bluuebunny/crossref_metadata_2025_split huggingface dataset:
How does the host‐specialized aphid deal with food deficiency?
Authors: Xu Ting‐Ting , Ma Ting‐Ting , Liu Xiang‐Dong 
Published: February 2014

AbstractAphis gossypii Glover shows obvious host specialization, with cucurbit‐ and cotton‐specialized biotypes or host races in many regions. Because its annual natal host crops senesce earlier the cucurbit‐specialized biotype may suffer food deficiency. The method this biotype uses to overcome this challenge is still poorly understood. In order to understand the potential of the cucurbit‐specialized biotype aphids in host shift and usage, the performance of this biotype on cotton (Gossypium hirsutum), a common but poor quality host plant, was explored in this study. The cucurbit‐specialized aphids could establish populations on cotton only when these plants had at least nine leaves, and subsequent populations developed rather slowly. The presence of whitefly populations on cotton improved the success rate of cucurbit‐specialized aphids. The cucurbit‐specialized aphids were mainly distributed on the older leaves of cotton, with only a few settling on the upper leaves. The cucurbit‐specialized aphids reared on cotton for 40, 54 and 61 days still maintained strong preference for their natal host plant, cucumber (Cucumis sativus), rather than cotton, and their net reproductive rates and intrinsic rates of natural increase were dramatically lower when they were transferred onto new six‐leaf cotton plants or detached leaves. Therefore, we concluded that the cucurbit‐specialized aphids have the potential to utilize mature or whitefly‐stressed cotton plants, but that this feeding experience on cotton did not alter their specialization for cucurbits. Some cotton plants could act as a temporary host for the cucurbit‐specialized aphids to overcome food deficiency arising from senescing cucurbits.
Discovery of the Highly Potent Fluoroquinolone‐Based Benzothiazolyl‐4‐thiazolidinone Hybrids as Antibacterials
Authors: Patel Rahul V. , Park Se Won 
Published: February 2014

A new series of fluoroquinolone‐based benzothiazolyl‐4‐thiazolidinone hybrids has been yielded via sulfated tungstate‐promoted highly accelerated N‐formylation at a piperazine residue of ciprofloxacin and norfloxacin entities. The formylated fluoroquinolone moieties were then coupled with substituted 2‐aminobenzothiazoles, which were generated from their respective para‐substituted amines to form corresponding Schiff base intermediates. The Schiff bases were then treated with thioglycolic acid to equip a new class of 4‐thiazolidinones to be analyzed for their antibacterial effects against two Gram‐positive (Staphylococcus aureus and Bacillus subtilis) and two Gram‐negative (Escherichia coli and Pseudomonas aeruginosa) bacterial strains and were found highly potent with lowest Minimum inhibitory concentrations (MIC), 1–2 μg/mL, that is, more potent than control drugs ciprofloxacin (3.12–6.25 μg/mL). Initial outcomes provided for these novel molecular systems will aid researchers to design and develop new antibacterial drugs. The structural assignments of the new products were done on the basis of FT‐IR, 1H NMR and 13C NMR spectroscopy, and elemental analysis.
Pharmacodynamics of the glucagon‐like peptide‐1 receptor agonist lixisenatide in Japanese and Caucasian patients with type 2 diabetes mellitus poorly controlled on sulphonylureas with/without metformin
Authors: Seino Y. , Takami A. , Boka G. , Niemoeller E. , Raccah D. ,   on behalf of the PDY6797 investigators
Published: February 2014

AimsThe PDY6797 study evaluated efficacy, safety and pharmacodynamics of lixisenatide in Japanese and Caucasian patients with type 2 diabetes mellitus (T2DM) insufficiently controlled with sulphonylureas with/without metformin.MethodsThis randomized, double‐blind, placebo‐controlled trial comprised a single‐dose assessment of lixisenatide 5 and 10 µg, and a 5‐ to 6‐week repeated dose‐escalation assessment of lixisenatide 5 to 30 µg once (QD) or twice daily (BID). The primary endpoint was change in postprandial plasma glucose (PPG) area under the curve (AUC)[0:29–4:30 h] after a standardized breakfast at the highest tolerated lixisenatide dose. Change from baseline in glycated haemoglobin (HbA1c), 2‐h PPG and fasting plasma glucose (FPG) were assessed, as were adverse events.ResultsChange from baseline in PPG AUC[0:29–4:30 h] with lixisenatide QD and BID was significantly greater than placebo (p < 0.0001 for all study populations), with particularly prominent effects in Japanese patients. Greater reductions in PPG AUC[0:29–4:30 h] were seen with lixisenatide QD versus BID, while the totality of evidence suggested that the lixisenatide 20 µg dose was optimal. In the overall population, changes from baseline for 2‐h PPG, HbA1c and FPG were significant with lixisenatide QD and BID versus placebo (p < 0.01 for all). Lixisenatide was well tolerated.ConclusionsLixisenatide significantly reduced PPG AUC[0:29–4:30 h] versus placebo at the highest well‐tolerated dose in patients with T2DM treated with sulphonylureas with/without metformin and had a good safety and tolerability profile. Japanese patients experienced particular benefits with lixisenatide in terms of reductions in PPG excursions.
Archaeobotanical evidence for climate as a driver of ecological community change across the anthropocene boundary
Authors: Ellis Christopher J. , Yahr Rebecca , Belinchón Rocío , Coppins Brian J. 
Published: February 2014

AbstractThe biodiversity response to climate change is a major focus in conservation research and policy. Predictive models that are used to project the impact of climate change scenarios – such as bioclimatic envelope models – are widely applied and have come under severe scrutiny. Criticisms of such models have focussed on at least two problems. First, there is an assumption that climate is the primary driver of observed species distributions (‘climatic equilibrium’), when other biogeographical controls are often reliably established. Second, a species' sensitivity to macroclimate may become less relevant when impacts are down‐scaled to a local level, incorporating a modifying effect of species interactions structuring communities. This article examines the role of different drivers (climate, pollution and landscape habitat structure) in explaining spatial community variation for a widely applied bioindicator group: lichen epiphytes. To provide an analysis free of ‘legacy effects’ (e.g. formerly higher pollution loads), the study focused on hazel stems as a relatively short‐lived and recently colonized substratum. For communities during the present day, climate is shown to interact with stem size/age as the most likely explanation of community composition, thus coupling a macroclimatic and community‐scale effect. The position of present‐day communities was projected into ordination space for eight sites inEngland and compared to the position of historical epiphyte communities from the same sites, reconstructed using preserved hazel wattles dating mainly to the 16th Century. This comparison of community structure for the late‐ to post‐Mediaeval period, with the post‐Industrial period, demonstrated a consistent shift among independent sites towards warmer and drier conditions, concurrent with the end of the Little Ice Age. Long‐term temporal sensitivity of epiphyte communities to climate variation thus complements spatial community patterns. If more widely applied, preserved lichen epiphytes have potential to generate new baseline conditions of environment and biodiversity for preindustrial lowlandEurope.
Effects on Boiler Efficiency Standards and Computed Coal Flow Given Variable Ambient Oxygen and Humidity
Authors: Lang Fred D. , Mason Dean , Rodgers David A. T. 
Published: February 2014

This paper examines the sensitivities of ambient conditions on the most basic understanding of fossil-fired power plants: boiler efficiency and associated computed fuel flow. Conditions studied were ambient oxygen in the combustion air, and the air’s water content. This research was conducted at the 610 MWe Boardman Coal Plant operated by Portland General Electric. Burning Powder River Basin coal, it has been tested numerous times by the authors including several 4 to 6 month long projects used to throughly understand the system. This experience, coupled with many other such projects, has suggested that ambient oxygen and humidity — normally taken as constants or simply ignored in common analyses — may have significant influence on boiler efficiency.
There are, of course, any number of inputs which might affect a computed efficiency, and associated computed fuel flow. This work separates data making up efficiency into water-side data and system stoichiometric data. We argue that fundamental understanding of fossil-fired systems begins with system stoichiometrics, and, for this work, ambient oxygen and humidity.
Demonstrated is that depletion of ambient oxygen can cause a very high error in boiler efficiency (>1% Δη) if unrecognized. In addition, given intrinsic complexity of combustion air systems, uncertainty in the amount of water in combustion air can well contribute to error. Further, this work demonstrates a technique whereby plant fuel flow can be verified based on ambient conditions.
This paper demonstrates the very real advantage of using high accuracy ambient instrumentation — for oxygen and relative humidity — whose measurements may not have dramatic affects when used at a well run plant such as Boardman, but whose use at plants not well monitored will easily justify their employment. Taking such ambient measurements a step further, this paper demonstrates a method whereby ambient humidity can be used to verify a coal-fired plant’s fuel flow.
Natural Convection Heat Transfer in Horizontal Cylindrical Cavities: A Computational Fluid Dynamics (CFD) Investigation
Authors: Ludovisi Daniele , Garza Ivo A. 
Published: February 2014

Many processes in power plants involve the storage and transfer of fluids including water in outdoor pipelines. Under extreme cold weather conditions, water can freeze if allowed to cool down to the freezing temperature. Installing insulation and maintaining adequate flow rate can sometimes prevent problems. However, during extended non-processing times, there are circumstances where cool down cannot be avoided and heat tracing along the piping becomes a necessity.
In many instances, the need for the installation of heat tracing is simply determined based on pipe size. However, by performing accurate calculations, it is possible to determine if the need for heat tracing is real or not, thus saving on installation and maintenance costs. Correlations for the estimation of the heat transfer coefficient in horizontal cavities are not sufficiently documented in literature. In the present work, two-dimensional CFD models are used to investigate the natural convection in water-filled horizontal pipes of different diameters. The analysis has been carried out based on the assumption of a uniform pipe surface temperature. The Nusselt number is estimated as a function of the Rayleigh number and shown not to be strongly dependent on the Prandtl number.
The analysis and the results of the numerical investigation are presented and compared to experimental data and other correlations available in literature. The documented correlation has an expanded range of applicability to high and low Rayleigh numbers, is supported by numerical and experimental results and is expressed in a simple form.
Improved Alternatives for Monitoring Flow Accelerated Corrosion in the Steam Cycle
Authors: Kuruc Ken , Slovacek Denton , Sadar Michael J. , Johnson Luke 
Published: February 2014

To date, a particle counter or monitor has traditionally been used to detect the transfer of corrosion products in a power generation steam cycle. While this method has been generally well accepted and documented, particle counters do not have a standardized method of calibration and usually need to be calibrated at each facility. Where multiple measurement points are desired, it can also become rather costly. The technology is also limited to detecting particles with a size of 2 microns or greater.
Quantifying the amount of iron in the water on site has also been challenging in the ultra low range. Colorimetric methods that could be readily used at the plant were limited to 9 μg/L or greater. This has furthered added to the challenge of ascertaining whether significant corrosion product transfer was occurring at a particular point in the process.
Data has recently been gathered to determine whether corrosion product transfer in the steam cycle could be detected using a laser nephelometer. The added benefit of this methodology is the ability to detect particles in the sub-micron size range. Preliminary results have been very encouraging.
To further support these results, a modified trace level iron test has been documented using colorimetric methods and a lab spectrophotometer. Finally, a correlation has been made between these two methods, offering the opportunity of using a continuous measurement to determine iron concentrations to 1 μg/L or lower. The data can be further related to plant load and cycle pH in order to shed further light on how these parameters influence flow accelerated corrosion.
Assessment of Life of Pressure Vessels and Pipes in Crude Oil and Gas Industries
Authors: Khalil M. Shahid , Akbar Sajjad 
Published: February 2014

Fitness-for-service (FFS) assessments are quantitative engineering evaluations which are required to be preformed periodically in accordance with the published codes and standards to demonstrate the structural integrity of in-service components. This report summarizes the results of nondestructive in-service-inspection (ISI) of pressurized components conducted for condition assessment of the Dakhani Gas Processing Plant of Oil and Gas Development Corporation Ltd. (OGDCL) for the first time since its commissioning in December,1989. The non-destructive evaluation of the plant was required because of concerns for occurrence of sulphide-stress-cracking. Hydrogen embrittlement, hydrogen-including-cracking, weight-loss-corrosion, sulphur-stress-corrosion due to determental service conditions at Dakhani having low PH, High H2S, high chlorides and pressure of CO2.
The results have shown that microstructural changes associated with first and second stage of hydrogen attack have occurred in almost all of the pipe joints and pressure vessels. Hardness of some vessels has even exceeded the NACE limit of 220 HB. Effect of second stage of hydrogen attack are dominant in pipe joints, resulting in loss of hardness and strength because of decarburization. The results based on ultrasonic attenuation monitoring also indicate degradation of components. Random rounded indications have also been observed in some pipe joints during X-Ray radiographic testing that could serve as sites for failure initiation. The corrosion-under-insulation is observed for joints of piping spreading over a significant length. Localized corrosion and pitting is also observed in some locations of pressure vessels and piping. Ultrasonic thickness gauging has shown a significant variation in thickness for dish end and shell of some pressure vessels as well as for various joints of piping. In absence of periodic ISI data for the plant and keeping in view the results of non-destructive evaluation summarized above, the end-of-life (EOL) assessment of pressure vessels and piping is not possible and operation of the plant should be continued with a degree of caution. Any estimate of safe life assessment of the plant made at this stage would require revision on the basis of observed level of degradation through essential periodic in-service monitoring. In order to cope with the situation, it is recommended that monitoring of further degradation of microstructure and hardness along with flaw growth should be carried out after a period of 8x103 hours. Necessary remedial measures for rectification of flaws are requested. Non-destructive strain gauging is recommended to estimate data for safe life assessment of pressure vessels. Thermographic scanning of on-line in-service insulated pipelines is proposed for monitoring corrosion-under-insulation during plant operation.
Corrosion-Fatigue Prediction Methodology for 12% Cr Steam Turbine Blades
Authors: Salzman Ronald , Gandy David , Rieger Neville , Schönbauer Bernd , Tschegg Stefanie , Zhou Shengqi , Turnbull Alan 
Published: February 2014

The useful life of a steam turbine and the establishment of turbine outage schedules are often determined by corrosion fatigue to the low pressure (LP) blades in the phase transition zone (PTZ). Developing an effective corrosion damage prediction methodology is an important step to successfully reduce the number of unscheduled steam turbine outages.
Tests with dual certified 403/410 12% Cr martensitic steel were performed to quantify the influence of corrosion pits on the fatigue life during testing in environments that are comparable to operational conditions. Threshold stress intensity factors ΔKth and fatigue limits Δσ0 were determined in air and two aqueous solutions. Additionally, stress-life tests were performed with pre-pitted specimens in air and aqueous solutions.
The data for transition from a pit-to-a-crack have been correlated using the Kitagawa Diagram. This presentation of the data relates the steady stress, cyclic stress and pit width to the prediction of fatigue failure. Ultrasonic fatigue testing was an essential aspect of this program. This testing technique makes it possible to accumulate cycles at a rate of approximately 20 kHz. At this rate one billion (109) cycles are accumulated in less than 14 hours. One billion cycles has been used as the definition for non-progressive crack or specimen run-out life. All of the data for the survival and failure stress intensity factor was well represented by the El Haddad refinement to the Kitagawa Diagram.
Based on these test results a comprehensive methodology has been developed to quantify the risk of corrosion-fatigue failure at a pit.
Considerations in Converting a Dual Shell or a Dual Pressure Coal Fired Plant Condenser Into a Combined Cycle Plant Condenser
Authors: Nadig Ranga 
Published: February 2014

The design of a dual shell or a dual pressure condenser employed in a coal fired plant is different from that in a combined cycle plant. The coal fired plant dual pressure condenser is equipped with feedwater heaters in the condenser neck, extraction piping, an external flash tank and a large number of vents and drains. Dual shell or dual pressure condenser in a combined cycle plant does not include feedwater heaters in the condenser neck and the related extraction piping. There is no external flash tank and the number of vents and drains are minimal. Combined cycle plants have a higher steam flowrate, are required to operate in bypass mode and in certain instances have high make up water flowrate. Apart from the above major differences there are a number of minor differences that must be accounted and addressed when converting a coal fired plant dual shell or dual pressure condenser into a combined cycle plant condenser.
This paper highlights the major and minor differences in the design, construction and operation of dual shell or dual pressure condenser operating in a coal fired plants and combined cycle plant. The modifications required to convert the condenser from coal fired application to combined cycle application are discussed. Precautions to be followed in operating the condenser in the new role are addressed.
A New Paradigm: Cycling Operations at Nuclear Power Plants in the United States
Authors: Lefton Steven , Kumar Nikhil , Hilleman Douglas , Agan Dwight 
Published: February 2014

Nuclear power plants are no longer immune to cycling operation. While certain nuclear power plants in Europe have been performing load following operation, this type of operation has largely been avoided in the United States. Due to increasing contribution of nuclear generation in the mix, European operators were forced to make modifications to increase the maneuverability of their nuclear generation assets. However, in the United States, nuclear generation is still a relatively smaller contributor (19%), but with rapid increase in renewable generation, some nuclear plans are being asked to operate at reduced power and cycle to lower power levels. These shutdowns are typically of a short-term duration on a weekend or in periods of high renewable megawatt generation. With most future renewable integration studies advocating for increased flexibility on the grid, nuclear generation maneuverability will allow system operators with another resource to mitigate and reduce system costs.
This paper presents the results of a detailed study of a 1,150 MW boiling water reactor (BWR) nuclear plant when cycled to low loads. The authors present the relative damage of cycling to various reduced power levels 80% to 15% power levels compared to a cold startup and shutdown of a nuclear plant. An assessment was made of the systems that had fatigue damage and costs. We also discuss some of the limitations of cycling that a nuclear plant has and present and discuss recommendations to reduce damage and costs.
Thermal Analysis of Nuclear Concrete Containment in Transition Zones Between Regions With Different Reinforcement
Authors: Wang Shen , Munshi Javeed A. 
Published: February 2014

Primary and secondary nuclear containments serve the critical function of providing an external protection and a leak proof boundary for containing radiation in nuclear power plants. Reinforced concrete containment in a nuclear power plant typically has a cylindrical wall and a spherical dome. Within the cylindrical shell, it is common to use different hoop reinforcing ratios at different elevations, in order to optimize the design. Reinforced concrete containments are designed for thermal effects, generally following methods provided in the committee reports of ACI 307 for chimneys or ACI 349 commentary for nuclear concrete structures. The behavior of concrete structures under thermal effects has been studied for decades. It is well know that stresses resulting from thermal effects are self-relieving and that magnitudes of thermal forces and moments are directly related to the reinforcement within the concrete member. In particular, for a given thermal and mechanical load combination, more reinforcing steel the concrete section contains, larger thermal forces/moments will be observed with correspondingly less deformations. The conventional approach provided in aforementioned building codes is to solve the equilibrium of a given reinforced concrete section with a predetermined reinforcement configuration. However, no research has been conducted to study thermal forces and moments in transition zones interfacing two regions with different reinforcement configurations. The compatibility at the interface between two regions with different reinforcement introduces further redistribution of thermal forces and moments within the transition zone, which should be considered in the design.
In this paper, a comprehensive study has been carried out using the closed form mechanical solution, in order to evaluate the redistribution of thermal forces and moments at a conceptual interface within a reinforced concrete cylindrical containment, between two regions with different reinforcement configurations. Based on this, consideration for thermal design at such an interface is provided. A practical example is presented at the end of the paper to illustrate the use of the proposed design method, followed by the conclusion.