Vacuum Value Research Articles

A novel application of automatic vacuum membrane bioreactor in wastewater reclamation

An automatic vacuum membrane bioreactor (AVMBR) equipped with an on-line air–water–chemicals backwashing system was developed for a purpose of the reclamation of domestic wastewater (300–800 mg-COD/L) and traditional Chinese medicine (TCM) wastewater (259–12775 mg-COD/L). The experimental setups were operated in pilot scale at hydraulic retention times (HRTs) of 3, 1 and 0.5 h for domestic wastewater, and at HRTs of 1, 3, 5 and 8 h for TCM wastewater. Experimental results indicated that membrane flux was able to resume as the fouled membrane modules being operated for 150 days were repeatedly subject to an air–water–chemicals backwashing procedure. Compared to a new membrane module, the contaminated membrane fluxes were resumed to 94.7% after the first cleaning, to 82.7% after the second cleaning and to 70.0% after the third cleaning at a vacuum value of 0.02 MPa. To meet reuse standard (effluent COD, less than 30 mg/L), the minimum HRT required by the AVMBR system was 1 h for domestic wastewater reclamation, and 1 h for less than 1000 mg-COD/L, 3.0 h for 1000–3000 mg-COD/L, and 5.0 h for 3000–6000 mg-COD/L TCM wastewater reclamation.However, when the TCM wastewater COD was larger than 6000 mg/L, an 8-h HRT operation of the AVMBR system failed to produce an effluent having a COD concentration less than 30 mg/L. It is concluded that the pilot-scale AVMBR system developed is feasible for the reclamation of domestic wastewater and TCM wastewater with a COD concentration less than 6000 mg/L.

Simulation of resistive microwave resonator probe for high-pressure plasma diagnostics

A U-shape probe for microwave resonance in plasma was investigated in a range of high pressure (10–760 Torr). The electromagnetic field finite difference time domain-simulation of the probe revealed that, in the resistive resonance at high pressure, the resonant frequency fr approaches the dipole-antenna resonance frequency in vacuum, with almost no dependence on the electron density ne. However, the resonance width Δf is sensitive to the pressure, showing the maximum value at ∼20 Torr. The normalized resonance width (Δf/fr) corrected by the one of vacuum value (no plasma) is linearly proportional to ne, and inversely proportional to νm (electron–molecule collision frequency) for high-pressure plasmas. These simulation results are successfully explained in a model of two-conductor transmission line in cold collisional plasma. According to the resonance analysis, the methods for measuring the electron density and the electron collision frequency at high pressures (, ) were proposed.

Intermolecular resonance energy transfer in the presence of a dielectric cylinder

Using a Green's tensor method, we investigate the rate of resonance electronic energy transfer between two molecules near a dielectric cylinder. Both the case of a real and frequency-independent dielectric constant $ϵ$ and the case of a Drude-Lorentz model for $ϵ(\ensuremath{\omega})$ are considered, the latter case including dispersion and absorption. If the donor is placed at a fixed position near the cylinder, we find that the energy transfer rate to the acceptor is enhanced compared to its vacuum value in a number of discrete hotspots, centered at the cylinder's surface. In the absence of dispersion and absorption the rate of energy transfer may be enhanced at most a few times. On the other hand, for the Drude-Lorentz model the enhancement may be huge (up to ${10}^{6}$) and the hotspots are sharply localized at the surface. We show that these observations can be explained from the fact that in the resonance region of the Drude-Lorentz dielectric surface plasmons occur, which play the dominant role in transferring the electronic energy between the donor and the acceptor. The dependence of the energy transfer rate on the molecular transition frequency is investigated as well. For small intermolecular distances, the cylinder hardly affects the transfer rate, independent of frequency. For larger distances, the frequency dependence is quite strong, in particular in the stop-gap region. The role of the intermolecular distance in the frequency dependence may be explained qualitatively using Heisenberg's uncertainty principle to calculate the spread in the frequencies of the intermediate photons.

Quark and gluon condensates in isospin matter

Applying the Hellmann-Feynman theorem to a charged pion gas, the quark and gluon condensates at low isospin density are determined by precise pion properties. At intermediate density around $ f_\pi^2m_\pi$, from both the estimation for the dilute pion gas and the calculation with Nambu--Jona-Lasinio model, the quark condensate is strongly and monotonously suppressed, while the gluon condensate is enhanced and can be larger than its vacuum value. This unusual behavior of the gluon condensate is universal for Bose condensed matter of mesons. Our results can be tested by lattice calculations at finite isospin density.

Geometry and symmetry structures in two-time gravity

Two-time (2T) gravity in d+2 dimensions predicts 1T general relativity in d dimensions, augmented with a local scale symmetry known as the Weyl symmetry in 1T field theory. The emerging general relativity comes with a number of constraints, particularly on scalar fields and their interactions in 1T field theory. These constraints, detailed in this paper, are footprints of 2T gravity and could be a basis for testing 2T physics. Some of the conceptually interesting consequences of the 'accidental' Weyl symmetry include that the gravitational constant emerges from vacuum values of the dilaton and other Higgs-type scalars and that it changes after every cosmic phase transition (inflation, grand unification, electroweak phase transition, etc.). We show that this consequential Weyl symmetry in d dimensions originates from coordinate reparametrization, not from scale transformations, in the d+2 spacetime of 2T gravity. To recognize this structure we develop in detail the geometrical structures, curvatures, symmetries, etc. of the d+2 spacetime which is restricted by a homothety condition derived from the action of 2T gravity. Observers that live in d dimensions perceive general relativity and all degrees of freedom as shadows of their counterparts in d+2 dimensions. Kaluza-Klein type modes are removed by gauge symmetries andmore » constraints that follow from the 2T-gravity action. However some analogs to Kaluza-Klein modes, which we call 'prolongations' of the shadows into the higher dimensions, remain but they are completely determined, up to gauge freedom, by the shadows in d dimensions.« less

77Se NMR Spectroscopic, DFT MO, and VBT Investigations of the Reversible Dissociation of Solid (Se6I2)[AsF6]2·2SO2in Liquid SO2to Solutions Containing 1,4-Se6I22+in Equilibrium with Sen2+(n= 4, 8, 10) and Seven Binary Selenium Iodine Cations: Preliminary Evidence for 1,1,4,4-Se4Br42+andcyclo-Se7Br+

The composition of a complex equilibrium mixture formed upon dissolution of (Se(6)I(2))[AsF(6)](2).2SO(2) in SO(2)(l) was studied by (77)Se NMR spectroscopy at -70 degrees C with both natural-abundance and enriched (77)Se-isotope samples (enrichment 92%). Both the natural-abundance and enriched NMR spectra showed the presence of previously known cations 1,4-Se(6)I(2)(2+), SeI(3)(+), 1,1,4,4-Se(4)I(4)(2+), Se(10)(2+), Se(8)(2+), and Se(4)(2+). The structure and bonding in 1,4-Se(6)I(2)(2+) and 1,1,4,4-Se(4)I(4)(2+) were explored using DFT calculations. It was shown that the observed Se-Se bond alternation and presence of thermodynamically stable 4ppi-4ppi Se-Se and 4ppi-5ppi Se-I bonds arise from positive charge delocalization from the formally positively charged tricoordinate Se(+). The (77)Se chemical shifts for cations were calculated using the relativistic zeroth-order regular approximation (ZORA). In addition, calculations adding a small number of explicit solvent molecules and an implicit conductor-like screening model were conducted to include the effect that solvent has on the chemical shifts. The calculations yielded reasonable agreement with experimental chemical shifts, and inclusion of solvent effects was shown to improve the agreement over vacuum values. The (77)Se NMR spectrum of the equilibrium solution showed 22 additional resonances. These were assigned on the basis of (77)Se-(77)Se correlation spectroscopy, selective irradiation experiments, and spectral simulation. By combining this information with the trends in the chemical shifts, with iodine, selenium, and charge balances, as well as with ZORA chemical shift predictions, these resonances were assigned to acyclic 1,1,2-Se(2)I(3)(+), 1,1,6,6-Se(6)I(4)(2+), and 1,1,6-Se(6)I(3)(+), as well as to cyclic Se(7)I(+) and (4-Se(7)I)(2)I(3+). A preliminary natural-abundance (77)Se NMR study of the soluble products of the reaction of (Se(4))[AsF(6)](2) and bromine in liquid SO(2) included resonances attributable to 1,1,4,4-Se(4)Br(4)(2+)(.) These assignments are supported by the agreement of the observed and calculated (77)Se chemical shifts. Resonances attributable to cyclic Se(7)Br(+) were also observed. The thermal stability of (Se(6)I(2))[AsF(6)](2).2SO(2)(s) was consistent with estimates of thermodynamic values obtained using volume-based thermodynamics (VBT) and the first application of the thermodynamic solvate difference rule for nonaqueous solvates. (Se(6)I(2))[AsF(6)](2).2SO(2)(s) is the first example of a SO(2) solvate for which the nonsolvated parent salt, (Se(6)I(2))[AsF(6)](2)(s), is not thermodynamically stable, disproportionating to Se(4)I(4)(AsF(6))(2)(s) and Se(8)(AsF(6))(2)(s) (DeltaG degrees for the disproportion reaction is estimated to be -17 +/- 15 kJ mol(-1) at 298 K from VBT theory).

Calculation offπandmπat finite chemical potential

Based on the previous work in [Y. Jiang, Y.M. Shi, H.T. Feng, W.M. Sun and H.S. Zong, Phys. Rev. C {\bf 78}, 025214 (2008)] on the quark-meson vertex and pion properties at finite quark chemical potential, we provide an analytical analysis of the weak decay constant of the pion ($f_\pi[\mu]$) and the pion mass ($m_\pi[\mu]$) at finite quark chemical potential using the model quark propagator proposed in [R. Alkofer, W. Detmold, C.S. Fischer and P. Maris, Phys. Rev. D {\bf 70}, 014014 (2004)]. It is found that when $\mu$ is below a threshold value $\mu_0$ (which equals $0.350 \mathrm{GeV}$, $0.377 \mathrm{GeV}$ and $0.341 \mathrm{GeV}$, for the $\mathrm{2CC}$, $\mathrm{1R1CC}$ and $\mathrm{3R}$ parametrizations of the model quark propagator, respectively.), $f_\pi[\mu]$ and $m_\pi[\mu]$ are kept unchanged from their vacuum values. The value of $\mu_0$ is intimately connected with the pole distribution of the model quark propagator and is found to coincide with the threshold value below which the quark-number density vanishes identically. Numerical calculations show that when $\mu$ becomes larger than $\mu_0$, $f_\pi[\mu]$ exhibits a sharp decrease whereas $m_\pi[\mu]$ exhibits a sharp increase. A comparison is given between the results obtained in this paper and those obtained in previous literatures.

Polarizable Continuum Model Study on the Solvent Effect of Polymer Matrix in Poly(ethylene oxide)-Based Solid Electrolyte

The Polarizable Continuum Model has been used to study the effect of polymer matrix on Li (+) and Mg (2+) complexation in poly(ethylene oxide)-based solid electrolyte. Structures of complexes, stabilization energies, and vibrational frequencies are compared with corresponding vacuum values. The solvent effect of the polymer decreases with increasing cation coordination number. Optimized complex geometries do not differ significantly compared to vacuum calculations. Calculated shifts in vibrational frequencies depend on the complex structure; for hexacoordinated ion most frequencies are slightly red-shifted. The most important effect is the decrease of differences between relative stabilities of different structures in the solvent.

Response of quark condensate to the chemical potential

In this paper we propose a new method for calculating the response of the quark condensate to the chemical potential. Based on the method of calculating the dressed-quark propagator at finite chemical potential in the framework of the rainbow-ladder approximation of the Dyson-Schwinger approach proposed in [H. S. Zong, L. Chang, F. Y. Hou, W. M. Sun, and Y. X. Liu, Phys. Rev. C 71, 015205 (2005).] and adopting the meromorphic form of the quark propagator given in [R. Alkofer, W. Detmold, C. S. Fischer, and P. Maris, Phys. Rev. D 70, 014014 (2004).][M. S. Bhagwat, M. A. Pichowsky, and P. C. Tandy, Phys. Rev. D 67, 054019 (2003).], the quark condensate at finite chemical potential [{mu}] is calculated analytically. The obtained expression for [{mu}] is real, which is different from the results in the previous literature. In addition, it is found that when the chemical potential {mu} is less than a critical one [{mu}] is kept unchanged from its vacuum value. A comparison is made between this behavior of the quark condensate and those reported in the previous literatures.

Magnetic Susceptibility of the QCD Vacuumat a Finite Quark-chemical Potential

We investigate the magnetic susceptibility (chi) of the QCD vacuum at finite density (the quark chemical potential mu_q > 0) and at zero temperature in the chiral limit, within the framework of the medium-modified nonlocal chiral quark model from the instanton vacuum. The model is characterized by the average inter-instanton distance R ~ 1 fm and average instanton size rho ~ 1/3 fm. It is found that the magnetic susceptibility chi decreases smoothly with respect to mu_q and turns out to be about a half of its vacuum value at the critical density (mu_q ~ mu_c).

Spontaneous Lorentz and diffeomorphism violation, massive modes, and gravity

Theories with spontaneous local Lorentz and diffeomorphism violation contain massless NambuGoldstone modes, which arise as field excitations in the minimum of the symmetry-breaking potential. If the shape of the potential also allows excitations above the minimum, then an alternative gravitational Higgs mechanism can occur in which massive modes involving the metric appear. The origin and basic properties of the massive modes are addressed in the general context involving an arbitrary tensor vacuum value. Special attention is given to the case of bumblebee models, which are gravitationally coupled vector theories with spontaneous local Lorentz and diffeomorphism violation. Mode expansions are presented in both local and spacetime frames, revealing the Nambu-Goldstone and massive modes via decomposition of the metric and bumblebee fields, and the associated symmetry properties and gauge fixing are discussed. The class of bumblebee models with kinetic terms of the Maxwell form is used as a focus for more detailed study. The nature of the associated conservation laws and the interpretation as a candidate alternative to Einstein-Maxwell theory are investigated. Explicit examples involving smooth and Lagrange-multiplier potentials are studied to illustrate features of the massive modes, including their origin, nature, dispersion laws, and effects on gravitational interactions. In the weak static limit, the massive mode and Lagrange-multiplier fields are found to modify the Newton and Coulomb potentials. The nature and implications of these modifications are examined.

Using hydrostatic pressure for evaluating the effect of a fluctuating potential on the energy spectrum of charge carriers in crystalline semiconductors

As known [1, 2], doped compensated semiconductors (in which the concentration of free charge carriers is small compared to the concentration of ionized impurities) exhibit smooth, large-scale fluctuations of random potential with certain characteristic amplitudes ( γ ). The role of this chaotic potential increases with decreasing temperature, while at a fixed temperature it grows under the action of pressure as the free carrier concentration decreases [3]. It is important to develop a method for evaluating the effect of the chaotic potential on the energy spectrum of charge carriers and to assess the correctness of relations obtained for defect-free crystals so as to provide a quantitative analysis of experimental data in each particular case. It should be noted that the pressure coefficients of the energy gaps in semiconductors are virtually pressure-independent at not very high pressures. Moreover, the pressure-induced changes of the deepest minima e Γ , e L , and e X in the conduction bands of various semiconductors (IV, II‐VI, III‐V, IV‐VI, and II–IV–V 2 ) are also approximately the same [4‐8]. Previously, the pressure coefficients of the e Γ , e L , and e X extrema relative to the values in absolute vacuum were determined [5] based on a concept according to which the energy of deep strongly localized states in some semiconductors is independent of the uniform (hydrostatic) pressure.

In-medium chiral condensate beyond linear density approximation

In-medium chiral perturbation theory is used to calculate the density dependence of the quark condensate $\ensuremath{\langle}\overline{q}q\ensuremath{\rangle}$. The corrections beyond the linear density approximation are obtained by differentiating the interaction contributions to the energy per particle of isospin-symmetric nuclear matter with respect to the pion mass. Our calculation treats systematically the effects from one-pion exchange (with ${m}_{\ensuremath{\pi}}$-dependent vertex corrections), iterated $1\ensuremath{\pi}$-exchange, and irreducible $2\ensuremath{\pi}$-exchange including intermediate $\ensuremath{\Delta}(1232)$-isobar excitations, with Pauli-blocking corrections up to three-loop order. We find a strong and nonlinear dependence of the ``dropping'' in-medium condensate on the actual value of the pion (or light quark) mass. In the chiral limit, ${m}_{\ensuremath{\pi}}=0$, chiral restoration appears to be reached already at about $1.5$ times normal nuclear matter density. By contrast, for the physical pion mass, ${m}_{\ensuremath{\pi}}=135$ MeV, the in-medium condensate stabilizes at about $60%$ of its vacuum value above that same density. Effects from $2\ensuremath{\pi}$-exchange with virtual $\ensuremath{\Delta}(1232)$-isobar excitations turn out to be crucial in generating such pronounced deviations from the linear density approximation above ${\ensuremath{\rho}}_{0}$. The hindered tendency toward chiral symmetry restoration provides a justification for using pions and nucleons as effective low-energy degrees of freedom at least up to twice nuclear matter density.

RESEARCH ON A NEW TYPE OF ENERGY SAVING PNEUMATIC PISTON VACUUM GENERATOR

Currently used jet vacuum ejector has a defect of high air consumption due to its requirement of continuous air supply. Focusing on this problem, a new type of piston vacuum generator (PVG for short) has been researched. The PVG has two pairs of pistons. One is for driving and another is for vacuum generating. Besides the maximum vacuum value, the vacuum response time and air consumption are the most concerning performances. Special structural design is made so as to meet all the requirements, in which the unequal diameters of pistons, using directional control valves instead of the check valves and stepped flow rate control scheme are proposed and realized. Experimental results have shown that for the prototype of piston vacuum generator its maximum vacuum is about 93kPa, the response time is about 3.7s and the air consumption is reduced by about 71.3% in time interval of 60s compared to the same level of vacuum ejector.

Supersymmetric field theory in two-time physics

We construct N=1 supersymmetry in 4+2 dimensions compatible with the theoretical framework of 2T physics field theory and its gauge symmetries. The fields are arranged into 4+2-dimensional chiral and vector supermultiplets, and their interactions are uniquely fixed by supersymmetry (SUSY) and 2T-physics gauge symmetries. Many 3+1 spacetimes emerge from 4+2 by gauge fixing. Gauge degrees of freedom are eliminated as one comes down from 4+2 to 3+1 dimensions without any remnants of Kaluza-Klein modes. In a special gauge, the remaining physical degrees of freedom, and their interactions, coincide with ordinary N=1 supersymmetric field theory in 3+1 dimensions. In this gauge, SUSY in 4+2 is interpreted as superconformal symmetry SU(2,2|1) in 3+1 dimensions. Furthermore, the underlying 4+2 structure imposes some interesting restrictions on the emergent 3+1 SUSY field theory, which could be considered as part of the predictions of 2T-physics. One of these is the absence of the troublesome renormalizable CP violating F*F terms. This is good for curing the strong CP violation problem of QCD. An additional feature is that the superpotential is required to have no dimensionful parameters. To induce phase transitions, such as SUSY or electroweak symmetry breaking, a coupling to the dilaton is needed. This suggests amore » common origin of phase transitions that is driven by the vacuum value of the dilaton and needs to be understood in a cosmological scenario as part of a unified theory that includes the coupling of supergravity to matter. Another interesting aspect of the proposed theory is the possibility to utilize the inherent 2T gauge symmetry to explore dual versions of the N=1 theory in 3+1 dimensions, such as the minimal supersymmetric standard model (MSSM) and its duals. This is expected to reveal nonperturbative aspects of ordinary 1T field theory.« less

Gauge mediated supersymmetry breaking and moduli stabilization

A generic lesson of string theory is that the coupling constants of an effective low energy theory are determined by the vacuum values of a set of fields---the so-called moduli---some of which are stabilized at relatively low masses by nonperturbative effects. We argue that the physics of these moduli cannot be separated from the issues of dynamical and gauge mediated supersymmetry breaking. To illustrate this point we present a modified version of the type IIB Kachru-Kallosh-Linde-Trivedi model where the criteria for gauge mediated supersymmetry breaking may be realized.

전자선조사와 포장방법이 발효소시지의 냉장 저장 중 품질 특성에 미치는 영향

ABSTRACT The study was carried out to examine combined effects of packaging and electron-beam irradiation on lipid oxidation and meat color of fermented sausages during storage. Fermented and aged sausages were exposed to electron-beam at 2 kGy. The samples were vacuum or aerobic-packaged with the non-irradiated samples at 4±1. Regardless of irradiation, the pH values of vacuum-packaged samples was lower than those of aerobic-packaged ones at 14 day (p<0.05). Total microbes and lactic acid bacteria counts significantly decreased during the storage period (p<0.05). And counts of non-irradiated samples were significantly higher than those of irradiated (2 kGy) samples with aerobic packaging. The TBARS values of 2 kGy-irradiated samples were significantly higher than those of non-irradiated samples. The TBARS values of vacuum packaged samples had lower than those of aerobic-packaged ones (p<0.05). Colors (parameters L*, a* and b* values) tended to decrease as the storage period increased. Redness(a*) and yellowness (b*) of 2 kGy irradiated samples were higher than those of non-irradiated ones (p<0.05). In sensory analysis, irradiated (2 kGy) samples with aerobic packaging had higher off-flavor than non-irradiated ones (p<0.05). Therefore, results indicated that irradiation coupled with vacuum packaging may minimize TBARS values of irradiated sausages during storage.(

Quantum theory of radiation of an excited atom placed near a microresonator containing a single-photon wavepacket: Photon correlation properties

The strong resonance interaction of a two-level atom with the continuum of quantized electromagnetic modes falling within the contour of a resonance mode of a dielectric microsphere is considered within the framework of quantum electrodynamics. Analytical solutions are derived. As an initial condition, we consider the case when, at time t = 0, the atom is excited and the resonance modes of the microsphere contain a single-photon wavepacket. It is shown that the properties of the emitted photon pair depend crucially on space-time properties of the photon wavepacket contained in the resonator. When the mean square of the electric field of the photon wavepacket at the initial instant of time at the atom position is close to the vacuum value, the radiation of an atom is similar to a spontaneous one and the emitted photon pair has no correlations. On the contrary, if the mean square of the electric field of the photon wavepacket at the initial instant of time at the atom position is substantially greater than the vacuum value, the radiation of an atom has a stimulated nature and the emitted photon pair has very complicated strong correlations. The relationship between the results obtained and the predictions of the dressed states theory are briefly discussed. The results obtained are of a general character and can be applied to the description of the resonant interaction of an excited atom and an excited resonator of an arbitrary shape.

Effect of Mg Content in Matrix on Infiltration Height in Producing MgO/Al Composite by Vacuum Infiltration Method

Vacuum infiltration is one of the composite production method. Reinforcement volume ratio, vacuum value, molten matrix composition and temperature, infiltration atmosphere and time are important parameters in infiltration of molten metal into preformed reinforcement. In this study, MgO powder and Al were used as reinforcement and matrix respectively. Mixture of MgO and Al powders with –105 μm particle size were filled in quartz tubes freely to form 30 % reinforcement volume ratio. Liquid pure Al with varying Mg contents were vacuum infiltrated into the MgO powder under 550 mmHg vacuum at two different temperatures in normal atmosphere for 3 min. After vacuuming, infiltration height and density of produced composite have been determined. Fracture behavior of composites has also been determined by three point fracture test. Microstructure of composites and fracture surface were investigated by SEM analysis. It has been found that fracture strength of composites decreased although infiltration height and density increased with increasing Mg content of liquid Al. It has been also determined that molten metal temperature facilitates infiltration.

Brane Lorentz symmetry from Lorentz breaking in the bulk

We propose the mechanism of spontaneous symmetry breaking of a bulk vector field as a way to generate the selection of bulk dimensions invisible to the standard model confined to the brane. By assigning a nonvanishing vacuum value to the vector field, a direction is singled out in the bulk vacuum, thus breaking the bulk Lorentz symmetry. We present the condition for induced Lorentz symmetry on the brane, as phenomenologically required.