bluuebunny/crossref_metadata_2025 huggingface dataset:
Astragaloside IV synergizes with ferulic acid to inhibit renal tubulointerstitial fibrosis in rats with obstructive nephropathy
Authors: Meng LQ , Tang JW , Wang Y , Zhao JR , Shang MY , Zhang M , Liu SY , Qu L , Cai SQ , Li XM
Published: January 2011

BACKGROUND AND PURPOSE The combination of Chinese herbs, Astragali Radix and Angelicae Sinensis Radix, could alleviate renal interstitial fibrosis. Astragaloside IV (AS‐IV) and ferulic acid (FA) are the two major active constituents in this combination. In this study, we employed rats with unilateral ureteral obstruction to determine whether AS‐IV and FA have the same renoprotective effects and investigated the mechanisms of this action.

EXPERIMENTAL APPROACH Renal pathological changes were evaluated after treatment with AS‐IV, FA or AS‐IV + FA (AF) for 10 days. Meanwhile, the expression of transforming growth factor β1 (TGF‐β1), fibronectin, α‐smooth muscle actin (α‐SMA), phosphorylation of c‐Jun NH2‐terminal kinase (p‐JNK) and nitric oxide (NO) production in kidney were determined. The expressions of fibronectin, α‐SMA, mitogen‐activated protein kinases [JNK, extracellular signal‐regulated kinases (ERK), P38] in TGF‐β1‐treated NRK‐49F cells or interleukin‐1‐treated HK‐2 cells after AS‐IV, FA or AF were assessed.

KEY RESULTS AF alleviated the infiltration of mononuclear cells, tubular atrophy and interstitial fibrosis; reduced the expression of fibronectin, α‐SMA, TGF‐β1 and p‐JNK; and dramatically increased the production of NO in obstructed kidneys. Neither AS‐IV nor FA alone improved renal damage, but both increased NO production. AF inhibited α‐SMA and fibronectin expression in NRK‐49F or HK‐2 cells. Furthermore, AF significantly inhibited IL‐1β‐induced JNK phosphorylation, without affecting ERK or P38 phosphorylation. Neither AS‐IV nor FA alone had any effect on the cells.

CONCLUSIONS AND IMPLICATIONS AS‐IV synergizes with FA to alleviate renal tubulointerstitial fibrosis; this was associated with inhibition of tubular epithelial–mesenchymal transdifferentiation (EMT) and fibroblast activation, as well as an increase in NO production in the kidney.
Different sensitivities of rat skeletal muscles and brain to novel anti‐cholinesterase agents, alkylammonium derivatives of 6‐methyluracil (ADEMS)
Authors: Petrov Konstantin A , Yagodina Lilia O , Valeeva Guzel R , Lannik Natalya I , Nikitashina Alexandra D , Rizvanov Albert A , Zobov Vladimir V , Bukharaeva Ellya A , Reznik Vladimir S , Nikolsky Eugeny E , Vyskočil František
Published: January 2011

BACKGROUND AND PURPOSE

The rat respiratory muscle diaphragm has markedly lower sensitivity than the locomotor muscle extensor digitorum longus (EDL) to the new acetylcholinesterase (AChE) inhibitors, alkylammonium derivatives of 6‐methyluracil (ADEMS). This study evaluated several possible reasons for differing sensitivity between the diaphragm and limb muscles and between the muscles and the brain.

EXPERIMENTAL APPROACH

Increased amplitude and prolonged decay time of miniature endplate currents were used to assess anti‐cholinesterase activity in muscles. In hippocampal slices, induction of synchronous network activity was used to follow cholinesterase inhibition. The inhibitor sensitivities of purified AChE from the EDL and brain were also estimated.

KEY RESULTS

The intermuscular difference in sensitivity to ADEMS is partly explained caused by a higher level of mRNA and activity of 1,3‐bis[5(diethyl‐o‐nitrobenzylammonium)pentyl]‐6‐methyluracildibromide (C‐547)‐resistant BuChE in the diaphragm. Moreover, diaphragm AChE was more than 20 times less sensitive to C‐547 than that from the EDL. Sensitivity of the EDL to C‐547 dramatically decreased after treadmill exercises that increased the amount of PRiMA AChE(G4), but not ColQ AChE(A12) molecular forms. The A12 form present in muscles appeared more sensitive to C‐547. The main form of AChE in brain, PRiMA AChE(G4), was apparently less sensitive because brain cholinesterase activity was almost three orders of magnitude more resistant to C‐547 than that of the EDL.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that ADEMS compounds could be used for the selective inhibition of AChEs and as potential therapeutic tools.
Capsaicin in the periaqueductal gray induces analgesia via metabotropic glutamate receptor‐mediated endocannabinoid retrograde disinhibition
Authors: Liao H‐T , Lee H‐J , Ho Y‐C , Chiou L‐C
Published: January 2011

BACKGROUND AND PURPOSE

Capsaicin, an agonist of transient receptor potential vanilloid 1 (TRPV1) channels, is pro‐nociceptive in the periphery but is anti‐nociceptive when administered into the ventrolateral periaqueductal gray (vlPAG), a midbrain region for initiating descending pain inhibition. Here, we investigated how activation of TRPV1 channels in the vlPAG leads to anti‐nociception.

EXPERIMENTAL APPROACH

We examined synaptic transmission and neuronal activity using whole‐cell recordings in vlPAG slicesin vitroand hot‐plate nociceptive responses in rats after drug microinjection into the vlPAGin vivo.

KEY RESULTS

Capsaicin (1–10 µM) depressed evoked GABAergic inhibitory postsynaptic currents (eIPSCs) in vlPAG slices presynaptically, while increasing miniature excitatory PSC frequency. Capsaicin‐induced eIPSC depression was antagonized by cannabinoid CB1and metabotropic glutamate (mGlu5) receptor antagonists, and prevented by inhibiting diacylglycerol lipase (DAGL), which converts DAG into 2‐arachidonoylglycerol (2‐AG), an endocannabinoid. Capsaicin induced membrane depolarization in 2/3 neurons recorded but, overall, increased neuronal firings by increasing evoked postsynaptic potentials. Intra‐vlPAG capsaicin reduced hot‐plate responses in rats, effects blocked by CB1and mGlu receptor antagonists. Effects of capsaicin were antagonized by SB 366791, a TRPV1 channel antagonist.

CONCLUSIONS AND IMPLICATIONS

Capsaicin activated TRPV1s on glutamatergic terminals to release glutamate which activated postsynaptic mGlu5receptors, yielding 2‐AG from DAG by DAGL hydrolysis. 2‐AG induces retrograde inhibition (disinhibition) of GABA release via presynaptic CB1receptors. This disinhibition in the vlPAG leads to anti‐nociception by activating the descending pain inhibitory pathway. This is a novel TRPV1 channel‐mediated anti‐nociceptive mechanism in the brain and a new interaction between vanilloid and endocannabinoid systems.
An Explorative Study of Australian Nursing Scholars and Contemporary Scholarship
Authors: Stockhausen Lynette , Turale Sue
Published: January 2011

Purpose: To explore Australian nurse scholars’ personal and professional perspectives on the nature and development of contemporary Australian scholarship, including its facilitators and barriers.

Design and Methods: A qualitative exploratory design, with snowball sampling, identified 13 well‐regarded nurse scholars from Australian universities or clinical health services. Semistructured, in‐depth interviews were conducted in 2008–2009, and transcripts of data were subjected to Morse's content analysis method.

Results: Four themes with supporting subthemes emerged: Views on Scholarship; Locations; Facilitators and Barriers; and Visioning the Future. New and reinforced information about Australian nursing scholarship was revealed.

Conclusions: The study revealed contemporary Australian perspectives on nursing scholarship. It included participants’ personal and professional histories; definitions of the attributes of scholars; mentoring; and that educational and practice maturity contribute to contemporary definitions of nursing scholarship. Scholars, working in either academic or practice environments, provided points of difference on scholarship. High workloads associated with curricula, lack of recognition of a scholar's achievements, and securing research funding were seen as barriers to scholarship. Moreover, current scholars are aging, and there is a looming shortage of scholars prepared for the future. Urgent attention needs to be paid to capacity building of clinicians and academics for the future scholarship of Australian nursing.

Clinical Relevance: Scholarship is seen as the hallmark of the intellectual pursuit of knowledge and understanding and is essential for the practice of nursing and improvements to health. Educators, policy makers, and nursing leaders need to clearly develop strategies to sustain Australian nursing scholarship for the future.
Faint resonantly scattered Lyα emission from the absorption troughs of damped Lyα systems at z ∽ 3
Authors: Rauch Michael , Haehnelt Martin G.
Published: January 2011

We demonstrate that the Lyα emission in the absorption troughs of a large sample of stacked damped Lyα absorption systems (DLAS) presented by Rahmani et al. is consistent with the spectral profiles and luminosities of a recently detected population of faint Lyα emitters at z∼ 3. This result supports the suggestion that the faint emitters are to be identified with the host galaxies of DLAS at these redshifts.
Near opposition photometry of comet C/2007 N3 (Lulin)
Authors: Joshi U. C. , Ganesh S. , Baliyan K. S.
Published: January 2011

Observations of comet C/2007 N3 (Lulin) were made at phase angles close to opposition (). Photometric observations were carried out during 2009 February 24–28, in the International Halley Watch (IHW) blue and red continuum and R broad-band using a photopolarimeter mounted on the 1.2-m telescope at Mount Abu Infrared Observatory. In all the bands, a significant linear increase in brightness with decreasing phase angle is detected for the above phase angle range. The phase coefficient [β= 0.040 ± 0.001 mag deg−1 estimated in the IHW red (6840 Å) filter band] is found to be independent of wavelength. No non-linear opposition surge is observed for phase angle . The linear increase in brightness with decreasing phase angle in the range mentioned earlier can be explained using the shadow hiding model. The colour of the comet is found to be similar to the solar colour, indicating the dominance of grains larger than 0.1 μm. A dip in the brightness of about 0.20 mag is seen at the phase angle .
Site‐Specific Free Energy Changes in Proteins upon Ligand Binding by Nuclear Magnetic Resonance: Ca2+‐Displacement by Ln3+ in a Ca2+‐Binding Protein from Entamoeba histolytica
Authors: Chandra Kousik , Mustafi Sourajit M. , Muthukumar Subramanian , Chary Kandala V. R.
Published: January 2011

The study of protein–ligand interaction has been of a great interest in contemporary structural biology. The understanding of the nature of such interaction and determining the associated binding affinities are of utmost importance. Nuclear magnetic resonance has become a powerful tool in deriving information related to such interactions in proteins. Nuclear magnetic resonance data provide the site‐specific information even in the case of proteins having multiple‐binding sites and populations of respective species. In this communication, we set out to use such information to derive the associated microscopic binding constants.
Mechanism of cytochrome P450-3A inhibition by ketoconazole
Authors: Greenblatt David J , Zhao Yanli , Venkatakrishnan Karthik , Duan Su X , Harmatz Jerold S , Parent Sarah J , Court Michael H , von Moltke Lisa L
Published: January 2011

Objectives

Ketoconazole is extensively used as an index inhibitor of cytochrome P450-3A (CYP3A) activity in vitro and in vivo, but the mechanism of ketoconazole inhibition of CYP3A still is not clearly established.

Methods

Inhibition of metabolite formation by ketoconazole (seven concentrations from 0.01 to 1.0 µm) was studied in human liver microsomes (n = 4) at six to seven substrate concentrations for triazolam, midazolam, and testosterone, and at two substrate concentrations for nifedipine.

Key findings

Analysis of multiple data points per liver sample based on a mixed competitive–noncompetitive model yielded mean inhibition constant Ki values in the range of 0.011 to 0.045 µm. Ketoconazole IC50 increased at higher substrate concentrations, thereby excluding pure noncompetitive inhibition. For triazolam, testosterone, and midazolam α-hydroxylation, mean values of α (indicating the ‘mix’ of competitive and noncompetitive inhibition) ranged from 2.1 to 6.3. However, inhibition of midazolam 4-hydroxylation was consistent with a competitive process. Determination of Ki and α based on the relation between 50% inhibitory concentration values and substrate concentration yielded similar values. Pre-incubation of ketoconazole with microsomes before addition of substrate did not enhance inhibition, whereas inhibition by troleandomycin was significantly enhanced by pre-incubation.

Conclusions

Ketoconazole inhibition of triazolam α- and 4-hydroxylation, midazolam α-hydroxylation, testosterone 6β-hydroxylation, and nifedipine oxidation appeared to be a mixed competitive–noncompetitive process, with the noncompetitive component being dominant but not exclusive. Quantitative estimates of Ki were in the low nanomolar range for all four substrates.
Modulated pharmacokinetics and increased small intestinal toxicity of methotrexate in bilirubin-treated rats
Authors: Yokooji Tomoharu , Mori Nobuhiro , Murakami Teruo
Published: January 2011

Objectives

The effect of bilirubin treatment on the pharmacokinetics and small intestinal toxicity of methotrexate was evaluated in rats, since bilirubin and its glucuronide conjugates can suppress multidrug resistance-associated protein-mediated transport.

Methods

Rats were treated intravenously with bilirubin and the various clearances and tissue distribution of methotrexate were estimated under a steady-state plasma concentration. Intestinal toxicity induced by methotrexate was also evaluated by measuring the leakage of alkaline phosphatase (ALP) activity. Probenecid, an inhibitor for multidrug resistance-associated protein and organic anion transporters, was used for comparison.

Key findings

The treatment with bilirubin increased the steady-state plasma concentration and reduced biliary excretion clearance, urinary excretion clearance and intestinal exsorption clearance of methotrexate, as did treatment with probenecid. The intestinal absorption and jejunum distribution of methotrexate also significantly increased in bilirubin- and probenecid-treated rats. A greater leakage of ALP activity to the luminal fluid, with a lower ALP activity in the intestinal mucosal membrane after intestinal perfusion of methotrexate, was observed in bilirubin- and probenecid-treated rats.

Conclusions

Hyperbilirubinemia, which is involved under various disease states, may increase the small intestinal accumulation and toxicities of methotrexate, since high plasma concentrations of conjugated bilirubin can suppress the function of multidrug resistance-associated proteins, which facilitate the efflux of methotrexate out of cells.
Effect of High Sulfur Military JP-8 Fuel on Heavy Duty Diesel Engine Emissions and EGR Cooler Condensate
Authors: Smith Michael , Filipi Zoran , Schihl Peter , Assanis Dennis
Published: January 2011

Low-sulfur “clean” diesel fuel has recently been mandated in the U.S. market. However, quality of diesel fuel, particularly the sulfur content, varies significantly in other parts of the world. Due to logistical issues in various theaters of operation, the Army is often forced to rely on local fuel supplies, which exposes vehicles to diesel fuel or jet fuel (JP8) with elevated levels of sulfur. Currently, modern diesel engines typically use cooled Exhaust Gas Recirculation (EGR) to meet emissions regulations. Using high sulfur fuels and cooled EGR has potential to lead to EGR cooler fouling and corrosion of engine components. Therefore, an experimental study has been setup to investigate the EGR heat exchanger condensate in a heavy duty diesel engine running on JP-8 fuel doped with 3512 ppm of sulfur. Gas was sampled from the EGR cooler and analyzed. A Condensate Collection Device (CCD) was developed and setup according to a modified ASTM 3226-73T standard, to perform analysis of sulfur condensate species of SO2 and H2SO4 in the EGR system. Results have shown that SO2 values to have the highest concentration of gaseous sulfur species. SO2 is also shown to increase as sulfur content in JP-8 increases, but not by the same order of magnitude. Results have also shown low levels of H2SO4 from 2–5 ppm with negligible differences while varying sulfur content in JP-8, EGR levels of the engine, and condenser temperatures in the CCD. Due to suspicion that all sulfur has not been accounted for in experiments with the modified CCD, further experiments were performed using a Fourier Transform Infrared (FTIR) emissions bench for gaseous SO2 emissions and a Differential Mobility Spectrometer (DMS) for particulate size spectrum analysis. FTIR results yielded similar results for gaseous SO2 as the modified CCD with SO2 levels increasing as sulfur content in fuel increases but not by the same order of magnitude. While the results from the DMS have shown that increasing sulfur content in JP-8 will increase the particle sizes in the particle size distribution curve. This also translates to an increase in PM mass concentration in the exhaust stream when sulfur content is increased in JP-8 on an engine with and without EGR.
An Assessment of the Thermodynamics Associated With High-Efficiency Engines
Authors: Caton Jerald A.
Published: January 2011

Recent advancements have demonstrated new combustion modes that exhibit low nitric oxide emissions and high thermal efficiencies. These new combustion modes involve various combinations of stratification, lean mixtures, high levels of EGR, multiple injections, variable valve timings, two fuels, and other such features. Although the exact combination of these features that provides the best design is not yet clear, the results (low emissions with high efficiencies) are of major interest. The current work is directed at determining some of the fundamental thermodynamic reasons for the relatively high efficiencies and to quantify these factors. Both the first and second laws are used in this assessment. An automotive engine (5.7 liter) which included some of the features mentioned above (e.g., high compression ratios, lean mixtures, and high EGR) was evaluated using a thermodynamic cycle simulation. These features were examined for two operating conditions: a moderate load, moderate speed condition (“A”), and a lower load, lower speed condition (“B”). By the use of lean operation, high EGR levels, high compression ratio and other features, the net indicated thermal efficiency increased from 35.6% to 48.2% (condition “A”), and from 30.3% to 44.6% (condition “B”). These increases are explained in a step-by-step fashion. One of the major reasons for these improvements was the lower heat losses associated with the advanced conditions. Other thermo-dynamic features are described.
Optical Investigation Into Wall Wetting From Late-Cycle Post-Injections Used for Diesel Particulate Filter Regeneration
Authors: Bozic Goran , Kook Sanghoon , Ekoto Isaac W. , Petersen Ben R. , Miles Paul C.
Published: January 2011

Wall wetting phenomena were investigated in a light-duty diesel optical engine operating under typical diesel particulate filter regeneration conditions through the use of liquid spray imaging during late-cycle post-injections. Three post-injection timings were explored: 1) an ‘early’ timing (44.5°aTDC) where high ambient temperatures and densities were expected to decrease the liquid penetration, 2) a ‘conventional’ timing (78.5°aTDC) that is typically used to produce the necessary aftertreatment regeneration exhaust conditions, and 3) a ‘late’ timing (133.5°aTDC) where in-cylinder flows generated by exhaust valve opening-induced blowdown can disrupt the liquid penetration. In addition to a 2007 US certification diesel fuel, a palm-derived B20 biodiesel blend and soy-derived B100 biodiesel were examined since liquid spray impingement is thought to worsen for biodiesel blends due to the higher fuel distillation temperature, density, and viscosity. No significant wall wetting was observed for the early post-injection. However, considerable impingement occurred for the conventional and late post-injections. Liquid penetration and the persistence of liquid fuel in the cylinder were found to increase with biodiesel content, while exhaust blowdown flows were ineffective in reducing the severity of wall wetting. Negligible distortion of jet structure was observed for the liquid spray at the late post-injection. Short pulse durations decreased the severity of liquid penetration with the soy-derived biodiesel during the early post-injection SOI, but were otherwise ineffective.
Cylinder Head Gasket With Integrated Miniature Combustion Pressure Sensors
Authors: Wlodarczyk Marek T. , Toth David
Published: January 2011

The design and preliminary performance of a multi layer metal cylinder head gasket with integrated 1.7mm diameter combustion pressure sensors is described. The pressure sensors are either removable from the gasket without need for engine head removal or permanently fixed to the gasket. The gasket design is suitable for all sizes and types of internal combustion engines including gasoline, diesel, or alternative fuel, with peak pressures ranging from 100bar to 350bar. The sensors’ diaphragms are positioned semi-flush with the gasket surface exposed to combustion gasses while the sensors’ sealing surfaces are located 5mm-7mm from the diaphragms. The devices miniature signal conditioners are mounted inside a gasket extension protruding beyond the engine block. The miniature fiber optic pressure sensor operates on the principle of light intensity changes transmitted by two fibers upon reflection from a metal diaphragm deflecting under the effect of cylinder pressure. Preliminary test results are reported here collected on a 4-cylinder gasoline engine demonstrating good agreement with a reference transducer. When optimized, it is expected that a gasket integrated sensor will offer the accuracy of +/-1.5% enabling advanced engine controls based on Indicated Mean Effective Pressure (IMEP), Mass Fraction Burned (MFB), Peak Pressure as well as control of pilot fuel injection and virtual Mass Air Flow and NOx sensing.
Simulation of Combustion and Emission Characteristics in a Dual Fuelled Diesel Engine
Authors: Debnath Biplab K. , Sahoo Bibhuti B. , Saha Ujjwal K. , Sahoo Niranjan
Published: January 2011

In this paper, Computational Fluid Dynamics (CFD) approach is adopted to study the combustion and emission progression in a single cylinder four stroke diesel engine, operated in both diesel and dual-fuel modes. The study of dual-fuel mode is performed by using synthesis gas (syngas) with 75:25 and 50:50 volumetric combinations of hydrogen and carbon monoxide, respectively. The modeling and meshing of the constant volume combustion chamber is carried out by using GAMBIT tool. The meshing of the combustion chamber is performed using tetrahedral elements and the k–ε turbulence model is introduced along with non-premixed combustion modeling. The modeled hemispherical-piston-top combustion chamber is then simulated in FLUENT solver across the experimental boundary conditions at 40%, 60%, 80% and 100% of full load for both diesel and dual-fuel. The results of simulation incorporate the study of maximum combustion temperature, maximum combustion velocity and H2O mole fraction subsequent to combustion. Further, the concentrations of emissions have also been investigated for both diesel and dual-fuel modes. The results of simulations show a good agreement with the corresponding experimental data.
CNG Injector Nozzle Design and Flow Prediction
Authors: Baratta Mirko , Catania Andrea E. , Pesce Francesco C.
Published: January 2011

In the last few years, a great research effort has been made for developing and enhancing Direct Injection (DI) compressed natural gas (CNG) engines. A number of research projects has been promoted by the European Community (EC) in this field with the objectives of finding new solutions for the automotive market and also of encouraging a fruitful knowledge exchange among car manufacturers and technical universities. The present paper concerns part of the research activity that has been carried out at Politecnico di Torino (PT) within the EC VII Framework Program (FP) InGAS Integrated Project (IP). The target of the work was to support the design phase of a new injector for CNG direct injection, paying specific attention to the nozzle configuration and also to its behavior under different conditions and over runtime. The needle design was carried out with the aims of enhancing the injector reliability and reducing the injector internal friction, which usually causes injector wear due to the lack of lubrication effect with respect to liquid-fuel injectors. The new needle design concept which was considered in the present research project was oriented to maximize the contact area between the needle and its cartridge so as to reduce needle wear. For this reason, the injector feeding part was realized by means of two series of holes. The design was assisted by 3D numerical simulations which indicated the best feeding-hole number and geometry to obtain a maximum mass-flow rate. For this investigation, the needle was kept at its maximum lift and the feeding pressure was gradually increased up to the design rail pressure. The results indicated that the hole number remarkably influences the flow losses along the internal flow path and, in turn, the resultant mass-flow rate. These effects, along with the flow field characteristics inside the injector, are examined and discussed in detail throughout the paper.
The Effect of Stroke-to-Bore Ratio on Combustion Performance of a Lean Burn Heavy-Duty Gaseous SI Engine
Authors: Qin Xiao , Ntone Francois , LaPointe Leon , Lyford-Pike Edward J.
Published: January 2011

This paper presents a numerical investigation into the effect of stroke-to-bore (S/B) ratio on the combustion performance of a lean burn heavy-duty gaseous spark-ignited engine. The S/B ratio was varied from 0.94 to 1.32 by changing the stroke length for a fixed bore and connecting rod length. Identical cylinder head and valve events were used throughout the analysis. The compression ratio was kept unchanged by scaling the volume of the piston bowl while keeping the piston squish areas and head volume constant. FLUENT was used to conduct 3-dimensional transient flow analysis of the intake process. A Cummins modified version of KIVA-3V utilizing a G-Equation combustion model was employed to conduct simulation of the combustion process. The intake processes predicted by FLUENT were mapped to KIVA-3V at the time of intake valve closing. Both FLUENT and KIVA simulations were validated with experimental results at S/B ratio of 1.2. Simulations were also conducted at various engine speeds for different S/B ratios. When ignited at the same spark timing, the most important observations are: (1) The S/B ratio has a significant effect on turbulence intensity during the intake stroke and thus affects the in-cylinder peak pressure, heat release rates, power, and NOx emissions. (2) The gross indicated mean effective pressure and fuel specific NOx emission increase with increase of S/B ratio and decrease with increase of engine speed. (3) The gross indicated specific fuel consumption and burn duration (in crank angle) decrease with increasing S/B ratio and increase with increasing engine speed. (4) In general, a larger S/B ratio leads to higher thermal efficiency through faster combustion, and better fuel economy can be achieved for a long-stroke engine at low engine speeds. The primary influences with S/B ratio observed at constant spark timing are valid also when spark timing is modified to achieve the same centroid of heat release rates.
Review of Waste Heat Recovery Mechanisms for Internal Combustion Engines
Authors: Armstead John R. , Miers Scott A.
Published: January 2011

The demand for more fuel efficient vehicles has been growing steadily and will only continue to increase given the volatility in the commodities market for petroleum resources. The internal combustion engine utilizes approximately one third of the chemical energy released during combustion. The remaining two-thirds are rejected from the engine via the cooling and exhaust systems. Significant improvements in fuel conversion efficiency are possible through the capture and conversion of these waste energy streams. Promising waste heat recovery techniques include turbocharging, turbo compounding, Rankine engine compounding, and thermoelectric generators. These techniques have shown increases in engine thermal efficiencies that range from 2% to 20%, depending on system design, quality of energy recovery, component efficiency, and implementation. The purpose of this paper is to provide a broad review of the advancements in the waste heat recovery methods; thermoelectric generators and Rankine cycles for electricity generation, which have occurred over the past 10 years as these two techniques have been at the forefront of current research for their untapped potential. The various mechanisms and techniques, including thermodynamic analysis, employed in the design of a waste heat recovery system are discussed.
Fast Methods to Analyze High-Speed Images of HCCI and Spark-Assisted HCCI Ignition Events
Authors: Keros Peter E. , Assanis Dimitris , Schlechtweg Jill , Wooldridge Margaret S.
Published: January 2011

This study presents two new methods to rapidly analyze the ignition and combustion events recorded during in-cylinder high-speed imaging of homogeneous charge compression ignition (HCCI) and spark-assisted (SA) HCCI engine operation. Two categories of ignition have been observed during HCCI and SA HCCI: auto-ignition of parcels of fuel/air and ignition and propagation of reaction fronts. In this work, two methods of image analysis are developed which accommodate differences in the ignition and propagation events for the two categories. The methods are described by application to high speed imaging data acquired from an optically accessible engine operated in HCCI and SA HCCI modes using indolene fuel. Using method I, the projected area of reaction is identified in each frame, and a circle with a characteristic radius that yields the equivalent area is defined. The rate of area expansion is used to define the speed of reaction. Using method II, an edge-finding algorithm is used to identify the location of well-defined reaction fronts. The maximum dimensions of the reaction front in an x-y coordinate frame are measured. The projected area based on the average of these maximum dimensions is then determined. The change in the characteristic radius of the projected area is defined as the average propagation speed for the reaction front. The two analytical methods are applied to typical HCCI and SA HCCI image sequences. Outcomes of the image analysis indicate propagation speeds are typically between 2–5 m/s prior to volumetric ignition. Volumetric ignition is identified by propagation speeds greater than 20 m/s. The imaging data also identify times when reaction quenching occurred after spark ignition as times when negative propagation speeds are observed. When applied to the same imaging sequence, the two methods yield consistent results for propagation speeds; however, the method based on edge-finding exhibits larger variance.
Fuel Property Effects on PCCI Combustion in a Heavy-Duty Diesel Engine
Authors: Dumitrescu Cosmin E. , Neill W. Stuart , Guo Hongsheng , Hosseini Vahid , Chippior Wallace L.
Published: January 2011

An experimental study was performed to investigate fuel property effects on Premixed-Charge Compression Ignition (PCCI) combustion in a heavy-duty diesel engine. A matrix of research diesel fuels designed by the Coordinating Research Council, referred to as the Fuels for Advanced Combustion Engines (FACE), was used. The fuel matrix design covers a wide range of cetane numbers (30 to 55), 90% distillation temperatures (270 to 340°C) and aromatics content (20 to 45%). The fuels were tested in a single-cylinder Caterpillar diesel engine equipped with a common-rail fuel injection system. The engine was operated at 900 rpm, a relative air/fuel ratio of 1.2 and 60% exhaust gas recirculation (EGR) for all fuels. The study was limited to a single fuel injection event starting between −30° and 0°CA with a rail pressure of 150 MPa. The brake mean effective pressure (BMEP) ranged from 3.2 to 3.6 bar depending on the fuel and fuel injection timing. The experimental results show that cetane number was the most important fuel property affecting PCCI combustion behavior. The low cetane number fuels had better BSFC due to more optimized combustion phasing and shorter combustion duration. They also had a longer ignition delay period available for premixing, which led to near-zero soot emissions. The two fuels with high cetane number and high 90% distillation temperature produced significant soot emissions when the start of combustion occurred before the end of fuel injection. The two fuels with high cetane number and high aromatics produced the highest brake specific NOx emissions, although the absolute values were below 0.1 g/kW-hr. Brake specific HC and CO emissions were primarily a function of the combustion phasing, but the low cetane number fuels had slightly higher HC and lower CO emissions than the high cetane number fuels.
Numerical Study on Combustion Characteristics of Biodiesel Using a New Reduced Mechanism for Methyl Decanoate as Surrogate
Authors: Luo Zhaoyu , Lu Tianfeng , Som Sibendu , Longman Douglas E.
Published: January 2011

A skeletal mechanism with 118 species and 837 reactions was developed from a detailed LLNL mechanism for a biodiesel surrogate mixture with equal mole fraction of methyl decanoate, methy-9-decenoate and n-heptane, through subsequent applications of a revised method for directed relation graph (DRG), isomer lumping, and DRG-aided sensitivity analysis (DRGASA). The reduction was performed within a parameter range of pressure from 1 to 100atm, equivalence ratio from 0.5 to 2, and temperature above 1000K for both auto-ignition and perfect stirred reactors. The detailed mechanism consists of 3329 species and 10806 reactions. With the reduction in mechanism size by almost a factor of 30, the skeletal mechanism was shown to still feature a good accuracy for temperature higher than 1000K, both in predicting the system parameters, such as ignition delay and extinction time, and detailed species profiles, compared with the detailed mechanism. Numerical simulations in jet stirred reactors were also performed and compared with experimental measurements for rapeseed oil methyl ester. This skeletal mechanism can be used to model methyl esters from different feedstocks since it is a tri-component mixture.
An Accelerated Testing Approach for Lubricant Oil Consumption Reduction on an EMD 710 Diesel Engine
Authors: Froelund Kent , Fritz Steve , Hedrick John , Garcia Jaime , Blythe Neil
Published: January 2011

Real-Time Da Vinci Lubricant Oil Consumption (DALOC™) measurements were made on a 2,942 kW (4,000 hp) EMD 16-710G3 locomotive diesel engine, as part of a program to evaluate prototype cylinder kits that hold the potential to reduce lubricating oil consumption and hence reduce exhaust particulate matter emissions towards meeting EPA Tier 0+ locomotive emissions certification. The DALOC technique uses sulfur dioxide (SO2) measured in the exhaust gas stream as a tracer for oil consumption. The engine was operated on an ultra-low sulfur diesel fuel (3 ppm by weight) and commercially available SAE grade 20W40 mineral-based lubricating oil (4,865 ppm by weight). Knowing the SO2 concentration in the exhaust, the air and fuel flow rates, and the lubricating oil consumption rate can be calculated in real-time, i.e. on a second-to-second basis. Use of this measurement technique on the locomotive engine application has proven to be a cost- and time-reducing tool for mapping steady-state lubricating oil consumption rate. Numerous prior publications describe the evolution of this technique over time as well as the prior art in the area of lubricant impact on emissions [1–12]. As part of this project, the lubricant oil consumption of 4 different cylinder kits were accurately quantified at 4 steady-state operating conditions typical of North American freight locomotive operation within less than 40 hours of actual engine running. Applying this measurement technique, a reduction of lubricant oil consumption of 75%+ in comparison to the baseline cylinder kits were documented.
Assessment Techniques Using the R6 Procedure: Investigation of Limit Load Approach for Pipe Branch Connections
Authors: Frost Peter A.
Published: January 2011

The R6 Revision 4 Procedure ‘Assessment of the Integrity of Structures Containing Defects’, states that the use of the finite element ‘global’ limit load derived for pipe branch components can be non-conservative when used with the Option 1 and 2 failure assessment curves but that ‘local’ limit loads, based on the spread of plasticity through the pipe wall, should lead to conservative results. The current advice of R6 is based on separate studies by Fox and Connors of pipe branch components with fully extended surface defects. Their studies provide two distinct methods for calculating a suitably conservative local limit load. However, there is concern that these two methods may provide an overly conservative local limit load with therefore a less realistic prediction of defect tolerance. Furthermore, typical defectiveness is perhaps most commonly characterised as a semi-elliptic surface defect and it is therefore necessary to adapt both these methods in order to accommodate such defects. The purpose of this study was therefore to investigate local limit load approaches for pipe branch components with postulated semi-elliptic surface defects. A typical pipe branch component was chosen for assessment during this study, as part of a series of separate studies on a variety of pipe branch components. Local limit loads were calculated using two approaches. The first approach adapted the ‘Connors’ method by applying an adjustment to allow for the semi-elliptic surface defect; this is referred to as the ‘Modified Connors’ approach. The second approach used cracked body finite element analysis and evaluated the local limit load by consideration of the onset of plasticity at the crack ligament. The global limit load was also derived from the cracked body finite element analysis. Assessment points were developed using global and local limit loads, both obtained by cracked body finite element analysis, and also by using the ‘Modified Connors’ local limit load approach. R6 Option 3 failure assessment curves were produced for each limit load approach in order to investigate the extent of any non-conservatism in the Option 1 and 2 failure assessment curves with the chosen limit load approach.
Significance of the Plastic Eta Factor in J Estimation Procedures for Tensile SE(T) Fracture Specimens
Authors: Carvalho Henrique S. S. , Ruggieri Claudio
Published: January 2011

Current evaluation procedures for toughness measurements, such as the J-integral and the crack tip opening displacement (CTOD), focus primarily on single-specimen estimation schemes which essentially relate the plastic contribution to the strain energy with J based upon a plastic η-factor. This work addresses the significance of the η-factor on estimation procedures for J in pin-loaded and clamped single edge notch tension (SE(T)) specimens using load-displacement records. Very detailed non-linear finite element analyses for plane-strain models provide the evolution of load with increased load-line displacement and crack mouth opening displacement to define the applied load as a separable function dependent upon crack geometry and material deformation. The analyses reveal that η-factors based on load-line displacement (LLD) are very sensitive to plasticity changes at locations remote from the crack-tip region. In contrast, η-factors based on crack mouth opening displacement (CMOD) appear less affected by remote crack-tip plasticity. Overall, the present results provide a strong support to use η-based procedures in toughness measurements for clamped SE(T) fracture specimens.
Stress Predictions at Elbow Ends Under Internal Pressure and System Moments
Authors: Shi Jinhua , Lee Granson , Blythe David , Buckland John , Lei Yuebao , Soanes Timothy
Published: January 2011

In order to assess postulated defects in the butt weld joining a 90 degree elbow to a seamless straight pipe, both axial and hoop stress components at this position are required. ASME III NB-3685 provides a method of calculating elbow stresses. However, this gives the maximum stress values in the elbow and applies to the central section of the bend. If these values are directly used in the defect assessments of welds at the ends of the elbow, the assessment results will be overly conservative. In order to obtain appropriate defect assessment results, more accurate axial and hoop stress distributions at the elbow ends are desirable. In this paper, the axial and hoop stress distributions at the elbow ends are predicted by deriving generalized stress relationships between the elbow end and the central section of the elbow, based on detailed finite element analyses and ASME III NB-3685 calculations. In order to do so, a series of small displacement elastic 3D finite element analyses have been performed. The finite element results were then compared with the ASME III NB-3685 stress predictions. Finally, the axial and hoop stress relationships between the elbow end and the central section of the elbow for internal pressure, in-plane moment and out-of-plane moment were derived. A comparison of the calculated stress values using the derived equations, the finite element analysis results and the ASME III NB-3685 stress calculations confirms that the derived stress relationships are appropriate to predict the axial and hoop stresses at the elbow ends. The objective of this paper is to show: 1) the ASME III NB-3685 stress calculations agree well with the 3D finite element analysis results at the central section of the elbow and 2) the derived stress relationships are appropriate to predict the axial and hoop stresses at the elbow ends.
Acoustic Resonance in a Reservoir-Pipeline-Orifice System
Authors: Tijsseling Arris S. , Hou Qingzhi , Svingen Bjo̸rnar , Bergant Anton
Published: January 2011

The fundamentals of oscillating flow in a reservoir-pipe-orifice system are revisited in a theoretical study related to acoustic resonance experiments carried out in a large-scale pipeline. Four different types of system excitation are considered: forcing velocity, forcing pressure, linear oscillating resistance and nonlinear oscillating resistance. Analytical solutions are given for the periodic responses to the first three excitations. Analytical and numerical results for the large-scale pipeline are presented and some peculiarities are discussed.
Effect of Thermo-Mechanical History on Reheat Cracking in 316H Austenitic Stainless Steel Weldments
Authors: Chen Bo , Spindler Michael W. , Smith David J. , Flewitt Peter E. J.
Published: January 2011

Reheat cracking has been observed in the heat affected zone of the 316H austenitic stainless steel thick section weldments during service at a temperature of ∼500°C. This has been attributed to the creep dominated relaxation of the highly triaxial residual stresses. Here the role of thermo-mechanical variables that contribute to the susceptibility of thick section 316H austenitic stainless steel weldments is briefly reviewed. The influence of the plastic strain, carbide precipitation and impurity element segregation on the subsequent creep deformation behaviour and the susceptibility to creep cavitation damage is discussed. A systematically designed experiment which includes these parameters has been undertaken for a 316H austenitic stainless steel. In addition, residual stress profiles have been introduced into cylindrical pre-treated specimens and the relaxation of these profiles with heat treatment has been measured by neutron diffraction. The experimental results are considered with respect to the effect of the microstructure on subsequent creep deformation and stress relaxation. The susceptibility to intergranular brittle fracture is discussed and an attempt is made to correlate the microstructure and stress state factors encountered in the HAZ with the accumulation of the creep cavitation associated with reheat cracking.
Load Limiting Gapped Strut and New Generation Whip Restraint
Authors: Gray John H. , Verma Vijay K. , Pressburger Maury A.
Published: January 2011

Load Limiting Gapped Struts (LLGS’s) can be used to reduce the number of snubbers required for seismic protection. However, it is the LLGS’s ability to absorb energy that makes it unique, and ideal for use as a restraint for infrequent dynamic loads, such as water hammer and pipe whip. LLGS’s can be designed to yield at a predetermined limit load. For example, E-BARs (a type of LLGS) absorb energy through plastic deformation of the outer metal housing. This controls pipe displacements and stresses to acceptable values while limiting loads transferred to the structure. By using LLGS’s as a “fuse”, system designers can limit loads transferred to buildings, resulting in less costly structures. A description of how the LLGS functions is presented for various applications in this paper, based on experience with the E-BAR LLGS.
Type 304L and 316L HIP Powder Processing for PWR Components: Design and Manufacturing Benefits and Safety Case Progress
Authors: Burdett W. Barry
Published: January 2011

Hot Isostatic Pressing (HIP) has been used for many years to consolidate porosity in cast metal shapes to improve mechanical properties. When applied to fine metal powders, it is possible to produce Near Net Shape (NNS) items and more complex geometry components that are fully dense and offer an attractive set of properties at reduced cost. NNS items manufactured from powder deliver cost savings by reducing initial material usage and subsequent machining costs. Powder production and HIP processing are automated methods, which provide protection against forging route obsolescence. Setup costs are lower and batch sizes smaller, which makes the process particularly well suited to small numbers of high integrity components. HIPped powder microstructures are isotropic and equiaxed, with uniformly fine grain sizes not normally achieved in heavy section components, which facilitates ultrasonic NDE examination. Improved features to facilitate NDE are readily incorporated into the HIP assembly. Inclusion contents are lower and of more benign geometry, easing fracture assessment. Use of the technology has grown, particularly in the offshore oil industry where it is already established in high integrity applications, particularly in place of welded joints. Take-up in the more conservative nuclear industry has been slow. The quality of HIPped powder items can provide through life cost savings since there is greater assurance of structural integrity compared to welded or wrought components. In a broad programme of testing, Rolls-Royce has established that HIPped powder 316L/304L components, in items up to several tons in weight, have equivalent or slightly better strength, toughness and corrosion resistance than conventional forgings. Rolls-Royce now has a robust methodology in place to develop safety cases and is extending the number of applications in pressure boundary components on current and future classes of equipment. A strength-in-depth argument has been endorsed by external approval organisations and is supporting current submarine build programmes. Other applications in the growing civil nuclear market are now under consideration. A plan for developing an ASME Code Case for Powder HIP is being considered. This paper presents an update on the implementation process.