Variable Masses Research Articles

Foaming Characteristics of the Food-Industry Biological Wastewater Treatment Plant

Intensive foaming observed during aeration of the aerobic food industry wastewater treatment plant is presented. Thisstudy was conducted to establish the foaming characteristics using a pilot three-phase fluidized bed bioreactor (TPFBB).A fluidization column (0.2 m i.d. and 6 m high) was used. The TPFBB was loaded with variable masses of novel biomasssupport particles (BSP). Wastewater samples collected from a plant processing both vegetable oil (VOPWW) and soap(SPWW) were immediately introduced in the TPFBB for aeration. The characteristics studied include: variation of foamvolume with time, foam multiplicity, foaming and foam collapse rates. The SPWW produced excessive foam volumes at ahigher rate and higher foam multiplicity compared to VOPWW. Dilution, increasing aeration rate or BSP loading led tohigher foaming rate, which decreased with time. Spraying wastewater at the top of the liquid surface minimized foamingrate.

The influence of dynamic properties of ground soil on vibration characteristics of rigid body on sand ground

This study aims to investigate the influence of dynamic properties of the ground soil on vibration properties of a rigid body placed on the sand ground surface to clarify the vibration behavior of a structure in terms of the interaction between the structure and the ground. A series of cyclic triaxial tests and three types of model vibration tests were performed. The dynamic properties of ground soil were clarified using cyclic triaxial tests. It was found that the equivalent shear modulus markedly depends on confining pressure and relative density, and that the hysteresis-damping ratio also depends on confining stress but not upon relative density. In model vibration tests, rigid body models with variable masses, inertial moment, base size and base shape were prepared and their vibration behaviors were observed. Vibration characteristics were estimated from the observed behavior, and the period and damping ratio were examined. It was found that the period depends on not only the mechanical properties of the rigid body and the relative density of ground, but also upon the magnitude of the vibration amplitude. A simple model of a spring and a dashpot was used to correlate period and damping ratio of ground soil in a model vibration test with equivalent shear modulus and hysteresis damping ratio by cyclic triaxial testing. The relationship between normalized inverse squares of the period and rotation amplitude was similar to the relationship between the normalized equivalent shear modulus and the shear strain amplitude. Normalized damping ratio also showed good agreement with the normalized hysteresis-damping ratio. The calculated equivalent shear modulus from the simple model linearly increased with increased average contact pressure, as the equivalent shear modulus of the cyclic triaxial test 1 inearly increased with effective confining pressure on a log-log scale.

Sobre parâmetros dependentes do tempo em lagrangianas e seus invariantes adiabáticos

O emprego de lagrangianas com parâmetros dependentes do tempo é discutido. Enquanto que a justificativa de uso de 'constantes de força' dependentes do tempo é simples, a de massas dependentes do tempo se deve a um usualmente não notado fato de que as massas, nas equações de Lagrange para a energia cinética e força generalizada, não são necessariamente constantes. Os correspondentes invariantes adiabáticos são obtidos de forma muito simples, seguindo método sugerido em livro aparecido recentemente, para vários tipos de constante de força.

Conservative two-body problem with variable masses

We consider the conservative two-body problem with a constant total mass, but with variable individual masses. The problem is shown to be completely integrable for any mass variation law. The Keplerian motion known for the classical two-body problem with constant masses remains valid for the relative motion of the bodies. The absolute motions of the bodies depend on the center-of-mass motion. Hitherto unknown quadratures that depend on the mass variation law were derived for the integrals of motion of the center of mass. We consider some of the laws that are of interest in studying the motion of close binary stars with mass transfer.

Jacobi dynamics of variable-mass gravitational systems

Some consequences of the generalized forms of the Lagrange–Jacobi equation for model gravitational systems with variable masses are given.

Magnetic fines from the Kaali impact-site (Holocene, Estonia): Preliminary SEM investigation

The Kaali crater field (1 sq. kilometre, 9 craters) offers a unique opportunity to recover large amounts of magnetic fines still partly preserved from late-stage weathering. SEM studies of these materials reveal an unusually wide spectrum of derivatives from the initial iron meteorite body, including minor amounts of unmelted metal fragments, and an abundance of more evolved products resulting from primary oxidation processes. Most of these products are sprays and splashes of liquid iron oxides, and some particles may be ascribed to oxide condensates from a vapor phase, as a result of both atmospheric ablation and vaporization upon impact. This wide range reflects varied impact conditions, due to variable masses and velocities of fragments after atmospheric disruption of the original meteoritic body. The large spectrum of magnetic fines from Kaali should provide an excellent probe into the chemical- and isotopic-fractionation of elements over a range of impact processes, from atmospheric entry to post-impact alteration. Magnetic fines from other sites of multiple impacts may have the same potential, and deserve more systematic attention.

Dynamic and experimental analysis for inchwormlike biomimetic robots Ver-Vite

The intent of this work was to design an innovative robot to imitate inchworm locomotion. The prototype built demonstrates successful implementation of using only friction and variable masses to generate the motion. The theoretical model was simulated using working model and validated experimentally. The computer simulation shows the dynamic and kinetic effects on inchworm mobility, providing a complete understanding of the design concept. The experimental results compare well with the theoretical model, although the exact coefficient of friction during the experiment was not measured. Theoretical and experimental results both indicate a slight backward motion of the robot during the contractile phase of the cycle of motion. Although the results are similar, the theoretical model fails to include such phenomena as the friction in the revolute joints and the vibration produced by the pump and servos. The theoretical model will be used in future work to optimize the design of the robot for dynamic performance.

Telomerization of Butyl Methacrylate and 1‐Octadecanethiol by Reactive Extrusion

AbstractButyl methacrylate and 1‐octadecanethiol telomers were prepared by radical reactive extrusion. The main advantages of the use of this processing technique are that mass reactions can be conducted and continuous production is achieved within a reduced reaction time and a correct temperature control. Preliminary studies concerned the choice of the reactants for the telomerization reaction and the adaptation of the telomerization reaction to the reactive extrusion process. The transfer constant to C18H37SH was measured, and then experimental studies were conducted to verify that the hypothesis and approximations made for kinetic modeling are realistic. Particularly, it was shown that the use of relatively high chain‐transfer agent to monomer concentration ratio had no perceptible effect on the monomer conversion kinetic. These results allowed the choice of reactive extrusion conditions. Telomers were prepared using a laboratory co‐rotating twin‐screw extruder. The effect of reaction conditions (temperature, 1‐octadecanethiol to monomer concentration ratio) and of processing conditions (throughput, screw rotation speed) on the residence time distributions, molar mass and monomer conversions were examined. This study allowed the continuous synthesis of butyl methacrylate telomers having variable controlled molar masses and complete monomer conversion. Screw profile used in reactive extrusion telomerization.magnified imageScrew profile used in reactive extrusion telomerization.

Reconstruction of A Non-Stationary Potential of Gravitating System on Given Evolving Orbits

We study the problem of the reconstruction of a non-stationary space symmetrical regular planar potential of the gravitating system on a family of evolving types of orbits being used in the dynamics of stationary stellar systems. An application of such an inverse problem to the dynamical evolution of stellar systems with variable masses is given. The general form of the evolving orbit which we use when writing out the differential equations for non-stationary potential may also be interpreted as an osculating orbit of the perturbed Keplerian motion. In this case we are making an additional transformation of the basic equation of the problem and demonstrating an appropriate example of the construction of a non-stationary potential of a gravitating system. In connection with the stellar dynamical character of our inverse problem, we also give a generalized form of its basic equation in a rotating coordinate system.

On The Dynamics of Non-Stationary Stellar Cluster in Galaxy

We followed Wielen's (1974) and Osipkov's, Kozhanov's (1986) procedure to derive the equation of motion of a cluster in the solar neighborhood in taking into account of a galactic tidal field, which is assume to have axial symmetry, and gravitational influence of spherical stellar clouds.On the basic of this equations and using the linear approximation for the galactic field (Wielen 1974) one can derive virial equation of Jacobi for variable masses of stellar clusters. The non-stability by Lagrange condition, describing behavior of this system is obtained.

Biological and physical dynamics of domoic acid production off the Washington coast

The relationship among Pseudo‐nitzschia distributions, particulate toxin levels in seawater, and the energetic and highly variable water masses of an upwelling‐dominated region are explored using data collected during summer cruises off the Washington coast in 1997 and 1998. In the early summer of both years, an area of maximum domoic acid (DA) accumulation was located approximately 50 km off the coast within a counterclockwise, cold feature known as the Juan de Fuca eddy. The stations in the eddy with the highest domoic acid concentrations coincided with high numbers of Pseudo‐nitzschia pseudodelicatissima (Hasle) Hasle (2.7 µg DA equivalents L-1, up to 0.6 X 106 cells L-1 in 1997 and 0.2 µg DA equivalents L-1, up to 0.2 X 106 cells L-1 in 1998), a species known to produce toxin in this region. Other known toxin‐producing species were sometimes present, but at ≪5% of the total Pseudo‐nitzschia population when ≫0.1 µg DA equivalents L-1 were measured. In 1998, large‐scale surveys indicated that high levels of particulate DA in seawater persisted at least until 1 October, covering a maximum area of 100 km2 off the Washington coast in midsummer. The appearance of high levels of DA (up to 2.7 µg DA equivalents L-1), coincident with high numbers of P. pseudodelicatissima (up to 15.4 X 106 cells L-1) at Kalaloch beach on the central coast in late September, was followed by the accumulation of record levels of toxin in razor clams. This toxic episode was preceded by a downwelling‐favorable wind event, with associated onshore transport in near‐surface layers. We suggest that the Juan de Fuca eddy may be one source of DA to the Washington coast. The duration of upwelling and the exact timing of fall storms likely play an influential role in the intensity of the bloom and the movement of toxic cells from the eddy to the coast.

Plasmid localisation of atrazine-degrading genes in newly described Chelatobacter and Arthrobacter strains

Abstract In a previous study, we isolated a collection of atrazine-degrading bacteria from various soils. The aim of this study was to localise the atrazine-degrading genes in these 25 atrazine-degrading strains. In the case of the Gram-negative strains of Chelatobacter heintzii, six to seven plasmids were observed. The atzABC and trzD genes were located on two or three plasmids with variable molecular masses. For the Gram-positive strains of Arthrobacter crystallopoietes, the atzBC genes were located on a single plasmid of 117 kb. The organisation of atrazine-degrading genes seems to be highly variable between the strains studied. We have shown by a specific PCR the occurrence of IS1071-like sequences in all strains carrying atzBC genes, while these sequences seem to be absent in strains carrying only the atzA gene. Thus, we show a strong correlation between the presence of these insertion sequences and the presence of some genes involved in atrazine degradation.

Plasmid localisation of atrazine-degrading genes in newly described Chelatobacter and Arthrobacter strains

In a previous study, we isolated a collection of atrazine-degrading bacteria from various soils. The aim of this study was to localise the atrazine-degrading genes in these 25 atrazine-degrading strains. In the case of the Gram-negative strains of Chelatobacter heintzii, six to seven plasmids were observed. The atzABC and trzD genes were located on two or three plasmids with variable molecular masses. For the Gram-positive strains of Arthrobacter crystallopoietes, the atzBC genes were located on a single plasmid of 117 kb. The organisation of atrazine-degrading genes seems to be highly variable between the strains studied. We have shown by a specific PCR the occurrence of IS 1071-like sequences in all strains carrying atzBC genes, while these sequences seem to be absent in strains carrying only the atzA gene. Thus, we show a strong correlation between the presence of these insertion sequences and the presence of some genes involved in atrazine degradation.

Association and regulation of casein kinase 2 activity by adenomatous polyposis coli protein.

Mutations in the adenomatous polyposis coli (APC) gene are responsible for familial adenomatous polyposis coli and also sporadic colorectal cancer development. By using antibodies raised against the N-terminal region of APC protein, we have detected the variable masses of endogenous APC proteins in individual cell lines established from human colorectal carcinomas caused by nonsense mutations of the gene. Phosphorylation of immunoprecipitates of full-length and truncated APC were observed in in vitro kinase reaction, indicating association of APC with protein kinase activity. The kinase activity complexed with APC was sensitive to heparin and used GTP as phosphoryl donor, suggesting an involvement of casein kinase 2 (CK2). Both CK2alpha- and beta-subunits were found to associate with APC in immunoprecipitates as well as in pull-down assays, with preferential interaction of APC with tetrameric CK2 holoenzyme. In synchronized cell populations, the association of APC with CK2 was cell cycle dependent, with the highest association in G(2)/M. Unexpectedly, APC immunoprecipitates containing full-length APC protein inhibited CK2 in vitro, whereas immunoprecipitates of truncated APC had little effect. This was confirmed by using recombinant APC, and the inhibitory region was localized to the C terminus of APC between residues 2086 and 2394. Overexpression of this fragment in SW480 cells suppressed cell proliferation rates as well as tumorigenesis. These results demonstrate a previously uncharacterized functional interaction between the tumor suppressor protein APC and CK2 and suggest that growth-inhibitory effects of APC may be regulated by inhibition of CK2.

Asymptotic and Numerical Analyses for Mechanical Models of Heat Baths

A mechanical model of a particle immersed in a heat bath is studied, in which a distinguished particle interacts via linear springs with a collection of n particles with variable masses and random initial conditions; the jth particle oscillates with frequency j p , where p is a parameter. For p>1/2 the sequence of random processes that describe the trajectory of the distinguished particle tends almost surely, as n→∞, to the solution of an integro-differential equation with a random driving term; the mean convergence rate is 1/n p−1/2. We further investigate whether the motion of the distinguished particle can be well approximated by an integration scheme—the symplectic Euler scheme—when the product of time step h and highest frequency n p is of order 1, that is, when high frequencies are underresolved. For 1/2<p<1 the numerical solution is found to converge to the exact solution at a reduced rate of |log h| h 2−1/p . These results shed light on existing numerical data.

Multisensitive polymers based on 2‐vinylpyridine and N‐isopropylacrylamide *

AbstractPoly(2‐vinylpyridine) (P2VP) containing functionalized end groups was synthesized using nitroxyl‐mediated radical polymerization with a hydroxy‐functionalized stable free radical. It was shown that P2VP could be synthesized with variable molar masses and low polydispersities. The transformation of the hydroxy groups to an acrylic ester led to the formation of macromonomers. A free‐radical copolymerization of these macromonomers with N‐isopropylacrylamide gave a graft copolymer with a poly(N‐ispopropylacrylamide) backbone and P2VP side chains. Polymers containing different amounts of the monomers were synthesized. It was possible to vary both the amount of P2VP side chains at a constant chain length of the macromonomer and the chain length at a nearly constant chain number. The behavior of the multifunctional macromolecules at different temperatures and pH values was investigated using dynamic light scattering and DSC. The macromolecules were found to retain the specific properties of the homopolymers. The hydrodynamic radii of the synthesized graft copolymers were both dependent on the temperature and pH value. © 2001 John Wiley &amp; Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3797–3804, 2001

Anholonomic Soliton-Dilaton and Black Hole Solutions in General Relativity

A new method of construction of integral varieties of Einstein equations in three dimensional (3D) and 4D gravity is presented whereby, under corresponding redefinition of physical values with respect to anholonomic frames of reference with associated nonlinear connections, the structure of gravity field equations is substantially simplified. It is shown that there are 4D solutions of Einstein equations which are constructed as nonlinear superpositions of soliton solutions of 2D (pseudo) Euclidean sine-Gordon equations (or of Lorentzian black holes in Jackiw-Teitelboim dilaton gravity). The Belinski-Zakharov-Meison solitons for vacuum gravitational field equations are generalized to various cases of two and three coordinate dependencies, local anisotropy and matter sources. The general framework of this study is based on investigation of anholonomic soliton-dilaton black hole structures in general relativity. We prove that there are possible static and dynamical black hole, black torus and disk/cylinder like solutions (of non-vacuum gravitational field equations) with horizons being parametrized by hypersurface equations of rotation ellipsoid, torus, cylinder and another type configurations. Solutions describing locally anisotropic variants of the Schwarzschild-- Kerr (black hole), Weyl (cylindrical symmetry) and Neugebauer--Meinel (disk) solutions with anisotropic variable masses, distributions of matter and interaction constants are shown to be contained in Einstein's gravity. It is demonstrated in which manner locally anisotropic multi-soliton-- dilaton-black hole type solutions can be generated.

Equations of Motion of the Elliptical Restricted Problem of Three Bodies with Variable Masses

The differential equations of motion of the elliptical restricted problem of three bodies with variable masses are derived with the help of Meshcherskii's transformation. Here we see that these equations of motion differ from the equations of motion of the elliptical restricted problem of three bodies with constant mass only by a factor Δ = (β2 - γα).

Foundations of dissipative particle dynamics

We derive a mesoscopic modeling and simulation technique that is very close to the technique known as dissipative particle dynamics. The model is derived from molecular dynamics by means of a systematic coarse-graining procedure. This procedure links the forces between the dissipative particles to a hydrodynamic description of the underlying molecular dynamics (MD) particles. In particular, the dissipative particle forces are given directly in terms of the viscosity emergent from MD, while the interparticle energy transfer is similarly given by the heat conductivity derived from MD. In linking the microscopic and mesoscopic descriptions we thus rely on the macroscopic or phenomenological description emergent from MD. Thus the rules governing this form of dissipative particle dynamics reflect the underlying molecular dynamics; in particular, all the underlying conservation laws carry over from the microscopic to the mesoscopic description. We obtain the forces experienced by the dissipative particles together with an approximate form of the associated equilibrium distribution. Whereas previously the dissipative particles were spheres of fixed size and mass, now they are defined as cells on a Voronoi lattice with variable masses and sizes. This Voronoi lattice arises naturally from the coarse-graining procedure, which may be applied iteratively and thus represents a form of renormalization-group mapping. It enables us to select any desired local scale for the mesoscopic description of a given problem. Indeed, the method may be used to deal with situations in which several different length scales are simultaneously present. We compare and contrast this particulate model with existing continuum fluid dynamics techniques, which rely on a purely macroscopic and phenomenological approach. Simulations carried out with the present scheme show good agreement with theoretical predictions for the equilibrium behavior.

Roles of the surface layer proteins of Campylobacter fetus subsp. fetus in ovine abortion.

The role of the surface (S)-layer proteins of Campylobacter fetus subsp. fetus has been investigated using an ovine model of abortion. Wild-type strain 23D induced abortion in up to 90% of pregnant ewes challenged subcutaneously. Isolates recovered from both dams and fetuses expressed S-layer proteins with variable molecular masses. The spontaneous S-layer-negative variant, strain 23B, neither colonized nor caused abortions in pregnant ewes. A series of isogenic sapA and recA mutants, derived from 23D, also were investigated in this model. A mutant (501 [sapA recA(+)]) caused abortion in one of five challenged animals and was recovered from the placenta of a second animal. Another mutant (502 [sapA recA]) with no S-layer protein expression caused no colonization or abortions in challenged animals but caused abortion when administered intraplacentally. Mutants 600(2) and 600(4), both recA, had fixed expression of 97- and 127-kDa S-layer proteins, respectively. Two of the six animals challenged with mutant 600(4) were colonized, but there were no abortions. As expected, all five strains recovered expressed a 127-kDa S-layer protein. In contrast, mutant 600(2) was recovered from the placentas of all five challenged animals and caused abortion in two. Unexpectedly, one of the 16 isolates expressed a 127-kDa rather than a 97-kDa S-layer protein. Thus, these studies indicate that S-layer proteins appear essential for colonization and/or translocation to the placenta but are not required to mediate fetal injury and that S-layer variation may occur in a recA strain.