bluuebunny/crossref_metadata_2025 huggingface dataset:
Serological characterization and partial purification of an Lyt‐1 homolog in tunicate hemocytes
Authors: Negm Hoda I. , Mansour Mohamed H. , Cooper Edwin L.
Published: February 2012

Summary— A panel of alloantisera and monoclonal antibodies specific to murine Lyt‐1 allotypic and framework determinants was used in indirect immunofluorescence and FACS analysis to investigate the occurrence of an Lyt‐1 homolog in tunicate (protochordate) hemocytes. Binding assays and quantitative absorption experiments established the expression of Lyt‐1 cross‐reacting determinants on a distinct population of tunicate hemocytes. These determinants were expressed exclusively by cells with the morphological characteristics of hemoblasts and lymphocytes. In a rapid two‐step purification procedure, Lyt‐1 glycoproteins from tunicate hemocytes and C57B1/6 mouse thymocytes were solubilized and partially purified by affinity chromatography using a mAb anti‐Lyt‐1 frame‐work determinant. In both cell types, antigenic activities were associated with a major 67‐kDa component. Our findings suggest an early phylogenetic emergence of an Lyt‐1 homolog at this level of evolution.
Some ultrastructural observations on the mode of association of microtubules with the plasmalemma in epidermal tendon cells of the river crab
Authors: Nakazawa Eiko , Ishikawa Harunori
Published: February 2012

Summary— The ultrastructural aspects of the association of microtubules (MTs) with the plasmalemma in epidermal tendon cells of the river crab, Polamon dehaani, were studied by thin‐section electron microscopy combined with detergent treatment. In the tendon cell, MTs were linked laterally by anchoring filaments to the plasmalemma via a submembranous electron‐dense layer called the plasmalemmal undercoat. To further clarify how such anchoring filaments are spatially related to the plasmalemma through the undercoat, we carefully examined and compared thin‐section images obtained from various specimen preparations using saponin and Triton X‐100. When the tissues were treated with saponin or Triton, electron‐dense materials in the undercoat were extracted in varying degrees to expose internal substructures. The undercoat appeared to show a two‐layer organization, the inner and outer layers. In more extracted samples, filamentous networks became prominent in the outer layer. Anchoring filaments were seen to attach to such filamentous networks, which in turn were linked to the plasmalemma proper. Thus, it may be reasonable to consider that the filamentous network constitutes the core structure of the plasmalemmal undercoat which is structurally reinforced by extractable electron‐dense materials.
Growth and differentiation of rabbit tracheal outgrowths in primary cultures: Influence of substrata
Authors: Bourgeois Claire A , Blanquart Catherine , Jeanne Nicole , Moreau Anne , Marano Francelyne
Published: February 2012

Summary— We show that in rabbit tracheal outgrowths, ciliated cells can express an affinity for the isolectin BSI‐B4, known to preferentially bind to basal cells. In multi‐layered outgrowths grown on a thick collagen gel, a low percentage of ciliated cells are labelled by BSI‐B4. This percentage increases with the aging of cultures. In monolayers developed on thin coatings of collagen or matrigel, a high percentage of ciliated cells show affinity for BSI‐B4, even within young cultures.
A clusterwise simultaneous component method for capturing within‐cluster differences in component variances and correlations
Authors: De Roover Kim , Ceulemans Eva , Timmerman Marieke E. , Onghena Patrick
Published: February 2012

This paper presents a clusterwise simultaneous component analysis for tracing structural differences and similarities between data of different groups of subjects. This model partitions the groups into a number of clusters according to the covariance structure of the data of each group and performs a simultaneous component analysis with invariant pattern restrictions (SCA‐P) for each cluster. These restrictions imply that the model allows for between‐group differences in the variances and the correlations of the cluster‐specific components. As such, clusterwise SCA‐P is more flexible than the earlier proposed clusterwise SCA‐ECP model, which imposed equal average cross‐products constraints on the component scores of the groups that belong to the same cluster. Using clusterwise SCA‐P, a finer‐grained, yet parsimonious picture of the group differences and similarities can be obtained. An algorithm for fitting clusterwise SCA‐P solutions is presented and its performance is evaluated by means of a simulation study. The value of the model for empirical research is illustrated with data from psychiatric diagnosis research.
Firing patterns of spontaneously active motor units in spinal cord‐injured subjects
Authors: Zijdewind Inge , Thomas Christine K.
Published: February 2012

Key points 

Muscles below a human spinal cord injury start to contract involuntarily a few weeks after trauma. The basis for this spontaneous activity is still unclear.

We show motor units in these muscles exhibited regular or irregular activity for several minutes. The regularly firing motor units had longer estimated afterhyperpolarisation potentials, higher mean firing rates and generated weaker forces.

These observations suggest that regularly firing motor units are more excitable than those that fire irregularly.

Spontaneous firing of motor units at regular rates may reflect active properties (such as persistent currents) within motoneurones, visible here in the absence of voluntary drive.

This basic motor unit firing behaviour may underlie the firing patterns typically recorded during voluntary contractions.
Compliant Cardan Universal Joint
Authors: Tanık Engin , Parlaktaş Volkan
Published: February 2012

In this study, a compliant version of the Cardan universal joint is introduced. The original design consists of two identical parts assembled at right angle with respect to each other. The single piece part can be produced from planar materials; thus, it has the advantage of easiness in manufacturing. Dimensions of the mechanism are devised in order to satisfy the Cardan joint theory and to avoid an undesired contact between the identical parts. As a design example, a mechanism is dimensioned. The resultant stresses at flexural hinges of this sample are determined via finite element analysis method and torque transmission capability of this mechanism is determined. Further, this sample is manufactured and operated under a considerable output loading. Therefore, robustness of the compliant Cardan joint is verified with this prototype. As well, it is verified that the results of experiments are consistent with the theoretical approaches.
Robust Feed-Forward Controls for Better Tracking: A Practical Approach to Optimal Air-Fuel Controls and Low Emissions
Authors: Makki Imad H. , Kerns James M.
Published: February 2012

When designing control systems, it is important to keep in mind the end-users. In general, the complexity and difficulty of implementing and tuning a control strategy determine if such a strategy should be adopted, despite its performance. The automotive industry is no exception to that; powertrain control system engineers are constantly tasked to design controllers that are simple to follow, fairly robust, and require moderate resources for implementation and validation. Obviously, stability is critical for any control strategy; an oscillating controller not only could result in fluctuation in engine torque which could lead to customer dissatisfaction, but also could have a negative impact on vehicle tailpipe emissions. Bottom line is the controller must provide good stability as well as superb reference tracking. Proportional–Integral-Derivative (PID) controllers are attractive solutions for powertrain calibrators. They are widely used in the automotive industry as they are easy to implement and tune, especially when the Derivative term is dropped to reduce the sensitivity of the system and improve its robustness. Consequently, with only two gains to adjust, tuning a PI controller is a relatively simple task, but quite often calibrators struggle trying to meet both stability requirements and tracking performance. Adding a Smith Predictor (SP) to the PI controller, is one way to achieve the tracking performance desired. This is indeed a well known approach that allows for much higher gains to be used in order to improve the tracking ability while maintaining stability in the presence of plant models changing dynamics and system delays. However, with this combination (PI-SP), the robustness of the overall control strategy suffers as errors in the plant models tend to reduce the stability of the over all system and could potentially lead to an unstable or undesirable performance. In this paper, we will present a practical approach to improve the performance and robustness of the PI controller. This is achieved by adding unity-gain feed-forward (FF) of the air fuel set point for improved tracking plus a set-point filter in the input to the PI controller (FF-PI) to prevent overshoots. We will also show that this control structure provides excellent and robust reference tracking without destabilizing the system in the presence of errors in the plant model. In addition, we will include results obtained with the FF-PI controller when applied to two applications: Air-fuel ratio (A/F) control for gasoline lean burn vehicles (5.4L F150 and 4.0L Ford of Australia Falcon), and Exhaust Gas Recirculation (EGR) control on a 2.0L Gasoline, Turbocharged, Direct Injection Engine.
Design and Development of a New Landfill/Biogas Engine Oil for Modern, High BMEP Natural Gas Engines
Authors: Palazzotto John D. , Timar Joseph , Beckman Alan T.
Published: February 2012

The use of higher brake mean effective pressure (BMEP) engines in landfill or alternative gas applications has increased dramatically in the past few years. Operators are using these engines due to their ability to provide lower emissions coupled with improved economics for the end user due to the higher density or power output capability compared to an engine of similar size and displacement. Landfill gas (LFG) quality can vary greatly as well as the contaminant level due to the composition of the landfill. This environment poses unique challenges to both the engine and the engine oil, including shorter oil drain intervals, corrosive attack of engine components, with increased piston and combustion chamber deposits, to name but a few. Maintaining longer oil drain intervals minimizes unscheduled oil drains which can decrease the overall cost of the landfill operation. High BMEP engines provide higher power output but at the cost of increased maintenance in severe fuel applications. Excessive piston crown and combustion chamber deposits from landfill gas impurities can have a deleterious effect on engine emissions, which may lead to the inability to meet local emissions regulations. Engine lubricants must provide adequate oil life as well as minimizing deposit related issues that may negatively impact regular scheduled maintenance cycles, thus reducing engine downtime and increasing revenues. Traditionally, the approach has been that oils formulated for landfill applications used excess base reserve to sufficiently neutralize the acids being formed during the combustion process. Unfortunately, this approach increases the sulfated ash content of the lubricant which lends itself to increased ash deposits and negatively impacts the combustion dynamics of these high BMEP engines, which are sensitive to ash deposition. Based on requests for a longer life lubricant without compromising deposit control characteristics in serve landfill applications, a new product development project was specifically targeted for late model, high BMEP engines, which are prone to detonation and sensitive to ash related deposits. This paper presents the development bench testing, and proof of performance field evaluations of a new generation, low ash landfill gas engine oil.
Analysis of Ignition Behavior in a Turbocharged Direct Injection Dual Fuel Engine Using Propane and Methane as Primary Fuels
Authors: Polk A. C. , Gibson C. M. , Shoemaker N. T. , Srinivasan K. K. , Krishnan S. R.
Published: February 2012

This paper presents experimental analyses of the ignition delay (ID) behavior for diesel-ignited propane and diesel-ignited methane dual fuel combustion. Two sets of experiments were performed at a constant speed (1800 rev/min) using a 4-cylinder direct injection diesel engine with the stock ECU and a wastegated turbocharger. First, the effects of fuel-air equivalence ratios (Φpilot ∼ 0.2–0.6 and Φoverall ∼ 0.2–0.9) on IDs were quantified. Second, the effects of gaseous fuel percent energy substitution (PES) and brake mean effective pressure (BMEP) (from 2.5 to 10 bar) on IDs were investigated. With constant Φpilot (> 0.5), increasing Φoverall with propane initially decreased ID but eventually led to premature propane autoignition; however, the corresponding effects with methane were relatively minor. Cyclic variations in the start of combustion (SOC) increased with increasing Φoverall (at constant Φpilot), more significantly for propane than for methane. With increasing PES at constant BMEP, the ID showed a nonlinear (initially increasing and later decreasing) trend at low BMEPs for propane but a linearly decreasing trend at high BMEPs. For methane, increasing PES only increased IDs at all BMEPs. At low BMEPs, increasing PES led to significantly higher cyclic SOC variations and SOC advancement for both propane and methane. Finally, the engine ignition delay (EID) was also shown to be a useful metric to understand the influence of ID on dual fuel combustion.
A Study on Soot Formation and Oxidation of Ethanol / Diesel Blends Using the Two-Color Method
Authors: Wakikawa Masanori , Tachibana Nobuhide , Chen Zhili , Oguma Mitsuharu
Published: February 2012

In this study, two dimensional distribution of flame temperature and soot concentration was measured with constant volume vessel by the two color method for diesel ethanol blends. As a result, because two factors of decreasing soot formation, which are low adiabatic flame temperature and high oxygen concentration, are synergistic in the beginning of combustion, soot formation is reduced remarkably. In the later stage of the combustion, the flame temperature does not fall, so two enhance effects of soot oxidation, which are early reversal timing and high oxygen concentration, are synergistic. Therefore, in case of diesel ethanol blends, soot formation is reduced by low adiabatic flame temperature and high oxygen concentration, and soot oxidation is enhanced by early reversal timing and high oxygen concentration. Even for an actual engine, soot emission will be decreased because soot formation is reduced and soot oxidation is enhanced.
Advanced Metal Substrate Technology for Large Engine Exhaust Gas Aftertreatment Systems
Authors: Downey Markus , Pfahl Ulrich
Published: February 2012

In the coming years non-road and locomotive diesel engine exhaust gas emissions will become regulated by EPA Tier4 legislation. The stringent emission limits of Tier 4 will require the use of aftertreatment technology currently being used in on-road applications. Based on the potentially large displacements of these engines, the aftertreatment systems will be large and expensive. The flow restriction that is added by the aftertreatment system will result in additional engine pumping work and lower fuel efficiency. The high durability requirements that are demanded of the aftertreatment systems is another factor that needs to be considered. Technologies that reduce complexity, size and cost of the aftertreatment system and minimize incremental fuel consumption are needed. Metal substrate technology offers a number of solutions for the challenges in meeting Tier 4 legislation. The substrates can be used for oxidation catalysts, selective catalytic reduction and slip catalysts depending on what kind of coating is applied to them. The thin wall technology that metal substrates can offer, even at coarse cell densities and lack of required retention mat for system integration provides more open frontal area, leading to lower flow restriction and lower fuel consumption. When designing a modular exhaust system, the shape flexibility will allow for denser packaging of the catalysts. This maximizes the amount of available cross-sectional area, leading to a most compact exhaust system and again better fuel efficiency. Large diameter catalysts can be manufactured in one piece, rather than being joined together from several pieces. A more robust substrate is the outcome.
ExhAUST: A Two Dimensional Numerical Soot Model for Advanced Design and Control of Diesel Engine Aftertreatment Systems
Authors: Mulone Vincenzo , Abeyratne Prabash , Cozzolini Alessandro , Besch Marc C. , Littera Daniele , Gautam Mridul
Published: February 2012

Despite their overwhelming popularity and widespread use, diesel engines have to strive to meet the continually tightening emission regulations. One of the most effective methods to control diesel particulate matter (PM) emissions from heavy duty diesel engines is to use wall flow Diesel Particulate Filters (DPFs). It is still a major challenge to get an accurate estimation of soot loading, which is crucial for the engine aftertreatment assembly optimization. In the recent past, several advanced computational models of DPF filtration and regeneration have been presented to assess the cost effective optimization of future particulate trap systems. In this study, the already presented 1D code [1,2] was extended to understand the impact of 2D representation to predict the transient behavior of a catalyzed Diesel Particulate Filter (CDPF). Quasi-steady state conservation of mass and momentum was solved to find the flow velocity and a previously validated, advanced filtration/regeneration model allowed a highly detailed representation of the soot loading, permeability, porosity and filtration efficiency. Results are presented in terms of comparison with the 1D code, over FTP engine transient cycle data gathered at the West Virginia University Engine and Emissions Research Laboratory (WVU-EERL), by keeping constant parameter set, for the sake of general validation of simplifying assumptions of the 1D code. Results generally state that the ID representation is effective toward PM loading prediction, although presenting considerable axial effects at higher DPF temperature.
Effect of Inlet Air Temperature on Auto-Ignition of Fuels With Different Cetane Number and Volatility
Authors: Jayakumar Chandrasekharan , Zheng Ziliang , Joshi Umashankar M. , Bryzik Walter , Henein Naeim A. , Sattler Eric
Published: February 2012

This paper investigates the effect of air inlet temperature on the auto-ignition of fuels that have different CN and volatility in a single cylinder diesel engine. The inlet air temperature is varied over a range of 30°C to 110°C. The fuels used are ultra-low-sulfur-diesel (ULSD), JP-8 (two blends with CN 44.1 & 31) and F-T SPK. Detailed analysis is made of the rate of heat release during the ignition delay period, to determine the effect of fuel volatility and CN on the auto-ignition process. A STAR-CD CFD model is applied to simulate the spray behavior and gain more insight into the processes that immediately follow the fuel injection including evaporation, start of exothermic reactions and the early stages of combustion. The mole fractions of different species are determined during the ignition delay period and their contribution in the auto-ignition process is examined. Arrhenius plots are developed to calculate the global activation energy for the auto-ignition reactions of these fuels. Correlations are developed for the ID and the mean air temperature and pressure.
A Computational Investigation of Piston Bowl Geometry for a Large Bore Two-Cycle Diesel Engine
Authors: Dolak Jonathan , Bandyopadhyay Deep
Published: February 2012

The objective of this research was to optimize an Electro-Motive Diesel (EMD) large-bore, two-cycle diesel engine (710 cubic inches of displacement per cylinder) at high load to minimize soot, nitrogen oxide (NOx) and fuel consumption. The variables considered were the number of spray-hole nozzles per injector, including spray angle and piston bowl geometry, for a range of injection pressures. Analytical simulations were conducted for a calibrated EMD 710 Tier 2 engine and a few of the top-performing cases were studied in detail. CONVERGE™, a commercially available, advanced combustion simulation software was used in this analysis. A surface deforming tool, Sculptor®, was used to obtain various piston bowl geometries. MiniTab® was utilized for statistical analysis. Results show that optimal combinations of injection variables and piston bowl shape exist to simultaneously reduce emissions and fuel consumption compared to Tier 2 EMD 710 engines. These configurations will be further tested in a single-cylinder test cell and presented later. This investigation shows the importance of bowl geometry and spray targeting on emissions and fuel consumption for large-bore, two-stroke engines with high power density.
Compression Ignition Linear Engine Design Variable Effects
Authors: To´th-Nagy Csaba , Farmouri Parviz , Clark Nigel N.
Published: February 2012

A linear engine/alternator was simulated and designed, and a prototype was built at West Virginia University. This paper describes the engine and presents original operational data. The linear engine was a two-cylinder, two-stroke, common rail direct injection, compression ignition engine. The engine was built using off the shelf components to reduce cost where it was possible. Engine control, injection duration and timing, were achieved using a microcontroller with piston position as a control input. Experiments on the engine were performed to study its behavior. The studied variables included mass of the translator, amount of fuel injected, injection timing, load, and stroke with operating frequency and mechanical efficiency as the basis of comparison. At this point of development, the engine was far from optimized; however, the trends in engine behavior were clear. Increasing the translator mass resulted in decreased operating frequency. Increasing the stroke length also resulted in decreased operating frequency. Overcharging and increased fueling rate, both, resulted in increased power output, efficiency, and operating frequency. Advancing injection timing resulted in increased frequency, efficiency and power output, and decreased stalling frequency. This suggests that the engine operated in an HCCI-like fashion.
Assessment of Residual Mass Estimation Methods for Cylinder Pressure Heat Release Analysis of HCCI Engines With Negative Valve Overlap
Authors: Ortiz-Soto Elliott A. , Vavra Jiri , Babajimopoulos Aristotelis
Published: February 2012

Increased residual levels in Homogeneous Charge Compression Ignition (HCCI) engines employing valve strategies such as recompression or negative valve overlap (NVO) imply that accurate estimation of residual gas fraction (RGF) is critical for cylinder pressure heat release analysis. The objective of the present work was to evaluate three residual estimation methods and assess their suitability under naturally aspirated and boosted HCCI operating conditions: i) the Simple State Equation method employs the Ideal Gas Law at exhaust valve closing (EVC); ii) the Mirsky method assumes isentropic exhaust process; and iii) the Fitzgerald method models in-cylinder temperature from exhaust valve opening (EVO) to EVC by accounting for heat loss during the exhaust process and uses measured exhaust temperature for calibration. Simulations with a calibrated and validated “virtual engine” were performed for representative HCCI operating conditions of engine speed, fuel-air equivalence ratio, NVO and intake pressure (boosting). The State Equation method always overestimated RGF by more than 10%. The Mirsky method was most robust, with average errors between 3–5%. The Fitzgerald method performed consistently better, ranging from no error to 5%, where increased boosting caused the largest discrepancies. A sensitivity study was also performed and determined that the Mirsky method was most robust to possible pressure and temperature measurement errors.
Dynamic Analysis of Prime Mover Combined Heat and Power Delivery to Chemical Processing
Authors: Reed Michael E. , Grauer Diana K.
Published: February 2012

This paper presents a study of the impact of combined heat and power generation from prime mover engines on coupled chemical processes. Medium- and large-bore engines are frequently used in refineries and chemical plants to provide dedicated mechanical power to unit operations. Currently, the prime mover is included in the chemical process design as a single, steady-state power input. This design does not take into account, dynamic engine operation including load changes, start-up, shut-down, and malfunction, all of which have a direct and immediate impact on unit operations. The research team has developed a dynamic model of a “proof of concept” example chemical process in Aspen Custom Modeler to investigate the impact of dynamic operation and integration of a dedicated prime mover unit on an example chemical process.
Validated Thermal CFD in an Outboard Marine Engine Enclosure
Authors: Morton Scott , Narasingamurthi Sivagaminathan
Published: February 2012

Modern, high-performance, outboard marine engines operate in severe environments. They are typically mounted to a planing boat operating at high horsepower levels due to high hydrodynamic drag. The engine also experiences high vertical impact loads in rough-water conditions. In the ocean, corrosive salt water circulates through the engine to provide necessary engine cooling. Splashing water can be ingested into the combustion air inlets on the outside of the engine cowl (engine enclosure) and must be appropriately managed. In addition, the engine often operates in very warm climates with a sealed cowl wrapped tightly around it. The warm atmospheric air that flows through the cowl inlets and into the engine compartment must first circulate around the power head in order to cool thermally sensitive components such as engine controllers and ignition coils. In some applications, the same air stream mixes with fuel then participates in the combustion process inside the cylinder. At Mercury Marine, computational fluid dynamics, CFD, is used to aid the design of outboard engines that will operate robustly in these extreme conditions. One specific application for CFD is the management of the flow and thermal aspects of engine-compartment air flow. Studies can be done with CFD to assist product design decisions that aim to balance the need to protect thermally sensitive electronics and to efficiently provide the engine with the combustion air. The CFD simulation predicts the air flow behavior from the cowl duct inlets, around the power-head, and into the throttle body inlet of the engine. The simulation also predicts air temperatures, component temperatures, and heat flow to and from the air. The CFD model typically includes rotating components such as alternators and flywheels. A recent study was conducted to validate the CFD method. The CFD model and the dynamometer experiments were conducted with a mid-size outboard 4-stroke engine. The test engine was fully instrumented to measure air temperatures, air velocities, and component temperatures. The validation exercise included a detailed comparison of these values between the CFD predictions and the experimental results. A high level of agreement was achieved and a few lessons were captured for future implementation.
CFD Methodology for the Simulation of Mixture Formation of High Performance PFI Engines
Authors: Forte Claudio , Bianchi Gian Marco , Corti Enrico , Argento Gaspare , Fantoni Stefano
Published: February 2012

Mixture composition strongly influences the stability of combustion of spark ignition engines. The control of air to fuel ratio at ignition is a critical issue for high performance engines: due to the low stroke-to-bore ratio the maximum power is reached at very high regimes, letting little time to the fuel to evaporate and mix with air. The aim of this work is to present a CFD methodology for the evaluation of mixture formation applied to a Ducati high performance engine. The phenomena involved in the process are highly heterogeneous, and particular care must be taken to the choice of CFD models and their validation. In the present work all the main models involved in the simulations are validated against experimental tests available in the literature, selected based on the similarity of physical conditions with those of the engine configuration under analysis. The multi-cycle simulation methodology here presented reveals to be a useful tool for the evaluation of the mixture quality around the spark plug at ignition, allowing a parametric analysis of the effects of the injection process on engine output.
A Study of the Effects of Biofuel Use on Piston Lubrication During Fuel Post Injection in a DI Diesel Engine
Authors: Kikuhara Koji , Shibata Akihiro , Ito Akemi , Kim Dallwoo , Ishikawa Yasuhiro , Usui Miyuki
Published: February 2012

The reduction of both exhaust gases and carbon dioxide emissions is necessary to meet future emissions regulations for diesel engines. Exhaust after-treatment devices are gradually being applied to diesel engines to reduce exhaust gases. Diesel Particulate Filters (DPF), an after-treatment device for diesel engines, in some cases require post injection of fuel for its regeneration. Post injection is usually carried out at the mid point of the expansion stroke, and therefore causes fuel adhesion to the cylinder wall. However, using biofuels in a diesel engine is an effective way of reducing carbon dioxide emissions. It is well known that biofuels are chemically unstable, but the effects of biofuels on piston lubrication condition have not been thoroughly studied. In this study, piston lubrication condition during post injection in a single cylinder DI diesel engine using biofuel was investigated. Piston and ring friction forces were measured under engine operating conditions by means of a floating liner device to investigate the lubrication condition of the piston and rings. Both light fuel oil and biofuel were used in the measurements, with Rapeseed Methyl Ester (RME) being used as the biofuel. Lubricating oil on the cylinder wall was also sampled under engine operating conditions and the effect of post injection on fuel adhesion to the cylinder wall was analyzed. It was found that the effect of post injection on fuel adhesion to the cylinder wall was remarkable around the Top Dead Center (TDC), and the fuel dilution rate reached approximately 90%. The results of the measurement of the piston friction forces showed that post injection caused an increase in the friction forces at the Compression TDC (CTDC) in the cases of both RME and light fuel oil, and the friction forces at CTDC increased according to the delay of the post injection timing. The increase in the piston friction forces was moderate in the case of RME. It seems that the higher viscosity and the oiliness of RME suppressed the increase in piston friction forces at TDC. The following effects were found in this study. Fuel post injection caused fuel adhesion to the cylinder wall. Such phenomena affected the lubrication condition of the piston. In the case of RME, the increase in the piston friction forces caused by post injection was smaller than that of light fuel oil, but the effects on piston lubrication condition in the case of using other biofuels needs to be investigated.
The High Performance Toroidal Engine Concept (HiPerTEC)
Authors: Hoose Karl V. , Shorey Eric E.
Published: February 2012

The traditional reciprocating I.C. engine has evolved to a point where significant improvements in thermal efficiency and specific power are not expected. Modifications to existing engines may prove to be difficult and expensive while resulting in only marginal gains. In addition, most modifications result in added components that often increase cost and decrease reliability of the system as a whole. For applications requiring major advances in performance, such as unmanned vehicles, meeting mission requirements will likely stem from a revolutionary rather than an evolutionary engine design. The slider crank mechanism is a major impediment to the traditional reciprocating I.C. engine. Although this mechanism has been used for the past 100 years, it is very wasteful of the available energy supplied by the combustion process, where piston-liner interactions from this arrangement accounts for 50–70% of the total friction losses in this engine design. Eliminating the slider crank could significantly reduce friction losses and provide additional benefits that can increase fuel conversion efficiency. The HiPerTEC engine is an opposed, free-piston engine arranged in a toroidal configuration with two counter reciprocating sets of pistons. The counter reciprocating masses eliminate the vibration found in linear free-piston engines. The HiPerTEC employs a unique shared volume configuration where the swept volume is twice the physical cylinder volume. This attribute offers a significant increase in specific power, while the free-piston characteristics provide for substantial gains in thermodynamic cycle efficiency. An eight cylinder/chamber arrangement offers balanced operation in both two and four-stroke cycle modes to allow for a wide operating envelope. The final HiPerTEC configuration will require advanced materials to address lubrication and cooling requirements. This paper discusses the HiPerTEC design, operating characteristics, development progress to date, and the challenges that lie ahead.
Gas Phase Deposition of Trichloro(1H,1H,2H,2H-perfluorooctyl)silane on Silicon Dioxide, by XPS
Authors: Lee Michael V. , Husseini Ghaleb , Sautter Ken , Linford Matthew R.
Published: February 2012

Monolayers of trichloro(lH,1H,2H,2H-perfluorooctyl)silane, Cl3SiCH2CH2(CF2)5CF3, were deposited via chemical vapor deposition onto the native oxide layer on silicon after plasma-cleaning. The samples have high hydrophobicity, and provide a valuable comparison to perfluorinated alkyl silane layers obtained by liquid deposition. Gas-phase deposition of perfluorinated alkyl silanes is a useful means for reducing stiction in micro- and nano-electromechanical systems, which have narrow spaces that can trap bubbles and prevent liquid-based silane passivation.
Science Signaling
Podcast: 7 February 2012
Authors: Taylor Kathryn M. , VanHook Annalisa M.
Published: February 2012

Activity of the kinase CK2 promotes the generation of intracellular zinc waves by stimulating the zinc channel ZIP7.
Comparative Efficacies of Artemisinin Combination Therapies in Plasmodium falciparum Malaria and Polymorphism of
pfATPase6
,
pfcrt
,
pfdhfr
, and
pfdhps
Genes in Tea Gardens of Jalpaiguri District, India
Authors: Saha Pabitra , Guha Subhasish K. , Das Sonali , Mullick Shrabanee , Ganguly Swagata , Biswas Asit , Bera Dilip K. , Chattopadhyay Gaurangadeb , Das Madhusudan , Kundu Pratip K. , Ray Krishnangshu , Maji Ardhendu K.
Published: February 2012

In India, chloroquine has been replaced by a combination of artesunate and sulfadoxine-pyrimethamine (AS-SP) for uncomplicated
P. falciparum
malaria. Other available combinations, artemether-lumefantrine (AM-LF) and artesunate-mefloquine (AS-MQ), not included in the national program, are widely used by private practitioners. Little is known about the therapeutic efficacy of these artemisinin combinations and the prevalence of molecular markers associated with antimalarial drug resistance. A total of 157 patients with
P. falciparum
monoinfection were recruited and randomized into three study groups (AS-SP, AM-LF, and AS-MQ). All patients were followed up for 42 days to study the clinical and parasitological responses according to the WHO protocol (2009). We assessed the polymorphism of the
pfATPase6
,
pfcrt
,
pfdhfr
, and
pfdhps
genes by the DNA-sequencing method. The PCR-corrected therapeutic efficacies of AS-SP, AM-LF, and AS-MQ were 90.6% (95% confidence interval [CI], 0.793 to 0.969), 95.9% (95% CI, 0.860 to 0.995), and 100% (95% CI, 0.927 to 1.00), respectively. No specific mutational pattern was observed in the
pfATPase6
gene. All isolates had a K76T mutation in the
pfcrt
gene. In the
pfdhfr-pfdhps
genotype, quadruple mutation was frequent, and quintuple mutation was documented in 6.3% of
P. falciparum
isolates. The significant failure rate of AS-SP (9.5%), although within the limit (10%) for drug policy change, was due to SP failure because of prevailing mutations in
pfdhfr
, I
51
R
59
N
108
, with
pfdhps
, G
437
and/or E
540
. The efficacy of this ACT needs periodic monitoring. Artemether-lumefantrine and artesunate-mefloquine are effective alternatives to the artesunate-sulfadoxine-pyrimethamine combination.
Wild Coastline Birds as Reservoirs of Broad-Spectrum-β-Lactamase-Producing Enterobacteriaceae in Miami Beach, Florida
Authors: Poirel Laurent , Potron Anaïs , De La Cuesta Carolina , Cleary Timothy , Nordmann Patrice , Munoz-Price L. Silvia
Published: February 2012

A high rate of broad-spectrum-β-lactamase-producing
Escherichia coli
isolates was identified from seagull and pelican feces collected in the Miami Beach, Florida, area. The most commonly identified resistance determinants were CMY-2 and CTX-M-15. Those wild birds might be therefore considered vehicles for wide dissemination of multidrug-resistant
Enterobacteriaceae
in the United States.
Microbiological Aetiology, Epidemiology, and Clinical Profile of Prosthetic Joint Infections: Are Current Antibiotic Prophylaxis Guidelines Effective?
Authors: Peel Trisha N. , Cheng Allen C. , Buising Kirsty L. , Choong Peter F. M.
Published: February 2012

Prosthetic joint infections remain a major complication of arthroplasty. At present, local and international guidelines recommend cefazolin as a surgical antibiotic prophylaxis at the time of arthroplasty. This retrospective cohort study conducted across 10 hospitals over a 3-year period (January 2006 to December 2008) investigated the epidemiology and microbiological etiology of prosthetic joint infections. There were 163 cases of prosthetic joint infection identified. From a review of the microbiological culture results, methicillin-resistant
Staphylococcus aureus
(MRSA) and coagulase-negative staphylococci were isolated in 45% of infections. In addition, polymicrobial infections, particularly those involving Gram-negative bacilli and enterococcal species, were common (36%). The majority (88%) of patients received cefazolin as an antibiotic prophylaxis at the time of arthroplasty. In 63% of patients in this cohort, the microorganisms subsequently obtained were not susceptible to the antibiotic prophylaxis administered. The results of this study highlight the importance of ongoing reviews of the local ecology of prosthetic joint infection, demonstrating that the spectrum of pathogens involved is broad. The results should inform empirical antibiotic therapy. This report also provokes discussion about infection control strategies, including changing surgical antibiotic prophylaxis to a combination of glycopeptide and cefazolin, to reduce the incidence of infections due to methicillin-resistant staphylococci.
Endoscopy and implantable electronic devices
Authors: Corbett G D , Buttery P C , Pugh P J , Cameron E A B
Published: February 2012

The increasing use of implantable electronic devices such as cardiac pacemakers and neurostimulators means that they are being increasingly encountered in endoscopy departments. The electromagnetic fields generated during electrosurgery and with magnetic imaging systems have the potential to interfere with such devices. The authors present a case that highlights some of the steps necessary for minimising risk, review the evidence and summarise the currently available guidance.
DECAY PROPERTIES OF SOLUTIONS TO THE LINEARIZED COMPRESSIBLE NAVIER–STOKES EQUATION AROUND TIME-PERIODIC PARALLEL FLOW
Authors: BŘEZINA JAN , KAGEI YOSHIYUKI
Published: February 2012

Decay estimates on solutions to the linearized compressible Navier–Stokes equation around time-periodic parallel flow are established. It is shown that if the Reynolds and Mach numbers are sufficiently small, solutions of the linearized problem decay in L2 norm as an (n - 1)-dimensional heat kernel. Furthermore, it is proved that the asymptotic leading part of solutions is given by solutions of an (n - 1)-dimensional linear heat equation with a convective term multiplied by time-periodic function.
RELAXATION OF FLUID SYSTEMS
Authors: COQUEL FRÉDÉRIC , GODLEWSKI EDWIGE , SEGUIN NICOLAS
Published: February 2012

We propose a relaxation framework for general fluid models which can be understood as a natural extension of the Suliciu approach in the Euler setting. In particular, the relaxation system may be totally degenerate. Several stability properties are proved. The relaxation procedure is shown to be efficient in the numerical approximation of the entropy weak solutions of the original PDEs. The numerical method is particularly simple in the case of a fully degenerate relaxation system for which the solution of the Riemann problem is explicit. Indeed, the Godunov solver for the homogeneous relaxation system results in an HLLC-type solver for the equilibrium model. Discrete entropy inequalities are established under a natural Gibbs principle.
PASSING TO THE LIMIT IN MAXIMAL SLOPE CURVES: FROM A REGULARIZED PERONA–MALIK EQUATION TO THE TOTAL VARIATION FLOW
Authors: COLOMBO MARIA , GOBBINO MASSIMO
Published: February 2012

We prove that solutions of a mildly regularized Perona–Malik equation converge, in a slow time scale, to solutions of the total variation flow. The convergence result is global-in-time, and holds true in any space dimension. The proof is based on the general principle that "the limit of gradient-flows is the gradient-flow of the limit". To this end, we exploit a general result relating the Gamma-limit of a sequence of functionals to the limit of the corresponding maximal slope curves.
DYNAMIC REARRANGEMENT OF VACUUM AND THE PHASE TRANSITIONS IN THE GEOMETRIC STRUCTURE OF SPACE-TIME
Authors: BOGOSLOVSKY GEORGE YU.
Published: February 2012

It is shown that in the case of spontaneous breaking of the original gauge symmetry, a dynamic rearrangement of vacuum may lead to the formation of some anisotropic condensates. The appearance of such condensates causes the respective phase transitions in the geometric structure of space-time and creates a flat anisotropic, i.e. Finslerian event space. Actually there arises either a flat relativistically invariant Finslerian space with partially broken 3D isotropy, i.e. axially symmetric space, or a flat relativistically invariant Finslerian space with entirely broken 3D isotropy. The fact that any entirely anisotropic relativistically invariant Finslerian event space belongs to a 3-parameter family of such spaces gives rise to a fine structure of the respective geometric phase transitions. In the present paper the fine structure of the geometric phase transitions is studied by classifying all the metric states of the entirely anisotropic event space and the respective mass shell equations.
AN OPERATOR-THEORETIC APPROACH TO INVARIANT INTEGRALS ON QUANTUM HOMOGENEOUS SLn+1(ℝ)-SPACES
Authors: CASTRO OSVALDO OSUNA , WAGNER ELMAR
Published: February 2012

We present other examples illustrating the operator-theoretic approach to invariant integrals on quantum homogeneous spaces developed by Kürsten and the second author. The quantum spaces are chosen such that their coordinate algebras do not admit bounded Hilbert space representations and their self-adjoint generators have continuous spectrum. Operator algebras of trace class operators are associated to the coordinate algebras which allow interpretations as rapidly decreasing functions and as finite functions. The invariant integral is defined as a trace functional which generalizes the well-known quantum trace. We argue that previous algebraic methods would fail for these examples.
Concert Viewing Headphones
Authors: Atsuta Kazuya , Hamanaka Masatoshi , Lee SeungHee
Published: February 2012

An audiovisual interface equipped with a projector, an inclina-tion sensor, and a distance sensor for zoom control has been developed that enables a user to selectively view and listen to specific performers in a video-taped group performance. DubbedConcert Viewing Headphones, it has both image and sound processing functions. The image processing extracts the portion of the image indicated by the user and projects it free of distortion on the front and side walls. The sound processing creates imaginary microphones for those performers without one so that the user can hear the sound from any performer. Testing using images and sounds captured using a fisheye-lens camera and 37 lavalier microphones showed that sound locali-zation was fastest when an inverse square function was used for the sound mixing and that the zoom function was useful for locating the desired sound performance.
HumanDirofilaria repensInfection in Romania: A Case Report
Authors: Popescu Ioana , Tudose Irina , Racz Paul , Muntau Birgit , Giurcaneanu Calin , Poppert Sven
Published: February 2012

Human dirofilariasis is a zoonotic infectious disease caused by the filarial nematodes of dogsDirofilaria repensandDirofilaria immitis. Depending on the species involved, human infections usually manifest as one cutaneous or visceral larva migrans that forms a painless nodule in the later course of disease. Dirofilariae are endemic in the Mediterranean, particularly in Italy. They are considered as emerging pathogens currently increasing their geographical range. We present one of the few known cases of human dirofilariasis caused byD. repensin Romania. The patient developed unusual and severe clinical manifestations that mimicked pathological conditions like cellulitis or deep venous thrombosis.
Serum Cytokine Profile by ELISA in Patients with Echinococcal Cysts of the Liver: A Stage-Specific Approach to Assess Their Biological Activity
Authors: Piccoli Luca , Meroni Valeria , Genco Francesca , Tamarozzi Francesca , Tinelli Carmine , Filice Carlo , Brunetti Enrico
Published: February 2012

To investigate the usefulness of serum cytokine dosage in the clinical management of cystic echinococcosis (CE), we analyzed serum levels of Th1 and Th2 cytokines in patients with hepatic CE in different cyst stages, CE1-2 (active), CE3a-3b (transitional), and CE4-5 (inactive).Ex vivoassessment of Th1 (IFN-γ) and Th2 (IL-4, IL-13, and IL-10) cytokines in sera was carried out using ELISA. IL-10 was undetectable in all serum samples of patients and controls, while a few sera contained measurable amounts of IFN-γ, IL-4, and IL-13. No statistically significant difference was found between the percentages of positive samples for each cytokine and the different groups analyzed (patients/controls, stage, number, location, and size of the cyst, serology, and sex of patients), with the exception of the association of IL-4 and IL-13 with the cyst stage. Overall, this investigation showed many limits of serum cytokine dosage as a marker of biological activity of echinococcal cysts. Because of low sensitivity and lack of specificity of this test, we believe that other ways to evaluateex vivobiological activity of the cysts should be explored.