bluuebunny/crossref_metadata_2025_split huggingface dataset:
Candida tropicalis BPU1, a novel isolate from the rumen of the Malabari goat, is a dual producer of biosurfactant and polyhydroxybutyrate
Authors: Priji Prakasan , Unni K. N. , Sajith S. , Benjamin Sailas 
Published: January 2013

AbstractThis unique study reports a new strain (BPU1) of Candida tropicalis isolated from the rumen of the Malabari goat, showing dual production of biosurfactant and polyhydroxybutyrate. C. tropicalis strain BPU1, a facultative anaerobe, was tuned to become an aerobe in specially designed flask, the Benjamin flask. The puffy circular colonies were smooth, white‐to‐cream in colour, with pseudo‐filaments. The strain fermented glucose, sucrose, maltose and dextrose, but not lactose and cellulose. It assimilated (NH4)2SO4, peptone, glycine and arginine, but not NaNO3, as the nitrogen source. Interestingly, it utilized groundnut oil (up to 0.3%) in a specially designed basal mineral salt medium (BSM). Its capability for dual production of a biosurfactant and a polyhydroxybutyarate (PHB) was explored by various methods from the BSM–oil medium. Extracted biosurfactant from 6 day‐old culture was biochemically characterized as a complex of lipid and carbohydrate with an Rf value of 0.88 by thin layer chromatography. Its PHB production was confirmed by specific staining methods with Nile blue sulphate, Sudan black B and Sudan 3. Briefly, this first‐ever report gives ample physical evidence for the dual production of a glycolipid (biosurfactant) and PHB by C. tropicalis strain BPU1 on a specially designed medium, which would open up elaborate research on this yeast. Copyright © 2013 John Wiley & Sons, Ltd.
Solutions to Exercises
Authors: Minty Michiko G. , Zimmermann Frank 
Published: January 2013

AbstractFrom (1.12) at a fixed location s we can write
$$x = \sqrt {2{I_x}{\beta _x}} \cos {\phi _x},$$
where φx includes the initial phase φ0 We then have
$$\begin{array}{*{20}{c}}{{{ \in }_{x}} = \frac{{\left\langle {{{x}^{2}}\left( s \right)} \right\rangle }}{{{{\beta }_{x}}\left( s \right)}}} \\{ = \int {d{{\phi }_{x}}d{{I}_{x}}2{{I}_{x}}{{{\cos }}^{2}}{{\phi }_{x}}\rho \left( {{{I}_{x}},{{\phi }_{x}}} \right)} } \\{ = \int {d{{\phi }_{x}}d{{I}_{x}}2{{I}_{x}}{{{\cos }}^{2}}{{\phi }_{x}}\rho \left( {{{I}_{x}}} \right)\frac{1}{{2\pi }}} } \\{ = \int {d{{I}_{x}}{{I}_{x}}\rho \left( {{{I}_{x}}} \right) = \left\langle {{{I}_{x}}} \right\rangle .} } \\\end{array}$$
Orbit Measurement and Correction
Authors: Minty Michiko G. , Zimmermann Frank 
Published: January 2013

AbstractIn practice, there are many uncertainties whose presence must be appreciated when correcting the beam orbit in both linear and circular accelerators. Such uncertainties include the variations in the electronic and/or mechanical centers of the beam position monitors (BPMs), in the magnetic center of the quadrupoles (inside which the position monitors are often mounted), or in the electromagnetic center of accelerating structures. Consider the case illustrated in Fig. 3.1.
Antenatal manifestations of mitochondrial disorders
Authors: Tavares Mariana Vide , Santos Maria João , Domingues Ana Patrícia , Pratas João , Mendes Cândida , Simões Marta , Moura Paulo , Diogo Luísa , Grazina Manuela 
Published: January 2013

AbstractMitochondrial respiratory chain diseases are a heterogeneous group of pathologies caused by genetic alterations affecting mitochondrial energy production. Theoretically, this deficiency may lead to any symptoms, in any organ or tissue, at any age even before birth. The aim of our study was to identify the frequency and characterize antenatal manifestations identifying possible associations between mitochondrial disease and more specific and earlier manifestation. We retrospectively review the files of 44 paediatric subjects with genetic and biochemical alterations of respiratory chain identified in the first decade of life and compare data with a control group (n = 88). Our results show that maternal age was similar in both groups. The female gender was predominant in patients group. Gestational age at delivery was similar in both groups. Concerning birth weight, it was significantly lower (p = 0.001) in patients (2899.9 ± 538.3 vs. 3246.6 ± 460.2 g). Fifteen pregnancies of the patients group were considered abnormal. Our findings show that intrauterine growth restriction was the most frequent antenatal feature observed. Neonatal morbidity was significantly higher (fivefold) in patients (p < 0.001). The clinical findings are independent of the molecular defect type. Our results are preliminary and more studies are needed, in order to learn more about mitochondrial physiology and activity in embryological development for the assessment of mitochondrial disease progress in fetal life. However, the present work is a significant contribution, given the scarcity of information in this field.
Nonlinear optimal perturbations in a Couette flow: bursting and transition
Authors: Cherubini S. , De Palma P. 
Published: January 2013

AbstractThis paper provides the analysis of bursting and transition to turbulence in a Couette flow, based on the growth of nonlinear optimal disturbances. We use a global variational procedure to identify such optimal disturbances, defined as those initial perturbations yielding the largest energy growth at a given target time, for given Reynolds number and initial energy. The nonlinear optimal disturbances are found to be characterized by a basic structure, composed of inclined streamwise vortices along localized regions of low and high momentum. This basic structure closely recalls that found in boundary-layer flow (Cherubini et al., J. Fluid Mech., vol. 689, 2011, pp. 221–253), indicating that this structure may be considered the most ‘energetic’ one at short target times. However, small differences in the shape of these optimal perturbations, due to different levels of the initial energy or target time assigned in the optimization process, may produce remarkable differences in their evolution towards turbulence. In particular, direct numerical simulations have shown that optimal disturbances obtained for large initial energies and target times induce bursting events, whereas for lower values of these parameters the flow is directly attracted towards the turbulent state. For this reason, the optimal disturbances have been classified into two classes, the highly dissipative and the short-path perturbations. Both classes lead the flow to turbulence, skipping the phases of streak formation and secondary instability which are typical of the classical transition scenario for shear flows. The dynamics of this transition scenario exploits three main features of the nonlinear optimal disturbances: (i) the large initial value of the streamwise velocity component; (ii) the streamwise dependence of the disturbance; (iii) the presence of initial inclined streamwise vortices. The short-path perturbations are found to spend a considerable amount of time in the vicinity of the edge state (Schneider et al., Phys. Rev. E, vol. 78, 2008, 037301), whereas the highly dissipative optimal disturbances pass closer to the edge, but they are rapidly repelled away from it, leading the flow to high values of the dissipation rate. After this dissipation peak, the trajectories do not lead towards the turbulent attractor, but they spend some time in the vicinity of an unstable periodic orbit (UPO). This behaviour led us to conjecture that bursting events can be obtained not only as homoclinic orbits approaching the UPO, as recently found by van Veen & Kawahara (Phys. Rev. Lett., vol. 107, 2011, p. 114501), but also as heteroclinic orbits between the equilibrium solution on the edge and the UPO.
A thermo-mechanically consistent Burnett regime continuum flow equation without Chapman–Enskog expansion
Authors: Dadzie S. Kokou 
Published: January 2013

AbstractChapman–Enskog expansion is the orthodox approach to derive continuum flow models from Boltzmann’s kinetic equation for dilute gases. Beyond the Navier–Stokes–Fourier order these models, known as Burnett hydrodynamic-regime equations, violate a number of fundamental mechanical and thermodynamic principles in their original forms. This has generated a widely investigated problem in the kinetic theory of gases. In this short article, we derive a Burnett hydrodynamic-regime continuum model that is systematically consistent with all known mechanical and thermodynamic principles without using any series expansion. A close comparison with the conventional Burnett hydrodynamic set of equations is made and the linear stabilities around an equilibrium point under small perturbations are presented.
Flows in annuli with longitudinal grooves
Authors: Moradi H. V. , Floryan J. M. 
Published: January 2013

AbstractAnalysis of pressure losses in laminar flows through annuli fitted with longitudinal grooves has been carried out. The additional pressure gradient required in order to maintain the same flow rate in the grooved annuli, as well as in the reference smooth annuli, is used as a measure of the loss. The groove-induced changes can be represented as a superposition of a pressure drop due to a change in the average position of the bounding cylinders and a pressure drop due to flow modulations induced by the shape of the grooves. The former effect can be evaluated analytically while the latter requires explicit computations. It has been demonstrated that a reduced-order model is an effective tool for extraction of the features of groove geometry that lead to flow modulations relevant to drag generation. One Fourier mode from the Fourier expansion representing the annulus geometry is sufficient to predict pressure losses with an accuracy sufficient for most applications in the case of equal-depth grooves. It is shown that the presence of the grooves may lead to a reduction of pressure loss in spite of an increase of the surface wetted area. The drag-decreasing grooves are characterized by the groove wavenumber $M/ {R}_{1} $ being smaller than a certain critical value, where $M$ denotes the number of grooves and ${R}_{1} $ stands for the radius of the annulus. This number marginally depends on the groove amplitude and does not depend on the flow Reynolds number. It is shown that the drag reduction mechanism relies on the re-arrangement of the bulk flow that leads to the largest mass flow taking place in the area of the largest annulus opening. The form of the optimal grooves from the point of view of the maximum drag reduction has been determined. This form depends on the type of constraints imposed. In general, the optimal shape can be described using the reduced-order model involving only a few Fourier modes. It is shown that in the case of equal-depth grooves, the optimal shape can be approximated using a special form of trapezoid. In the case of unequal-depth grooves, where the groove depth needs to be determined as part of the optimization procedure, the optimal geometry, consisting of the optimal depth and the corresponding optimal shape, can be approximated using a delta function. The maximum possible drag reduction, corresponding to the optimal geometry, has been determined.
Nonlinear stability, bifurcation and vortical patterns in three-dimensional granular plane Couette flow
Authors: Alam Meheboob , Shukla Priyanka 
Published: January 2013

AbstractThe effects of three-dimensional (3D) perturbations, having wave-like modulations along both the streamwise and spanwise/vorticity directions, on the nonlinear states of five types of linear instability modes, the nature of their bifurcations and the resulting nonlinear patterns are analysed for granular plane Couette flow using an order-parameter theory which is an extension of our previous work on two-dimensional (2D) perturbations (Shukla & Alam, J. Fluid Mech., vol. 672, 2011b, pp. 147–195). The differential equations for modal amplitudes (the fundamental mode, the mean-flow distortion, the second harmonic and the distortion of the fundamental mode), up to cubic-order in perturbation amplitude, are solved using a spectral-based numerical technique, yielding an estimate of the first Landau coefficient that accounts for the leading-order nonlinear effect on finite-amplitude perturbations. In the near-critical regime of flows, we found evidence of mean-flow resonance, characterized by the divergence of the first Landau coefficient, that occurs due to the interaction/resonance between a linear instability mode and a mean-flow mode. The nonlinear solutions are found to appear via both pitchfork and Hopf bifurcations from the underlying linear instability modes, leading to supercritical nonlinear states of stationary and travelling wave solutions. The subcritical travelling wave solutions have also been uncovered in the linearly stable regimes of flow. It is shown that multiple nonlinear states of both stationary and travelling waves can coexist for a given parameter combination of mean density and Couette gap. The 3D nonlinear solutions persist for a range of spanwise wavenumbers up to ${k}_{z} = O(1)$ that originate from 2D instabilities which occur beyond a moderate value of the mean density. For purely 3D instabilities in dilute flows (having no analogue in 2D flows), the supercritical finite-amplitude solutions persist for a much larger range of spanwise wavenumber up to ${k}_{z} = O(10)$. For all instabilities, the vortical motion on the cross-stream plane has been characterized in terms of the fixed/critical points of the underlying flow field: saddles, nodes (sources and sinks) and vortices have been identified. While the cross-stream velocity field for supercritical solutions in dilute flows contains nodes and saddles, the subcritical solutions are dominated by large-scale vortices in the background of saddle-node-type motions. The latter type of flow pattern also persists at moderate densities in the form of supercritical nonlinear solutions that originate from the dominant 2D instability modes for which the vortex appears to be driven by two nearby saddles. The location of this vortex is found to be correlated with the local maxima of the streamwise vorticity.
Invariants of the reduced velocity gradient tensor in turbulent flows
Authors: Cardesa J. I. , Mistry D. , Gan L. , Dawson J. R. 
Published: January 2013

AbstractIn this paper we examine the invariants $p$ and $q$ of the reduced $2\times 2$ velocity gradient tensor (VGT) formed from a two-dimensional (2D) slice of an incompressible three-dimensional (3D) flow. Using data from both 2D particle image velocimetry (PIV) measurements and 3D direct numerical simulations of various turbulent flows, we show that the joint probability density functions (p.d.f.s) of $p$ and $q$ exhibit a common characteristic asymmetric shape consistent with $\langle pq\rangle \lt 0$. An explanation for this inequality is proposed. Assuming local homogeneity we derive $\langle p\rangle = 0$ and $\langle q\rangle = 0$. With the addition of local isotropy the sign of $\langle pq\rangle $ is proved to be the same as that of the skewness of $\partial {u}_{1} / \partial {x}_{1} $, hence negative. This suggests that the observed asymmetry in the joint p.d.f.s of $p{{\ndash}}q$ stems from the universal predominance of vortex stretching at the smallest scales. Some advantages of this joint p.d.f. compared with that of $Q{{\ndash}}R$ obtained from the full $3\times 3$ VGT are discussed. Analysing the eigenvalues of the reduced strain-rate matrix associated with the reduced VGT, we prove that in some cases the 2D data can unambiguously discriminate between the bi-axial (sheet-forming) and axial (tube-forming) strain-rate configurations of the full $3\times 3$ strain-rate tensor.
Asymmetrical Dynamic Propagation Problem on the Edges of Mode III Interface Crack Subjected to Superimpose Loads
Authors: Lü N.-C. , Li X.-G. , Cheng Y.-H. , Cheng J. 
Published: January 2013

AbstractBy application of the theory of complex variable functions, asymmetrical dynamic propagation problem on the edges of mode III interface crack subjected to superimpose loads was studied. Analytical solutions of the stresses displacements and dynamic stress intensity factors are obtained by means of self- similar functions. The problems researched can be facilely transformed into Riemann-Hilbert problems and their closed solutions are attained rather simple according to this measure. After those solutions are utilized by superposition theorem, the solutions of arbitrarily complex problems can be gained.
Static and Dynamic Mathematical Modeling of a Micro Gas Turbine
Authors: Hosseinalipour S. M. , Abdolahi E. , Razaghi M. 
Published: January 2013

AbstractThis paper presents a static and linear dynamic model to simulate the performance of a Micro Gas Turbine (MGT). The static model is obtained using thermodynamic equations and maps of the components to determine off design performance of the MGT with constant output power. The linear dynamic model is developed using linearized static and dynamic nonlinear equations around an operating point as state-space model to predict the behaviour of the MGT in transient conditions. To validate the results of the static model, important information such as fuel flow, fuel to air ratio, and turbine inlet temperature are compared with the results of Aspen-HYSYS software during an increase in ambient temperature. In addition, static model results are compared with experimental data of the MGT test by previous studies. Also, the compressor equilibrium running line of the MGT is derived in constant ambient condition. In order to evaluate the linear dynamic model, the verification is performed using the results of nonlinear model of previous studies. The comparison between the results confirms the ability of proposed dynamic model to simulate a MGT while decreasing the computational effort and complexity of equations. Moreover, a comparison is carried out between static model results and steady state values predicted by dynamic model.
Effects of Hall Current and Ion-Slip on MHD Flow Induced by Torsional Oscillations of a Disc in a Rotating Fluid
Authors: Ghara N. , Das S. , Maji S. L. , Jana R. N. 
Published: January 2013

AbstractThe unsteady hydromagnetic flow due to torsional oscillations of a rotating disc in a viscous incompressible electrically conducting fluid which is also rotating is studied taking the effects of the Hall current and ion-slip into consideration. The governing equations are solved analytically. The results show that the inclusion of the Hall current and ion slip have important effects on the velocity distributions as well as shear stresses at the disc. The flow is characterized by two opposite circularly polarized waves, travelling with different velocities. It is found that there is a formation of two-deck boundary layers, thicknesses of which increase with increase in either Hall parameter or ion-slip parameter. The radial velocity increases with an increase in Hall parameter and the azimuthal velocity increases with an increase in either Hall parameter or ion-slip parameter. Further, it is found that the amplitude of the transverse shear stress at the disc decreases with an increase in either Hall parameter or ion-slip parameter.
Theoretical Analysis of Diffusion Flames Using Perturbation Method for Different Lewis and Damkohler Numbers
Authors: Bidabadi Mehdi , Asadollahzadeh Payam , Meibudy Mohammad N. P. 
Published: January 2013

AbstractThis paper presents a two dimensional asymptotic model of counterflow diffusion flame in the presence of radiation heat loss. The fuel and oxidizer, respectively, are injected from left and right hand side of the flame. The effects of burning rate, Lewis and Damkohler number on the structure and extinction of the flame is studied using perturbation method. To do so, the structure of the flame is considered to be composed of reaction zone with a thickness of O(ε) and radiation heat loss zone, of O(δ) thickness, that sandwiches the reaction zone. The effect of burning rate is illustrated by burning pre-exponential parameter, B. It is found that with the increase of the parameter, the flame temperature is also increased, and flame location moves toward the fuel side. In addition, the variation of Lewis number of fuel and oxidizer has a significant effect on the location and temperature of the flame.
Cordycepin (3′-deoxyadenosine) pentostatin (deoxycoformycin) combination treatment of mice experimentally infected withTrypanosoma evansi
Authors: ROSA LUCIANA DALLA , DA SILVA ALEKSANDRO S. , GRESSLER LUCAS T. , OLIVEIRA CAMILA B. , DAMBRÓS MARIA G. C. , MILETTI LUIZ C. , FRANÇA RAQUELI T. , LOPES SONIA T. A. , SAMARA YASMIN N. , DA VEIGA MARCELO L. , MONTEIRO SILVIA G. 
Published: January 2013

SUMMARYThe aim of this study was to evaluate the anti-trypanosomal effect of treatment with 3′-deoxyadenosine (cordycepin) combined with deoxycoformycin (pentostatin: inhibitor of the enzyme adenosine deaminase)in vitroby using mice experimentally infected withTrypanosoma evansi. In vitro, a dose-dependent trypanocidal effect of cordycepin was observed against the parasite. In thein vivotrials, the two drugs were used individually and in combination of different doses. The drugs when used individually had no curative effect on infected mice. However, the combination of cordycepin (2 mg kg−1) and pentostatin (2 mg kg−1) was 100% effective in theT. evansi-infected groups. There was an increase in levels of some biochemical parameters, especially on liver enzymes, which were accompanied by histological lesions in the liver and kidneys. Based on these results we conclude that treatment using the combination of 3′-deoxyadenosine with deoxycoformycin has a curative effect on mice infected withT. evansi. However, the therapeutic protocol tested led to liver and kidney damage, manifested by hepatotoxicity and nephrotoxicity.
Characterization of heat shock protein 70 gene fromHaemonchus contortusand its expression and promoter analysis inCaenorhabditis elegans
Authors: ZHANG HONGLI , ZHOU QIANJIN , YANG YI , CHEN XUEQIU , YAN BAOLONG , DU AIFANG 
Published: January 2013

SUMMARYHaemonchus contortusinfections in small ruminants are of major economic importance worldwide. Heat shock proteins (HSPs) are a family of molecular chaperones that play important roles in the process of invasion and survival of nematodes. Although HSP70 has been identified in several parasitic nematodes, little is known of its distribution and function inHaemonchus contortus. The aims of this study were to characterize HSP70 fromHaemonchus contortus(designed as Hc-hsp70), express Hc-hsp70 and analyse the promoter activity inCaenorhabditis elegans. Bioinformatic analysis revealed that the open reading frame of the Hc-hsp70 cDNA encodes a 646-amino acid peptide, which is highly conserved in comparison to HSP70 in other nematodes. Phylogenetic analysis indicated thatH. contortusis closely related toCaenorhabditis. The 5′-flanking region promoted green fluorescence protein (GFP) expression in the intestine in all larval stages and adult with 2 expression patterns inC. elegans. Expression of Hc-hsp70 mRNA transcripts inC. elegansincreased following 2, 4, 6 h of heat shock and peaked at 4 h. However, its expression induced down-regulation ofhsp-1ofC. elegans. These results suggest that theH. contortushsp70 might have a similar function to that ofC. elegans hsp-1.