Mass Ratio Of Components Research Articles

Preparation of KOH/CaO/C Supported Biodiesel Catalyst and Application Process

KOH/CaO/C supported catalyst was prepared via incipient wetness impregnation and used in synthesis of biodiesel. First, the effects of carrier/active components mass ratio, calcination temperature and calcination time on catalytic activity were investigated aiming at biodiesel yield, and the optimal process conditions for preparation of KOH/CaO/C catalysts were: mass ratio of C/CaO was 4:6; KOH solution (mass concentration) was 25%; impregnation time was 24 h; drying temperature was 105°C and time was 4 h; calcination temperature was 500°C and time was 5 h. Then the complex catalysts prepared under the optimal conditions were applied to synthesize biodiesel, and the effects of dose of catalyst, reaction temperature, and reaction time on the yield of biodiesel were investigated. At last, the optimal process conditions for synthesis of biodiesel were concluded: methanol-oil ratio was 10:1; catalyst dose was 2% of that of soybean oil; reaction temperature was 65°C; reaction time was 5 h. The yield of as-prepared biodiesel could be 98%.

Study of Electrolyte Components in Li Ion Cells Using Liquid-Liquid Extraction and Gas Chromatography Coupled with Mass Spectrometry

LiCoO2/graphite and LiNi0.33Mn0.33Co0.33O2/graphite Li-ion pouch-type cells filled with 1 M LiPF6 EC: EMC (3:7 by weight) with the additives vinylene carbonate (VC) or vinyl ethylene carbonate (VEC) were prepared. Some cells underwent partial or complete formation while others underwent full formation followed by charge-discharge cycling or high potential storage. Following a simple liquid-liquid extraction step, the mass ratios of the organic components of the electrolyte were analyzed using gas chromatography (GC) coupled with electron impact mass spectroscopy (MS). This semi-quantitative method proved to be very effective for the removal of the LiPF6 from the electrolyte, thus preventing damage to the gas chromatograph and mass spectrometer. It also allowed for a quick and simple assessment of the consumption of additives as a function of state of charge and cycling. The purpose of this paper is to make this method widely available to the Li-ion battery research community.

Composite spectra XIX: HD 208253, a long‐period binary whose hot secondary has enhanced strontium and barium

AbstractWe separate and analyse the component spectra of the composite‐spectrum binary HD 208253. We find that the cool primary is an evolving star of spectral type G7 III, while its hot secondary is an early‐A dwarf. The giant is currently near the lowest point of the red‐giant branch and is slightly less luminous than its dwarf companion. We provide a set of precise radial‐velocity measurements for both stars. The double‐lined orbit which we derive from them shows that the component mass ratio is close to unity (q = 1.05 ± 0.01). We deduce the physical properties of both stars, determine their respective masses to be 2.75 ± 0.07 Me (giant) and 2.62 ± 0.07 Me (dwarf), and show that the orbit's inclination is within a degree or two of 68°. The spectrum of the A‐type component has quite component has quite narrow lines (we infer a rotational velocity of 18 km s–1), though since the period of the orbit is well over 1 year that component cannot be in synchronous rotation. An intriguing property of the dwarf is its enhanced Sr and Ba, though it does not exhibit the other spectral peculiarities that would signal a classical Am star. While by no means unique amongst the multitude of oddities exhibited by A and early‐F stars, this dwarf which we have uncovered in a long‐period binary offers valuable constraints and challenges to stellar‐evolution theory. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Capture of Terrestrial-Sized Moons by Gas Giant Planets

Terrestrial moons with masses >0.1 M (symbol in text) possibly exist around extrasolar giant planets, and here we consider the energetics of how they might form. Binary-exchange capture can occur if a binary-terrestrial object (BTO) is tidally disrupted during a close encounter with a giant planet and one of the binary members is ejected while the other remains as a moon. Tidal disruption occurs readily in the deep gravity wells of giant planets; however, the large encounter velocities in the wells make binary exchange more difficult than for planets of lesser mass. In addition, successful capture favors massive binaries with large rotational velocities and small component mass ratios. Also, since the interaction tends to leave the captured moons on highly elliptical orbits, permanent capture is only possible around planets with sizable Hill spheres that are well separated from their host stars.

Influence of gelatin–sodium stearoyl lactylate interaction on the rheological properties of gelatin gels

Addition of surfactants to the polymer solutions induces changes in the bulk of solutions as well as at the interface due to their interactions, thus changing the properties of the systems. Therefore, investigations of these interactions have a great practical and theoretical interest. In the present study, interaction between gelatin and anionic surfactant sodium stearoyl lactylate (SSL) was investigated by different methods. Conductometry and tensiometry were applied to define a region of gelatin–SSL interaction. On the basis of these investigations: cac, defined as concentration at which SSL molecules start to form aggregates with gelatin molecules, and psp at which interaction finishes, were determined. Solutions of gelatin–SSL mixtures at characteristic mass ratios of components were prepared for detailed rheological investigations. Considering that gel formation and network stabilization is time dependent, rheological measurements were performed on gels after 2 and 6 days of storage. Rheological and viscoelastic investigations showed that the presence of SSL molecules influence gelatin ability for gel formation. Increase in SSL concentration decreases thixotropy of gelatin gels which show more viscose, fluid-like properties.

Analysis of reflection effects in HS 2333+3927

The results of photometric and spectroscopic observations of the pre-cataclysmic variable HS 2333+3927, which is a HW Vir binary system, are analyzed. The parameters of the sdB subdwarf companion (Teff = 37 500 ± 500 K, log g = 5.7 ± 0.05) and the chemical composition of its atmosphere are refined using a spectrum of the binary system obtained at minimum brightness. Reflection effects can fully explain the observed brightness variations of HS 2333+3927, changes in the HI and HeI line profiles, and distortions of the radial-velocity curve of the primary star. A new method for determining the component-mass ratios in HW Vir binaries, based on their radial-velocity curves and models of irradiated atmospheres, is proposed. The set of parameters obtained for the binary components corresponds to models of horizontal-branch sdB subdwarfs and main-sequence stars.

Search for gravitational waves from intermediate mass binary black holes

We present the results of a weakly modeled burst search for gravitational waves from mergers of non-spinning intermediate mass black holes (IMBH) in the total mass range 100--450 solar masses and with the component mass ratios between 1:1 and 4:1. The search was conducted on data collected by the LIGO and Virgo detectors between November of 2005 and October of 2007. No plausible signals were observed by the search which constrains the astrophysical rates of the IMBH mergers as a function of the component masses. In the most efficiently detected bin centered on 88+88 solar masses, for non-spinning sources, the rate density upper limit is 0.13 per Mpc^3 per Myr at the 90% confidence level.

Dual-source dual-power electrospinning and characteristics of multifunctional scaffolds for bone tissue engineering.

Electrospun tissue engineering scaffolds are attractive due to their distinctive advantages over other types of scaffolds. As both osteoinductivity and osteoconductivity play crucial roles in bone tissue engineering, scaffolds possessing both properties are desirable. In this investigation, novel bicomponent scaffolds were constructed via dual-source dual-power electrospinning (DSDPES). One scaffold component was emulsion electrospun poly(d,l-lactic acid) (PDLLA) nanofibers containing recombinant human bone morphogenetic protein (rhBMP-2), and the other scaffold component was electrospun calcium phosphate (Ca–P) particle/poly(lactic-co-glycolic acid) (PLGA) nanocomposite fibers. The mass ratio of rhBMP-2/PDLLA fibers to Ca–P/PLGA fibers in bicomponent scaffolds could be controlled in the DSDPES process by adjusting the number of syringes used to supply solutions for electrospinning. Through process optimization, both types of fibers could be evenly distributed in bicomponent scaffolds. The structure and properties of each type of fibers in the scaffolds were studied. The morphological and structural properties and wettability of scaffolds were assessed. The effects of emulsion composition for rhBMP-2/PDLLA fibers and mass ratio of fibrous components in bicomponent scaffolds on in vitro release of rhBMP-2 from scaffolds were investigated. In vitro degradation of scaffolds was also studied by monitoring their morphological changes, weight losses and decreases in average molecular weight of fiber matrix polymers.

Gravothermal oscillations in two-component models of star clusters

In this paper, gravothermal oscillations are investigated in two-component clusters with a range of different stellar mass ratios and total component mass ratios. The critical number of stars at which gravothermal oscillations first appeared is found using a gas code. The nature of the oscillations is investigated and it is shown that the oscillations can be understood by focusing on the behaviour of the heavier component, because of mass segregation. It is argued that, during each oscillation, the re-collapse of the cluster begins at larger radii while the core is still expanding. This re-collapse can halt and reverse a gravothermally driven expansion. This material outside the core contracts because it is losing energy both to the cool expanding core and to the material at larger radii. The core collapse times for each model are also found and discussed. For an appropriately chosen case, direct N -body runs were carried out, in order to check the results obtained from the gas model, including evidence of the gravothermal nature of the oscillations and the temperature inversion that drives the expansion.

Gap discrete breathers in a two-component two-dimensional crystal in thermal equilibrium

Crystals having a gap in the phonon spectrum can maintain gap discrete breathers (DBs), i.e., nonlinear localized oscillatory modes existing in the absence of defects and having a frequency lying in the gap. The lifetime of gap DBs in a two-dimensional perfect crystal of the composition A 3 B in thermal equilibrium has been studied by the molecular dynamics method. As was shown earlier, the existence of gap DBs in such a crystal is provided by the presence of a wide gap in the phonon spectrum if the component mass ratio m A /m B is sufficiently large. For comparison, a crystal with a relatively small ratio m A /m B is considered when the gap in the spectrum is absent and the existence of gap DBs is impossible in the case of a weak nonlinearity realized in the considered case. It has been shown that, in contrast to the opposite case, in a crystal maintaining gap DBs, long-lived localized oscillatory modes of large amplitude can emerge, whose concentration and lifetime increase with temperature.

Synthetic light curves of close binaries in a cool-disk model. The “hot line” and “hot spot” as visual indicators of interaction between the flow and disk

We present a “combined” model taking into account visual manifestations of the interaction between the gas flow and the accretion disk in a close binary system in the form of a “hot line” and a “hot spot.” The binary consists of a red dwarf that fills its Roche lobe and a compact spherical star (a white dwarf or neutron star) surrounded with a thick ellipsoidal accretion disk of a complex shape. The disk thickness is not large near the compact star but increases according to a parabolic law towards its outer edge. The oblique collision of the gaseous flow with matter of the cool, rotating disk, whose outer edge has a temperature <10 000 K, creates an extended region of enhanced energy release. In the combined model, this region is represented with a hot line that coincides with the optically opaque part of the flow and is located outside the disk, together with a hot spot at the outer surface of the disk, on the leeward side of the flow. The synthetic light curves for the combinedmodel and a hot-line model demonstrate that both models are able to fairly accurately reproduce the shapes of both classical and atypical light curves of cataclysmic variables in quiescence. Our determination of the parameters of the cataclysmic variable OY Car from an analysis of its light curves using the two models shows that the basic characteristics of the close binary, such as the component mass ratio q = M1/M2, orbital inclination i, effective temperatures of the red dwarf (T2) and white dwarf (T1), and orientation of the disk αe, remain the same within the errors. The parameters describing the size of the slightly elliptical disk and the radiation flux from the disk differ by several percent (∼ 2–8%). A more significant difference is detected in the parameters of the hot line, due to the different shape and alignment of the flow and the presence of an additional radiation source—the hot spot—on the disk.

Raman spectroscopy of bio‐SiC ceramics

AbstractBiomorphic SiC ceramics produced by the forced infiltration with liquid silicon of carbon matrices derived from hardwood precursors were investigated. The phase composition of the ceramics obtained was found to be dependent on the mass ratio of the initial silicon and carbon components, the synthesis temperature, and the process duration. Raman spectroscopy (RS) investigations showed that the 3C polytype is formed at a synthesis temperature of about 1550 °C, and that both 3C and 6H‐SiC are formed at temperatures of about 1800 °C. Further temperature rises up to 2100 °C lead to an increase in the fraction of the 6H polytype. In the specimens obtained by impregnation under excess Si conditions, the residual silicon inside the SiC pores is recorded. Analysis of the parameters of phonon peaks allowed us to conclude that the residual silicon in these samples is under significant compressive strain.magnified image Surface morphology of axial profiles of SiC ceramics produced from pear‐tree wood for ψ = 2.33 component mass ratio.

ESTABLISHING α Oph AS A PROTOTYPE ROTATOR: IMPROVED ASTROMETRIC ORBIT

The nearby star Alpha Oph (Ras Alhague) is a rapidly rotating A5IV star spinning at ~89% of its breakup velocity. This system has been imaged extensively by interferometric techniques, giving a precise geometric model of the star's oblateness and the resulting temperature variation on the stellar surface. Fortuitously, Alpha Oph has a previously known stellar companion, and characterization of the orbit provides an independent, dynamically-based check of both the host star and the companion mass. Such measurements are crucial to constrain models of such rapidly rotating stars. In this study, we combine eight years of Adaptive Optics imaging data from the Palomar, AEOS, and CFHT telescopes to derive an improved, astrometric characterization of the companion orbit. We also use photometry from these observations to derive a model-based estimate of the companion mass. A fit was performed on the photocenter motion of this system to extract a component mass ratio. We find masses of 2.40^{0.23}_{0.37} solar masses and 0.85^{0.06}_{0.04} solar masses for Alpha Oph A and Alpha Oph B, respectively. Previous orbital studies of this system found a mass too high for this system, inconsistent with stellar evolutionary calculations. Our measurements of the host star mass are more consistent with these evolutionary calculations, but with slightly higher uncertainties. In addition to the dynamically-derived masses, we use IJHK photometry to derive a model-based mass for Alpha Oph B, of 0.77 +/- 0.05 solar masses marginally consistent with the dynamical masses derived from our orbit. Our model fits predict a periastron passage on 2012 April 19, with the two components having a ~50 milliarcsec separation from March to May 2012. A modest amount of interferometric and radial velocity data during this period could provide a mass determination of this star at the few percent level.

ON THE REALITY OF THE SUGGESTED PLANET IN THE ν OCTANTIS SYSTEM

The aim of this study is to explore an enigmatic finding about the ν Octantis binary system that indicates the possible existence of a Jupiter-type planet even though the planet seems to be located outside the zone of orbital stability. We perform a detailed analysis of orbital stability based on previous studies that carefully considers the ν Octantis system parameters including their observationally deduced uncertainties. In our analysis, we confront the probability distribution of the parameter space of the system with the requirements of planetary orbital stability. Our results indicate that the suggested planet, if in a prograde orbit with respect to the motion of the binary components, is virtually impossible. However, the estimated probability of existence for a planet in a retrograde orbit is nearly 60%, an estimate that encapsulates the probability distribution of the mass ratio of the stellar components. This estimate increases if a relatively low stellar mass ratio (within the error bars) is assumed. The principal possibility of a planet in a retrograde orbit is also consistent with long-term orbital stability simulations pursued as part of our study. Thus, the existence of the suggested planet in the ν Octantis system constitutes a realistic possibility.

Brightness oscillations in models of young binary systems with low-mass secondary components

We consider a model for the cyclic brightness variations of a young star with a low-mass companion that accretes matter from the remnants of a protostellar cloud. At small inclinations of the binary orbit to the line of sight, the streams of matter and the density waves excited in the circumbinary disk can screen the primary component of the binary from the observer. To study these phenomena, we have computed grids of hydrodynamic models for binary systems by the SPH method based on which we have constructed the phase light curves as a function of the rotation angle of the apsidal line relative to the observer. The model parameters were varied within the following ranges: the component mass ratio q = 0.01-0.1 and the eccentricity e = 0-0.5. We adopted optical grain characteristics typical of circumstellar dust. Our computations have shown that the brightness oscillations with orbital phase can have a complex structure. The amplitudes and shapes of the light curves depend strongly on the inclination of the binary orbit and its orientation relative to the observer and on the accretion rate. The results of our computations are used to analyze the cyclic activity of UX Ori stars.

Bimodal brightness oscillations in models of young binary systems

We consider a model for the cyclic activity of young binary stars that accrete matter from the remnants of a protostellar cloud. If the orbit of such a binary system is inclined at a small angle to the line of sight, then the streams of matter and the density waves excited in the circumbinary disk can screen the primary component of the binary from the observer. To study these phenomena by the SPH (smoothed particle hydrodynamics) method, we have computed grids of hydrodynamic models for binary systems based on which we have constructed the light curves as a function of the orbital phase.The main emphasis is on investigating the properties of the brightness oscillations. Therefore, the model parameters were varied within the following ranges: the component mass ratio q = M2 : M1 = 0.2 - 0.5 and the eccentricity e = 0 - 0.7. The parameter that defined the binary viscosity was also varied. We adopted optical grain characteristics typical of circumstellar dust. Our computations have shown that bimodal oscillations are excited in binaries with eccentric orbits, provided that the binary components do not differ too much in mass. In this case, the ratios of the periods and amplitudes of the bimodal oscillations and their shape depend strongly on the inclination of the binary plane and its orientation relative to the observer. Our analysis shows that the computed light curves can be used in interpreting the cyclic activity of UX Ori stars.

10.1007/s11444-008-1005-2

Three-dimensional numerical hydrodynamical modeling of a radiative wind and accretion disk in a close binary system with a compact object is carried out, using the massive X-ray binary LMC X-3 as an example. This system contains a precessing disk, and may have relativistic jets. These computations show that an accretion disk with a radius of about 0.20 (in units of the component separation) forms from the radiative wind from the donor when the action of the wind on the central source is taken into account, when the accretion rate is equal to the observed value (about 3.0 × 10−8 M ⊙/year, which corresponds to the case when the donor overflows its Roche lobe by nearly 1%). It is assumed that the speed of the donor wind at infinity is about 2200 km/s. The disk that forms is geometrically thick and nearly cylindrical in shape, with a low-density tunnel at its center extending from the accretor through the disk along the rotational axis. We have also modeled a flare in the disk due to short-term variations in the supply of material through the Lagrange point L1, whose brightnesses and durations are able to explain flares in cataclysmic variables and X-ray binaries. The accretion disk is not formed when the donor underfills its Roche lobe by 0.5%, which corresponds to an accretion rate onto the compact object of 2.0 × 10−9 M ⊙/year. In place of a disk, an accretion envelope with a radius of about 0.03 forms, within which gas moves along very steep spiral trajectories before falling onto the compact object. As in the accretion-disk case, a tunnel forms along the rotational axis of the accretion envelope; a shock forms behind the accretor, where flares occur in a compact region a small distance from the accretor at a rate of about six flares per orbital period, with amplitudes of about 10 m or more. The flare durations are two to four minutes, and the energies of individual particles at the flare maximum are about 100–150 keV. These flares appear to be analogous to the flares observed in gamma-ray and X-ray burst sources. We accordingly propose a model in which these phenomena are associated with massive, close X-ray binary systems with component-mass ratios exceeding unity, in which the donor does not fill its Roche lobe. Although no accretion disk forms around the compact object, an accretion region develops near the accretor, where the gamma-ray and X-ray flares occur.

Tracing the young massive high-eccentricity binary system $\theta^{\mathsf 1}$Orionis C through periastron passage

Context. The nearby high-mass star binary system θ 1 Ori C is the brightest and most massive of the Trapezium OB stars at the core of the Orion Nebula Cluster, and it represents a perfect laboratory to determine the fundamental parameters of young hot stars and to constrain the distance of the Orion Trapezium Cluster. Aims. By tracing the orbital motion of the θ 1 Ori C components, we aim to refine the dynamical orbit of this important binary system. Methods. Between January 2007 and March 2008, we observed θ 1 Ori C with VLTI/AMBER near-infrared (H -a ndK-band) longbaseline interferometry, as well as with bispectrum speckle interferometry with the ESO 3.6 m and the BTA 6 m telescopes (B � and V � -band). Combining AMBER data taken with three different 3-telescope array configurations, we reconstructed the first VLTI/AMBER closure-phase aperture synthesis image, showing the θ 1 Ori C system with a resolution of ∼2 mas. To extract the astrometric data from our spectrally dispersed AMBER data, we employed a new algorithm, which fits the wavelength-differential visibility and closure phase modulations along the H -a ndK-band and is insensitive to calibration errors induced, for instance, by changing atmospheric conditions. Results. Our new astrometric measurements show that the companion has nearly completed one orbital revolution since its discovery in 1997. The derived orbital elements imply a short-period (P ≈ 11.3 yr) and high-eccentricity orbit (e ≈ 0.6) with periastron passage around 2002.6. The new orbit is consistent with recently published radial velocity measurements, from which we can also derive the first direct constraints on the mass ratio of the binary components. We employ various methods to derive the system mass (Msystem = 44 ± 7 M� ) and the dynamical distance (d = 410 ± 20 pc), which is in remarkably good agreement with recently published trigonometric parallax measurements obtained with radio interferometry.

Volumetric relaxation in simple liquid: Molecular dynamics simulation

The example of a mixture of simple liquids with Lennard-Jones potentials and soft spheres is used for considering the general principles of relaxation of energy in dense media. The processes of relaxation to uniform velocity distribution are studied, and the main stages of relaxation from nonisothermal state are identified. The dependences of characteristic relaxation times on parameters of the medium such as the density, initial temperature, and the mass ratio of components of the mixture are obtained. The results are compared with the data on nonideal plasma for determining the importance of the concrete interaction potential.

Stabilizing the slag conditions in blast-furnace smelting at OAO Zaporozhstal

828 The blast-furnace process is greatly influenced by the quality of the iron ore, which determines the composition, properties, and formation of the smelting products. In smelting multicomponent batch—in particular, the batch used in blast furnace 2 at OAO Zaporozhstal—each component generates a characteristic liquid phase of definite composition and properties, which in most cases are not well suited to the furnace. Accordingly, we need to establish an optimal ratio of the batch components, corresponding to the formation of primary and final slags of specified composition. In calculating the composition and properties of the smelting products from the specified initial chemical composition and mass ratio of the batch components, the use of constant interphase distribution coefficients does not always ensure satisfactory results. Stabilizing the Slag Conditions in Blast-Furnace Smelting at OAO Zaporozhstal N. V. Krutas a, A. V. Kaz’min a , M. E. Sharanov a , V. V. Mandra a, and D. A. Stepanenko b