dissolved organic matters (DOMs) of protein-like and fulvic acid in LB-EPS and TB-EPS, which indicated the decrease of counterparts in EAS, and therefore facilitated sludge dewaterability and reduction. The dominant microbial communities in EAS, including Proteobacteria, Bacteroidota, Chloroflexi, and Actinobacteriota, were not significantly affected by MB pretreatment. The results collectively revealed the effects of MB pretreatment on EAS and indicated that MBs could be an effective pretreatment technique for EAS treatment process.

Deciphering the unusual stellar progenitor of GRB 210704A

ABSTRACT GRB 210704A is a burst of intermediate duration (T90 ∼ 1–4 s) followed by a fading afterglow and an optical excess that peaked about 7 d after the explosion. Its properties, and in particular those of the excess, do not easily fit into the well-established classification scheme of gamma-ray bursts (GRBs) as being long or short, leaving the nature of its progenitor uncertain. We present multiwavelength observations of the GRB and its counterpart, observed up to 160 d after the burst. In order to decipher the nature of the progenitor system, we present a detailed analysis of the GRB high-energy properties (duration, spectral lag, and Amati correlation), its environment, and late-time optical excess. We discuss three possible scenarios: a neutron star merger, a collapsing massive star, and an atypical explosion possibly hosted in a cluster of galaxies. We find that traditional kilonova and supernova models do not match well the properties of the optical excess, leaving us with the intriguing suggestion that this event was an exotic high-energy merger.

Low-temperature sintering and piezoelectric properties of Na2O excess (Na0.52K0.44Li0.04)(Nb0.88Sb0.08 Ta0.04)O3 ceramics

This paper presents the application of an ordinary sintering process for 3 h in air to fabricate highly dense (Na0.52K0.44Li0.04)(Nb0.88Sb0.08Ta0.04)O3 (NKN-LST) ceramics with excellent piezoelectric properties at a lower sintering temperature through the use of excess Na2O as a sintering aid. The effects of sintering temperature in the range 940–1100 °C and Na2O addition in the range of 0 to 3.0 mol% on the density, sintering behavior, microstructure, dielectric and piezoelectric properties of the NKN-LST ceramics are investigated. Analysis reveals that NKN-LST ceramics samples sintered at 1020 °C for 3 h in air with 1.5 mol% excess Na2O achieve the highest electromechanical coupling factor and piezoelectric coefficient values of 0.45 and 364 pC/N, respectively.

The temperature dependence of magnetic losses in CoO-doped Mn-Zn ferrites

CoO-doping is known to stabilize the temperature dependence of initial permeability and magnetic losses in Mn-Zn ferrites, besides providing, with appropriate dopant contents, good soft magnetic response at and around room temperature. These effects, thought to derive from the mechanism of anisotropy compensation, are, however, poorly assessed from a quantitative viewpoint. In this work, we overcome such limitations by providing, besides extensive experimental investigation vs frequency (DC–1 GHz), CoO content (0 ≤ CoO ≤ 6000 ppm), and temperature (−20 °C ≤ T ≤ 130 °C) of permeability and losses of sintered Mn-Zn ferrites, a comprehensive theoretical framework. This relies on the separate identification of domain wall motion and moment rotations and on a generalized approach to magnetic loss decomposition. The average effective anisotropy constant ⟨Keff⟩ is obtained and found to monotonically decrease with temperature, depending on the CoO content. The quasistatic energy loss Wh is then predicted to pass through a deep minimum for CoO = 3000–4000 ppm at and below the room temperature, while becoming weakly dependent on CoO under increasing T. The rotational loss Wrot(f) is calculated via the complex permeability, as obtained from the Landau-Lifshitz equation for distributed values of the local effective anisotropy field Hk,eff (i.e., ferromagnetic resonance frequency). Finally, the excess loss Wexc(f) is derived and found to comply with suitable analytical formulation. It is concluded that, by achieving, via the rotational permeability, value and behavior of the magnetic anisotropy constant, we can predict the ensuing properties of hysteresis, excess, and rotational losses.

Spectral analysis of SXP59.0 during its 2017 outburst and properties of the soft excess in X-ray binary pulsars

We report the results provided by theXMM-Newtonobservation of the X-ray binary pulsar SXP59.0 during its most recent outburst in April 2017. The source was detected atfX(0.2–12 keV) = 8 × 10−11erg cm−2s−1, one of its highest flux levels reported to date. The measured pulse period wasPspin= 58.949(1) s, very similar to the periods measured in most of the previous observations. The pulsed emission was clearly detected over the whole energy range between 0.2 and 12 keV, but the pulse profile is energy dependent and the pulsed fraction increases as the energy increases. Although the time-averaged EPIC spectrum is dominated by a power-law component (with photon index Γ = 0.76 ± 0.01), the data show an evident soft excess, which can be described with the sum of a black-body and a hot thermal plasma component (with temperatureskTBB= 171+11−14eV andkTAPEC= 1.09+0.16−0.09keV, respectively). Moreover, the EPIC and RGS spectra show narrow emission lines due to N, O, Ne, Mg, and Fe. The phase-resolved spectral analysis of the EPIC data shows that the flux of the black-body component varies with the pulse phase, while the plasma component is almost constant. We show that the black-body component can be attributed to the reprocessing of the primary emission by the optically thick material at the inner edge of the accretion disc, while the hot plasma component is due to a diffuse gas far from the accretion region and the narrow emission lines of the RGS spectrum are most probably due to photoionized matter around the accreting source.

Peculiarities of clarifiers’ reconstruction at waste water treatment plants

The article reveals the ways in which the reconstruction of clarifiers for wastewater treatment plant can be performed. One of the most common method is bioflocculation that means use of corresponding properties of excess activated sludge or biofilm, which both have in its composition so called extracellular biopolymers that determine the spatial structuring and bioflocculation of cell formations. Multiple researches showed that use of surplus sludge as bioflocculant provides increased efficiency of sedimentation in any waste water up to 85–90% and reduce biochemical oxygen demand (BOD) in the clarified water by 40–50%. The other method to be implemented for reconstruction of clarifying facilities is thin-layer modules to raise the efficiency of settling. Thin-layer modules can be used in a wide range of capacity of sewage works. The possibility of application depends on the structural size and condition of building structures, the amount of suspended solids and other parameters.

Improved cosmic-ray injection models and the Galactic Center gamma-ray excess

Fermi-LAT observations of the Galactic Center (GC) have revealed a spherically- symmetric excess of GeV gamma rays extending to at least 10 deg from the dynamical center of the Galaxy. A critical uncertainty in extracting the intensity, spectrum, and morphology of this excess concerns the accuracy of astrophysical diffuse gamma-ray emission models near the GC. Recently, it has been noted that many diffuse emission models utilize a cosmic-ray injection rate far below that predicted based on the observed star formation rate in the Central Molecular Zone. In this study, we add a cosmic-ray injection component which non-linearly traces the Galactic H2 density determined in three-dimensions, and find that the associated gamma-ray emission is degenerate with many properties of the GC gamma-ray excess. In models that utilize a large sideband (40x40 deg surrounding the GC) to normalize the best-fitting diffuse emission models, the intensity of the GC excess decreases by a factor of 2, and the morphology of the excess becomes less peaked and less spherically symmetric. In models which utilize a smaller region of interest (15x15 deg) the addition of an excess template instead suppresses the intensity of the best-fit astrophysical diffuse emission, and the GC excess is rather resilient to changes in the details of the astrophysical diffuse modeling. In both analyses, the addition of a GC excess template still provides a statistically significant improvement to the overall fit to the gamma-ray data. We also implement advective winds at the GC, and find that the Fermi-LAT data strongly prefer outflows of order several hundred km/s, whose role is to efficiently advect low-energy cosmic rays from the Galactic center. Finally, we perform numerous tests of our models, and conclude that they significantly improve our understanding of multi-wavelength non-thermal emission from the GC.

Type I planet migration in weakly magnetized laminar discs

The migration of low-mass planets, or type I planetary migration, has been studied in hydrodynamical disc models for more than three decades. For a long time, it was thought to be very rapid and directed inwards due to Lindblad torques. More recently, it has been shown that the corotation torque, linked to the horseshoe motion of the gas near the planet, may slow down or even reverse migration. How is this picture modified by the expected presence of a magnetic field in the protoplanetary disc? When the magnetic field is strong enough to prevent horseshoe motion, the corotation torque is replaced by a torque arising from magnetic resonances which may significantly alter the migration rate. In the case of a weaker magnetic field, the magnetic field is not strong enough to prevent horseshoe motion and a corotation torque then exists. In this regime, recent turbulent magnetohydrodynamical (MHD) simulations have reported the existence of an additional component of the corotation torque due to the presence of the magnetic field. The aim of this paper is to investigate the physical origin and the properties of this additional corotation torque. We performed MHD simulations of a low-mass planet embedded in a 2D laminar disc threaded by a weak toroidal magnetic field, where the effects of turbulence are modelled by a viscosity and a resistivity. We confirm that the interaction between the magnetic field and the horseshoe motion of the gas results in an additional corotation torque on the planet, which we dub the MHD torque excess. We demonstrate that it is caused by the accumulation of the magnetic field along the downstream separatrices of the horseshoe region, which gives rise to an azimuthally asymmetric underdense region at that location. The properties of the MHD torque excess are characterized by varying the slope of the density, temperature and magnetic field profiles, as well as the diffusion coefficients and the strength of the magnetic field. The sign of the torque excess and its radial distribution are found to be in agreement with the earlier full magnetorotational instability simulations. This sign depends on the density and temperature gradients only and is positive for profiles expected in protoplanetary discs. The magnitude of the torque excess is in turn mainly determined by the strength of the magnetic field and the turbulent resistivity. It can be strong enough to reverse migration even when the magnetic pressure is less than 1 per cent of the thermal pressure. The MHD torque excess can therefore lead to outward planetary migration in the radiatively efficient outer parts of protoplanetary discs, where the hydrodynamical corotation torque is too weak to prevent fast inward migration.

ASTEROID BELTS IN DEBRIS DISK TWINS: VEGA AND FOMALHAUT

Vega and Fomalhaut, are similar in terms of mass, ages, and global debris disk properties; therefore, they are often referred as "debris disk twins". We present Spitzer 10-35 um spectroscopic data centered at both stars, and identify warm, unresolved excess emission in the close vicinity of Vega for the first time. The properties of the warm excess in Vega are further characterized with ancillary photometry in the mid infrared and resolved images in the far-infrared and submillimeter wavelengths. The Vega warm excess shares many similar properties with the one found around Fomalhaut. The emission shortward of ~30 um from both warm components is well described as a blackbody emission of ~170 K. Interestingly, two other systems, eps Eri and HR 8799, also show such an unresolved warm dust using the same approach. These warm components may be analogous to the solar system's zodiacal dust cloud, but of far greater. The dust temperature and tentative detections in the submillimeter suggest the warm excess arises from dust associated with a planetesimal ring located near the water-frost line and presumably created by processes occurring at similar locations in other debris systems as well. We also review the properties of the 2 um hot excess around Vega and Fomalhaut, showing that the dust responsible for the hot excess is not spatially associated with the dust we detected in the warm belt. We suggest it may arise from hot nano grains trapped in the magnetic field of the star. Finally, the separation between the warm and cold belt is rather large with an orbital ratio >~10 in all four systems. In light of the current upper limits on the masses of planetary objects and the large gap, we discuss the possible implications for their underlying planetary architecture, and suggest that multiple, low-mass planets likely reside between the two belts in Vega and Fomalhaut.

Fabrication and electrical properties of potassium excess and poor (Bi<sub>1/2</sub>K<sub>1/2</sub>)TiO<sub>3</sub> ceramics

Fabrication and electrical properties of potassium excess and poor (Bi<sub>1/2</sub>K<sub>1/2</sub>)TiO<sub>3</sub> ceramics

Effects of potassium ferrate on extracellular polymeric substances (EPS) and physicochemical properties of excess activated sludge

The activated sludge process of wastewater results in the generation of a considerable amount of excess activated sludge. In many wastewater treatment plants, the bottleneck of the sludge handling system is the dewatering operation. This paper investigated the effect of potassium ferrate pretreatment on the physicochemical properties of the excess activated sludge at various dosages of potassium ferrate. The particle size, extracellular polymeric substances (EPS) content and chemical components, and sludge disintegration degree were measured to explain the observed changes of physicochemical properties. It was expected that potassium ferrate could enhance the filterability and dewaterability of the sludge. However, the results showed that potassium ferrate had a negative effect on the filterability by measuring the capillary suction time (CST), but improved the settleability and dewaterability extent by determining the water content in the dewatered cake, although the flocs size reduced slightly. Loosely bound EPS (LB-EPS) content, polysaccharides (PS) and proteins (PN) contents in LB-EPS all increased with increasing the amount of potassium ferrate. However, Tightly bound EPS (TB-EPS) content, PS and PN contents in TB-EPS did not changed significantly at first, and decreased slightly under higher dosage of potassium ferrate. EPS, especially LB-EPS played more important role in the observed changes of the settleability and filterability than the sludge particle size.

Existence of modulated structure and negative magnetoresistance in Ga excess Ni-Mn-Ga

Ni2−xMnGa1+x (0.4 ≤ x ≤ 0.9) show the existence of modulated crystal structure at room temperature (RT) in the martensite phase, exhibit ferromagnetic behavior and have high martensitic transition temperature. The saturation magnetic moment decreases as Ga content increases, and this is related to antisite defects between Mn and Ga atoms leading to Mn-Mn nearest neighbor antiferromagnetic interaction. Negative magnetoresistance is observed at RT that increases linearly with magnetic field. These properties of Ga excess Ni-Mn-Ga show that it is a potential candidate for technological applications.

Piezoelectric properties of Li2O excess (Na0.4875K0.4625Li0.05)(Nb0.95Ta0.5)O3 ceramics by conventional sintering method

Lead-free piezoelectric ceramics, (Na 0.4875 K 0.4625 Li 0.05 )(Nb 0.95 Ta 0.05 )O 3 systems, were developed using the conventional sintering process. The grain growth behavior and piezoelectric properties of the ceramics were investigated. Their sintering temperature was lowered by adding 1 mol% of Li 2 O as a sintering aid. When the sample was sintered at 1050°C for 4 h with a composition of 1 mol% of excess Li 2 O (Na 0.4875 K 0.4625 Li 0.o5 )(Nb 0.95 Ta 0.05 )O 3 , the electro-mechanical coupling factor (k P ) and the piezoelectric coefficient (d 33 ) were found to reach the highest values of 0.42 and 244 pC/N, respectively.

Efeito da variação estequiométrica na formação de ferritas BaM produzidas pelo método SHS e pelo método cerâmico tradicional

As ferritas do tipo BaM são cerâmicas ferrimagnéticas, usualmente aplicadas em sistemas de gravação magnética e como magnetos duros. Possuem alta estabilidade química, resistência a corrosão e baixo custo de produção. Diante da sua crescente importância, foi estudado o efeito da contribuição do excesso de bário no processamento e formação da fase ferrita BaM por duas distintas rotas: processamento por mistura de óxidos e a síntese por reação de combustão (método SHS) com o uso de carbonato e nitrato de bário. Duas relações de concentração entre bário e ferro foram utilizadas, uma estequiométrica (n = Fe2O3/BaO = 6) e uma outra não estequiométrica (n = Fe2O3/BaO = 5,45). Os pós processados com excesso de bário resultaram na presença da fase intermediária de formação BaFe2O4, a qual permanece após altas temperaturas de calcinação e mesmo após a sinterização de compactos obtidos a partir dos pós calcinados. As conclusões foram baseadas em difratogramas de raios X das ferritas BaM em pó após calcinação e nas amostras conformadas e sinterizadas, além de imagens obtidas por microscopia eletrônica de varredura. Os resultados de medidas magnéticas indicam a diminuição da coercividade, da indução magnética remanente e dos valores de BH Máx dos pós obtidos com a contribuição do excesso de bário, provavelmente devido à presença da fase intermediária não magnética. Este efeito negativo foi mais efetivo nos pós processados pelo método SHS, chegando a uma redução de 28,8% no valor de coercividade e 35,1% no valor de BH Máx. Os pós de ferritas BaM obtidos pelo método cerâmico tradicional apresentaram maiores valores de coercividade (4,28 kOe) e BH Máx (0,87 MOe*emu/g) e a influência do excesso de bário na formulação foi menos prejudicial sobre suas propriedades magnéticas.

Probabilistic structure of storm surface runoff considering the dependence between average intensity and storm duration of rainfall events

The probabilistic nature of rainfall and surface runoff events forms the basis of hydrologic design. Two defining characteristics of rainfall events, average intensity and duration, are selected to construct the probabilistic structure of storms using Gumbel's bivariate exponential distribution. This bivariate stochastic rainfall model is then utilized to derive the probabilistic structure of surface runoff using the Soil Conservation Service rainfall runoff model. The zero‐runoff probability, mean, and standard deviation of rainfall excess are evaluated. Copulas serve as an alternative way to derive zero‐runoff probability. The results indicate that the dependence between average intensity and duration has a significant effect on statistical properties of rainfall excess. The advantage of using copulas for complicated multivariate stochastic models is demonstrated. The proposed model is associated with land use and soil type information from the geographic information system to produce maps of statistical properties of rainfall excess. A case study of model application is performed for the state of Indiana, United States. Results show that while the mean and standard deviation of rainfall excess increase with curve number, these quantities are very sensitive to the dependence between average intensity and duration of storm events.

The Sonnenschein-Mantel-Debreu Results after Thirty Years

The properties of aggregate excess demand or market demand play a key role in the existence, uniqueness, stability, and comparative statics of competitive general equilibrium. They are also important for the theory of imperfectly competitive general equilibrium and the microfoundations of macroeconomics. Because observations of demand are likely to occur at the aggregate level, whereas economic theory has been largely concerned with individual behavior, the properties of aggregate excess or market demand are central to econometric identification. The importance of these projects for the development of general equilibrium theory can be seen in Kenneth Arrow and Frank Hahn’s General Competitive Analysis (1971). Soon after their book was published, though, Hugo Sonnenschein (1973) posed the following problem. Consider a function that maps prices into quantities. What conditions must this function satisfy if it is to be the aggregate excess demand function of a well-behaved exchange economy? The existence theory highlighted the importance of the function’s satisfying continuity, homogeneity of degree zero, and Walras’s law. Were these all of the restrictions on aggregate excess demand implied by the usual

Sampling properties of homozygosity-based statistics for linkage disequilibrium

Homozygosity-based statistics such as Ohta’s identity-in-state (IIS) excess offer the potential to measure linkage disequilibrium for multiallelic loci in small samples. However, previous observations have suggested that for independent loci, in small samples these statistics might produce values that more frequently lie on one side rather than on the other side of zero. Here we investigate the sampling properties of the IIS excess. We find that for any pair of independent polymorphic loci, as sample size n approaches infinity, the sampling distribution of the IIS excess approaches a normal distribution. For large samples, the IIS excess tends towards symmetry around zero, and the probabilities of positive and of negative IIS excess both approach 1/2. Surprisingly, however, we also find that for sufficiently large n, independent loci can be chosen so that the probability of a sample having positive IIS excess is arbitrarily close to either 0 or 1. The results are applied to interpretation of data from human populations, and we conclude that before employing homozygosity-based statistics to measure LD in a particular sample, especially for loci with either very small or very large homozygosities, it is useful to verify that loci with the observed homozygosity values are not likely to produce a large bias in IIS excess in samples of the given size.

Improved electrochemical properties of Li 1+ x(Ni 0.3Co 0.4Mn 0.3)O 2− δ ( x = 0, 0.03 and 0.06) with lithium excess composition prepared by a spray drying method

Layered Li 1+ x (Ni 0.3Co 0.4Mn 0.3)O 2− δ ( x = 0, 0.03 and 0.06) materials were synthesized through the different calcination times using the spray-dried precursor with the molar ratio of Li/Me = 1.25 (Me = transition metals). The physical and electrochemical properties of the lithium excess and the stoichiometric materials were examined using XRD, AAS, BET and galvanostatic electrochemical method. As results, the lithium excess Li 1.06(Ni 0.3Co 0.4Mn 0.3)O 2− δ could show better electrochemical properties, such as discharge capacity, capacity retention and C rate ability, than those of the stoichiometric Li 1.00(Ni 0.3Co 0.4Mn 0.3)O 2− δ . In this paper, the effect of excess lithium on the electrochemical properties of Li 1+ x (Ni 0.3Co 0.4Mn 0.3)O 2− δ materials will be discussed based on the experimental results of ex situ X-ray diffraction, transmission electron microscopy (TEM) and galvanostatic intermittent titration technique (GITT)

Ajuste de parâmetros de interação em modelos termodinâmicos

Para misturas nas quais existem interações entre moléculas diferentes aparece um parâmetro energético de interação ajustável na relação das variáveis. As grandezas termodinâmicas de excesso dão informação qualitativa dos possíveis tipos de interação. Duas grandezas importantes neste sentido são o volume de excesso e a entalpia de excesso. Neste artigo se estudam diferentes métodos, regressão com mínimos quadrados e por minimização do valor absoluto e relativo dos resíduos, para determinar a possibilidade de aplicação dos mesmos no cálculo de parâmetros de interação molecular em modelos termodinâmicos de soluções. Usam-se dados experimentais de volume molar de excesso para todo o intervalo de frações molares de 10 sistemas binários formados por acetonitrila + um álcool primário (do metanol ao n-decanol). Comparam-se os valores calculados e os dados experimentais das grandezas, e são feitas análises dos resultados.

Reaction-diffusion and ballistic annihilation near an impenetrable boundary

The behavior of the single-species reaction process $A+A\to O$ is examined near an impenetrable boundary, representing the flask containing the reactants. Two types of dynamics are considered for the reactants: diffusive and ballistic propagation. It is shown that the effect of the boundary is quite different in both cases: diffusion-reaction leads to a density excess, whereas ballistic annihilation exhibits a density deficit, and in both cases the effect is not localized at the boundary but penetrates into the system. The field-theoretic renormalization group is used to obtain the universal properties of the density excess in two dimensions and below for the reaction-diffusion system. In one dimension the excess decays with the same exponent as the bulk and is found by an exact solution. In two dimensions the excess is marginally less relevant than the bulk decay and the density profile is again found exactly for late times from the RG-improved field theory. The results obtained for the diffusive case are relevant for Mg$^{2+}$ or Cd$^{2+}$ doping in the TMMC crystal's exciton coalescence process and also imply a surprising result for the dynamic magnetization in the critical one-dimensional Ising model with a fixed spin. For the case of ballistic reactants, a model is introduced and solved exactly in one dimension. The density-deficit profile is obtained, as is the density of left and right moving reactants near the impenetrable boundary.