bluuebunny/crossref_metadata_2025 huggingface dataset:
Tribological Investigation of the Polymer-Based Lubrication System With Micropores Used in a Manufacturing Transfer Line
Authors: Tung Simon C. , Huang Yong , Karczynski Dennis C.
Published: November 2008

Flooded oil lubrication systems are commonly utilized for many manufacturing processes. However, there is an increasing concern with the flooded lubrication systems due to their biological and environmental impact as well as maintenance and disposal cost. A polymer-based lubrication system with micropores, a sponge like solid lubricant allowing the oil to weep out while in use, provides a promising alternative solution to satisfy the lubrication requirements for some manufacturing processes. In addition, it can minimize contamination of the coolant system, reduce waste processing and disposal costs, and alleviate the in-plant safety hazard from oil leakage on floor surfaces. The goal of this study is to develop and improve the current lubrication system by applying a polymer-based lubrication system with micropores in order to replace the oil flooded transfer line lubrication systems currently in production use. Using a laboratory reciprocating bench test based on design of experiments, this study characterized the tribological performance of the polymer-based lubrication system with micropores under a variety of operating conditions, identified the main factor which impacts the tribological performance of the polymer-based lubrication system with micropores, and developed a model to predict the wear loss of the new lubrication system with micropores. These results provide the guidelines for possible applications of the polymer-based lubrication system used in the manufacturing process.
Friction and Wear of a Polymer-Matrix Reinforced With Nanocrystalline Alloy
Authors: Iglesias P. , Bermu´dez M. D. , Chandrasekar S. , Compton W. D.
Published: November 2008

The tribological behavior of a polymer-matrix composite containing discontinuous nanocrystalline alloy reinforcements is studied using a model system composed of a bakelite matrix reinforced with unitary Al6061 nanostructures. Chip formation by machining is used to produce the unitary nanostructures with grain size in the range of 50–200 nm. The hardness and strength of the unitary nanostructures are seen to be substantially greater than those of micro-crystalline Al 6061. Polymer-matrix composites containing these nanocrystalline metal reinforcements in a bakelite matrix are prepared using standard polymer processing routes. The friction and wear characteristics of the composites are studied using block-on-cylinder and pin-on-disk configurations. The wear performance of the nanocrystalline, metal-reinforced polymer is compared with that of the unfilled polymer and also with that of the polymer reinforced with microcrystalline alloy reinforcements, and shown to be superior.
Effects of Tip Compliance in Friction Force Microscopy
Authors: Conley William G. , Raman Arvind , Krousgrill Charles M.
Published: November 2008

Friction force microscopy (FFM) enables the unprecedented measurement of friction at the nanoscale. It is known that when FFM microcantilevers are dragged across surface, the nanometer tip executes stick-slip motions as the tip “plucks” individual atoms on the surface. Tomlinson’s model is usually used to explain these effects. In what follows we investigate the effects of tip compliance on the stick-slip motions in FFM. New results are predicted describing the transition from steady sliding to single and multiple atom stick-slip. Additionally, the effect of these different motions on the average frictional force is calculated.
Surface Textures for Enhanced Lubrication: Fabrication and Characterization Techniques
Authors: Venkatesan Sriram , Stephens Lyndon Scott
Published: November 2008

In hydrodynamic lubricated thrust load bearing contacts, commonly found in mechanical seals and bearings, ‘engineered’ surface textures have the potential to enhance lubrication in terms of reduction in friction, leakage and increasing load support. These surface textures or features are in the form of micron scaled posts or cavities having arbitrarily definable geometries. The height/depth of these features is of the same order of magnitude as the film thickness of the lubricated contact. This paper presents an overview of a photolithographic process for fabricating the deterministic asperities on a ‘flat’ stainless steel surface. The textured surface is then characterized using an optical profiler to evaluate the surface form error and edge rounding error in surface texture features. It was found that the circumferential waviness of the substrate was sinusoidal with amplitude of 0.2μm. When the micro features are lapped for height control, slight rounding around the edges of the features having an average radius of about 10% of asperity length is observed.
An Experimental Examination of the Effect of Interface Cooling on Thermal Wear Mechanisms in Carbon Graphite
Authors: Schneider Daryl S. , Stephens Lyndon S.
Published: November 2008

Premature failure of mechanical seal components is often a result of the elevated temperatures at the sealing interface that arise due to frictional heating. The Heat Sink Mechanical Seal (HSS) is a new approach to interface cooling in which a micro heat sink is constructed within millimeters of the sealing interface. Coolant circulated through the highly structured pin fin region carries away the generated heat. This work investigates the impact of interface cooling on carbon wear rates for a tungsten carbide (WC) and carbon graphite material pair. Experiments are performed using a thrust washer rotary tribometer to simulate a mechanical seal operating in dry running conditions within and in excess of the PV limit for the material pair (17.5 MPa*m/s or 500,000 psi*ft/min). Results show stable operation of sealing components in harsh operating conditions as well as the potential to reduce the occurrence of thermally induced wear and failure.
Simulation of Space Shuttle Gear Performance
Authors: Kratz S. H. , Wedeven L. D. , Black W. F. , Carlisle D. J. , Wedeven G. G.
Published: November 2008

Scuffing damage was found on Space Shuttle Power Drive Unit gears for the Rudder Speed Brake. Scuffing simulation tests rule out a predicted scuffing scenario. Scuff initiation is caused by tooth interference under unique transient high speed and torque conditions. Simulation tests for subsequent operation following a scuffing event show limited wear much less than the thickness of the gear case hardened layer.
Tire/Pavement Strain Tensor Measurement With an Infrastructure-Based Approach
Authors: Coiret A. L. , Gallenne M.-L. V. , Texier P.-Y. M.
Published: November 2008

Studies are conducted at the LCPC for investigating the role of infrastructures in road safety. In this context, tire/pavement contact characterization is a key point for both vehicle and road surface optimization. For this purpose, car industry usually instruments dedicated cars with wheel dynamometers but this procedure doesn’t offer the possibility to observe a large set of vehicles in practice. Regarding road management, it has been chosen to use the infrastructure itself as an instrument for acquiring the complete 6-components stress tensor. In this paper, a new test apparatus allowing this is shown, using a mechanically isolated part of the pavement. Validations are presented on a variety of situations such as emergency braking and constant speed driving. Correlations with inboard vehicle sensors measurements and numerical models have been worked out.
Tribochemical Reactions at the Water-Lubricated Silicon Nitride Interface: Gel Formation Mechanism
Authors: Gates Richard S. , Ying Z. Charles , Hsu Stephen M.
Published: November 2008

Silicon-based ceramics such as silicon nitride can be very effectively lubricated by water under certain conditions (1–3). After a wear-in period a condition of very low friction coefficient (<0.01) can be achieved for average contact pressures of 40 MPa and lower. Tomizawa & Fischer (1) proposed a chemomechanical polishing mechanism to reduce surface roughness enabling the onset of hydrodynamic lubrication by water. We suggest that there is an additional soft hydrated silica gel layer adhering to the rubbing surfaces that provides a deformable protective film to enable effective hydrodynamic lubrication of water and protect the surfaces from occasional asperity contacts. The existence of such films was indicated by the nanomechanical data performed on worn surfaces.
Friction Effect on Loading Process and Multiple Stable Flying States of Air Bearing Sliders
Authors: Zeng Qinghua , Huang Fu-Ying
Published: November 2008

One reason to use load/unload (L/UL) technology in hard disk drives is to avoid friction and stiction between sliders and disks during a start and stop process. However, friction between sliders and disks can still exist and has a strong effect on loading because sliders may contact disks during loading. In this paper, a new simplified friction model was proposed and implemented into the L/UL simulation code. Then, we studies two cases: A 10000 rpm server drive and A 1.0 inch Microdrive. It was found that the friction effect is smaller in the server drive case, while it is dramatic in the Microdrive case. Simulation with the proposed friction model shows that sliders will load to the third stable state if PSA is negative and the friction is big enough. In the third stable state, the slider has a negative pitch angle, and its leading edge continuously drags on the disk. In this state, we cannot do any reading/writing, and disks and sliders can be damaged.
The Journal Bearing Analysis Suite: A New Analytical Tool Applied and Presented
Authors: Clark D. A. , Tevaarwerk J. L. , Brewe D. E.
Published: November 2008

Planetary gear systems with hydrodynamic journal bearings can efficiently achieve high gear reduction ratios with minimum space and weight. For optimal designs, analytical tools are needed which provide accurate journal bearing modeling capabilities. At NASA Glenn a journal bearing is being prepared to support a compressor test. During check-out tests, a lubricant temperature problem came to light. As the unloaded bearing reached 6000 RPM, the lubricant exceeded the 93° C facility maximum. With a 30% increase in clearance, the bearings ran to 16,200 RPM; however, testing conditions entail 18,100 RPM with 9000 HP load. A parametric study was performed to determine the effects of clearance and loading upon lubricant temperature. A 1-D analysis was used, followed by the newly developed 3-D Journal Bearing Analysis Suite. The new software package incorporates the Army/NASA PGear Journal Bearing code. An overview of suite features and study results is presented.
Friction and Wear Behaviour of Nanocrystalline Nickel
Authors: Shafiei M. , Alpas A. T.
Published: November 2008

The tribological behaviours of conventional nickel with a grain size of 20±5 μm and nanocrystalline (nc) nickel with a grain size of 15±3 nm were compared. A pin-on-disc tribometer was employed for the friction and wear measurements under unlubricated conditions in ambient air with ∼35% relative humidity. As the grain size was decreased to the nanometer size, a reduction of about 18% was observed in the peak value of coefficient of friction (COF), but the steady-state COF remained almost unchanged. Also it was shown that the wear rate of nc nickel was about 82% lower than that of conventional nickel at 2 N load. This behaviour is mainly attributed to considerable reduction in plastic deformation and microplowing due to increased hardness.
Heat Transfer Properties of Engine Oils
Authors: Wrenick Scott , Sutor Paul , Pangilinan Harold , Schwarz Ernest E.
Published: November 2008

The thermal properties of engine oil are important traits affecting the ability of the oil to transfer heat from the engine. The larger the thermal conductivity and specific heat, the more efficiently the oil will transfer heat. In this work, we measured the thermal conductivity and specific heat of a conventional mineral oil-based diesel engine lubricant and a Group V-based LHR diesel engine lubricant as a function of temperature. We also measured the specific heat of ethylene glycol. The measured values are compared with manufacturers’ data for typical heat transfer fluids. The Group V-based engine oil had a higher thermal conductivity and slightly lower specific heat than the mineral oil-based engine oil. Both engine oils had values comparable to high-temperature heat transfer fluids.
Dynamics of a Reduced Scale Landing Gear System Considering the Effect of the Viscoelastic Interaction of the Brake Pads and Rotors
Authors: Farhang Kambiz , Balasubramanian Karthik
Published: November 2008

Gear walk is a dynamic instability condition that can pose serious harm to an aircraft and its passengers. The instability is believed to be borne as a result of braking, in which vibration of the landing gear can be induced generating motion reminiscent of a walking movement. This paper focuses on the theoretical account of a Reduced Scale Landing Gear (RSLG) apparatus and studies gear walk phenomenon. The mathematical approach involves lumped-parameter model representation of the RSLG that accounts for the landing gear’s struts, the wheels and the caliper-disc brake dynamics. The theoretical treatment of the RSLG apparatus entails consideration of the structure of the device that includes the account of dynamic response of the assembly consisting of a fuselage, two struts and two wheels. Various physical and geometrical parameters are determined and included in the mathematical model of the apparatus. It is demonstrated that the occurrence of gear walk vibration is greatly influenced by the structural stiffness of the system. Both synchronous and 180° out of phase motion of the struts are generated in a parametric study in which structural stiffness is varied.
The Effect of Nitrogen on Friction and Wear of Hard Materials
Authors: Kato Koji
Published: November 2008

Nitrogen gas (N2) has been considered as inert and has been used to form atmosphere similar to vacuum. However, it has been shown in these years that friction between Si3N4/CNx [1], CNx/CNx [2], steel/CNx [3] or Diamond/DLC [4] is much smaller in Nitrogen gas than in high vacuum. This paper reviews those recent observations showing low friction in N2 and discusses on its mechanism.
First-Principles Study of Superlow Friction Between Hydrogenated Diamond Surfaces
Authors: Ciraci S. , Dag S.
Published: November 2008

Attractive interaction between two clean diamond(001) slabs turns repulsive upon the hydrogenation of surfaces. Even under high loading forces, this repulsive interaction prevents the sliding surfaces from being closer to each other. As a result, calculated lateral force variation generated during sliding has small magnitude under high constant loading forces. Superlow friction observed earlier between diamond like carbon coated surfaces can be understood by the steady repulsive interaction between sliding surfaces, as well as strong and stiff carbon-carbon and carbon-hydrogen bonds which do not favor energy dissipation. In ambient conditions, the steady repulsive interaction is, however, destroyed by oxygenation of hydrogenated surface.
Dynamics of Bearing Shaft Systems
Authors: Sadeghi Farshid , Wassgren Carl , Prenger Nicholas , Ghaisas Niranjan , Chamberlain Eric
Published: November 2008

The objective of this study was to develop a bearing model which can be combined with shafts, gears etc. to virtually investigate the motion and loading of the elements in the bearing. Models for ball, cylindrical and tapered rolling bearing dynamics have been designed, developed and combined with rigid and flexible shafts subject to various loading conditions and eccentric masses. The results from this investigation demonstrated that for rotating shaft bearing systems, the motion and the loads on the rolling elements are significantly different than that predicted by static and / or quasi-static type analysis. Results from shaft bearing system, where shaft may be supported by combinations of ball and rolling element bearings will be demonstrated. Cage motion and stability under various load and speed combinations will be discussed.
Effects of Stress-Relieving Slots on Fretting Fatigue Behavior of Ti-6Al-4V
Authors: Wang R. H. , Jain V. K. , Mall S.
Published: November 2008

Fretting is a complex phenomenon, it alters the stress and strain fields in the contact region between two bodies, due to micro-slip, which decreases the fatigue resistance of materials. This study investigates the effect of stress-relieving slots, machined in flat pads, on the fretting fatigue behavior of Ti-6Al-4V alloy. Three types of slots including U-notch, V-notch, and a simple hole were used. Conventional fretting fatigue model, involving a contact between a flat pad with rounded edges and a fatigue specimen loaded by a cyclic axial load, was used. Several fretting fatigue parameters such as the maximum tensile stress, Smith Watson Topper, Maximum Shear Stress Range, and MSSR parameters were considered for this study. The stress, strain, and displacement distribution in the contact region of fatigue specimen were computed using the finite element analysis code ABAQUS. The data were used to calculate the fretting fatigue parameters and evaluate the effectiveness of the slots in improving the fretting fatigue resistance. The analytical results were verified by the experimental data.
Ceramic Coated Piston Rings for Internal Combustion Engines
Authors: Kamo Lloyd , Saad Philipe , Bryzik Walter , Mekari Milad
Published: November 2008

This paper reports the development and formulation of a new cost effective means of applying ceramic tribology coatings to sealing rings. This coating, though developed with the support of the U.S. Army Tank Automotive and Armaments Command for use on Low Heat Rejection (LHR) high output diesel engines, can be used on any internal engine compression seal ring. It is not limited for use in LHR diesel engines. Applying ceramic coating, especially on the compression piston ring, reduces the friction losses and wear of sliding contact surfaces. This will result in increased engine efficiency and durability. The work presented examines both laboratory and small bore engine testing of this technology. Laboratory tribometer tests compare the ceramic coating to existing and experimental piston ring tribosurfaces. Friction and wear performance demonstrated in the laboratory is verified for use in LHR diesel engine application. Low raw material cost coupled with ease of application and high deposit efficiency of the ceramic make this coating a viable candidate for commercialization.
Modeling the Pressure-Density Relationship in Thin Films at Asperity Contacts in Mixed Lubrication
Authors: Martini A. , Cantrell R. , Wang Q. , Snurr R. Q.
Published: November 2008

In mixed lubricated contact, the asperity contact regions may be separated by a thin layer of lubricant film. Simulations of mixed lubrication often use empirical formulae to describe the change of density with pressure in the lubricated areas. However, these models may not be applicable to molecularly thin films at asperity contact regions. We present a molecular simulation approach for density characterization of the fluid at asperity contact regions in mixed lubrication. The resultant density-pressure relationship is compared to the traditional Dowson-Higginson model. It is found that the two models predict comparable densities at low pressures but diverge at higher pressures.
A Locally Refined Finite Element Approach for Journal-Bearing System Analysis
Authors: Xiong S. W. , Wang Q. Jane , Liu W. K. , Lin Chih , Zhu D. , Lisowsky B. , Yang Q. , Vaidyanathan K.
Published: November 2008

The effect of roughness should be taken into consideration in the lubrication and geometric design of heavy-duty machine elements. Deterministic simulation techniques have been developed for the investigation of point-contact mixed-lubrication problems. Such approaches should also been extended to deterministic mixed lubrication solutions for journal-bearing conformal-contact systems. However, journal-bearing mixed lubrication involves a much larger area of surface interaction as compared to point contact problems. It is difficult to use similar micro/nano scale meshes directly to journal bearings under the current computer capability. It is a great challenge to develop a new deterministic numerical technique for the mixed lubrication of journal bearing systems with the consideration of the effect of surface roughness design. This paper presents a special technique for deterministic analyses of journal-bearings in mixed lubrication conditions, in which the coarse mesh is used to determine the elastic deformation of the journal bearing, whilst locally refined meshes are used for the effect of roughness. Journal-bearing systems in heavy machinery are often subject to dynamic loading. Therefore, a transient refinement scheme is also introduced.
Effects of Contact Modes on Wear of Railroad
Authors: Asthana Pranay , Liang Hong
Published: November 2008

In this study the wear behavior of rail road steel under rolling with sliding and pure sliding conditions was investigated. Experiments were conducted using a modified linear reciprocating tribometer. Friction and wear were estimated against different conditions. Surface characterization techniques include a scanning electron microscope (SEM) with attached energy dispersive X-ray (EDX) for wear and tribochemical wear studies. It was found that rolling with sliding provided higher friction and wear than pure sliding. The addition of crystalline hydrated sodium borate (Na2B4O7-10H2O) increased friction in both contact conditions, while there was a significant decrease in the wear volume. This research proposes new friction and wear mechanisms.
Roles of Surfactant Molecules in Post-CMP Cleaning
Authors: Ng Dedy , Kulkarni Milind , Liang Hong
Published: November 2008

One major concern in post-CMP cleaning is particles contamination on the substrate surface after the CMP process. These particles can be abrasive particles from the slurry, debris from pad material, and particles of film being polished. The cleaning method used in this study is direct contact of the substrate surface and brush sweeping. To enhance the cleaning process, an anionic surfactant is added in the cleaning solution. In order to understand effects of surfactant molecules on post-CMP cleaning, for the first time, we use a tribological approach over a range of surfactant concentration and temperature. In this regard, we observe how the surfactant behavior before and after it reaches the critical micelles concentration (cmc). Experimental results show that increase in surfactant concentration can promote bilayer interaction of micelles on the hydrophilic particles. Based on our study, we propose an interactive explanation of surface molecules with the wafer surface and nanoparticles through friction. This understanding will serve as a guide on how much surfactant should be added in order to achieve effective particle removal.
Triboelectrification Between Dissimilar Smooth Metal Surfaces With Self-Assembled Monolayers
Authors: Akbulut Mustafa , Godfrey Alig Anna R. , Israelachvili Jacob
Published: November 2008

We have simultaneously measured the friction and triboelectrification between two adhering SAM-coated molecularly smooth dissimilar metal surfaces using a modified surface forces apparatus. As the pressure is increased, triboelectrification increases drastically with large fluctuations about the mean. When the surfaces are in static contact, none of these effects is observed. Triboelectrification strongly depends on the friction type and force, sliding distance, contact area and sliding history. We also show that both SAMs and metal substrates contribute to the charge transfer mechanism.
How Piezoelectric Actuators Can Improve Dry Friction
Authors: Garbuio L. , Rouchon J.-F.
Published: November 2008

Our research deals with the use of simple piezoelectric actuators able to modulate the dry friction between two solids in contact via an electric control. Ultrasonic vibrations can modify apparent friction between metals. By the direct stress of the contact stiffness, an artificial lubrication is maintained. This technique particularly used in metal forging in the Sixties becomes actually considered thanks to the performances of new actuators: piezoelectric materials. This actuator technology makes possible to generate high contact pressures on ranges of micrometric displacement at frequencies of a hundred kilocycles. From contact models resulting from the Hertz theory associated with the laws of behavior in mode of fretting, we define conditions of excitation allowing a reduction of friction. These conditions permit validating the choice of using the piezoelectric actuators. Experimental results are carried out in order to validate the interest and the potentiality of this technique.
Lubricant Degradation Studies Using a Single Cylinder Research Engine
Authors: Lee P. M. , Priest M. , Stark M. S. , Wilkinson J. J. , Lindsay Smith J. R. , Gamble R. , Hammond C. J. , Taylor R. I. , Chung S.
Published: November 2008

With increasing pressure on engine oil manufacturers to extend oil drain intervals and reduce fuel consumption, whilst changing the composition of fully formulated oils to meet new CEC, ILSAC and OEM specifications, there is ever increasing need to understand the effect of oil degradation on the operating conditions and tribological performance of engines. This poster presents mechanical changes made to a single cylinder research engine to enable the study of lubricant degradation, its transport and how this links to piston assembly tribology. A summary of the research undertaken using these changes and a sample of results obtained to date are also presented.
Effect of Reinforcing Carbon Fiber Morphology on Tribological Behavior of PEEK Polymers
Authors: Greco Aaron C. , Ajayi Oyelayo O. , Erck Robert A. , Johnson Jacqueline A. , Fenske George R.
Published: November 2008

This paper evaluates the effect of reinforcing carbon fiber morphology on friction and wear behavior of polyether ether ketone (PEEK) under relatively severe high-speed sliding contact conditions. Three materials are evaluated in the study: (1) un-reinforced PEEK, (2) short and randomly oriented carbon fiber reinforced PEEK (450FC30), and (3) continuous woven fiber reinforced PEEK (CPK53). Test results show that the existence and morphology of the reinforcement has a significant effect on both the wear and friction under these severe contact conditions.
Challenges and Solutions of Recent Thick-Film Bearings (Keynote)
Authors: Tanaka Masato
Published: November 2008

Recent challenges and solutions are outlined and discussed for various thick-film bearings in this keynote address. What come into focus are large bearings for utility turbines, titling pad journal bearings for high speed rotating machinery, small bearings for turbochargers and HDD systems, automobile engine bearings and air-lubricated foil bearings for micro gas turbines. Depending on the challenges, different solutions are proposed, such as bearing design tools based on highly reliable hydrodynamic lubrication models, bearing materials for higher performance and less maintenance costs, and countermeasures for unstable shaft vibrations. Effective solutions have been given to some challenges, but not yet to the others. Tribologists are encouraged to pioneer new horizon in this field, defying hard routes.
Tribological Investigation of Porcine Articular Cartilage
Authors: Rennie A. C. , Sawyer W. G.
Published: November 2008

This poster examines the tribological properties and effective elastic modulus of porcine articular cartilage plugs. Two methods of obtaining an effective elastic modulus are explored for the different initial material conditions during the indentation loading and unloading. The average values of coefficient of friction varied from 0.04–0.14, but ended with a steady-state average of 0.06. It was validated that increasing pressure during sliding produces an increase in friction coefficient. From a contact model fit to the loading region of the indentation curve, effective elastic modulus had an average value of 300 MPa, which agrees with existing literature. From an examination of the linear portion of the unloading region of the indentation curve, the effective elastic modulus was an average of 8.9 MPa. A preliminary explanation for this is that before loading, a bulk material is present, but pressure effects could evacuate some of the interstitial fluid, leaving in the unloading curve an effective matrix without fluid.
Establishment of the Accuracy and Consistency of Using Automatic Image Analysis to Classify Wear Debris Particles
Authors: Leavers V. F. , Hanlon M. D.
Published: November 2008

Wear debris particle analysis is an equipment health monitoring technique used to identify possible failure modes in various engine components. One of the first stages in the analysis involves the examination under a microscope of particles collected from the component’s lubrication system on magnetic drain plugs and filters. However, the subjectivity of technicians’ judgements means that diagnosis may not be consistent between technicians. A software tool capable of automatically classifying the images of wear debris particles has been developed and tested using an 800-image database. It is shown that using automatic image analysis for the classification of wear debris particle images is more consistent, accurate and informative when compared to the classifications assigned by wear debris experts.
Asperity-Based Models of Micro-Scale Friction
Authors: Adams George G.
Published: November 2008

As surfaces become smoother and loading forces decrease in applications such as MEMS, NEMS, and magnetic recording devices, the size and number of the asperity contacts which comprise the real contact area continues to decrease. The tangential force which is measured between two sliding bodies is the combined result of friction forces which are present in a very large number of nano and micro scale asperity contacts. Recent experiments as well as modeling have shown considerable scale-dependence and nonlinear load-dependence of the friction force. These models will be reviewed and discussed.
Expert-Free Wear Particle Morphology Analysis (Keynote)
Authors: Stachowiak G. W.
Published: November 2008

Since the early 1970s wear particles have been used as indicators of the health status of industrial machinery. Their quantity, size and morphology was utilized in machine condition monitoring to diagnose and predict the likelihood or the cause of machine failure. In particular, the wear particle morphology was found useful as it contains the vast wealth of information about the wear processes involved in particle formation, and the wear severity. However, the application of wear particle morphology analysis in machine condition monitoring has limitations. This is due to the fact that the process largely depends on the experience of the technicians conducting the analysis. Research efforts are therefore directed towards making the whole wear particle analysis process experts-free, i.e. automated. To achieve that a detailed database of wear particle morphologies, generated under different operating conditions and with different materials for sliding pairs, must be assembled. Next, the reliable and accurate methods allowing for the description of 3-D wear particle morphology must be found. Multiscale and nonstationary characteristics of wear particle surface topographies must be accounted for. Finally, a reliable wear particle classification system must be developed. This classification system must be reliable and robust hence the selection of appropriate classifiers becomes a critical issue. It is hoped that the system, once fully developed, would eliminate the need for experts in wear particle analysis and make the whole analysis process less time consuming, cheaper and more reliable. In this presentation it is shown how the problems leading towards the development of such system are gradually overcome. Also, the recent advances towards the development of expert-free wear particle morphology system for the application in machine condition monitoring are presented.
Flying Characteristics of Head Sliders on Patterned Disk Surfaces
Authors: Hayashi Takefumi , Yoshida Hideyo , Mitsuya Yasunaga
Published: November 2008

To quantitatively predict the static, and dynamic characteristics of a head slider while flying over a patterned disk, the mixedly averaging method has been successfully applied to the molecular gas lubrication problem incurred by groove-shaped textures formed over the lubricating surface. First, formulation of ADI method by using mixedly averaged film thickness is derived and implemented into an interactive numerical simulation system. Then, spacing variations of typical sliders on a patterned disk surface are demonstrated.
Comparisons of Friction Characteristics of a Lightly Loaded Pin Sliding Over Magnetic Disks Coated With Polar and Non-Polar PFPE Lubricants
Authors: He Yinbo , Mitsuya Yasunaga , Zhang Hedong , Fukuzawa Kenji
Published: November 2008

This paper deals with the measurement of friction force exerted on molecularly thin lubricant film surfaces using a specially arranged pin-on-disk type friction tester. The measurements were carried out by sliding a 1.5-mm-diameter glass ball slider on a rotating disk surface with small loading force. Polar and non-polar PFPE lubricants were dip-coated on magnetic disks covered with diamond-like-carbon (DLC) film. Lubricant film thickness was varied to constitute multiple layered film structures on the DLC surface. To clarify the stratified effect of thin lubricant film on friction, a lightly loading force and a slow rotational speed were selected. The tested results showed that the friction force on non-polar lubricant surfaces increase slightly for mono-layer and multi-layer cases, while the friction force on polar lubricants show steady and gradual increase with increasing loading force. We conclude that friction force at small loading force is dependent intimately on the thickness, molecular weight and end-group functionality.
Focused Ion Beam Studies of Worn Surfaces
Authors: Rainforth W. M.
Published: November 2008

Focused ion beam (FIB) microscopy has been available for over 20 years, but substantial improvements in recent years has delivered a powerful technique for the study of surface structures. Ion channeling contrast, produced by secondary electron emission from the Ga ion interaction with the surface is a high sensitivity, high resolution technique for revealing phase distributions and deformed structures. Moreover, the ion beam can be used to take sections of the worn surface for subsequently removal for TEM. Despite the major advantages of ion channeling contrast and 3-D sectioning, the technique has only recently been applied to worn surfaces. This paper demonstrates the power of the technique in the study of the worn surface of 3 very different materials, namely 1) Al-alloy metal matrix composites, reinforced with MoSi2 and CrSi3, worn under lubricated sliding, with very low wear rates; 2) hot rolled aluminium alloys, where the surface structure leads to enhanced Filiform corrosion, and finally 3) the worn surface of TiAlN/VN multilayer coatings, where friction induced oxide formation results in significant changes in friction coefficient.
Rheological Modeling of Lubrication Flows (Keynote)
Authors: Tichy John
Published: November 2008

Impressive strides have been made in the atomistic modeling of lubrication, notably in the case of very thin (nanoscale) flows. However, from an engineering point of view, particularly as it pertains to design, practical predictive ability seems far away. Continuum approaches are surprisingly robust and appear to have validity to the nanometer range, although the Newtonian fluid model may need to be modified to account for non-classical behavior. Various fluid rheological models are discussed below as they pertain to lubrication in complex flow applications.
Fossil Pollen as a Guide to Conservation in the Galápagos
Authors: van Leeuwen Jacqueline F. N. , Froyd Cynthia A. , van der Knaap W. O. , Coffey Emily E. , Tye Alan , Willis Katherine J.
Published: November 2008

Paleoecological evidence from the past 8000 years in the Galápagos Islands shows that six presumed introduced or doubtfully native species (Ageratum conyzoides, Borreria laevis/Diodia radula‐type, Brickellia diffusa, Cuphea carthagenensis, Hibiscus diversifolius, and Ranunculus flagelliformis) are in fact native to the archipelago. Fossil pollen and macrofossils from four sites in the highlands of Santa Cruz Island reveal that all were present thousands of years before the advent of human impact, refuting their classification as introduced species. These findings have substantial implications not only for conservation in Galápagos but for the management of introduced species and pantropical weeds in general.
4D Imaging of Transient Structures and Morphologies in Ultrafast Electron Microscopy
Authors: Barwick Brett , Park Hyun Soon , Kwon Oh-Hoon , Baskin J. Spencer , Zewail Ahmed H.
Published: November 2008

With advances in spatial resolution reaching the atomic scale, two-dimensional (2D) and 3D imaging in electron microscopy has become an essential methodology in various fields of study. Here, we report 4D imaging, with in situ spatiotemporal resolutions, in ultrafast electron microscopy (UEM). The ability to capture selected-area-image dynamics with pixel resolution and to control the time separation between pulses for temporal cooling of the specimen made possible studies of fleeting structures and morphologies. We demonstrate the potential for applications with two examples, gold and graphite. For gold, after thermally induced stress, we determined the atomic structural expansion, the nonthermal lattice temperature, and the ultrafast transients of warping/bulging. In contrast, in graphite, striking coherent transients of the structure were observed in both image and diffraction, directly measuring, on the nanoscale, the longitudinal resonance period governed by Young's elastic modulus. The success of these studies demonstrates the promise of UEM in real-space imaging of dynamics.
Canonical Wnt Signaling Regulates Organ-Specific Assembly and Differentiation of CNS Vasculature
Authors: Stenman Jan M. , Rajagopal Jay , Carroll Thomas J. , Ishibashi Makoto , McMahon Jill , McMahon Andrew P.
Published: November 2008

Every organ depends on blood vessels for oxygen and nutrients, but the vasculature associated with individual organs can be structurally and molecularly diverse. The central nervous system (CNS) vasculature consists of a tightly sealed endothelium that forms the blood-brain barrier, whereas blood vessels of other organs are more porous.
Wnt7a
and
Wnt7b
encode two Wnt ligands produced by the neuroepithelium of the developing CNS coincident with vascular invasion. Using genetic mouse models, we found that these ligands directly target the vascular endothelium and that the CNS uses the canonical Wnt signaling pathway to promote formation and CNS-specific differentiation of the organ's vasculature.
Organic and GM—Why Not?
Authors: Tester Mark
Published: November 2008

Tomorrow's Table
. Organic Farming, Genetics, and the Future of Food.
By Pamela C. Ronald and Raoul W. Adamchak
. Oxford University Press, New York, 2008. 226 pp. $29.95, £17.99. ISBN 9780195301755.

Writing for nonspecialists, Ronald (a rice geneticist) and Adamchak (an organic farmer) argue that the best path to sustainable food production lies through a careful combination of organic farming and genetically engineered plants.
Global Perspectives
Authors: Jasny Barbara
Published: November 2008

The Termesphere Gallery
. 1920 Christensen Drive, Spearfish, SD 57783, USA.
www.termespheres.com

Using his sixfold perspective, Termes paints optical illusory scenes on the surfaces of spheres.
Development of an Antigen Capture Immunoassay Based on Monoclonal Antibodies Specific for Dengue Virus Serotype 2 Nonstructural Protein 1 for Early and Rapid Identification of Dengue Virus Serotype 2 Infections
Authors: Qiu Li-wen , Di Biao , Wen Kun , Wang Xin-shuai , Liang Wei-hua , Wang Ya-di , Pan Yu-xian , Wang Ming , Ding Yan-qing , Che Xiao-yan
Published: November 2008

The dengue virus (DENV) has four distinct serotypes (DENV1, DENV2, DENV3, and DENV4) that require differentiation for effective prevention of morbid diseases. The recently developed DENV1-specific NS1 antigen capture enzyme-linked immunosorbent assay (ELISA) based on the monoclonal antibodies (MAbs) that recognize distinct epitopes on nonstructural protein 1 (NS1) of a specific DENV serotype is convenient and cost-effective, but assays have not yet been developed for DENV serotypes 2 to 4. This paper describes the development and validation of a DENV2-specific NS1 antigen capture ELISA by selection and optimization of the pair of well-characterized MAbs that recognized epitopes specific for DENV2 NS1 from a large panel of MAbs. The DENV2 NS1 ELISA displayed exclusive sensitivity with the DENV2 serotype and did not cross-react with the other three DENV serotypes. The sensitivity and specificity of the DENV2 NS1 ELISA were 83.3% (25/30) and 100% (504/504) when used to test 30 acute-phase serum samples from patients infected with DENV2 identified by virus isolation or reverse transcription-PCR serotyping and 504 serum samples from healthy individuals, respectively. The specificity of this assay was also evaluated using a panel of serum samples which were positive for DENV1, other flaviviruses, and nonflaviviruses; no cross-reactions were observed in these clinical samples. The DENV2 NS1 ELISA was eightfold more sensitive than a commercially available serotype-cross-reactive NS1 ELISA (Panbio Diagnostics, Brisbane, Australia) when the two assays were used to test the DENV2-infected cell culture supernatants in parallel. The Panbio NS1 ELISA displayed variation in sensitivity between DENV serotypes. The DENV2-specific NS1 antigen capture ELISA can be used as a tool for the rapid identification of DENV2 infections.
Construction and Characterization of an Attenuated
Listeria monocytogenes
Strain for Clinical Use in Cancer Immunotherapy
Authors: Wallecha Anu , Maciag Paulo Cesar , Rivera Sandra , Paterson Yvonne , Shahabi Vafa
Published: November 2008

Listeria monocytogenes
has been exploited previously as a vaccine vector for the delivery of heterologous proteins such as tumor-specific antigens for active cancer immunotherapy. However, for effective use of live vector in clinics, safety is a major concern. In the present study, we describe an irreversibly attenuated and highly immunogenic
L. monocytogenes
platform, the
L. monocytogenes dal
-,
dat
-, and
actA
-deleted strain that expresses the human prostate-specific antigen (PSA) using an antibiotic resistance marker-free plasmid (the
dal dat
Δ
actA
142 strain expressing PSA). Despite limited in vivo survival, the
dal dat
Δ
actA
142 strain was able to elicit efficient immune responses required for tumor clearance. Our results showed that immunization of mice with the
dal dat
Δ
actA
142 strain caused the regression of the tumors established by the prostate adenocarcinoma cell line expressing PSA. An evaluation of immunologic potency indicated that the
dal dat
Δ
actA
142 strain elicits a high frequency of PSA-specific immune responses. Interestingly, immunization with the
dal dat
Δ
actA
142 strain induced significant infiltration of PSA-specific T cells in the intratumoral milieu. Collectively, our data suggest that the
dal dat
Δ
actA
142 strain is a safe and potent vector for clinical use and that this platform may be further exploited as a potential candidate to express other single or multiple antigens for cancer immunotherapy.
Abnormal Immunological Profile and Vaginal Microbiota in Women Prone to Urinary Tract Infections
Authors: Kirjavainen Pirkka V. , Pautler Stephen , Baroja Miren L. , Anukam Kingsley , Crowley Kate , Carter Kristine , Reid Gregor
Published: November 2008

The host determinants of susceptibility to recurrent urinary tract infections (UTI) are poorly understood. We investigated whether the susceptibility is associated with abnormalities in the immunological defense and further explored the linkage to vaginal microbiota. For this purpose, we compared vaginal, urine, and blood samples collected during a disease-free period from 22 women with recurrent UTI and from 17 controls. In UTI-prone women, interleukin-12 (IL-12) production in peripheral monocytes and myeloid dendritic cells (DCs) was significantly (
P
< 0.05) enhanced whether measured in relative numbers of IL-12-producing cells or in mean IL-12 production per cell. In contrast, no T-cell polarization was observed. Interestingly, it seemed that the cytokine production of DCs and monocytes did not translate into T-cell activation in the UTI-prone group in a manner similar to that seen with the controls. In vaginal mucosa, UTI-prone women had a lower concentration of tissue repair-associated vascular endothelial growth factor (VEGF) (
P
= 0.006) and less often had detectable amounts of the chief monocyte and DC chemoattractant, monocyte chemotactic protein 1 (
P
= 0.005), than the controls. The microbiota of UTI-prone women was characterized by a diminished lactobacillus morphotype composition, with an abnormally high (>3) mean Nugent score of 4.6 compared to 1.7 for the controls (
P
= 0.003). Normal lactobacillus composition was associated with increased IL-17 and VEGF concentrations in vaginal mucosa. In conclusion, immunological defects and a persistently aberrant microbiota, a lack of lactobacilli in particular, may contribute to susceptibility to recurrent UTI. Further studies of antigen-presenting-cell function and T-cell activation in recurrent UTI are called for.
Phylogenetic Analysis of Rubella Virus Strains from an Outbreak in Madrid, Spain, from 2004 to 2005
Authors: Martínez-Torres A. O. , Mosquera M. M. , Sanz J. C. , Ramos B. , Echevarría J. E.
Published: November 2008

An outbreak of rubella affected 460 individuals in 2004 and 2005 in the community of Madrid, Spain. Most of the patients were nonvaccinated Latin American immigrants or Spanish males. This study presents the first data on rubella virus genotypes in Spain. Forty selected clinical samples (2 urine, 5 serum, 3 blood, 2 saliva, and 28 pharyngeal exudate samples) from 40 cases were collected. The 739-nucleotide sequence recommended by the World Health Organization obtained from viral RNA in these samples was analyzed by using the MEGA v4.0 software. Seventeen isolates were obtained from 40 clinical samples from the outbreak, including two isolated from congenital rubella syndrome cases. Only viral RNA of genotype 1j was detected in both isolates and clinical specimens. Two variations in amino acids, G253C and T394S, which are involved in neutralization epitopes arose during the outbreak, but apparently there was no positive selection of either of them. The origin of the outbreak remains unknown because of poor virologic surveillance in Latin America and the African countries neighboring Spain. On the other hand, this is the first report of this genotype in Europe. The few published sequences of genotype 1j indicate that it comes from Japan and the Philippines, but there are no epidemiological data supporting this as the origin of the Madrid outbreak.