bluuebunny/crossref_metadata_2025 huggingface dataset:
A role forfoxd3andsox10in the differentiation of gonadotropin-releasing hormone (GnRH) cells in the zebrafishDanio rerio
Authors: Whitlock Kathleen E. , Smith Kalmia M. , Kim Hannah , Harden Maegan V.
Published: November 2005

Gonadotropin-releasing hormone (GnRH) is found in a wide range of vertebrate tissues, including the nervous system. In general, GnRH has two functions: endocrine, acting as a releasing hormone; and neuromodulatory,affecting neural activity in the peripheral and central nervous system. The best understood population of GnRH cells is that of the hypothalamus, which is essential for reproduction. Less well understood are the populations of GnRH cells found in the terminal nerve and midbrain, which appear to be neuromodulatory in function. The GnRH-containing cells of the midbrain are proposed to arise from the mesencephalic region of the neural tube. Previously, we showed that neuromodulatory GnRH cells of the terminal nerve arise from cranial neural crest. To test the hypothesis that neuromodulatory GnRH cells of the midbrain also arise from neural crest, we used gene knockdown experiments in zebrafish to disrupt neural crest development. We demonstrate that decrement of the function of foxd3 and/or sox10, two genes important for the development and specification of neural crest, resulted in a reduction and/or loss of GnRH cells of the midbrain, as well as a reduction in the number of terminal nerve GnRH cells. Therefore, our data support a neural crest origin for midbrain GnRH cells. Additionally, we demonstrate that knockdown of kallmann gene function resulted in the loss of endocrine GnRH cells of the hypothalamus, but not of neuromodulatory GnRH cells of the midbrain and terminal nerve, thus providing additional evidence for separate pathways controlling the development of neuromodulatory and endocrine GnRH cells.
The RNA-binding protein Squid is required for the establishment of anteroposterior polarity in theDrosophilaoocyte
Authors: Steinhauer Josefa , Kalderon Daniel
Published: November 2005

The heterogeneous nuclear ribonucleoprotein (hnRNP) Squid (Sqd) is a highly abundant protein that is expected to bind most cellular RNAs. Nonetheless, Sqd plays a very specific developmental role in dorsoventral (DV) axis formation during Drosophila oogenesis by localizing gurken(grk) RNA. Here, we report that Sqd is also essential for anteroposterior (AP) axis formation. We identified sqd in a screen for modifiers of the Protein Kinase A (PKA) oogenesis polarity phenotype. The AP defects of sqd mutant oocytes resemble those of PKA mutants in several ways. In both cases, the cytoskeletal reorganization at mid-oogenesis, which depends on a signal from the posterior follicle cells, does not produce a correctly polarized microtubule (MT)network. This causes the posterior determinant, oskar (osk)RNA, to localize to central regions of the oocyte, where it is ectopically translated. Additionally, MT-dependent anterior movement of the oocyte nucleus and the grk-dependent specification of posterior follicle cells are unaffected in both mutants. However, in contrast to PKA mutants, sqd mutants do not retain a discrete posterior MT organizing center(MTOC) capable of supporting ectopic posterior localization of bicoid(bcd) RNA. sqd mutants also display several other phenotypes not seen in PKA mutants; these probably result from the disruption of MT polarity in earlier stages of oogenesis. Loss of Sqd does not affect polarity in follicle cells, wings or eyes, indicating a specific role in the determination of MT polarity within the germline.
A novelC. eleganszinc finger transcription factor,lsy-2, required for the cell type-specific expression of thelsy-6microRNA
Authors: Johnston Robert J. , Hobert Oliver
Published: November 2005

The two Caenorhabditis elegans gustatory neurons, ASE left (ASEL)and ASE right (ASER) are morphologically bilaterally symmetric, yet left/right asymmetric in function and in the expression of specific chemosensory signaling molecules. The ASEL versus ASER cell-fate decision is controlled by a complex gene regulatory network composed of microRNAs (miRNAs) and transcription factors. Alterations in the activities of each of these regulatory factors cause a complete lateral cell-fate switch. Here, we describe lsy-2, a novel C2H2 zinc finger transcription factor that is required for the execution of the ASEL stable state. In lsy-2 null mutants, the ASEL neuron adopts the complete ASER gene expression profile,including both upstream regulatory and terminal effector genes. The normally left/right asymmetric ASE neurons are therefore `symmetrized' in lsy-2 mutants. Cell-specific rescue experiments indicate that lsy-2 is required autonomously in ASEL for the activation of ASEL-specifying factors and the repression of ASER-specifying factors. Genetic epistasis experiments demonstrate that lsy-2 exerts its activity by regulating the transcription of the lsy-6 miRNA in the ASEL neuron,thereby making lsy-2 one of the few factors known to control the cell-type specificity of miRNA gene expression.
Design and Evaluation Measurements of a Swirl Stabilized Laboratory Burner
Authors: Orfanoudakis N G , Hatziapostolou A , Krallis K , Vlachakis N
Published: November 2005

This article presents gas velocity and temperature measurements obtained in a versatile multi-fuel swirl-stabilized laboratory burner of 100 kW total thermal input, which was designed as a scale model of a 110 MW coal burner operating in a cement rotary kiln. The laboratory burner is able to produce flames with different aerodynamic characteristics, namely, the independent adjustment of swirl to axial air and to burn a combination of gaseous, liquid, and pulverized solid fuels; only gaseous fuel, i.e. methane, was used in the present investigation. Experimental measurements were obtained in the near-burner region, with and without combustion, under varying operating conditions. The present investigation was mainly focused on the effect of swirl and its interaction with the combustion process.
An Analytical Method for Elastic-Plastic Stress in a Thermoplastic Composite Cantilever Beam Subjected to Bias-Axis Tension Load
Authors: Wang X , Dong K , Xiao J
Published: November 2005

The paper presents an elastic-plastic stress analysis for a woven steel fibre-reinforced thermoplastic composite cantilever beam subjected to bias-axis tension load. A polynomial stress function is utilized to satisfy both the governing differential equation in the plane stress case and the corresponding boundary conditions for elastic-plastic deformation. An analytical solution for the elastic-plastic problem of the composite beam is obtained by means of Tsai-Hill strength theory of anisotropic material. The composite beam is composed of a steel fibre reinforced low-density polyethylene thermoplastic matrix with exponent hardening material property. In contrast, an elastic-plastic finite element for the same problem is also carried out by applying ANSYS finite element analysis system. Comparing the analytical solution with the finite element solution, it can be found that two kinds of results obtained by making use of two different solving methods are suitably approached. Finally, some examples for thermoplastic composite cantilever beams with two kinds of volume percentage of fibres are carried out and the corresponding results are discussed.
Experimental and Numerical Studies on the Performance of a Polydimethylsiloxane Valveless Micropump
Authors: Kim Y-S , Kim J-H , Na K-H , Rhee K
Published: November 2005

A low cost, simply structured micropump, which is actuated by piezoelectric discs, was fabricated using polydimethylsiloxane. As a flow-rectifying element, diffusers were used instead of passive check valves. To evaluate the performance of a micropump, the deflection of a diaphragm and the flowrate of a pump were measured experimentally for various applied voltages. The deflection of a glass diaphragm was measured using an atomic force microscope. It increased linearly (up to 0.4 μm) with the voltage (up to 150 V) when square voltage waves were applied across a piezoelectric disc. The flowrate of a micropump increased with the applied voltage and decreased with the backpressure. The maximum flowrate was 32.9 μI/min and the shut off pressure was 173 Pa when 150 V square wave voltages were applied at 300 Hz. The micropump was numerically modelled based on the experimentally measured diaphragm deflection-flowrate relationships, and the flow fields were analysed using a numerical method. The calculated flowrates were compared with the experimental measurements, and the results showed that the performance of a micropump could be predicted accurately using a computational model.
Driver Steering Control and a New Perspective on Car Handling Qualities
Authors: Sharp R S
Published: November 2005

The article is about steering control of cars by drivers, concentrating on following the lateral profile of the roadway, which is presumed visible ahead of the car. It builds on previously published work, in which it was shown how the driver's preview of the roadway can be combined with the linear dynamics of a simple car to yield a problem of discrete-time optimal-linear-control-theory form. In that work, it was shown how an optimal ‘driver’ of a linear car can convert the path preview sample values, modelled as deriving from a Gaussian white-noise process, into steering wheel displacement commands to cause the car to follow the previewed path with an attractive compromise between precision and ease.

Recognizing that real roadway excitation is not so rich in high frequencies as white-noise, a low-pass filter is added to the system. The white-noise sample values are filtered before being seen by the driver. Numerical results are used to show that the optimal preview control is unaltered by the inclusion of the low-pass filter, whereas the feedback control is affected diminishingly as the preview increases. Then, using the established theoretical basis, new results are generated to show time-invariant optimal preview controls for cars and drivers with different layouts and priorities. Tight and loose controls, representing different balances between tracking accuracy and control effort, are calculated and illustrated through simulation. A new performance criterion with handling qualities implications is set up, involving the minimization of the preview distance required. The sensitivities of this distance to variations in the car design parameters are calculated. The influence of additional rear wheel steering is studied from the viewpoint of the preview distance required and the form of the optimal preview gain sequence. Path-following simulations are used to illustrate relatively high-authority and relatively low-authority control strategies, showing manoeuvring well in advance of a turn under appropriate circumstances.

The results yield new insights into driver steering control behaviour and vehicle design optimization. The article concludes with a discussion of research in progress aimed at a further improved understanding of how drivers control their vehicles.
Experimental and Numerical Investigation of the Flow in a Vaneless Diffuser of a Centrifugal Compressor Stage. Part 1: Experimental Investigation
Authors: Sato T , Oh J M , Engeda A
Published: November 2005

The flow in a radial vaneless diffuser downstream of a centrifugal compressor is highly complex, as the flow is turbulent, unsteady, viscous, and three-dimensional. Depending on the initial state of the end-wall boundary layers and the diffuser length, the flow may become fully developed or may separate from one of the walls. Therefore, to improve the diffuser performance, it is important to understand the flow field in the diffuser in detail. As the diffuser width is generally very small for most radial stages and an adverse pressure gradient exists, secondary flows are generated, making the flow fields more complicated. In addition, skewed boundary layers form on the wall surfaces. As flowrate is reduced, the flow field becomes more complicated and leads to rotating stall.

This article presents detailed flow measurements in a vaneless diffuser of a centrifugal compressor stage with a very high flow coefficient radial impeller. Usually, centrifugal compressors with radial impellers are designed in the flow coefficient (ϕ) range ϕ = 0.01 - 0.16. Often, the need arises to design higher flow coefficient, ϕ, radial stages.

Detailed measurements were carried out in the vaneless diffuser at seven radial positions downstream of a radial impeller designed for a very high flow coefficient of ϕ = 0.2. The experimental investigation was carried at four rotational speeds 13 000, 15 500, 18 000, and 20 500 r/min, but only the result of 20 500 r/min at near-design-point flowrate (5.11 kg/s) is reported in this article.
Experimental and Numerical Investigation of the Flow in a Vaneless Diffuser of a Centrifugal Compressor Stage. Part 2: Numerical Investigation
Authors: Sato T , Oh J M , Engeda A
Published: November 2005

As user demands grew for improved performance and more reliable equipment and as compressor vendors sought improved analytical and design methodologies, the application of computational fluid dynamics (CFD) in the industrial world became a necessity. Fortunately, large increases in available, economic computing power together with development of improved computational methods now provide the industrial designer with much improved analytic capability. As CFD algorithms and software have continued to be developed and refined, it remains essential that validation studies be conducted in order to ensure that the results are both sufficiently accurate and can be obtained in a robust and predictable manner.

Part I of this paper presented detailed flow measurements in a vaneless diffuser of a centrifugal compressor stage with a very high flow coefficient radial impeller, where measurements were carried out in the vaneless diffuser at seven radial positions downstream of the radial impeller designed for a very high flow coefficient of ϕ = 0.2. This paper, Part II, attempts to verify and validate the results numerically.
Analysis and Verification of a Watt I Six-Bar Furniture Hinge Mechanism
Authors: Chen F-C
Published: November 2005

The analysis and verification of a Watt I six-bar furniture hinge mechanism were carried out in this article. Using the characteristics of the topological structure of existing hinge mechanisms and design requirement specification, six hinge designs were synthesized. The most suitable design was selected for kinematic analysis with the vector loop method. The equations of motion of the mechanism were then derived by the Hamilton principle and Lagrange undetermined multipliers method and simplified using coordinate partitioning method. The differential algebraic equation was subsequently solved by using the Runge-Kutta method. From numerical simulation, the dynamic response of the door under various loading conditions was obtained and was found to fulfil the design requirements and constraints. Results obtained from experiments and numerical simulation were comparable, which demonstrated the success of this study. It is anticipated that this research will be beneficial to the further development of hinge designs for use in furniture.
Rules-6: A Simple Rule Induction Algorithm for Handling Large Data Sets
Authors: Pham D T , Afify A A
Published: November 2005

RULES-3 Plus is a member of the RULES family of simple inductive learning algorithms with successful engineering applications. However, it requires modification in order to be a practical tool for problems involving large data sets. In particular, efficient mechanisms are needed for handling continuous attributes and noisy data. This article presents a new rule induction algorithm called RULES-6, which is derived from the RULES-3 Plus algorithm. The algorithm employs a fast and noise-tolerant search method for extracting IF-THEN rules from examples. It also uses simple and effective methods for rule evaluation and handling of continuous attributes. A detailed empirical evaluation of the algorithm is reported in this paper. The results presented demonstrate the strong performance of the algorithm.
Modal Coordinate Formulation for a Simply Supported Bridge Subjected to a Moving Train Modelled as Two-Stage Suspension Vehicles
Authors: Lou P , Dai G-L , Zeng Q-Y
Published: November 2005

Modal coordinate formulation for analysing the dynamic interaction between a moving train and a simply supported bridge is presented in this article. The train is composed of a series of identical vehicles, and each vehicle is modelled as a four-wheelset mass-spring-damper multi-rigid body system with two-stage suspension having ten degrees of freedom (DOFs). A simply supported bridge, together with the track, is modelled as a Bernoulli-Euler beam. The deflection of the beam is described by superimposing modes. The train and the beam are regarded as an entire dynamic system, and then the modal coordinate formulation with time-dependent coefficients for this system is directly derived from the principle of virtual work. The formulation is solved by direct time integration method, to obtain the dynamic responses of this system. The correctness of the proposed formulations is illustrated by a comparison with the existing literature. The formulation helps save computer time using a few beam modes for analysing the dynamic responses of an entire train-bridge interaction system. The proposed formulation can also be applied to analyse the dynamic responses of a simply supported bridge subjected to a moving train modelled as two-wheelset four DOFs vehicles. Two numerical examples are given for illustrating the applications of the proposed formulation.
Microslip friction in flat belt drives
Authors: Kong L , Parker R G
Published: November 2005

The microslip shear model of belt mechanics is extended to fully incorporate belt inertia effects and used to analyse the steady state of a two-pulley drive. The belt is modelled as an axially moving string consisting of a tension-bearing member and a pliable elastomer envelope. Relative displacement between the tension-bearing member and the pulley surfaces shears the elastomer envelope, transferring the friction from the pulley surface to the tension-bearing member. The belt-pulley contact arcs consist of adhesion and sliding zones. Static friction exists in the adhesion zones, whereas kinetic friction exists in the sliding zones. An iteration method involving one outer and two inner loops is proposed to find the steady mechanics, including the sliding and adhesion zones, belt-pulley friction, and belt tension distribution. The outer loop iterates on the tight span tension similar to that used in published creep models. Two inner loops iterate on the tight span and driven pulley speeds respectively, necessitated by the speed differences between the tension-bearing member and the pulley at the entry points in the shear theory. Comparisons between the shear and creep models are conducted. Dramatic differences in belt-pulley mechanics between these two models are highlighted. Nevertheless, the key system performance measures such as the belt tight/slack span tensions, the maximum transmissible moment, and efficiency differ only modestly for the most normal operating conditions. Correspondingly, the adoption of the creep model for flat belts in industry is well justified because it is well developed and simple, although the shear model seems more relevant for modern belts with grid layers.
Some Guidelines on the Use of Profile Reliefs of High Contact Ratio Spur Gears
Authors: Yildirim N
Published: November 2005

With reference to the previous articles of the author(s) based on the systematic approach to the profile relief design of both low contact ratio and high contact ratio spur gears, some guidelines are drawn for the use of short and double reliefs of the HCRG profile design under the effect of realistic parameters like variable tooth stiffness and manufacturing errors regarding the profile relief values.

Root stress of the double relief can be minimized by optimizing the maximum tooth load value, hence the tooth load diagram with constant and variable tooth stiffness. Interaction of the manufacturing errors with the relief parameters is put into a form of analytical relation between manufacturing grades, hence the manufacturing tolerance and some gear parameters such as contact ratio, base pitch, and the load at which the smooth transmission error curve is required. In case of double relief, design load plays a major role in its selection. A relation and also a tabular form of guideline are given: for the required manufacturing grade if the contact ratio and other gear parameters are known and for the minimum contact ratio required if the manufacturing grade of the gears are known for either of the two cases short and double reliefs.
The effect of wake parameters on the transitional boundary layer on turbine blade
Authors: Zarzycki R , Elsner W
Published: November 2005

This paper presents an experimental analysis of the interaction between wakes and boundary layers on an aerodynamic blade profile. The main objective of this research was to investigate the simultaneous influence of the freestream conditions and wake parameters on the wake-induced transition process. The investigations were performed for two levels of inlet freestream turbulence Tu = 0.4 and 3 per cent. The wakes were generated by cylindrical bars mounted in the rotating wheel.

It was shown that wake parameters and especially the turbulence in the wake and wake width have a great influence on the position and extent of the induced transition. The role of freestream turbulence on the wake structure passing over the blade surface was also emphasized.
The impact of rotor labyrinth seal leakage flow on the loss generation in an axial turbine
Authors: Anker J E , Mayer J F , Casey M V
Published: November 2005

This paper examines the impact of labyrinth seal leakage flow over the rotor shroud on the loss generation in an axial turbine stage. Numerical studies have been carried out with an in-house solver using the Baldwin-Lomax turbulence model to identify the changes in secondary flow structures. The code has been validated for this application using test data from a low-speed axial turbine stage with a simple generic rotor shroud labyrinth seal. Numerical simulations are carried out with different clearance gaps (0, 1, and 3 mm) and without cavity wells. The simulations are used to distinguish the separate interactions of the main flow with the leakage flow and the cavity flow. The leakage flow causes a strong increase in the secondary flow kinetic energy in the downstream stator. Both the leakage flow and the cavity flow lead to an increase in the secondary kinetic energy in the rotor.
Blade-tip heat transfer in a transonic turbine
Authors: Thorpe S J , Yoshino S , Thomas G A , Ainsworth R W , Harvey N W
Published: November 2005

The blade-tips of high-pressure turbine blades in a gas turbine engine are subjected to strong convective heat transfer and continued to present a significant design challenge to manufacturers. This paper is concerned with developing an understanding of the unsteady flow physics that influences the blade-tip heat transfer. Experimental investigations of bladetip heat transfer and aerodynamics have been conducted in a transonic turbine stage test facility. The data reveal the effect of vane-rotor interactions on the unsteady heat transfer along the blade-tip mean camber line. In particular, the vane shock and potential field interaction establish characteristic unsteady heat transfer signatures at different axial positions along the blade-tip. The fluctuations in heat transfer are discussed in terms of vane-periodic changes in both relative total temperature and aerodynamic conditions.
Effect of vane-rotor interaction on the unsteady flowfield downstream of a transonic high pressure turbine
Authors: Dénos R , Paniagua G
Published: November 2005

This paper analyses the effect of the stator-rotor interference on the stage exit flow field of a transonic turbine operated under engine representative conditions in the von Karman Institute (VKI) compression tube facility. The test programme comprises three pressure ratios and two Reynolds numbers.

The time-averaged radial distributions of total pressure and temperature downstream of the rotor are affected by the hub passage vortices and the interaction between the tip passage vortex and the rotor tip leakage vortex. The azimuthal distributions exhibit significant non-uniformities with a periodicity of one vane pitch. The amplitude of this non-uniformity is very sensitive to the pressure ratio. A simple model shows that, contrary to the common belief, the transport of the vane wake and secondary flows across the rotor is not enough to explain the magnitude of the variations. The pitch-wise vane exit static pressure distribution, which is significantly distorted owing to the transonic regime of the vane, should be taken into account.

The amplitude of the time-resolved fluctuations of pressure and temperature, which are due to rotor blade passing events, also varies significantly depending on the probe location in a vane pitch. The measured time-accurate rotor relative inlet total pressure suggests that the rotor relative exit undergoes periodic excursions in the transonic regime.
An experimental study of reverse compound lean in a linear turbine cascade
Authors: Bagshaw D A , Ingram G L , Gregory-Smith D G , Stokes M R
Published: November 2005

This paper describes a detailed experimental investigation into the effects of reverse compound lean (RCL) in a highly loaded axial turbine cascade. The geometry was designed using fully three-dimensional viscous CFD calculations to achieve a reduction in secondary flow. Traverses were made upstream and downstream with three-hole and five-hole probes to quantify the effects on the flow and losses produced by the leaned blade compared with a prismatic blade. These measurements were supplemented with blade static pressure measurements and surface flow visualization. It was found that the RCL blade produced higher overturning at the end-wall accompanied by higher secondary loss but this was constrained closer to the end-wall. Near mid-span, the turning was reduced slightly but the overall turning for the row was unaltered. The mid-span showed much less loss, so that overall the loss was reduced by 11 per cent. An understanding of these effects may be gained by consideration of the three-dimensional effects produced by the RCL.
Unsteady boundary layer studies on ultra-high-lift low-pressure turbine blades
Authors: Zhang X F , Hodson H P , Harvey N W
Published: November 2005

The unsteady boundary layer development on the suction surface of two ultra-high-lift low-pressure (LP) turbine blades, known as T106C and U2, was investigated to further understand the loss reduction mechanism, which is integral to optimize the blade design in unsteady flow.

The T106C profile is a mid-loaded ultra-high-lift LP turbine blade. Owing to the strong local adverse pressure gradient, the laminar boundary layer on the suction surface separates shortly after the suction side peak velocity. The turbulence within the incoming wakes cannot induce transition around the separation point because of the low receptivity of the laminar boundary layer. This allows the wake's negative jet to induce roll-up vortex, which reduces the benefits of the wake-induced transition. The wake-turbulence induced transition, which occurs downstream of the separation point, helps the separated boundary layer to reattach earlier. Owing to its mid-loaded nature, a large portion of the suction surface is covered by the reattached turbulent flow, which also contributes to the high profile loss. Therefore, LP turbine blades designed to make best use of unsteady flow effects should be aft-loaded.

The ultra-high-lift blade U2 is an aft-loaded profile. Furthermore, the mild local adverse pressure gradient after the suction side peak velocity allows the laminar boundary layer to further develop before separation and results in a local Reθ of about 250 at separation. Therefore, the turbulence in the passing wake is able to induce transition close to the separation point. The earlier wake-induced transition and calmed region significantly reduce the size of the separation bubble. Furthermore, the earlier occurrence of wake-turbulence induced transition prevents the wake's negative jet from generating roll-up vortex, which also leads to lower losses.
The dual thin-film probe for high-frequency flow temperature measurements
Authors: Iliopoulou V , Arts T
Published: November 2005

In turbomachines, the flow total temperature determination requires probes that are not only robust and withstand high temperatures, but also able to correctly determine their fluctuations. To obtain accurate measurements, three dual thin-film probes based on a transient heat flux measurement technique have been constructed for time-averaged and time-resolved quantities. The design of the probes is first discussed. The probes, placed behind a cascade in the von Karman Institute (VKI) compression tube facility CT-2, are validated through a comparison with thermocouples. Measurements are also successfully performed behind the rotor and the second stator of the 1.5 stage high-speed turbine in the VKI compression tube facility CT-3. The comparison is made with a cold wire probe. The maximum-minimum temperature fluctuations measured behind the rotor and the second stator are 24 and 7°, respectively.
Experimental investigations of rotating flow instabilities in the last stage of a low-pressure model steam turbine during windage
Authors: Gerschütz W , Casey M , Truckenmüller F
Published: November 2005

Experimental investigations on two different three-stage low-pressure (LP) model turbines operated on steam during windage are presented. At very low flows, strain gauges identified that the two turbines exhibit different dynamic stress characteristics of the last-stage rotor blades. The first turbine experienced the highest vibrations from aerodynamic excitations at the resonant frequency of the second mode in a narrow operating range around 13 per cent of the design flow, whereas the second turbine experienced no resonance up to the fourth mode and has the highest dynamic loading at zero flow.

Specially developed high-response total pressure probes have been used to determine the cause of the aerodynamic excitation from traverses of the unsteady pressure field at three planes in the last stage. The experimental data for both turbines show that unsteady pressure disturbances steadily grow when the flow is reduced below 25 per cent of design flow and that the excitations are strongest in the axial gap between the guide vane and the rotor of the last stage near the outer casing. Detailed analysis shows that high-amplitude disturbances occur at distinct frequencies and that these rotate in the circumferential direction at a fraction of the rotor speed. Comparison of the pressure signals measured at two circumferential locations on the casing of the second turbine confirmed the characteristic frequency pattern to be a so called ‘rotating instability’. This unsteady phenomenon arising from the tip leakage flow has previously been observed in axial flow fans and compressors and is demonstrated for the first time here in a turbine operating at very low flow rates.
Nucleation of steam in high-pressure nozzle experiments
Authors: Gyarmathy G
Published: November 2005

The nucleation characteristics of high-pressure saturated/subcooled steam were studied in Laval nozzles. By using nozzles designed for different expansion rates and varying the inlet stagnation state in wide limits, the Wilson lines and the fog structure (droplet size and number count) were determined between 0.5 and 5 MPa pressure for expansion rates ranging between 10 000 and 200 000 s−1. The results show that Wilson point nucleation typically occurs in such fast expansions at supersaturated conditions where 3.5-5 per cent moisture would be present in the case of equilibrium flow. Higher expansion rates entail higher supersaturation, causing the formation of smaller, but more numerous, fog droplets. The reported measurements were made in the early seventies and were originally evaluated on the basis of the IFC-67 Steam Tables. The present evaluation uses the new IF-97 equations and reveals significant differences between the old and the new steam tables, leading to severe discrepancies in the value of subcooling at the Wilson point.
Consent and the Rules of the Game: The Interplay of Civil and Criminal Liability for Sporting Injuries
Authors: Fafinski Stefan
Published: November 2005

Each year, millions of people are injured whilst playing sport. An increasing number of these seek civil redress for their injuries; however, the infliction of an injury during the course of sporting activity may also give rise to criminal liability if caused in a way that satisfies the requirements of a particular offence. This article examines the nature of the law's intervention in the sporting area. It provides a brief outline of the relatively well-established position at civil law before moving to consider how the issue has been addressed by the criminal law with particular emphasis on the role of consent. Finally, the article engages with the complex interplay between the law and the rules of the relevant sport that has been a pervasive feature at both civil and criminal law.
German Cures for English Ailments? Appropriation versus Taking Away—Significance and Consequences of Conceptual Differences between the English and the German Law of Theft
Authors: Weinrich Nils
Published: November 2005

The current law of theft continues to rely on the concept of ‘appropriation’ under the Theft Act 1968. The broadness of this concept has led to serious problems in its application by the courts. Amongst these are the problems of ‘appropriation with consent’ and ‘appropriation without taking possession’ which have manifested themselves in several counter-intuitive decisions by the courts such as Gomez, Hinks and Pitham and Hehl. As a result these decisions have given rise to strong criticism by academics and practitioners alike. The law of theft, therefore, is without doubt in strong need of reform. After examining these key problems this article conceptually analyses the German approach by way of comparative juxtaposition with the English approach. Far from suggesting any adaptation of continental solutions, the author aims to provide extra material for consideration for a future reform of the law by introducing a systematic construction of the offences of theft and fraud from a foreign jurisdiction.
‘Take it from Me…’—The Roles of the Judge and Lay Assessors in Deciding Questions of Law in Appeals to the Crown Court
Authors: Bohlander Michael
Published: November 2005

According to traditional jurisprudence, lay assessors sitting with professional judges at the Crown Court, whether at trial or appeal level, have to take the law from the judge as the legal professional. The same is not true when the same lay magistrates sit at the magistrates' court either with a clerk or a professional district judge. This article questions the traditional arguments for this discrepancy and argues that if lay assessors at the Crown Court have the status of full judges, they should also have the power to decide questions of law.
Production routes of the alpha emitting 149Tb for medical application
Authors: Beyer G. J. , Čomor J. J. , Daković M. , Soloviev D. , Tamburella C. , Hagebø E. , Allan B. , Dmitriev S. N. , Zaitseva N. G.
Published: November 2005

The partial alpha emitting lanthanide isotope 149Tb seems to have a great potential in systemic radioimmuno therapy (RIT), especially when single cells in transit or circulation are targeted. The isotope 149Tb has a half life of 4.118 h and decays by alpha emission (3.97 MeV, 17%) EC-process (76%) and β+-emission (7%). In this paper, we analyze the possible production routes: light- and heavy ion induced nuclear reactions and p-induced spallation.

The excitation functions for light- and heavy ion induced reactions have been calculated using the ALICE91 code. The direct nuclear reaction 152Gd (p, 4n) 149Tb was found to be the most promising production path. Alternatively, the indirect reaction 142Nd (12C, 5n) 149Dy → 149Tb seems to be much more suitable compared to the reaction on the mono-isotopic target element 141Pr 12C, 4n) 149Tb. In this case, both, the production yield of 149Tb and the radionuclidic purity are considerably lower, compared to the (p, 4n)-reaction. In preliminary experiments we produced 149Tb via the indirect reaction Nd (12C, 5n) 149Dy → 149Tb (108 MeV 12C+6 ions and 1 particle-µA) at the U-200 heavy ion cyclotron at the FLNR of the JINR Dubna. From a 1.25 h irradiation of a 12 mg/cm2
natNd2O3 target, we obtained 2.7 MBq of 149Tb (70 µCi) at 20 min EOB. This allows the conclusion, that a dedicated cyclotron equipped with a modern ECR-ion source, providing high ion currents would allow the continuous production of batches of the order of 10–20 GBq of 149Tb for routine RI-therapy.

The lower cross section of the spallation process can be compensated by using very thick targets. On-line mass separation technique provides high purity isotopically clean 149Tb preparations, independently on the production route chosen. At the ISOLDE facility at CERN, we prepared batches of up to 500 MBq 149Tb by combining on-line mass separation process followed by a cation exchange chromatography process using α-HIBA as eluent. The obtained 149Tb preparations showed excellent behavior in labeling of chelated monoclonal antibodies.
Selective dissolution of Am in basic media in the presence of ferricyanide ions: a mechanistic and structural study on Am(V) and Am(VI) compounds
Authors: Meyer D. , Fouchard S. , Simoni E. , DenAuwer C.
Published: November 2005

Americium exhibits a soluble form in aqueous alkaline media in the presence of ferricyanide ions (Fe(CN)6
3−), which is not the case for the other transplutonium elements (TPE). This soluble Am compound can be obtained by addition of a concentrated basic solution of ferricyanide ions on a trivalent americium hydroxide precipitate. Thus, this technique enables a complete and rapid extraction of americium through its soluble form in alkaline solutions whereas under these conditions, other TPE and the lanthanides remain in the solid state as trivalent hydroxides. In the case of dissolution involving large amounts of americium, the formation of the soluble americium species is followed by the appearance of a reddish precipitate in the basic solution. Dissolution of the reddish solid in NaOH or NaOH/Fe(CN)6
3− media demonstrated the existence of a media-dependent solubility of the precipitate, and therefore the existence of at least two forms of soluble Am.

Spectroscopic (UV-visible, EXAFS-XANES, Raman) and electrochemical investigations were carried out on the different forms of americium to determine the nature of the compounds. This study points out that the reddish solid Am compound is probably a Am(V) hydroxide: Na2AmO2(OH)3·3H2O while the other Am species is a mixed americyl–ferricyanide complex. This work demonstrates that this dissolution of Am(III) solid compound is much more complex than a simple oxidation by the ferricyanide ions. The existence of a molecular interaction between Am(V)O2
+ and ferricyanide ions is highly probable. This selective dissolution of americium by a basic ferricyanide solution can be used to define a separation process of Am from lanthanides and other transplutonium elements in the field of high level liquid waste treatment.
The kinetics and mechanism of the reduction of neptunium (VI) ions by uranium (IV) ions in nitric acid
Authors: Koltunov V. S. , Taylor Robin J. , Marchenko V. I. , Zhuravleva G.I. , Mezhov E.A. , Koltunov G. V. , Dvoeglazov K. N.
Published: November 2005

The rapid reduction of NpO22+ions to NpO2+by U(IV) ions in an aqueous nitric acid solution has been studied and, in many ways, is similar in character to the same reaction in HClO4. The major difference is that in HNO3the reaction proceedsviatwo parallel routes. The first isviathe hydrolysed UOH3+ion, as in the reaction in HClO4and the second isviathe non-hydrolysed U4+ion. These parallel routes lead to the observed order of reaction with respect to H+ions being reduced from −1 in HClO4to −0.7 in HNO3. After accounting for the reaction mechanism the rate equation is described by:

wherek8= 404 min−1,k19= 275 M−1min−1and β = 0.009 M at 10 °C and μ = 2. The activation energy was 66.5 ± 4.9 kJ mol−1. Nitrate ions had no effect on the reaction rate but sulphamic acid increased the observed rate, probably through catalysis by sulphate ions arising from sulphamic acid reaction with HNO2and hydrolysis.
Determination of237Np at trace level: evaluation of various analytical procedures
Authors: Baglan Nicolas , Bouvier-Capely C. , Cossonnet C.
Published: November 2005

237Np is a long-lived actinide (2.14 × 106y), an α emitter, which is present either in the fuel cycle or in the environment as a result of local fallout. Due to the low concentration level encountered in bioassays or environmental samples, a preconcentration is necessary and several analytical tools can be used, namely: α-spectrometry, PERALS (Photon Electron Rejecting Alpha Liquid Scintillation) or ICP-MS (Inductively Coupled Plasma-Mass Spectrometry).

In the case of actinide mixtures where interference can occur, a radiochemical separation is necessary prior to measurement in order to obtain a pure fraction of each actinide. In this paper different approaches, still in use for actinide mixtures and based on ion exchange, extraction chromatography and solvent extraction, are investigated and compared for237Np analysis on synthetic solutions.

In addition, the suitability of the various procedures is discussed for Np regarding several criteria such as the constraints of the analytical tool, the concentration level, the time needed for the analysis and waste generation.
Preparation of U(VI) and Th(IV) α-sources from calcium nitrate solutions by combining solvent extraction and electrodeposition procedures
Authors: Elyahyaoui A. , Zarki R. , Chiadli A.
Published: November 2005

A simple method of preparing α-sources for alpha spectrometric analysis of uranium and thorium is investigated by combining solvent extraction and electrodeposition procedures. Extraction of these actinides is performed by diethyl ether from calcium nitrate solution with various nitric acid concentrations. Recoveries of 90–100% are obtained for uranium and 83.5% for thorium. Good resolutions are also achieved under optimum conditions.

The dependence of the overall yield of U(VI) and Th(IV) is examined in relation to the aqueous phase acidity. A procedure combining solvent extraction and electrodeposition is proposed for a selective α-source preparation of U(VI) and Th(IV). Uranium is first extracted at pH range about 1 to 2. At this acidity, thorium remains in the aqueous phase and may be subsequently extracted from this after acidification with 2 M HNO3. A second decontamination of a specific nuclide is achieved by a selective electrodeposition using electrolyte consisting of about 70% ethanol, 0.45 M hydrochloric acid, 0.09 M acetic acid and 108 µg Fe2O3, with concentrations above 0.48 M in HCl for U(VI) or 0.06 to 0.09 M in HNO3 for Th(IV).
Complexation and luminescence spectroscopic studies of europium(III) with polymaleic acid
Authors: Montavon G. , Markai S. , Billard I. , Nehlig A. , Grambow Bernd
Published: November 2005

The complexation behavior of europium(III) with polymaleic acid (PMA) was studied at pH 5 in 0.1 M NaClO4 by anion exchange (AE). The concentration range investigated was from E-9 M to E-4 M for the europium ion and from 1 to 50 mg/l for the polymer. The quantitative description of experimental data showed the formation of a 1 : 1 Eu : PMA complex and the existence of at least two distinct interaction environments ("sites") of Eu with the polymer chain whose proportions varied with the ratio between total Eu and PMA concentrations. The existence of different sites was further demonstrated by Time Resolved Laser-induced Fluorescence Spectroscopy (TRLFS) measuring the lifetimes and emission spectra of EuPMA complexes. By using empirical relationships, environments implying 1 : 2 and 1 : 1 Eu : COO− coordination could be deduced. The results show similarities with published data obtained for fulvic and Aldrich humic acids as far as complexation properties at pH = 5 are concerned.
Multitracer study on the uptake mechanism of yttrium and rare earth elements by autumn fern
Authors: Ozaki Takuo , Ambe Shizuko , Enomoto S. , Minai Y. , Yoshida S. , Makide Y.
Published: November 2005

Irrespective of low bioavailability, some plant species accumulate Y and rare earth elements (REEs) to a great extent (accumulator species). The uptake mechanisms of Y and REEs were investigated for autumn fern, one of accumulator species. For comparison, plant species which accumulated poorly REEs (non-accumulator species) were also studied. In the present investigation, two noticeable phenomena were observed. (I) Autumn fern showed no ionic-radius dependence of Y-REE uptake by leaves, while non-accumulator species showed an extremely high uptake for Y compared with REEs. (II) Y-REE uptake by autumn fern was influenced by the addition of chelating reagents to the uptake solution, while no effect was observed for non-accumulator species.
Photosensitized Oxidation and Inactivation of Pyocyanin, a Virulence Factor of Pseudomonas aeruginosa
Authors: Reszka Krzysztof J. , Denning Gerene M. , Britigan Bradley E.
Published: November 2005

Pyocyanin (PyO−) (1‐hydroxy‐5‐methylphenazine) is a cyto‐toxic compound secreted by Pseudomonas aeruginosa, an omnipresent bacterium and a human pathogen. We report that visible light illumination in the presence of rose bengal, or riboflavin, in aerated solutions (pH 7.0‐7.2) induces irreversible loss of the pigment's characteristic absorption band at 690 nm, indicating its oxidation. This photobleaching was paralleled by generation of a multiline Electron Paramagnetic Resonance (EPR) spectrum attributed to a PyO−‐derived radical. The reaction was dependent on the presence of air, sensitizers and light, was inhibited by sodium azide and was unaffected by ethanol. This suggests that PyO− was oxidized largely via singlet oxygen and that hydroxyl radicals were not involved. The photochemically modified pigment was less efficient in oxidizing NAD(P)H and generated less superoxide (by ∼50%) than the intact PyO−, indicating its partial inactivation. l‐Methoxy‐5‐methylphenazine, a PyO− analog in which the ‐O− moiety was replaced by the methoxy group (‐OMe), was resistant to oxidation, suggesting that oxidation of PyO− involves its phenolate moiety. These results also suggest that photosensitization could be a potentially useful method for inactivation of PyO− and, possibly, detoxification of superficial wounds (skin, eye) infected with P. aeruginosa.