bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of Fuel Injection Timing During Negative Valve Overlap Period on a GDI-HCCI Engine
Authors: Ratnak Sok , Kusaka Jin , Daisho Yasuhiro , Yoshimura Kei , Nakama Kenjiro
Published: January 2019

Gasoline Direct Injection Homogeneous Charge Compression (GDI-HCCI) combustion is achieved by closing early the exhaust valves for trapping hot residual gases combined with direct fuel injection. The combustion is chemically controlled by multi-point auto-ignition which its main combustion phase can be controlled by direct injection timing of fuel. This work investigates the effect of single pulse injection timing on a supercharged GDI-HCCI combustion engine by using a four-stroke single cylinder engine with a side-mounted direct fuel injector.

Injection of primary reference fuel PRF90 under the near-stoichiometric-boosted condition is studied. The fuel is injected during negative valve overlap (NVO) or recompression period for fuel reformation under low oxygen concentration and the injection is retarded to intake stroke for the homogeneous mixture. It is found that the early fuel injection in NVO period advances the combustion phasing compared with the retarded injection in the intake stroke. Noticeable slower combustion rate from intake stroke fuel injection is obtained compared with the NVO injection due to charge cooling effect. Zero-dimensional combustion simulations with multiple chemical reaction mechanisms are simulated to provide chemical understanding from the effect of fuel injection timing on intermediate species generations. The species such as C2H4, C3H6, CH4, and H2 are found to be formed during the NVO injection period from the calculations. The effects of single pulse injection timings on combustion characteristics such pressure rise rate, combustion stability, and emissions are also discussed in this study.
Quantification and Analysis of the Charge Cooling Effect of Methanol in a Compression Ignition Engine Utilizing PPC Strategy
Authors: Shamun Sam , Zincir Burak , Shukla Pravesh , Garcia Valladolid Pablo , Verhelst Sebastian , Tunér Martin
Published: January 2019

The charge cooling effect of methanol was studied and compared to that of iso-octane. The reduction in compression work due to fuel evaporation and the gain in expansion work were evaluated by the means of in-cylinder pressure measurements in a HD CI engine. A single injection strategy was utilized to obtain a longer premixing period to adequately capture the cooling effect. The effect was clear for both tested fuels, however, methanol generally caused the pressure to reduce more than iso-octane near TDC. It was found that the contribution of reduced compression work to the increased net indicated efficiency is negligible. Regarding the expansion work, a slower combustion with higher pressure was obtained for methanol in comparison to that of iso-octane due to the cooling effect of fuel evaporation. As a result from this, a lower heat transfer loss was obtained for methanol, in addition to the significantly lower NOx emissions.
Design and Experimental Validation of a Spatially Discretized, Control-Oriented Temperature Model for a Ceria-Washcoated Gasoline Particulate Filter
Authors: Moser Sean , Onori Simona , Hoffman Mark
Published: January 2019

Gasoline particulate filters (GPFs) are the most promising and practically applicable devices to reduce Particulate Matter (PM) and Particulate Number (PN) emissions from gasoline direct ignition engines. A model that can predict internal GPF temperature dynamics during regeneration events can then be implemented online to maintain GPF health and aide in exotherm control algorithms without the associated instrumentation costs. This work demonstrates a control-oriented model, which captures the thermal dynamics in a catalyzed, ceria-coated GPF in the axial direction. The model utilizes soot oxidation reaction kinetics to predict internal GPF temperature dynamics during regeneration events using three finite volume cells.

A model methodology initially proposed by Arunachalam et al [18] is utilized with the GPF of this work, validating the broad applicability of that methodology. Then, the model’s temperature prediction fidelity is improved through axial discretization. The zonal model parameters are identified via a Particle Swarm Optimization using experimental results from the instrumented GPF. Identified parameters from the various data sets are used to develop a linear parameter varying model for prediction of the axial temperature distribution within the GPF. The resulting model is then validated against an experimental data set utilizing the exhaust temperature entering the GPF. The spatial discretization methodology employed both enables the prediction of spatial temperature variation within the GPF and improves the accuracy of the peak temperature prediction by a factor ranging from 2–10x.
Numerical Investigation of Fuel Effects on Soot Emissions at Heavy-Duty Diesel Engine Conditions
Authors: Tang Meng , Pei Yuanjiang , Zhang Yu , Traver Michael , Cleary David , Luo Zhaoyu , Naber Jeffrey , Lee Seong-Young
Published: January 2019

Gasoline compression ignition (GCI) engine technology has shown the potential to achieve high fuel efficiency with low criteria pollutant emissions. In order to guide the design and optimization of GCI combustion, it is essential to develop high-fidelity simulation tools. Building on the previous work in computational fluid dynamic (CFD) simulations of spray combustion, this work focuses on predicting the soot emissions in a constant-volume vessel representative of heavy-duty diesel engine applications for an ultra-low sulfur diesel (ULSD) and a high reactivity (Research Octane Number 60) gasoline, and comparing the soot evolution characteristics of the two fuels. Simulations were conducted using both Reynolds Averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) turbulence models. Extensive model validations were performed against the experimental soot emissions data for both fuels. It was found that the simulation results using the LES turbulence model agreed better with the measured ignition delays and liftoff lengths than the RANS turbulence model. In addition, two soot models were evaluated in the current study, including an empirical two-step soot formation and oxidation model, and a detailed soot model that involves poly-aromatic hydrocarbon (PAH) chemistry. Validations showed that the separation of the flame lift-off location and the soot lift-off location and the relative natural luminosity signals were better predicted by the detailed soot model combined with the LES turbulence model. Qualitative comparisons of simulated local soot concentration distributions against experimental measurements in the literature confirmed the model’s performance. CFD simulations showed that the transition of domination from soot formation to soot oxidation was fuel-dependent, and the two fuels exhibited different temporal and spatial characteristics of soot emissions. CFD simulations also confirmed the lower sooting propensity of gasoline compared to ULSD under all investigated conditions.
Modeling the Effect of Parametric Variations on Soot Particle Size Distribution in a Diesel Engine
Authors: Duvvuri Pavan P. , Sukumaran Sujith , Shrivastava Rajesh K. , Sreedhara Sheshadri
Published: January 2019

Stringent emission legislations, increasing environmental and health issues have driven extensive research in combustion engines to control pollutants. Modeling of emissions offers a cost saving alternative to experimental analysis for combustion chamber design and optimization. Soot modeling in diesel engines has evolved over four decades from simple empirical relations to detailed kinetics involving polycyclic aromatic hydrocarbons (PAH) and complex particle dynamics. Although numerical models have been established for predicting soot mass for parametric variations, there is a lack of modeling studies for predicting soot particle size distribution for parametric variations. This becomes important considering the inclusion of limits on soot particle count in recent emission norms. The current work aims at modeling the soot particle size distribution inside a heavy duty diesel engine and validating the results for a parametric variation of injection pressure and intake temperature. Closed cycle combustion simulations have been performed using CONVERGE, a 3D computational fluid dynamics (CFD) code. A sectional soot model coupled with gas phase kinetics has been used with source terms for inception, condensation, surface reactions and coagulation. Numerical predictions for soot mass and particle size distribution at the exhaust show good agreement with experimental data after increasing the transition regime collision frequency by a factor of 100.
Computational Fluid Dynamics Simulation of an Opposed-Piston Two-Stroke Gasoline Compression Ignition Engine
Authors: Moiz Ahmed Abdul , Kodavasal Janardhan , Som Sibendu , Hanson Reed , Redon Fabien , Zermeno Rodrigo
Published: January 2019

The paper describes the results from a computational fluid dynamics (CFD) simulation campaign that is complementary to an ongoing experimental program to develop an opposed-piston (OP) two-stroke gasoline compression ignition (GCI) engine for application in light-duty trucks. The simulation workflow and results are explained. First, open-cycle 3-D CFD simulations (in Converge CFD) are performed to simulate the scavenging process—gas exchange through the intake ports, cylinder, and exhaust ports. The results from these scavenging calculations are then fed into a model of this engine built in the system-level simulation tool (in GT-POWER), which in turn provides initial conditions for closed-cycle 3-D CFD simulations. These simulations are used to assess combustion by employing standard spray models and a chemical kinetic mechanism for gasoline. Validation of a representative set of engine operating points is performed in this way to gain confidence in the CFD model setup. Six injectors were then screened according to metrics of wall-wetting, maximum pressure rise rate, combustion efficiency and emission levels. Further CFD simulations have been carried out with parameter sweeps applying design of experiments (DoE) methods to finalize on candidate injectors, piston-bowls and injection strategies. The intended outcome of this program is a three-cylinder OP GCI engine equipped with a turbocharger and a supercharger targeting a 30% improvement in brake thermal efficiency (BTE) over conventional light-duty diesel engines.
Benefits of Higher-Temperature Operation in Boosted SI Engines Enabled by Advanced Materials
Authors: Mills Zachary G. , Finney Charles E. A. , Edwards K. Dean , Haynes J. Allen
Published: January 2019

To meet the demand for greater fuel efficiency in passenger vehicles, various strategies are employed to increase the power density of light-duty SI engines, with attendant thermal or system efficiency increases. One approach is to incorporate higher-performance alloys for critical engine components. These alloys can have advantageous thermal or mechanical properties at higher temperatures, allowing for components constructed from these materials to meet more severe pressure and temperature demands, while maintaining durability. Advanced alloys could reduce the need for charge enrichment to protect certain gas-path components at high speed and load conditions, permit more selective cooling to reduce heat-transfer losses, and allow engine downsizing, while maintaining performance, by achieving higher cylinder temperatures and pressures. As a first step in investigating downsizing strategies made possible through high-performance alloys, a GT-Power model of a 4-cylinder 1.6L turbocharged direct-injection SI engine was developed. The model was tuned and validated against experimental dynamometer data collected from a corresponding engine. The model was then used to investigate various operating strategies for increasing power density. Results from these investigations will provide valuable insight into how new materials might be utilized to meet the needs of future light-duty engines and will serve as the basis for a more comprehensive investigation using more-detailed thermo-mechanical modeling.
Modeling Fuel Effects in a Diesel Engine Using Multi-Component Fuel Surrogates in CFD
Authors: Puduppakkam Karthik V. , Naik Chitralkumar V. , Meeks Ellen
Published: January 2019

A continued challenge to engine combustion simulation is predicting the impact of fuel-composition variability on performance and emissions. Diesel fuel properties, such as cetane number, aromatic content and volatility, significantly impact combustion phasing and emissions. Capturing such fuel property effects is critical to predictive engine combustion modeling. In this work, we focus on accurately modeling diesel fuel effects on combustion and emissions. Engine modeling is performed with 3D CFD using multi-component fuel models, and detailed chemical kinetics. Diesel FACE fuels (Fuels for Advanced Combustion Engines) have been considered in this study as representative of street fuel variability. The CFD modeling simulates experiments performed at Oak Ridge National Laboratory (ORNL) [1] using the diesel FACE fuels in a light-duty single-cylinder direct-injection engine. These ORNL experiments evaluated fuel effects on combustion phasing and emissions. The actual FACE fuels are used directly in engine experiments while surrogate-fuel blends that are tailored to represent the FACE fuels are used in the modeling. The 3D CFD simulations include spray dynamics and turbulent mixing.

We first establish a methodology to define a model fuel that captures diesel fuel property effects. Such a model should be practically useful in terms of acceptable computational turnaround time in engine CFD simulations, even as we use sophisticated fuel surrogates and detailed chemistry. Towards these goals, multi-component fuel surrogates have been developed for several FACE fuels, where the associated kinetics mechanisms are available in a model-fuels database. A surrogate blending technique has been employed to generate the multi-component surrogates, so that they match selected FACE fuel properties such as cetane number, chemical classes such as aromatics content, T50 and T90 distillation points, lower heating value and H/C molar ratio. Starting from a well validated comprehensive gas-phase chemistry, an automated method has been used for extracting a reduced chemistry that satisfies desired accuracy and is reasonable for use in CFD. Results show the level of modeling necessary to capture fuel-property trends under these widely varying engine conditions.
Analysis of Different Uniflow Scavenging Options for a Medium-Duty 2-Stroke Engine for a U.S. Light-Truck Application
Authors: Turner J. W. G. , Head R. A. , Wijetunge R. , Chang J. , Engineer N. , Blundell D. W. , Burke P.
Published: January 2019

The work presented here seeks to compare different means of providing uniflow scavenging for a 2-stroke engine suitable to power a US light-duty truck. Through the ‘end-to-end’ nature of the uniflow scavenging process, it can in theory provide improved gas-exchange characteristics for such an engine operating cycle; furthermore, because the exhaust leaves at one end and the fresh charge enters at the other, the full circumference of the cylinder can be used for the ports for each flow and therefore, for a given gas exchange angle-area demand, expansion can theoretically be maximized over more traditional loop-scavenging approaches. This gives a further thermodynamic advantage.

The three different configurations studied which could utilize uniflow scavenging were the opposed piston, the poppetvalve with piston-controlled intake ports and the sleeve valve. These are described and all are compared in terms of indicated fuel consumption for the same cylinder swept volume, compression ratio and exhaust pressure, for the same target indicated mean effective pressure and indicated specific power.

A new methodology for optimization was developed using a one-dimensional engine simulation package which also took into account charging system work. The charging system was assumed to be a combination of supercharger and turbocharger to permit some waste energy recovery.

As a result of this work it was found that the opposed-piston configuration provides the best attributes since it allows maximum expansion and minimum heat transfer. Its advantage over the other two (whose results were very close) was of the order of 8.3% in terms of NSFC (defined as ISFC net of supercharger power). Part of its advantage also stems from its requirement for minimum air supply system work, included in this NSFC value.

Interestingly, it was found that existing experiential guidelines for port angle-area specification for loop-scavenged, piston-ported engines using crankcase compression could also be applied to all of the other scavenging types. This has not been demonstrated before. The optimization process that was subsequently developed allowed port design to be tailored to specific targets, in this case lowest NSFC. The paper therefore presents a fundamental comparison of scavenging systems using a new approach, providing new insights and information which have not been shown before.
Piston Rings Friction Comparison in a Free Piston and Conventional Crankshaft Engines
Authors: Bade Mehar , Clark Nigel N. , Musho Terence , Famouri Parviz
Published: January 2019

The conventional internal combustion engines driven by crankshafts and connecting rod mechanisms are restrained by combustion, thermal and mechanical inefficiencies. The Oscillating Free Piston Linear Engine Alternator (OFPLEA) produces electric power with no need to modify the reciprocating motion to rotary motion. In the most common geometry it consists of a linear alternator driven cyclically by one or two internal combustion engines. With the elimination of crankshaft mechanism linkages, the free piston engine offers potential benefits over crankshaft engines in terms of total mechanical losses. A significant proportion of 5% to 12% of total fuel energy in conventional engines is consumed to overcome the frictional losses. This research investigation addresses an analytical and numerical model to simulate the tribological performance of piston rings in an OFPLEA engine. The results are then compared with results from an equivalent conventional crankshaft driven engine. This axisymmetric, mixed lubrication tribological model is developed on the hydrodynamic process defined by Patir and Cheng’s modified Reynolds equation and an asperity contact process as defined by Greenwood and Tripp’s rough surface dry contact model. The asperity contact pressure distribution, hydrodynamic pressure distribution, lubricant oil film thickness, frictional force and frictional power losses are calculated using an explicit finite difference approach. In the absence of spring-dominated OFPLEA system, dissimilarity in the piston motion profile for compression and power stroke exhibited two different oil film thickness peaks. Whereas a similar oil film thickness peaks are observed for conventional engine due to the controlled and stable operation maintained by crankshaft mechanism. The simulation results state that the frictional losses due to piston ring - cylinder liner contact are found to be lower for a free piston engine than for those of a corresponding crankshaft engine. The simulated piston ring frictional power losses are found to be 342.8 W for the OFPLEA system and 382.6 W for the crankshaft engine. Further, an overall system efficiency improvement of 0.6 % is observed for an OFPLEA engine due to these reduced frictional losses from piston rings.
Enhanced green luminescence from ZnO nanorods
Authors: Hasabeldaim Emad H. H. , Ntwaeaborwa Odireleng M. , Kroon Robin E. , Coetsee Elizabeth , Swart Hendrik C.
Published: January 2019

Preferentially c-axis oriented ZnO nanorods were grown on a ZnO seed layer spin coated on a crystalline silicon substrate. A low-temperature aqueous chemical growth method using the chemical bath deposition technique was used to grow the ZnO nanorods. The samples were annealed at 700 °C in a reducing atmosphere (H2/Ar) with a relative ratio of 5%:95% for different times (20, 30, and 50 min). X-ray diffraction analysis revealed that the crystallite sizes increased with an increasing annealing time up to 30 min and then decreased for longer annealing time. Scanning electron microscope images showed a successful growth of the vertically aligned ZnO nanorods which were approximately 500 nm in length and 50 nm in diameter. The diameter of the nanorods increased with an increasing annealing time up to 30 min and then decreased when the annealing time was increased further. Photoluminescence (PL) measurements confirmed that the unannealed sample exhibited two distinct emissions, namely, the band to band emission around 378 nm and a broad orange emission centered at 600 nm which was due to the oxygen related defects. The annealed samples exhibited only a broad green emission centered at 500 nm and their intensities increased with annealing time. The highest intensity was recorded for the sample annealed for 30 min and the intensity decreased for further annealing time. The deconvoluted PL peak of the green emission indicated that three different kinds of defects were responsible for the emission at 500 nm. The decay measurements indicated that the green emission (500 nm) had an average lifetime of 11.58 μs. The quantum yield of the sample annealed for 30 min was measured using an integrating sphere at a wavelength of 325 nm, and it was found to be 43%. These ZnO nanorods can be very useful in optoelectronic applications, such as green light emitting diodes and field emission displays.
Synthesis and self-assembly of high-χ poly(4-tertbutylstyrene)-block-poly(2-hydroxyethylmethacrylate)
Authors: Breaux Caleb L. , Sharp Brandon L. , Ludovice Peter J. , Henderson Clifford L. , Li Haibo , Li Bing , Neisser Mark
Published: January 2019

Block copolymers (BCPs) are utilized by the microelectronics industry for their ability to phase separate at very small length scales (<20 nm). By casting these BCPs as a thin film on a substrate, the BCPs can phase separate into patterns that can be used as an etching template to transfer features into the substrate. The spacing between features is determined by the natural pitch of the BCP which is dependent on both the Flory–Huggins interaction parameter, χ, and the degree of polymerization, N. The pitch is more dependent on N than χ, meaning a low N, high-χ material is required to reach small pitches. Here, the synthesis and characterization of the BCP, poly(4-tertbutylstyrene)-b-poly(hydroxyethylmethacrylate) (PtBS-b-PHEMA), is reported. Small angle x-ray scattering and atomic force microscopy showed that PtBS-b-PHEMA was able to form cylindrical and lamellar forming morphologies with a pitch of 10 nm and sub-7 nm, respectively. With these pitches, the χ of PtBS-b-PHEMA is expected to be greater than 0.4. Random copolymer underlayers were crafted for the BCP to phase separate on in an attempt to perpendicular features; however, a neutral underlayer has yet to be found.
Rapid crystallization and controllable growth of perovskite thin films via a seeded approach
Authors: Zhou Ziyou , Shaik Shoieb , Ouyang Zhongliang , Yan Feng , Li Dawen
Published: January 2019

Organic–inorganic hybrid perovskite solar cells (PVSCs) have attracted extensive attention due to high efficiency, easy fabrication, and low-cost solution processes. One of the keys to achieve high-performance cost-effective PVSCs is to attain rapid crystallization with controlled morphology of the perovskite films. Herein, the authors report a technique for the rapid crystallization of perovskite with tunable crystal grain size and morphology via a seeded approach. Specifically, a solution of lead iodide (PbI2) was spin coated on a substrate, and a low-concentration solution of methylammonium iodide (MAI) was dropped onto the PbI2 film to form perovskite seeds prior to introducing high-concentration solution of MAI. The seeded nucleation and growth lead to dense and uniform perovskite thin films with controllable crystal grains. This seeded crystallization technique offers an effective way to boost the low-cost manufacture of efficient and reproducible PVSCs.
Functional rate-code models of the auditory brainstem for predicting lateralization and discrimination data of human binaural perception
Authors: Bouse Jaroslav , Vencovský Václav , Rund František , Marsalek Petr
Published: January 2019

This paper presents a rate-code model of binaural interaction inspired by recent neurophysiological findings. The model consists of a peripheral part and a binaural part. The binaural part is composed of models of the medial superior olive (MSO) and the lateral superior olive (LSO), which are parts of the auditory brainstem. The MSO and LSO model outputs are preprocessed in the interaural time difference (ITD) and interaural level difference (ILD) central stages, respectively, which give absolute values of the predicted lateralization at their outputs, allowing a direct comparison with psychophysical data. The predictions obtained with the MSO and LSO models are compared with subjective data on the lateralization of pure tones and narrowband noises, discrimination of the ITD and ILD, and discrimination of the phase warp. The lateralization and discrimination experiments show good agreement with the subjective data. In the case of the phase-warp experiment, the models agree qualitatively with the subjective data. The results demonstrate that rate-code models of MSO and LSO can be used to explain psychophysical data considering lateralization and discrimination based on binaural cues.
Influence of bubble distributions on the propagation of linear waves in polydisperse bubbly liquids
Authors: Fan Yuzhe , Li Haisen , Xu Chao , Zhou Tian
Published: January 2019

The influence of the spatial distributions of bubbles on the propagation of linear acoustic waves in polydisperse bubbly liquids is studied. Using the diagrammatic approach, the effective wavenumber, which includes both spatial information and higher orders of multiple scattering, is presented. The phase speed and attenuation coefficient of acoustic waves in bubbly liquids are calculated from the effective wavenumber. A three-dimensional random model, the Generalized Matérn's hard-core point process, is used to close the model. Numerical simulations reveal that as the bubble volume fraction becomes larger so does the effect of the bubble distributions on the attenuation and phase speed. The irregular discrepancy between previously reported experimental results and the classical theory is attributed to the influence of bubble clustering on the propagation of linear waves. The comparison between the present model and the experimental measurements [Leroy, Strybulevych, Page, and Scanlon. (2011). Phys. Rev. E 83, 046605] reveals that the proposed correction term significantly improves the theoretical predictions.
Echolocation adaptations during high-speed roost re-entry for Brazilian free-tailed bats (Tadarida brasiliensis)
Authors: Pudlo Allison , Kloepper Laura N.
Published: January 2019

Some bats re-enter their cave while using echolocation at very high speeds, but this behavior is poorly studied. Thermal imaging and an array of ultrasonic microphones were used to investigate the acoustic adaptations made during high-speed re-entry for single bats entering a cave. There was a significant overall effect between bat, distance to the ground, and its flight speed on pulse duration and interpulse interval (IPI). The data imply that overall bats reduce pulse duration, IPI, and bandwidth as they approach the cave and slow down, but the behavior changes among individuals.
IDH3α regulates one-carbon metabolism in glioblastoma
Authors: May Jasmine L. , Kouri Fotini M. , Hurley Lisa A. , Liu Juan , Tommasini-Ghelfi Serena , Ji Yanrong , Gao Peng , Calvert Andrea E. , Lee Andrew , Chandel Navdeep S. , Davuluri Ramana V. , Horbinski Craig M. , Locasale Jason W. , Stegh Alexander H.
Published: January 2019

IDH3α promotes glioblastoma progression and links mitochondrial metabolism to cSHMT-controlled one-carbon metabolism.
Dynamical interference in the vibronic bond breaking reaction of HCO
Authors: Han Shanyu , Zheng Xianfeng , Ndengué Steve , Song Yu , Dawes Richard , Xie Daiqian , Zhang Jingsong , Guo Hua
Published: January 2019

Oscillations in the photodissociation products of HCO arise from quantum interference between different paths along the PES.
A single-stranded coordination copolymer affords heterostructure observation and photoluminescence intensification
Authors: Toyoda Ryojun , Sakamoto Ryota , Fukui Naoya , Matsuoka Ryota , Tsuchiya Mizuho , Nishihara Hiroshi
Published: January 2019

A single-stranded coordination copolymer is subject to copolymer structure visualization by ambient AFM and photoluminescence enhancement.
Weak influence of near-surface layer on solar deep convection zone revealed by comprehensive simulation from base to surface
Authors: Hotta H. , Iijima H. , Kusano K.
Published: January 2019

One comprehensive calculation covers the whole solar convection zone.
Improving the metabolic fidelity of cancer models with a physiological cell culture medium
Authors: Vande Voorde Johan , Ackermann Tobias , Pfetzer Nadja , Sumpton David , Mackay Gillian , Kalna Gabriela , Nixon Colin , Blyth Karen , Gottlieb Eyal , Tardito Saverio
Published: January 2019

Plasmax, a physiological cell culture medium, prevents metabolic artifacts imposed on cancer cells by commonly used media.
“Yabba-GABA-Doo”: Meet the microbiome
Authors: Cohen Louis J.
Published: January 2019

The microbiome is an important regulator of GABA, which has implications for major depressive disorder.
Understanding the Components, Calculation, and Impact of Monthly and Seasonal Variation of the Standardized Antimicrobial Utilization Ratio (SAAR)
Authors: Avedissian Sean N. , Rhodes Nathaniel J. , Liu Jiajun , Aljefri Doaa , Postelnick Michael J. , Sutton Sarah H. , Zembower Teresa R. , Martin David , Pais Gwendolyn , Cruce Caroline E. , Scheetz Marc H.
Published: January 2019

This study sought to characterize the impact of 3 types of variation on the Standardized Antimicrobial Administration Ratio (SAAR) utilizing local National Healthcare Safety Network (NHSN) data. SAAR and antimicrobial days per 1,000 days present (AD/1000DP) were compiled monthly for Northwestern Memorial Hospital from 2014 to 2016.
Pharmacokinetics of Dapivirine Transfer into Blood Plasma, Breast Milk, and Cervicovaginal Fluid of Lactating Women Using the Dapivirine Vaginal Ring
Authors: Noguchi Lisa M. , Hoesley Craig , Kelly Cliff , Scheckter Rachel , Bunge Katherine , Nel Annalene , Marzinke Mark A. , Hendrix Craig W. , Dezzutti Charlene S. , Hillier Sharon L. , Bogen Debra L. , Piper Jeanna M. , Beigi Richard H.
Published: January 2019

Breastfeeding (BF) women are an important population for biomedical HIV prevention strategies, but they are rarely included in trials. The 25-mg dapivirine vaginal ring (VR) reduced women’s risk of sexually transmitted HIV infection in two phase 3 trials conducted in Africa.
Retention of EsxA in the Capsule-Like Layer of
Mycobacterium tuberculosis
Is Associated with Cytotoxicity and Is Counteracted by Lung Surfactant
Authors: Raffetseder Johanna , Iakobachvili Nino , Loitto Vesa , Peters Peter J. , Lerm Maria
Published: January 2019

Mycobacterium tuberculosis
, the pathogen that causes tuberculosis, primarily infects macrophages but withstands the host cell’s bactericidal effects. EsxA, also called virulence factor 6-kDa early secretory antigenic target (ESAT-6), is involved in phagosomal rupture and cell death.
Characterization of Pyrin Dephosphorylation and Inflammasome Activation in Macrophages as Triggered by the
Yersinia
Effectors YopE and YopT
Authors: Medici Natasha P. , Rashid Maheen , Bliska James B.
Published: January 2019

Pathogenic
Yersinia
species deliver Yop effector proteins through a type III secretion system into host cells. Among these effectors, YopE and YopT are Rho-modifying toxins, which function to modulate host cell physiology and evade immune responses.
SodA Contributes to the Virulence of Avian Pathogenic Escherichia coli O2 Strain E058 in Experimentally Infected Chickens
Authors: Gao Qingqing , Xia Le , Wang Xiaobo , Ye Zhengqin , Liu Jinbiao , Gao Song
Published: January 2019

Avian colibacillosis, caused by strains of avian pathogenic
Escherichia coli
, is a major bacterial disease of severe economic significance to the poultry industry worldwide. The virulence mechanisms of APEC are not completely understood. This study investigated the influence of an antioxidant protein, SodA, on the phenotype and pathogenicity of APEC O2 strain E058. This is the first report demonstrating that SodA plays an important role in protecting a specific APEC strain against hydrogen peroxide-induced oxidative stress and contributes to the virulence of this pathotype strain. Identification of this virulence factor will enhance our knowledge of APEC pathogenic mechanisms, which is crucial for designing successful strategies against associated infections and transmission.
Clinical Impact of Rapid Point-of-Care PCR Influenza Testing in an Urgent Care Setting: a Single-Center Study
Authors: Benirschke Robert C. , McElvania Erin , Thomson Richard B. , Kaul Karen L. , Das Sanchita
Published: January 2019

Seasonal influenza virus causes significant morbidity and mortality each year. Point-of-care (POC) testing using rapid influenza diagnostic tests (RIDTs), immunoassays that detect viral antigens, are often used for diagnosis by physician offices and urgent care centers.
High Permissiveness for Genetic Exchanges between Enteroviruses of Species A, including Enterovirus 71, Favors Evolution through Intertypic Recombination in Madagascar
Authors: Volle Romain , Razafindratsimandresy Richter , Joffret Marie-Line , Bessaud Maël , Rabemanantsoa Sendraharimanana , Andriamamonjy Seta , Raharinantoanina Jonhson , Blondel Bruno , Heraud Jean-Michel , Bailly Jean-Luc , Delpeyroux Francis
Published: January 2019

Human enteroviruses of species A (EV-A), including EV-A71, are the leading cause of hand-foot-and-mouth disease (HFMD) and may also cause severe neurological manifestations. We investigated the circulation and molecular evolution of EV-A in Madagascar, focusing particularly on the recently described EV-A71 genogroup F. Eight different types, collected mostly in 2011, were identified, highlighting the local circulation and diversity of EV-A. Comparative genome analysis revealed evidence of frequent genetic exchanges between the different types of isolates. The three EV-A71 isolates had different evolutionary histories in terms of recombination. The engineering and characterization of recombinants involving progenitors belonging to different EV-A types indicated a high degree of permissiveness for genetic exchange in EV-A. No outbreak of disease due to EV-A has yet been reported in Madagascar, but the diversity, circulation, and evolution of these viruses justify the surveillance of EV-A circulation to prevent possible HFMD outbreaks due to emerging strains.
HIV Subtype and Nef-Mediated Immune Evasion Function Correlate with Viral Reservoir Size in Early-Treated Individuals
Authors: Omondi Fredrick H. , Chandrarathna Sandali , Mujib Shariq , Brumme Chanson J. , Jin Steven W. , Sudderuddin Hanwei , Miller Rachel L. , Rahimi Asa , Laeyendecker Oliver , Bonner Phil , Yue Feng Yun , Benko Erika , Kovacs Colin M. , Brockman Mark A. , Ostrowski Mario , Brumme Zabrina L.
Published: January 2019

While combination antiretroviral therapies (cART) have transformed HIV infection into a chronic manageable condition, they do not act upon the latent HIV reservoir and are therefore not curative. As HIV cure or remission should be more readily achievable in individuals with smaller HIV reservoirs, achieving a deeper understanding of the clinical, immunological, and virological determinants of reservoir size is critical to eradication efforts. We performed a
post hoc
analysis of 30 participants of a clinical trial of early cART who had previously been assessed in detail for their clinical, immunological, and reservoir size characteristics. We observed that the HIV subtype and autologous Nef-mediated HLA downregulation function correlated with the viral reservoir size measured approximately 1 year post-cART initiation. Our findings highlight virological characteristics—both genetic and functional—as possible novel determinants of HIV reservoir establishment and persistence.
Lund Human Mesencephalic (LUHMES) Neuronal Cell Line Supports Herpes Simplex Virus 1 Latency
In Vitro
Authors: Edwards Terri G. , Bloom David C.
Published: January 2019

Herpes simplex virus (HSV) is responsible for significant morbidity in humans due to its ability to cause oral and genital lesions, ocular disease, and encephalitis. While antivirals can attenuate the severity and frequency of disease, there is no vaccine or cure. Understanding the molecular details of HSV latency and reactivation is key to the development of new therapies. One of the difficulties in studying HSV latency has been the need to rely on establishment of latent infections in animal models. While rodent primary neuron culture models have shown promise, they yield relatively small numbers of latently infected neurons for biochemical and molecular analyses. Here we present the use of a human central nervous system (CNS)-derived conditionally proliferating cell line that can be differentiated into mature neurons and latently infected with HSV-1. This model shows promise as a scalable tool to study molecular and biochemical aspects of HSV-1 latency and reactivation in human neurons.
Genetic Evidence for Two Carbon Fixation Pathways (the Calvin-Benson-Bassham Cycle and the Reverse Tricarboxylic Acid Cycle) in Symbiotic and Free-Living Bacteria
Authors: Rubin-Blum Maxim , Dubilier Nicole , Kleiner Manuel
Published: January 2019

Primary production on Earth is dependent on autotrophic carbon fixation, which leads to the incorporation of carbon dioxide into biomass. Multiple metabolic pathways have been described for autotrophic carbon fixation, but most autotrophic organisms were assumed to have the genes for only one of these pathways. Our finding of a cultivable bacterium with two carbon fixation pathways in its genome, the rTCA and the CBB cycle, opens the possibility to study the potential benefits of having these two pathways and the interplay between them. Additionally, this will allow the investigation of the unusual and potentially very efficient mechanism of electron flow that could drive the rTCA cycle in these autotrophs. Such studies will deepen our understanding of carbon fixation pathways and could provide new avenues for optimizing carbon fixation in biotechnological applications.
Identifying GP trainees’ priorities in simulation training: a questionnaire to aid course development in Scotland
Authors: Phillips Emma Claire , Lavery Sarah , Dickson Jamie
Published: January 2019

Simulation has been shown to be an effective method of delivering training in the management of acutely unwell patients. General practitioner (GP) trainees are a group in whom simulation training could contribute to their professional development. This project aimed to explore the potential impact of a simulation course for this group and to ascertain what trainees identified as their main training priorities regarding care of the acutely ill patient. A questionnaire was sent to GP trainees in Scotland to explore opinions on simulation through quantitative confidence scores and used qualitative free-text responses to identify their training priorities. Two-hundred and three GP trainees completed the questionnaire. They reported middle-to-low confidence levels in dealing with acutely unwell patients in the GP practice. Eighty-six per cent felt that simulation would be an effective method to increase confidence. The top five conditions identified as training priorities were: anaphylaxis, acute asthma, acute coronary syndromes, paediatric emergencies and cardiac arrest, and trainees highlighted the challenges specific to the primary care setting. GP trainees in Scotland would value simulation training and have identified their training priorities. These findings will be used to develop a simulation course for GP trainees in Scotland.
Outcomes of pneumatic dilatation and Heller’s myotomy for achalasia in England between 2005 and 2016
Authors: Harvey Philip R , Coupland Ben , Mytton Jemma , Evison Felicity , Patel Prashant , Trudgill Nigel J
Published: January 2019

Introduction

Achalasia is a disorder characterised by failed relaxation of the lower oesophageal sphincter. The aim of this study was to examine, at a national level, the long-term outcomes of achalasia therapies.

Methods

Hospital Episode Statistics include diagnostic and procedural data for all English National Health Service–funded hospital admissions. Subjects with a code for achalasia who had their initial treatment between January 2006 and December 2015 were grouped by treatment; pneumatic dilatation (PD) or surgical Heller’s myotomy (HM). Procedural failure was defined as time to a further episode of the same therapy or a change to a different therapy. Up to three PDs were permitted without being considered a therapy failure.

Results

6938 subjects were included; 3619 (52.2%) were men and median age at diagnosis was 59 (IQR 43–75) years. 4748 (68.4%) initially received PD and 2190 (31.6%) HM. The perforation rate following PD was 1.6%. Mortality at 30 days was 0.0% for HM and 1.9% for PD, and <8% after perforation following PD. Factors associated with increased mortality after PD included age quintile 66–77 (OR 4.55 (95% CI 2.00 to 10.38), p<0.001), >77 (9.78 (4.33 to 22.06), p<0.001); Charlson comorbidity score >4 (2.87 (2.08 to 3.95), p<0.001); previous HM (2.47 (1.33 to 4.62), p<0.001); and repeat PD 1–3 (1.58 (1.15 to 2.16), p=0.005), >3 (1.97 (1.21 to 3.19), p=0.006). Durability of up to 3 PD and HM over 10 years of follow-up was 86.2% and 81.9%, respectively (p<0.001).

Discussion

The efficacy of PD for achalasia appears to be greater than HM over 10 years. There was no mortality associated with HM, but 1.9% of subjects died within 30 days of PD. Mortality was associated with increasing age, comorbidity, previous HM and repeat PD.
Stability analysis of Cu–H2O nanofluid over a curved stretching–shrinking sheet: existence of dual solutions
Authors: Usama  , Nadeem S. , Khan A.U.
Published: January 2019

The effect of mass suction with temperature jump and velocity slip of viscous, unsteady nanofluid flow past a curved shrinking–stretching surface is analyzed in this work. Copper (Cu) and water are considered nanoparticles and base fluids, respectively. The complicated coupled system of differential equations is converted into non-dimensional form with some suitable similarity variables. The solution of the nonlinear problem is produced by use of numerical scheme available in the form of bvp4c package in MATLAB. In the case of shrinking towards the surface, a reverse flow situation is also developed and requires careful selection of solution by examining the stability of the solution. Detailed stability analysis is done and critical values are determined for the possible existence of dual solutions. Variation in parameters is analyzed by plotting graphs and tables. The numerical values are also calculated for the reduced Nusselt number and skin friction due to variation in values of different flow parameters. Results have shown that for the curved shrinking surfaces, one should expect multiple solutions for a set of parameter values such as mass suction, curvature, nanoparticles volume fraction, and unsteadiness.
Wear properties of two U71Mn K and U71Mn G rail steel welds during rolling contact fatigue
Authors: Peng Jinfang , Xie Xuhui , Song Weijun , Li Wei , Luo Zhiping
Published: January 2019

Wear behaviors of two U71Mn K and U71Mn G rail steels have been systematically investigated with the simulated experiments during the tolling contact fatigue using samples taken from their base materials, the heat-affected zones near the weld, and the weld zones, respectively. The results demonstrate that there are significant differences between the nonweld and the weld zones for both steels. With higher hardness of U71Mn G over U71Mn K, the U71Mn G steel has mild abrasion damage, reduced weight loss from wear and reduced corrugations of the weld zone during the experiment with increased simulative speed; while its other features such as the plastic deformation and cracks are almost the same compared with the U71Mn K steel. The U71Mn G steel demonstrates superior performance over U71Mn K at the high-speed rolling experiment.
Analysis of the Factors of Climatic Productivity
Authors: PAN Jiahua , HU Lei
Published: January 2019

Though researches about productivity from the aspects of economics and ecology have covered natural factors, the most basic climatic factors therein were ignored. The eco-footprint and climate capacity have an explicit coverage of the impact of climatic factors on productivity. It can be concluded that climate is also a kind of productivity and mitigating climate change is improving productivity, after an analysis of the primary, industrial, and ecological climatic productivities defined by the decisive factors of climatic productivity. In view of the above, the study of climatic productivity needs to be further deepened in both theory and methodology.
Effect of cooling on lung secretory phospholipase A2 activity in vitro, ex vivo, and in vivo
Authors: Autilio Chiara , Shankar-Aguilera Shivani , Minucci Angelo , Touqui Lhoussaine , De Luca Daniele
Published: January 2019

Hypothermia can modify surfactant composition and function. Secretory phospholipase A2 (sPLA2) hydrolyses surfactant phospholipids and is important in the pathobiology of several critical respiratory disorders. We hypothesize that sPLA2 activity might be influenced by the temperature partially explaining surfactant changes. This study aims to evaluate comprehensively the effect of hypothermia on sPLA2 activity. We measured sPLA2 activity at different temperatures, alone or combined with bile acids, in vitro (incubating human recombinant sPLA2-IIA and porcine sPLA2-IB), ex vivo (by cooling bronchoalveolar lavage samples from neonates with respiratory distress syndrome or no lung disease), and in vivo (using lavage samples obtained before and after 72 h of whole body cooling in neonates with hypoxic-ischemic encephalopathy). We also measured concentrations of various sPLA2 subtypes and natural sPLA2 inhibitors in in vivo cooled samples. Results were corrected for protein content and dilution. In vitro cooling did not show any effect of hypothermia on sPLA2. Ex vivo cooling did not alter total sPLA2 activity, and the addition of bile acids increased sPLA2 activity irrespective of the temperature and the type of sampled patient. In vivo hypothermia reduced median sPLA2 activity from 16.6 [15.2–106.7] IU/mg to 3.3 [2.7–8.5] IU/mg ( P = 0.026) and mean sPLA2-IIA from 1.1 (0.8) pg/μg to 0.6 (0.4) pg/μg ( P = 0.047), whereas dioleylphosphatidylglycerol increased from 8.3 (3.9)% to 12.8 (5.1)% ( P = 0.02). Whole body hypothermia decreases in vivo global sPLA2 activity in bronchoalveolar lavage fluids through the reduction of sPLA2-IIA and increment of dioleylphosphatidylglycerol. This effect is absent during in vitro or ex vivo hypothermia.