bluuebunny/crossref_metadata_2025 huggingface dataset:
Accessory Veins in Nonmaturing Autogenous Arteriovenous Fistulae: Analysis of Anatomic Features and Impact on Fistula Maturation
Authors: Engstrom Bjorn I. , Grimm Lars J. , Ronald James , Smith Tony P. , Kim Charles Y.
Published: December 2014

The appropriate management of nonmaturing arteriovenous (AV) fistulae continues to be a controversial issue. While coil embolization of accessory side‐branch veins can be performed to encourage maturation of nonmaturing AV fistulae, the true efficacy and optimal patient population are not well understood. Fistulagrams performed on nonmaturing AV fistulae were retrospectively reviewed in 145 patients (86 males, median age 63 years) for the presence of accessory veins. Fistula and accessory vein measurements were obtained, as were rates of eventual fistula maturation after accessory vein coil embolization. Of 145 nonmaturing fistulae, 49 (34%) had a stenosis without any accessory veins, 76 (52%) had a stenosis and one or more accessory veins, and 20 (14%) had an accessory vein without concurrent stenosis. Eighteen AV fistulae had one or more accessory veins without coexisting stenosis. Nine fistulae had a caliber decrease immediately downstream from the accessory vein. Coil embolization of dominant accessory veins with a caliber decrease immediately downstream (n = 6) resulted in a 100% eventual fistula maturation rate versus 67% for fistulae without this configuration (n = 6, p = 0.15). Accessory vein size was not correlated with maturation rates (p = 0.51). The majority of nonmaturing fistulae with accessory veins had a coexisting stenosis. Higher maturation rates may result with selected anatomic parameters, although additional studies with more robust sample sizes are needed prior to definitive conclusions.
Sport medicine and sport science practitioners' experiences of organizational change
Authors: Wagstaff C. R. D. , Gilmore S. , Thelwell R. C.
Published: December 2014

Despite the emergence of and widespread uptake of a growing range of medical and scientific professions in elite sport, such environs present a volatile professional domain characterized by change and unprecedentedly high turnover of personnel. This study explored sport medicine and science practitioners' experiences of organizational change using a longitudinal design over a 2‐year period. Specifically, data were collected in three temporally defined phases via 49 semi‐structured interviews with 20 sport medics and scientists employed by three organizations competing in the top tiers of English football and cricket. The findings indicated that change occurred over four distinct stages; anticipation and uncertainty, upheaval and realization, integration and experimentation, normalization and learning. Moreover, these data highlight salient emotional, behavioral, and attitudinal experiences of medics and scientists, the existence of poor employment practices, and direct and indirect implications for on‐field performance following organizational change. The findings are discussed in line with advances to extant change theory and applied implications for prospective sport medics and scientists, sport organizations, and professional bodies responsible for the training and development of neophyte practitioners.
Does type 1 diabetes alter post‐exercise thermoregulatory and cardiovascular function in young adults?
Authors: McGinn R. , Carter M. R. , Barrera‐Ramirez J. , Sigal R. J. , Flouris A. D. , Kenny G. P.
Published: December 2014

Recent data demonstrated that individuals with type 1 diabetes mellitus (T1DM) exhibit impaired sweating and increased rectal temperature (i.e., heat storage) during exercise compared with healthy controls. Our purpose in this study was to investigate the consequences of T1DM on post‐exercise thermal homeostasis. Sixteen participants (eight controls matched with eight T1DM) performed 90 min of cycling followed by 60 min of seated recovery. Esophageal and rectal temperatures, sweating (forearm, chest, and upper back), skin blood flow [forearm and upper back, presented as cutaneous vascular conductance (CVC)], and blood pressure [mean arterial pressure (MAP)] were measured at baseline and throughout recovery. Esophageal temperature was similar during baseline and recovery between groups (P = 0.88). However, rectal temperature was elevated in our T1DM group throughout recovery (P = 0.05). Sweating and CVC were similar between groups at all sites from 10‐min post‐exercise until the end of recovery (P ≥ 0.16). While absolute MAP was similar between groups (P = 0.43), the overall decrease in MAP post‐exercise was greater in controls from 20 min (T1DM: − 8 ± 5 vs control: − 13 ± 6 mmHg, P = 0.03) until the end of recovery. We conclude that despite increased heat storage during exercise, individuals with T1DM exhibit a suppression in heat loss similar to their healthy counterparts during recovery.
Leisure‐time physical activity and disability pension: 9 years follow‐up of the HUNT Study, Norway
Authors: Fimland M. S. , Vie G. , Johnsen R. , Nilsen T. I. L. , Krokstad S. , Bjørngaard J. H.
Published: December 2014

The objective of this study was to prospectively examine the association between leisure‐time physical activity and risk of disability pension, as well as risk of disability pension because of musculoskeletal or mental disorders in a large population‐based cohort. Data on participants aged 20–65 years in the Norwegian Nord‐Trøndelag Health Study 1995–1997 (HUNT2) were linked to the National Insurance Database. Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals for disability pension across physical activity categories. During a follow‐up of 9.3 years and 235 657 person‐years, 1266 of 13 823 men (9%) and 1734 of 14 531 women (12%) received disability pension. Compared with individuals in the inactive group, those in the highly active group had a 50% lower risk of receiving disability pension (HR for men: 0.50, 0.40–0.64; women: 0.50, 0.39–0.63). After comprehensive adjustment for potential confounders, the risk remained 32–35% lower (HR for men: 0.68, 0.53–0.86; women: 0.65, 0.51–0.83). The associations were stronger for disability pension due to musculoskeletal disorders than mental disorders. In summary, we observed strong inverse associations between leisure‐time physical activity and disability pension. Our findings strengthen the hypothesis that leisure‐time physical activity may be important for occupational health in reducing disability pension.
Utilization of laser Doppler flowmetry and tissue spectrophotometry for burn depth assessment using a miniature swine model
Authors: Lotter Oliver , Held Manuel , Schiefer Jennifer , Werner Ole , Medved Fabian , Schaller Hans‐Eberhard , Rahmanian‐Schwarz Afshin , Jaminet Patrick , Rothenberger Jens
Published: December 2014

Currently, the diagnosis of burn depth is primarily based on a visual assessment and can be dependent on the surgeons' experience. The goal of this study was to determine the ability of laser Doppler flowmeter combined with a tissue spectrophotometer to discriminate burn depth in a miniature swine burn model. Burn injuries of varying depth, including superficial‐partial, deep‐partial, and full thickness, were created in seven Göttingen minipigs using an aluminium bar (100 °C), which was applied to the abdominal skin for periods of 1, 3, 6, 12, 30, and 60 seconds with gravity alone. The depth of injury was evaluated histologically using hematoxylin and eosin staining. All burns were assessed 3 hours after injury using a device that combines a laser light and a white light to determine blood flow, hemoglobin oxygenation, and relative amount of hemoglobin. The blood flow (41 vs. 124 arbitrary units [AU]) and relative amount of hemoglobin (32 vs. 52 AU) were significantly lower in full thickness compared with superficial‐partial thickness burns. However, no significant differences in hemoglobin oxygenation were observed between these depths of burns (61 vs. 60%). These results show the ability of laser Doppler flowmeter and tissue spectrophotometer in combination to discriminate between various depths of injury in the minipig model, suggesting that this device may offer a valuable tool for burn depth assessment influencing burn management.
Research on the Static and Dynamic Characteristics of Misaligned Journal Bearing Considering the Turbulent and Thermohydrodynamic Effects
Authors: Xu Guohui , Zhou Jian , Geng Haipeng , Lu Mingjian , Yang Lihua , Yu Lie
Published: December 2014

Journal misalignment usually exists in journal bearings that affect nearly all the bearings static and dynamic characteristics including minimum oil film thickness, maximum oil film pressure, maximum oil film temperature, oil film stiffness, and damping. The main point in this study is to provide a comprehensive analysis on the oil film pressure, oil film temperature, oil film thickness, load-carrying capacity, oil film stiffness, and damping of journal bearing with different misalignment ratios and appropriately considering the turbulent and thermo effects based on solving the generalized Reynolds equation and energy equation. The results indicate that the oil thermo effects have a significant effect on the lubrication of misaligned journal bearings under large eccentricity ratio. The turbulent will obviously affect the lubrication of misaligned journal bearings when the eccentricity or misalignment ratio is large. In the present design of the journal bearing, the load and speed become higher and higher, and the eccentricity and misalignment ratio are usually large in the operating conditions. Therefore, it is necessary to take the effects of journal misalignment, turbulent, and thermal effect into account in the design and analysis of journal bearings.
Analysis of Thermal Stress and Its Influence on Carrier Mobility in Three-Dimensional Microelectronic Chip Stack
Authors: Johnson R. W. , Shen Y.-L.
Published: December 2014

A numerical assessment on the thermal stress in a three-dimensional (3D) microelectronic package structure is performed. The objectives are to study how the chip stack/microbump assembly responds to thermal mismatch induced deformation, and its influences on the electrical performance of devices. The 3D finite element model features a copper through-silicon-via (TSV)/microbump bonding structure connecting two adjacent silicon chips, with and without an underfill layer in between. A case that the entire solder layer has been transformed into an intermetallic layer is also considered. Potential for damage initiation is examined by the measure of stress and strain patterns. It was found that the part of TSV well inside the silicon chip is under high triaxial tensile stresses after thermal cooling, and plastic deformation in copper occurs in and around the microbump regions. The existence of underfill increases plastic strains in the solder joint. The underfill also leads to a significant change in local stress field when the soft solder is transformed entirely into an intermetallic layer. The carrier mobility for the p- and n-type devices is influenced by the stresses in silicon near the TSV; the sizes of “keep-out zone” for the various model configurations are also quantified.
Quantification of Efficiency Gains for Dilute IC Engines due to Increases of the Ratio of Specific Heats
Authors: Caton Jerald A.
Published: December 2014

Recent engine developments have demonstrated significant thermal efficiency gains for IC engines employing lean mixtures and high levels of exhaust gas recirculation (EGR). These efficiency gains have often been attributed to reduced heat losses and increases of the ratio of specific heats. No previous publication, however, has provided the quantitative contributions from these two items. This lack of information, therefore, motivated the current work. An automotive engine was selected for this study, and a thermodynamic engine cycle simulation was used for the evaluation. Engine conditions included a range of loads and speeds. For each engine condition, three cases were considered. These cases varied the equivalence ratio from stoichiometric to 0.7, and varied the EGR from zero to 45%. Depending on the engine conditions, the net indicated thermal efficiency increased between 4.2% and 8.9% (absolute) for the engine with the lean mixture (ϕ = 0.7) and EGR (45%). The lower gas temperatures and lean mixtures resulted in reduced heat losses and increases of the ratio of specific heats. For all conditions examined, the majority of the thermal efficiency gains were due to the increases of the ratio of specific heats. The contributions from the increases of the ratio of specific heats toward the efficiency gains ranged between about 46% and 82% for the conditions examined. The rest of the gains were from the reduced heat losses.
Systems Assessment of Engine Oil Consumption Through Various Paths
Authors: Karrip Kimm , Maschewske Max , Passow Eric
Published: December 2014

There is a rapid increase with application of turbochargers, variable valve timing engines, lubricant developments and other aspects that increase engine efficiency. As fuel consumption reduces through further engine developments, the engine lubricant oil consumption will become a larger contributor to engine exhaust emissions. Lubricant oil consumption can be through four systems within the turbocharged engine, which are: 1. PCV (positive crankcase ventilation), 2. VSS (valve stem seals), 3. Turbocharger, 4. PCU (power cylinder unit). Overall engine oil consumption is reliably quantified using the Tritium Tracer Oil Consumption Measurement System[1],[2] and with a gage repeatability and reproducibility study (R&R) of 6.4%. Test methods have been developed utilizing this measurement system that quantify the oil consumption contribution from the four different systems. This paper will summarize the techniques used and discuss potential challenges that new engine technologies pose on lube oil consumption.
Investigation of the Effect of Injection and Control Strategies on Combustion Instability in Reactivity Controlled Compression Ignition (RCCI) Engines
Authors: Klos David T. , Kokjohn Sage L.
Published: December 2014

This paper uses detailed CFD modeling with the KIVA-CHEMKIN code to investigate the influence of injection timing, combustion phasing and operating conditions on combustion instability. Using detailed computational fluid dynamics (CFD) simulations, a large design of experiments (DOE) is performed with small perturbations in the intake and fueling conditions. A response surface model (RSM) is then fit to the DOE results to predict cycle-to-cycle combustion instability. Injection timing had significant tradeoffs between engine efficiency, emissions and combustion instability. Near TDC injection timing can significantly reduce combustion instability, but the emissions and efficiency drop to close to conventional diesel combustion (CDC) levels. The fuel split between the two DI injections has very little effect on combustion instability. Increasing EGR rate, while making adjustments to maintain combustion phasing, can significantly reduce PPRR variation until the engine is on the verge of misfiring. Combustion phasing has a very large impact on combustion instability. More advanced phasing is much more stable, but produces high peak pressure rise rates, higher NOx levels, and can be less efficient due to increased heat transfer losses. The results of this study identify operating parameters that can significantly improve the combustion stability of dual-fuel RCCI engines.
Critical Review of Porter’s Work on Engine Torque Harmonics
Authors: Doughty Samuel
Published: December 2014

The classic 1943 paper by F.P. Porter on IC engine torque harmonics is best known for its data tables related to the gas pressure torques. However, it also presents Porter’s work on the inclusion of inertial and gravitational torques as excitation functions for torsional vibration. This latter part is relatively obscure because (1) it is presented without any supporting analysis, (2) a number of the quantities involved are not clearly defined, and (3) Porter’s presentation is entirely tied to the US Customary Units system. The present paper explains Porter’s results, with clear definitions of all terms and an appropriate system sketch, and provides a physical motivation for each of his terms in a framework suitable for use with any consistent system of units.
Modeling and Analysis of Mixed Lubrication in Automotive Valve Train
Authors: Ren Ning , Lockwood Frances E. , Piraner Ilya , Gabale Amit
Published: December 2014

Environmental regulation and high fuel cost are among the leading driving forces behind the demand of energy efficient vehicles. Together with new engine hardware technologies, engine oil is expected to significantly contribute to improving vehicle fuel economy. New fuel-efficient engine oils are often formulated with advanced additives and low viscosity base oils. Understanding the lubrication performance at key engine components such as the cam and follower in valve train systems becomes critically important to ensure engine durability with the new fuel-efficient low viscosity oils. A full numerical mixed lubrication analysis of the cam and roller follower pair is conducted using the three dimensional line contact mixed elastohydrodynamic lubrication (EHL) model. The results show significant effects of surface roughness, topography, slide-to-roll ratio, and viscosity grade on lubricant film, contact pressure, and subsurface stress.
Effects of EGR and Boost Pressure on Reactivity Controlled Compression Ignition (RCCI) Engine at High Load Operating Conditions
Authors: Wu Yifeng , Reitz Rolf D.
Published: December 2014

Reactivity Controlled Compression Ignition (RCCI) at engine high load operating conditions is investigated in this study. The effects of EGR and boost pressure on RCCI combustion were studied by using a multi-dimensional computational fluid dynamics (CFD) code. The model was first compared with a previous CFD model, which has been validated against steady-state experimental data of gasoline-diesel RCCI in a multi-cylinder light duty engine. An RCCI piston with a compression ratio of 15:1 was then proposed to improve the combustion and emissions at high load. The simulation results showed that 18 bar indicated mean effective pressure (IMEP) could be achieved with gasoline-diesel RCCI at an EGR rate of 35 % and equivalence ratio of 0.96, while the peak pressure rise rate (PPRR) and engine combustion efficiency could both be controlled at reasonable levels. Simulations using both early and late direct-injection (DI) of diesel fuel showed that RCCI combustion at high load is very sensitive to variations of the exhaust gas recirculation (EGR) amount. Higher IMEP is obtained by using early diesel injection, and it is less sensitive to EGR variation compared to late diesel injection. Reduced unburned hydrocarbon (HC), carbon monoxide (CO), soot and slightly more nitrogen oxides (NOx) emissions were seen for early diesel injection. HC, CO and soot emissions were found to be more sensitive to EGR variation at late diesel injection timings. However, there was little difference in terms of peak pressure, efficiencies, PPRR and phasing under varying EGR rates. The effect of boost pressure on RCCI at high load operating conditions was also studied at different EGR rates. It was found that combustion and emissions were improved, and the sensitivity of the combustion and emission to EGR was reduced with higher boost pressures. In addition, cases with similar combustion phasing and reasonable PPRR were analyzed by using an experimentally validated GT-Power model. The results indicated that although higher IMEP was generated at higher boost pressures, the brake mean effective pressure (BMEP) was similar compared to that obtained with lower boost pressures due to higher pumping losses.
Combustion Characteristics of Stratified Mixture in Lean-Burn LPG Direct-Injection Engine With Spray-Guided Combustion System
Authors: Park Cheolwoong , Oh Seungmook , Kim Taeyoung , Oh Heechang , Bae Choongsik
Published: December 2014

Today, we are faced with the problems of global warming and fossil fuel depletion, and they have led to the enforcement of new emissions regulations. Direct-injection spark-ignition engines are a very promising technology that can comply with the new regulations. These engines offer the advantages of better fuel economy and lower emissions than conventional port-injection engines. The use of LPG as the fuel reduces carbon emissions because of its vaporization characteristics and the fact that it has lower carbon content than gasoline. An experimental study was carried out to investigate the combustion process and emission characteristics of a 2-liter spray-guided LPG direct-injection engine under lean operating conditions. The engine was operated at a constant speed of 2000 rpm under 0.2-MPa brake mean effective pressure, which corresponds to a common operation point of a passenger vehicle. Combustion stability, which is the most important component of engine performance, is closely related to the operation strategy and it significantly influences the degree of fuel consumption reduction. In order to achieve stable combustion with a stratified LPG mixture, an inter-injection spark ignition (ISI) strategy, which is an alternative control strategy to two-stage injection, was employed. The effects of the compression ratio on fuel economy were also assessed; due to the characteristics of the stratified LPG mixture, the fuel consumption did not reduce when the compression ratio was increased.
Comparison of Alternative EGR Systems for a Medium Speed Diesel Engine
Authors: Freund Sebastian , Lavertu Thomas M. , Mischler Robert , Primus Roy J.
Published: December 2014

Meeting future regulations for diesel engine NOx emissions with in-cylinder solutions will require a high rate of exhaust gas recirculation (EGR). For medium speed diesel engines, the exhaust manifold pressure is typically lower than that of the intake manifold, necessitating a rise in the exhaust gas pressure for exhaust flow to be introduced into the intake manifold. In this study, four high-pressure EGR engine concepts are investigated as a means to meet EPA Tier 4 NOx emissions. These concepts include a system with an EGR pump, one with a power turbine downstream of the turbocharger (i.e., turbocompounding), one with dedicated donor EGR cylinders and the use of a backpressure valve. For each system, an optimum set of parameters that included intake valve timing, intake manifold pressure, and fuel injection timing were found that satisfy the emissions requirements while staying within the mechanical limits of the system. From an efficiency perspective, the turbocompound system is generally superior, followed by the donor cylinder concept. The EGR pumping system typically has lower overall efficiency due to the compressor power requirement and the use of a backpressure valve, representing the baseline for comparison, produced the lowest system efficiency.
Diesel Nozzle Flow Investigation in Non-Radial Multi Hole Geometry
Authors: Chiatti Giancarlo , Chiavola Ornella , Palmieri Fulvio
Published: December 2014

Flow features at hole inlet traditionally depend both on injector tip type (Minisac, VCO, Microsac), and on hole drilling & finishing technology (hydro grinding, paste honing); such a topic is going to be faced by researchers for many years, due to the importance of high pressure injection process in current and upcoming diesel engine.

In the present paper, investigations have been extended to an unconventional diesel nozzle layout, highlighting its capability on altering the flow structure at hole inlet, and thus influencing the flow development within the nozzle holes. As described in the article, the investigated nozzle is based on a multihole layout but, referring to the injector axis, nozzle holes have a non-radial arrangement.

The investigations on nozzle hole flow development have been based on modeling. Moving from the standard nozzle configuration towards non-radial arranged holes, 3D-CFD campaigns have been devoted to highlight the influence of such unusual nozzle layout on diesel nozzle flow.

In the modeling process, data concerning spatial distribution of velocity and cavitation behavior at hole exit have been computed; the effect of non-radial multi hole geometry has been investigated both on MicroSac and VCO layouts. Specific attention has been focused on the fuel flow distribution among the holes; the computations have evidenced how the unconventional layout is capable to improve the behavior of VCO geometries when needle eccentric displacement is considered. Results have been synthetized indicating how flow pattern properties are reflected at hole exit, quantitatively.
Lube Oil Soot Reduction Using Combustion Simulation for CPCB2 Compliant Cummins N14 Engine
Authors: Duvvuri Pavan Prakash , Deshpande Nilesh , Mahadevan Boopathi S. , Jain Parul , Yeole Rajesh
Published: December 2014

A combustion system has been optimized for the Cummins N14 diesel engine using KIVA-RIF to meet CPCB2 emission norms. It has been developed to reduce lube oil soot while meeting the legislative requirements for PM and NOx. The optimization involves closed cycle combustion simulation at three operating conditions: 110%, 75% & 50% load at rated speed. A combustion CFD code, KIVA-RIF has been calibrated to simulate the experimental results at all these points. Qualitative comparison has been done between soot on liner from simulation to lube oil soot from experiments. Parameters studied during combustion simulation involved the study of piston bowl profile, injector configuration (number of holes, spray angle, and through flow), injection timing and swirl. From combustion simulation, a deep spray angle bowl has been observed as a promising solution due to improved emissions and lube oil soot. The combustion recipe identified has a characteristic PM vs NOx curve for injection timing swing. Validation of simulation results with engine testing in terms of PM, NOx, and lube oil soot has been observed in good agreement.
Improving the Efficiency of Low Temperature Combustion Engines Using a Chamfered Ring-Land
Authors: Lim Jae Hyung , Reitz Rolf D.
Published: December 2014

In the present study a chamfered piston crown design was used in order to reduce unburned hydrocarbon (UHC) emissions from the ring-pack crevice. Compared to the conventional piston design, the chamfered piston showed 17%∼41% reduction in the crevice-borne UHC emissions in homogeneous charge compression ignition (HCCI) combustion. Through parametric sweeps 6 mm was identified to be a suitable chamfer size and the mechanism of the UHC reduction was revealed. Based on the findings in this study, the chamfered piston design was also tested in dual-fuel reactivity controlled compression ignition (RCCI) combustion. In the tested RCCI case using the chamfered piston the UHC and CO emissions were reduced by 79% and 36%, respectively, achieving 99.5% combustion efficiency. This also improved gross indicated thermal efficiency from 51.1% to 51.8% in a 9 bar IMEP RCCI combustion case.
Interactions of Piston Ring Pack With Coated Cylinder Liners of Heavy Duty Diesel Engines
Authors: Araujo Fabio , de Sá Filho Luiz , Bieneman Jason , Nocera Eduardo , Rejowski Edney Deschauer
Published: December 2014

The heavy duty diesel (HDD) engine market continues to strive for improvements in engine efficiency and durability which places ever increasing development demands on the power cylinder unit. One of the methods being developed to help meet these demands is coated cylinder bore technology. By applying a coating to the inner diameter surface of a cylinder liner the wear on the liner can be significantly reduced. The reduction in liner wear is not however the only advantage that this technology can offer. Liner coatings can also offer corrosion protection, reductions in wear on the running surface of the rings, improved scuff resistance, and enable improvements in the efficiency of the engine. New piston ring technologies will be valuable in maximizing these advantages and their contribution will be detailed. The system must be properly designed to take full advantage of all of these opportunities. In this paper both the advantages and difficulties coated liners present will be explored by evaluating the impact on the liner, rings and the fuel consumption. This paper will additionally provide details regarding the different liner coating technologies being developed today. To support these recommendations the system’s performance characteristics will be demonstrated through rig testing and engine performance measurements.
Natural Gas for High Load Dual-Fuel Reactivity Controlled Compression Ignition (RCCI) in Heavy-Duty Engines
Authors: Walker N. Ryan , Wissink Martin L. , DelVescovo Dan A. , Reitz Rolf D.
Published: December 2014

Reactivity controlled compression ignition (RCCI) has been shown to be capable of providing improved engine efficiencies coupled with the benefit of low emissions via in-cylinder fuel blending. Much of the previous body of work has studied the use of gasoline as the premixed low-reactivity fuel. However, there is interest in exploring the use of alternative fuels in advanced combustion strategies. Due to the strong market growth of natural gas as a fuel in both mobile and stationary applications, a study on the use of methane for RCCI combustion was performed. Single cylinder heavy-duty engine experiments were undertaken to examine the operating range of the RCCI combustion strategy with methane/diesel fueling, and was compared against gasoline/diesel RCCI operation. The experimental results show a significant load extension of RCCI engine operation with methane/diesel fueling compared to gasoline/diesel fueling. For gasoline/diesel fueling, a maximum load of 6.9 bar IMEPg at CA50 = 0° aTDC and 7.0 bar IMEPg at CA50 = 4° aTDC was obtained without use of EGR. For methane/diesel fueling a maximum load of 15.4 bar IMEPg at CA50 = 0° aTDC and 17.3 bar IMEPg at CA50 = 4° aTDC was achieved, showing the effectiveness of the use of methane in extending the load limit for RCCI engine operation.
A Study on the Effect of Pressure Balance Between the Second and Third Land of a Piston on Engine Oil Consumption
Authors: Ohno Yohei , Kikuhara Koji , Ito Akemi , Inui Masatsugu , Akamatsu Hirotaka
Published: December 2014

Engine oil consumption causes particulate matter, poisoning of catalysts, abnormal combustion like pre-ignition in a gasoline engine, and an increase in customer’s running cost. Oil consumption, therefore, must be reduced.

It is well known that pressure at a piston second land sometimes becomes larger than the cylinder pressure in the latter half of the expansion stroke. Larger pressure at the second land causes an increase in engine oil consumption. For reducing the second land pressure, increasing volume of a piston second land is one of design schemes. Pressure at a piston second land is calculated in piston design stage. In the calculation, pressure at a piston third land is assumed as same as pressure at the crankcase.

This study aimed the effect of volume of the third land of a piston on engine oil consumption. The third and the second lands pressure were measured using an optical fiber type pressure sensor. It was found that the third land pressure showed a quite different trend from the crankcase pressure. It was also found that the pressure balance between the second land and the third land affected engine oil consumption. It was suggested that the third land pressure should be considered in the calculation for lands pressure of a piston and further investigation on third land design for reducing engine oil consumption may be required.
Investigation on Spray and Soot Lift-Off Length of an ABE-Diesel Blend in a Constant Volume Chamber With Diesel Engine Conditions
Authors: Wu Han , Nithyanandan Karthik , Li Boqi , Lee Timothy H. , Lee Chia-fon F. , Zhang Chunhua
Published: December 2014

Acetone-Butanol-Ethanol (ABE), an intermediate product in the ABE fermentation process for producing bio-butanol, is considered as a promising alternative fuel because it not only preserves the advantages of oxygenated fuel, which typically emit less pollutants compared to conventional diesel, but also lowers the cost of fuel recovery for each individual component during the fermentation. In this work, 20% ABE with component ratio of 3:6:1 and 80% ultra-sulfur diesel by volume, referred as ABE20, and pure diesel, referred as D100, were injected and combusted in a constant volume chamber with the ability to mimic high temperature and high pressure conditions of real diesel cylinder near the top dead center. By adjusting intake partial pressure and injection timing, the ambient oxygen concentration and temperature for fuel injection can be controlled. Ambient temperatures were set at 1100K, 900K and 700K to cover conventional temperature combustion and low temperature combustion, while the ambient oxygen concentrations were set at 21%, 16% and 11% to cover different EGR ratios separately. Spray and natural flame images were captured by a high speed camera coupled with a copper vapor laser as a light source.

The results show that spray liquid penetration and soot lift-off length are shorter and much longer for ABE20 than those for D100 separately under all tested conditions, which form a much bigger gap from spray tip to the combustion area for ABE20. A big gap reduces the local equivalence ratio at the combustion area and then suppresses the soot formation due to the gap is the most effective area for air-fuel mixing processes. Indeed, the natural flame luminosity which represents the soot emission level of ABE20 is significantly lower than that of D100 at all tested conditions. At the same time, ABE20 performed a similar combustion phasing with D100 under high ambient temperature, but experienced an aggressive retardation under low ambient temperatures especially with low ambient oxygen concentrations. In addition, ABE20 did not show a stronger concentrated premixed combustion since its heat release rate peak is lower than that of D100, which was also confirmed by its longer combustion duration. Therefore, ABE20 expresses a high potential to reduce soot emissions but it also has to face combustion deterioration at low temperature combustion conditions.
An Experimental Investigation of Combustion Chamber Design Parameters for Hot Surface Ignition
Authors: Chown Dan , Habbaky Charles , Wallace James S.
Published: December 2014

Natural gas requires some form of ignition assist in order to autoignite in the time available in a compression ignition engine. Ignition assist using a glow plug — a heated surface — was investigated using an apparatus that consists of an optically accessible constant volume combustion bomb coupled to a single cylinder CFR engine through the spark plug port. Previous studies have shown the dominant effect of fuel injection pattern and glow plug shield geometry on ignition delay, combustion rate, and fuel utilization with 1–3 fuel jets. New work has been carried out to evaluate the ability of a shielded glow plug to ignite a full nine jet symmetrical fuel injection pattern. The sensitivity of ignition delay and fuel utilization to fuel injector angular alignment relative to the glow plug, glow plug shield opening angle, and glow plug power was analyzed using in-cylinder pressure data and exhaust hydrocarbon emissions concentrations. Two glow plugs, one conventional metallic and one ceramic, and two fuel injector nozzle orifice sizes were evaluated for their effect on ignition delay. The ignition and flame propagation process was observed using high speed images. Glow plug power was shown to have a dominant effect on ignition delay and fuel utilization, with a secondary effect from fuel injector angle and glow plug opening angle. The ceramic glow plug was shown to provide superior ignition assist while consuming less power than the metallic glow plug. The larger fuel injector nozzle size increased ignition delay times, likely due to increased convective cooling of the glow plug surface from the larger gas jet. Acquired images show that the smaller fuel injector orifice size created a flammable path in two distinct areas; along the periphery of the fuel jets and between the fuel jets. The higher mass flow rate and subsequent increased mixing of the larger fuel jets created flammable paths throughout the entirety of the combustion chamber.
Piston Ring and Groove Side Wear Analysis for Diesel Engines
Authors: Poort Mulyanto , Cheng Chao , Richardson Dan , Schock Harold
Published: December 2014

Piston ring wear is a major factor determining a diesel engine’s life. A ring is subjected to wear between its front face and the cylinder wall as well as at the interfaces between the ring and groove top and bottom flanks. In many modern engines, ring and groove wear are becoming more of a limiting factor for ring durability than face wear. The focus of this paper is on ring to groove side wear only.

In this paper two fundamental mechanisms for ring/groove side wear are identified: (1) wear due to piston secondary motion and (2) wear due to ring twist. The time in the cycle where each of these mechanisms results in maximum wear is shown.

Then the effect of ring static twist and the resulting effect on the pressure distribution around the ring are studied. The pressure distribution affects the force acting on the ring that causes the ring/groove side wear. It is also shown that the pressure distribution and the resultant wear can be influenced by the land diameter below the piston ring.

Progressive wear is also studied, showing a good correlation between predicted wear and measured wear on both ring sides and groove sides. It is noted that as the corner of the ring/groove wears, the ultimate wear of the ring side can accelerate by a phenomenon named pressure infiltration. Pressure infiltration occurs because the bottom side of the ring groove wears exposing more of bottom side of the ring to lower pressure force. This ultimately causes a higher difference between the high pressure above the ring and the low pressure below the ring. As a result, the net force acting on the ring increases and wear increases.

In addition to the study of the first ring, the second ring wear was studied. A comparison was made between the top ring and second ring groove side wear (RGSW) predictions. Also the effect of the second ring static twist on both top and second ring/groove side wear is described in detail.
Revealing a Role for Presynaptic Glutamate Receptors in LTP
Authors: Gough Nancy R.
Published: December 2014

Long-term potentiation of corticostriatal synapses involves presynaptic glutamate receptors and growth factor secretion.
Limited-Sampling Strategies for Anidulafungin in Critically Ill Patients
Authors: van Wanrooy Marjolijn J. P. , Proost Johannes H. , Rodgers Michael G. G. , Zijlstra Jan G. , Uges Donald R. A. , Kosterink Jos G. W. , van der Werf Tjip S. , Alffenaar Jan-Willem C.
Published: December 2014

Efficacy of anidulafungin is driven by the area under the concentration-time curve (AUC)/MIC ratio. Determination of the anidulafungin AUC along with MIC values can therefore be useful. Since obtaining a full concentration-time curve to determine an AUC is not always feasible or appropriate, limited-sampling strategies may be useful in adequately estimating exposure. The objective of this study was to develop a model to predict the individual anidulafungin exposure in critically ill patients using limited-sampling strategies. Pharmacokinetic data were derived from 20 critically ill patients with invasive candidiasis treated with anidulafungin. These data were used to develop a two-compartment model in MW\Pharm using an iterative 2-stage Bayesian procedure. Limited-sampling strategies were subsequently investigated using two methods, a Bayesian analysis and a linear regression analysis. The best possible strategies for these two methods were evaluated by a Bland-Altman analysis for correlation of the predicted and observed AUC from 0 to 24 h (AUC
0–24
) values. Anidulafungin exposure can be adequately estimated with the concentration from a single sample drawn 12 h after the start of the infusion either by linear regression (
R
2
= 0.99; bias, 0.05%; root mean square error [RMSE], 3%) or using a population pharmacokinetic model (
R
2
= 0.89; bias, −0.1%; RMSE, 9%) in critically ill patients and also in less severely ill patients, as reflected by healthy volunteers. Limited sampling can be advantageous for future studies evaluating the pharmacokinetics and pharmacodynamics of anidulafungin and for therapeutic drug monitoring in selected patients. (This study has been registered at ClinicalTrials.gov under registration no. NCT01047267.)
Assessment of Time to Clinical Response, a Proxy for Discharge Readiness, among Hospitalized Patients with Community-Acquired Pneumonia Who Received either Ceftaroline Fosamil or Ceftriaxone in Two Phase III FOCUS Trials
Authors: Lodise Thomas P. , Anzueto Antonio R. , Weber David J. , Shorr Andrew F. , Yang Min , Smith Alexander , Zhao Qi , Huang Xingyue , File Thomas M.
Published: December 2014

The primary driver of health care costs for patients with community-acquired pneumonia (CAP) is the hospital length of stay (LOS). Unfortunately, hospital LOS comparisons are difficult to make from phase III CAP trials because of their structured designs and prespecified treatment durations. However, an opportunity still exists to draw inferences about potential LOS differences between treatments through the use of surrogates for hospital discharge. The intent of this study was to quantify the time to a clinical response, a proxy for the time to discharge readiness, among hospitalized CAP patients who received either ceftaroline or ceftriaxone in two phase III CAP FOCUS clinical trials. On the basis of the Infectious Diseases Society of America and American Thoracic Society CAP management guidelines and recent FDA guidance documents for community-acquired bacterial pneumonia, a
post hoc
adjudication algorithm was constructed
a priori
to compare the time to a clinical response, a proxy for the time to discharge readiness, between patients who received ceftaroline or ceftriaxone. Overall, 1,116 patients (ceftaroline,
n
= 562; ceftriaxone,
n
= 554) from the pooled FOCUS trials met the selection criteria for this analysis. Kaplan-Meier analyses showed that ceftaroline was associated with a shorter time, measured in days, to meeting the clinical response criteria (
P
= 0.03). Of the patients on ceftaroline, 61.0, 76.1, and 83.6% achieved a clinical response by days 3, 4, and 5, compared to 54.3, 69.8, and 79.3% of the ceftriaxone-treated patients. In the Cox regression, ceftaroline was associated with a shorter time to a clinical response (HR, 1.16,
P
= 0.02). The methodology employed here provides a framework to draw comparative effectiveness inferences from phase III CAP efficacy trials. (The FOCUS trials whose data were analyzed in this study have been registered at
ClinicalTrials.gov
under registration no. NCT00621504 and NCT00509106.)
Mechanisms of Action of Substituted β-Amino Alkanols on Leishmania donovani
Authors: Abengózar María Ángeles , Bustos Luis A. , García-Hernández Raquel , Fernández de Palencia Pilar , Escarcena Ricardo , Castanys Santiago , del Olmo Esther , Gamarro Francisco , San Feliciano Arturo , Rivas Luis
Published: December 2014

Leishmaniasis is the protozoan disease second in importance for human health, superseded only by malaria; however, the options for chemotherapeutic treatment are increasingly limited due to drug resistance and toxicity. Under this perspective, a quest for new chemical compounds is urgently needed. An N-substituted 2-aminoalkan-1-ol scaffold has been shown to be a versatile scaffold for antiparasitic activity. Knowledge about its mechanism of action is still rather limited. In this work, we endeavored to define the leishmanicidal profile of such β-amino alkanol derivatives using a set of 15 N-mono- and disubstituted surrogates, tested on
Leishmania donovani
promastigotes and intracellular amastigotes. The best compound (compound 5), 2-ethylaminododecan-1-ol, had a 50% effective concentration (EC
50
) of 0.3 μM and a selectivity index of 72 for infected THP-1 cells and was selected for further elucidation of its leishmanicidal mechanism. It induced fast depletion of intracellular ATP content in promastigotes in the absence of vital dye intracellular entry, ruling out plasma membrane permeabilization as its origin. Confocal and transmission electron microscopy analyses showed that compound 5 induced severe mitochondrial swelling and vesiculation. Polarographic analysis using an oxygen electrode demonstrated that complex II of the respiratory chain (succinate reductase) was strongly inhibited by compound 5, identifying this complex as one of the primary targets. Furthermore, for other β-amino alkanols whose structures differed subtly from that of compound 5, plasma membrane permeabilization or interference with membrane traffic was also observed. In all, N-substituted β-amino alkanols were shown as appealing leishmanicidal candidates deserving further exploration.
Genomic Insights into Intrinsic and Acquired Drug Resistance Mechanisms in Achromobacter xylosoxidans
Authors: Hu Yongfei , Zhu Yuying , Ma Yanan , Liu Fei , Lu Na , Yang Xi , Luan Chunguang , Yi Yong , Zhu Baoli
Published: December 2014

Achromobacter xylosoxidans
is an opportunistic pathogen known to be resistant to a wide range of antibiotics; however, the knowledge about the drug resistance mechanisms is limited. We used a high-throughput sequencing approach to sequence the genomes of the
A. xylosoxidans
type strain ATCC 27061 and a clinical isolate,
A. xylosoxidans
X02736, and then we used different bioinformatics tools to analyze the drug resistance genes in these bacteria. We obtained the complete genome sequence for
A. xylosoxidans
ATCC 27061 and the draft sequence for X02736. We predicted a total of 50 drug resistance-associated genes in the type strain, including 5 genes for β-lactamases and 17 genes for efflux pump systems; these genes are also conserved among other
A. xylosoxidans
genomes. In the clinical isolate, except for the conserved resistance genes, we also identified several acquired resistance genes carried by a new transposon embedded in a novel integrative and conjugative element. Our study provides new insights into the intrinsic and acquired drug resistance mechanisms in
A. xylosoxidans
, which will be helpful for better understanding the physiology of
A. xylosoxidans
and the evolution of antibiotic resistance in this bacterium.