bluuebunny/crossref_metadata_2025 huggingface dataset:
Low Pressure Injection System Crossconnect Modification
Authors: Broughton Ronnie T.
Published: October 2008

How would you fix all of the Low Pressure Injection (LPI) system technical problems listed below with a single nuclear plant modification? • Large LPI Flow indication uncertainty; • Non-Safety power to important cross connect valves; • LPI Pump run-out / NPSH operator burden; • Unbalanced LPI cooling due to electrical single failure; • Unconventional response to valve single failure. A southeastern nuclear generation facility responded by contracting Framatome ANP to design a new passive single cross connect modification for each of their generating units. This new cross connect, consisting of approximately 130’ of 10” stainless steel piping, new gate valves, new check valves, and two new flow restrictors, was installed downstream of the LPI coolers and inside containment on each unit to tie the two injection trains together. The two flow restrictors (stemless globe valves with precision engineered disc stacks) were the centerpiece of the design. Though system resistance is increased, the flow restrictors eliminate all of the technical issues that the utility faced in the LPI system. The passive nature of this design eliminated the time-critical operator burden, the need for safety grade power on existing cross connect valves, the threat of pump run-out and marginal NSPHa, and the unusual single failure licensing basis to manually open LPI isolation valves in the event that they failed closed. The design also improved flow indication uncertainty with a change out of the existing flow measuring orifices. Framatome ANP faced many challenges during the design process. In addition to the problems to be solved, other constraints of the modification were significant, including: an unusually tight upper limit on pump strength, a narrow band of acceptable system resistance with an unknown baseline, first-of-a-kind accuracy requirements for the flow restrictor, and High Pressure Injection (HPI) system minimum flow limits challenged by modification operational changes. The NRC has approved the flow restrictor and the overall design for use in this facility. The passive cross connect modification has been installed in all units. All equipment has passed installation and post modification testing requirements.
Automated Design Life Evaluation for a Gas Turbine HRSG
Authors: Torkildson Steve V. , Somasundaran Susheerlal
Published: October 2008

Many combined cycle plants operate only during peak demand hours and start/stop at least once a day, Exposure of the HRSG to the repeated thermal gradients experienced during start-up has raised questions about fatigue durability. Additionally, portions of the superheater and reheater sections operate in the creep range and owners want assurance that these parts will provide 25–30 years of life. This paper illustrates the development of an automated process to evaluate the effects of creep and cycling induced fatigue. The process employs a dynamic thermal analysis computer program, spreadsheets, and finite element analysis to complete a comprehensive fatigue/creep evaluation of every significant pressure part in the HRSG. An automated life evaluation process offers many advantages to the owner. During the design stage of the project, the analysis allows designers to provide for correct materials and adequate strength. Once the plant is in operation, changed operating conditions can be easily evaluated to determine their effect on HRSG life.
The Use of Selective Bunkering to Optimise PRB Utilisation at Nanticoke Generating Station
Authors: Marshall Lester W.
Published: October 2008

Many stations are currently blending Powder River Basin (PRB) coals with bituminous coals to various blend ratios. However, this blending is almost always accomplished at the port, coal yard or a dedicated blend facility — i.e. prior to introducing the coal to the unit. As a result, the pulverizers and burners are forced to deal with two (or more) disparate coals, compromising the performance of these systems. Research originating in Europe confirms the negative repercussions of grinding and firing dissimilar blends. This paper will describe the “Selective Bunkering” system in place at Ontario Power Generations Nanticoke GS which involves feeding the pure parent coals to individual mills and conducting blending in the furnace. This innovation has increased the maximum PRB blend ratio from 50% to 70% at full load and also allows for a seamless transition to 100% PRB firing at lower loads. The techniques employed to coordinate and optimize the combustion system will be discussed.
Low Cost ESP Performance Enhancement: A Proactive Approach
Authors: Plaks Norman , Parker Ken , Sanyal Anupam , Allen Jeff
Published: October 2008

Increasingly more stringent particulate standards in India are being met by large and expensive electrostatic precipitators for new coal-fired power stations. The older and smaller units require upgrades. The Proactive Approach combining experience and knowledge with the application of a modern ESP model has been developed to help identify low-cost upgrade options. The approach was applied to a poorly operating medium sized Indian ESP not meeting the newer regulations. After defining the discharge electrode and particle size properties the precipitator was virtually restored to its proper design performance within the computer. Then a number of relatively low-cost options were identified to increase the migration velocity and decrease the gas flow. These approaches indicated that the precipitator could achieve lower emission levels that could meet the newer emission requirements. The Proactive Approach is easily and economically applicable to other precipitators in India and elsewhere.
Optimization of MHD Generator Based Combined Cycle Efficiency
Authors: Saidi M. H. , Mozafari A. A. , Rezaei H. D. , Dehkordy A. J.
Published: October 2008

Energy crisis has directed scientific efforts to increase the efficiency of power generation systems. Thermodynamic optimization of MHD (Magneto Hydrodynamic) generator based combined cycles due to their high operating temperatures may seriously reduce exergy, destruction and improve the second law efficiency. In this research a combined cycle, comprising of MHD cycle as topping and gas turbine cycle as bottoming cycle has been simulated and analyzed and its pros and cons have been exposed. The first and second law efficiencies have been estimated from the operating pressures and temperatures of the system. To calculate the second law efficiency, the entropy generation of all components of the combined cycle has been parametrically calculated. Furthermore, the optimal pressure ratio and working temperature for both cycles are represented. The influence of pressure loss in pipeline and the effect of heat exchanger performance on the cycle efficiency have been considered as well.
Impact of Voltage and Short Circuit Level on Harmonics Generated by Wind Turbines
Authors: Bhagwatikar G. R. , Gandhare W. Z.
Published: October 2008

The paper presents the measurements at wind power project and 220/33 kV sub-station, which is dedicated for wind power evacuation, Satara district of Maharashtra State, India for the comparison of voltage harmonics generated by grid connected wind turbines, at different voltage levels: 415 V, 33 kV and 220 kV to see the effect of voltage and short circuit level of the grid. The parameters like voltage distortion factor, harmonics and crest factor are monitored. The short circuit level of the grid network is very high than the wind power penetration into the network, the impact of wind turbines on power quality is not significant. A trend in wind power quality parameters is seen even though the measurements could not be taken simultaneously on all voltage levels.
Study on Self-Learning for Vibration Fault Diagnosis System of Rotating Machinery
Authors: Ge Zhihua , Niu Yuguang , Song Zhiping , Fu Zhongguang
Published: October 2008

For an established fault diagnosis system which is based on it own expert system, it is usually incapable to diagnosis the new operating conditions, of which the knowledge has not been explored by the system. It is the purpose of the paper to develop the approach of identifying new fault and self-learning for diagnosis based on non-linear fractal theorem. It has been generally accepted that the vibration series has obvious fractal feature, which can reflect the essential characteristics of new fault. When the novel fault is taken place in the system, a related sub-net is increased to the system and trained with this sample. We have verified experimentally that the fractal dimensions of the same class faults are distributed approximately around a definite value that can represents the dimension of the standard sample for the novel fault. Based on non-linear theorem, the approach of identifying new fault and self-learning for diagnosing is put forward.
A Sequential Approach for Gas Turbine Power Plant Preventive Maintenance Scheduling
Authors: Zhao Yongjun , Volovoi Vitali , Waters Mark , Mavris Dimitri
Published: October 2008

Traditionally the gas turbine power plant preventive maintenances are scheduled with constant maintenance intervals based on recommendations from the equipment suppliers. The preventive maintenances are based on fleet wide experiences, and they are scheduled in a one-size-fit-all fashion. However, in reality, the operating conditions for each gas turbine may vary from site to site, and from unit to unit. Furthermore, the gas turbine is a repairable deteriorating system, and preventive maintenance usually restores only part of its performance. This suggests the gas turbines need more frequent inspection and maintenance as it ages. A unit specific sequential preventive maintenance approach is therefore needed for gas turbine power plants preventive maintenance scheduling. Traditionally the optimization criteria for preventive maintenance scheduling is usually cost based. In the deregulated electric power market, a profit based optimization approach is expected to be more effective than the cost based approach. In such an approach, power plant performance, reliability, and the market dynamics are considered in a joint fashion. In this paper, a novel idea that economics drive maintenance expense and frequency to more frequent repairs and greater expense as the equipment and components age is introduced, and a profit based unit specific sequential preventive maintenance scheduling methodology is developed. To demonstrate the feasibility of the proposed approach, this methodology is implemented using a base load combined cycle power plant with single gas turbine unit.
Gas Turbine Nozzle and HRSG Damage Due to Liquids in Natural Gas Fuel
Authors: Norek R. S. , Newbound T. D.
Published: October 2008

Unusual damage was experienced by the first stage nozzles in a gas turbine and a heat recovery steam generator. (Nozzles are stationary vanes that channel hot gases to the rotating blades in the turbine). All pressure (concave) walls of the vanes experienced some degree of damage, least of which were cracking of the coating, erosion and wall thinning. About 30% of the vanes were damaged more severely. They experienced pitting, erosion, cracking and total disintegration of up to half of the pressure walls. The suction walls (convex) of the vanes showed very little damage and all leading edges were surprisingly fine. The only trailing edges that were severely damaged or partially missing were downstream of the severely damaged pressure walls. Metallurgical analysis revealed that the overheating caused oxidation and depletion of the coating and dense spiking of oxides into the coating. The oxide spikes facilitated dense cracking of the base metal that led to disintegration of the affected wall sections into tiny fragments. Even more unusual was the lack of evidence of melting at the rugged perimeters of remaining parts of the pressure walls. Also unusual was the relatively good condition of the first stage turbine blades despite the missing sizeable sections of the first stage nozzle pressure walls and trailing edges. The damage was attributed to localized overheating by liquid contaminants (most probably emulsions) in the natural gas fuel (97.8% methane).
A Model of a Hybrid Power Plant With Wind Turbines and Compressed Air Energy Storage
Authors: Arsie I. , Marano V. , Nappi G. , Rizzo G.
Published: October 2008

After a general overview of Hybrid Power Plants (HPP) and Compressed Air Energy Storage (CAES), the authors present a thermo-economic model for the simulation and optimization of a HPP consisting of a wind turbine coupled with CAES. In the proposed scheme, during periods of excess power production, atmospheric air is compressed in a multistage compressor and cooled; when there is power demand, the compressed air is heated in multiple expansion stages using the stored heat and conventional thermal sources. Such plants can offer significant benefits in terms of flexibility in matching a fluctuating power demand, particularly when renewable sources, characterized by high and often unpredictable variability, are utilized. The possible advantages in terms of energy and cost savings with respect to other solutions must be carefully assessed, critically depending on performance and efficiencies of each sub-system, most of them operating in transient and off-design conditions. To this purpose, a thermodynamic model composed of several sub-systems describing wind turbine, multi-stage compressor, intercooler, aftercooler, heat recovery system, compressed air storage and turbine has been developed in Matlab/Simulink® environment. In the paper, several scenarios are compared by simulation and optimization analysis and a parametric study of the plant performance with respect to the main design variables is presented.
An Investigation on Real and Imaginary Energy Transfer Mechanism Caused in Rotating Flow Passage of Centrifugal Pump
Authors: Tanaka Takaharu , Liu Chao
Published: October 2008

Hydraulic energy is constructed from real and imaginary energies. Their acting directions are normal to each other. Their physical properties are quite different. All the physical parameters, such as force, velocity, and acceleration therefore consist of two different type real and imaginary functions. Physically, there are three different types of fluid particles rotational motion: straightly forward non-rotational motion, which is based upon kinetic real physical parameters, circularly forward rotational motion, which is based upon un-kinetic imaginary physical parameters, and their combined rotational motion. Their interrelation is shown in diagram.
Experience With Emergency Response Planning and Rotor Flux Monitoring to Improve Generator Reliability
Authors: Williams Richard , Michael Paul
Published: October 2008

In today’s commercial environment, unplanned outages have a significant affect on revenues, and hence reliability, availability and maintainability of plant are key factors. Emergency Response Planning, combined with real time monitoring can have significant beneficial impacts on unplanned and planned outage duration’s. This paper details our company’s experience of Emergency Response Planning (ERP), giving detailed overview of how this is achieved and the benefits that can be obtained. The paper focuses on unit disaster recovery of large turbo-alternators and how the concept of Emergency Response planning can reduce unplanned outage duration’s, including the steps required to implement best practice. The paper uses a detailed a case study of a 1200MW, 4-pole generator with severe rotor winding inter-turn faults and associated vibration problems to demonstrate how a combination of condition monitoring, Emergency Response Planning, and a skilled repair team have been used to implement an effective maintenance strategy. The benefits to the customer have been detailed. The successful repair of all faults and the significant reduction in generator vibration levels without the requirement for any site balancing is illustrated on return of the unit to service. The paper details how Rotor Flux Monitoring (RFM) has been identified a series of winding faults and with ERP has mitigated areas of high risk within this turbo-generator.
A Design Model of a New Positive Displacement Rotary Compressor Based on Trochoidal Geometry for High Pressure Applications
Authors: Abdelwahab Ahmed
Published: October 2008

The desire to achieve high discharge pressures at low manufacturing and maintenance costs has resulted in the development of a number of new positive displacement rotary compressor designs. The proposed design involves a compressor with a trochoidal casing geometry and a rotor orbiting the casing interior. This arrangement generates a varying trapped volume between the rotor and the casing thus providing the necessary compression for the compressor. The major advantage of this design is its inherent simple two-dimensional configuration which makes it a very cheap device to manufacture. Furthermore, the oil-flooded lubrication system used with this design not only acts as a lubricant but also as a coolant to the main gas flow and consequently improves the mechanical reliability of the compressor. This paper presents a complete design model developed to investigate the performance of the compressor. The geometrical, kinematic, and dynamic equations of the casing and rotor are derived. A model of the compressor thermodynamic cycle and gasdynamic performance is presented. A comparison between the developed model and the experimental results of a prototype compressor testing is presented. The comparison shows that the developed model indeed captures the compressor performance trends with considerable accuracy at the design conditions. Deviation between the model and experimental results at the off design conditions is due to inaccuracies in the inlet and exit port loss models at the off design conditions.
Repair of Advanced Gas Turbine Blades
Authors: McGraw Julie , Anton Reiner , Ba¨hr Christian , Chiozza Mary
Published: October 2008

In order to promote high efficiency combined with high power output, reliability, and availability, Siemens advanced gas turbines are equipped with state-of-the-art turbine blades and hot gas path parts. These parts embody the latest developments in base materials (single crystal and directionally solidified), as well as complex cooling arrangements (round and shaped holes) and coating systems. A modern gas turbine blade (or other hot gas path part) is a duplex component consisting of base material and coating system. Planned recoating and repair intervals are established as part of the blade design. Advanced repair technologies are essential to allow cost-effective refurbishing while maintaining high reliability. This paper gives an overview of the operating experience and key technologies used to repair these parts.
Experimental Study for NOx Reduction Using Four Chinese Pulverized Coals
Authors: Wang Zhihua , Zhou Junhu , Cheng Jun , Zhou Hao , Cen Kefa
Published: October 2008

Four typical coals with different ranks around China were used as reburning fuels to evaluate its ability for NOx reduction in a pilot scale entrainment reactor. The selected four coals have similar fuel-N containing from 1.09% to 1.30% at different coal rank from bituminous to anthracite. Results show that Bituminous coal (Yanzhou, Huainan) are advantages than anthracite (Jincheng) and lean coal (Zhengzhou). Due to Yanzhou coal’s more moisture and less ash contents, it’s the best coal for reburning in this test. When using Huainan coal as reburning fuel, carbon in ash increased form 3.64% to 4.52% along with the increase of heat input from 15 to 25%. The optimal temperature for Huainan coal reburning is around 1300°C no larger than 1400°C. With the increasing of reburn zone stoichiometric ratio from 0.6 into 1.2 the NO reduction efficiency decreased from 52.1% into 17.6%. The impact of particle fineness on the NO reduction is not so evident.
Biohydrogen Production From Food Waste by Anaerobic Fermentation
Authors: Cheng Jun , Zhou Junhu , Xie Binfei , Xie Lin , Liu Jianzhong , Cen Kefa
Published: October 2008

The biohydrogen production from food wastes by anaerobic fermentation of digested sludge is studied. It is found by gas chromatography analysis that the volumetric ratios of H2 to CO2 in the biogases derived from rice, potato, lean meat and fat are respectively 0.77, 0.82, 0.93 and 0.82. The yield of methane is quite little, because the methane-producing activity is restrained and the hydrogen-producing activity is simultaneously kept when the digested sludge is preheated in the boiling water. Ethanol (0.43%) is the highest volatile fatty acid in the fermentation solution derived from lean meat, implying that it belongs to ethanol-type fermentation. The butyric acid concentrations are the highest (respectively 0.96%, 0.44% and 0.34%) in the fermentation solutions derived from rice, potato and fat, which implies that they all belong to butyric acid-type fermentation.
Experimental Research on Harmless Technology of Municipal Solid Waste Incineration With Direct Gasification and Ash Melting
Authors: Wang Hua , He Fang , Hu Jianhang , Bao Guirong
Published: October 2008

A novel harmless MSW disposal, incineration technology with direct gasification and ash melting was developed, with experimental investigation. The technological process can be represented as: the pretreated MSW was put into an incinerator and incinerated in a molten bath under reduction atmosphere at a temperature range from 1300°C to 1500°C. In order to maintain the stability of the combustion process, it is needed to blast combustion-supporting coal powder from the bottom of the incinerator. Combustible gases were leaded and burned completely in a secondary swirled combustion chamber, and the heat was recycled and come into utilization. In some cases, molten slag and alloy were discharged from a same slag notch, and then they were quenched and separated each other. In other cases, melted slag and alloy were discharged from two different notches, and quenched in their own quenching pool. In both the former and the later case, the alloy was recycled and the melted slag can be used as construction materials in the same way. Experimental results form an industrial-scale pilot plant show that the investments of capital construction and running cost of this incineration system are only 65–85 percent of those of the similar types incinerator developed by western countries. It is necessary to point that 99.8 percent of dioxins involved in primary MSW were decomposed, and the dioxins content in exhausted gases and melted slag were lower than 0.01ng-TEQ/Nm3 and 0.0012ng-TEQ/g respectively.
Development and Operating Experience of a Two-Casing 600MW Ultra-Super-Critical Steam Turbine
Authors: Tanaka Yoshinori , Ohyama Hiroharu , Tochitani Naoto , Nakazawa Tamiaki
Published: October 2008

600MW class steam turbines are typically manufactured in three casing configurations with two low-pressure casings. Mitsubishi Heavy Industries (MHI) has developed and manufactured a 600MW two-casing Ultra Super Critical turbine for the Hirono No.5, Tokyo Electric Power Co. in Japan, which comprises one combined high- and intermediate-pressure casing and one double-flow low-pressure casing. This unit started the commercial operation in July 2004. Two-casing design simplifies construction and maintenance requirements and saves capital cost of the plant. This compact design was realized mainly due to the development of 3000 rpm 48 inch steel low-pressure end blades, the longest steel blade in the industries for 3000 rpm machines. In addition, a highly efficient and compact design in achieving 600°C steam condition was realized by employing a combined high- and intermediate-pressure frame. This paper addresses the design features of the 600MW two-casing USC turbine, operating condition of the Hirono No.5 and the results of the verification tests performed.
Vibration Analysis on the Rotating Machinery
Authors: Morita Masao
Published: October 2008

The paper presents vibration analysis on the boiler feed water pump in thermal power plants. In the Tokyo Electric Power Company (TEPCO), mechanical vibration diagnosis of rotating machinery has been carried out, and got good results. However, in some cases, abnormal condition of machine at an initial stage couldn’t specify, or a machine’s life didn’t predict, because of diagnosing only by tendency of vibration severity. Mechanical vibration diagnoses are typical diagnosing method on the operating condition of the rotating machines, which are well known as one of the Condition Based Maintenance (CBM). It has already been established theoretically, however the actual activities of the vibration diagnosis are required special experiences, especially for the prediction of abnormal condition of rotating machine such as imbalance, and misalignment, and also prediction of bearing failures, etc., These diagnostics have been used for about 30 years in various fields of industries. Therefore, both of the condition survey such as tendency management of vibration severity and condition analysis such as frequency analysis and wave analysis, by using vibrometers, are applied for several power plants of the TEPCO.
Performance Prediction of High-Temperature CO2 Capture System Utilizing Lithium Silicate for Pulverized Coal-Fired Power Plant
Authors: Nakgaki Takao , Yamashita Katsuya , Kato Masahiro , Essaki Kenji , Iwahashi Takayuki , Fukuda Masafumi
Published: October 2008

Lithium silicate is a solid CO2-sorbent that can be used repeatedly, and uniquely features absorption of CO2 at temperatures between 500°C and 600°C with an exothermic reaction and regeneration at temperatures above 700°C with an endothermic reaction. This paper introduces the conceptual model and feasibility study of the CO2 capture system utilizing the lithium silicate applicable to a pulverized coal-fired power plant. In this system, assuming a moving bed, the sorbent reactor is installed in a 500MW boiler and absorbs CO2 in the flue gas, and after the absorption process, recirculation of CO2 transports the heat for regeneration. To design the system, unsteady state numerical analysis was used to predict the reactor performance in a 60-minute cycle for absorption and regeneration, which includes the reaction rate based on experimental data. The analysis result indicates that about 20% of CO2 can be captured from flue gas without significant loss in the power generation efficiency.
Structure-Activity Relationships of Antimicrobial and Lipoteichoic Acid-Sequestering Properties in Polyamine Sulfonamides
Authors: Warshakoon Hemamali J. , Burns Mark R. , David Sunil A.
Published: October 2008

We have recently confirmed that lipoteichoic acid (LTA), a major constituent of the gram-positive bacterial surface, is the endotoxin of gram-positive bacteria that induces proinflammatory molecules in a Toll-like receptor 2 (TLR2)-dependent manner. LTA is an anionic amphipath whose physicochemical properties are similar to those of lipopolysaccharide (LPS), which is found on the outer leaflet of the outer membranes of gram-negative organisms. Hypothesizing that compounds that sequester LPS could also bind to and inhibit LTA-induced cellular activation, we screened congeneric series of polyamine sulfonamides which we had previously shown effectively neutralized LPS both in vitro and in animal models of endotoxemia. We observed that these compounds do bind to and neutralize LTA, as reflected by the inhibition of TLR2-mediated NF-κB induction in reporter gene assays. Structure-activity studies showed a clear dependence of the acyl chain length on activity against LTA in compounds with spermine and homospermine scaffolds. We then sought to examine possible correlations between the neutralizing potency toward LTA and antimicrobial activity in
Staphylococcus aureus
. A linear relationship between LTA sequestration activity and antimicrobial activity for compounds with a spermine backbone was observed, while all compounds with a homospermine backbone were equally active against
S. aureus
, regardless of their neutralizing potency toward LTA. These results suggest that the number of protonatable charges is a key determinant of the activity toward the membranes of gram-positive bacteria. The development of resistance to membrane-active antibiotics has been relatively slower than that to conventional antibiotics, and it is possible that compounds such as the acylpolyamines may be useful clinically, provided that they have an acceptable safety profile and margin of safety. A more detailed understanding of the mechanisms of interactions of these compounds with LPS and LTA, as well as the gram-negative and -positive bacterial cell surfaces, will be instructive and should allow the rational design of analogues which combine antisepsis and antibacterial properties.
Role of Anthrax Toxins in Dissemination, Disease Progression, and Induction of Protective Adaptive Immunity in the Mouse Aerosol Challenge Model
Authors: Loving Crystal L. , Khurana Taruna , Osorio Manuel , Lee Gloria M. , Kelly Vanessa K. , Stibitz Scott , Merkel Tod J.
Published: October 2008

Anthrax toxins significantly contribute to anthrax disease pathogenesis, and mechanisms by which the toxins affect host cellular responses have been identified with purified toxins. However, the contribution of anthrax toxin proteins to dissemination, disease progression, and subsequent immunity after aerosol infection with spores has not been clearly elucidated. To better understand the role of anthrax toxins in pathogenesis in vivo and to investigate the contribution of antibody to toxin proteins in protection, we completed a series of in vivo experiments using a murine aerosol challenge model and a collection of in-frame deletion mutants lacking toxin components. Our data show that after aerosol exposure toBacillus anthracisspores, anthrax lethal toxin was required for outgrowth of bacilli in the draining lymph nodes and subsequent progression of infection beyond the lymph nodes to establish disseminated disease. After pulmonary exposure to anthrax spores, toxin expression was required for the development of protective immunity to a subsequent lethal challenge. However, immunoglobulin (immunoglobulin G) titers to toxin proteins, prior to secondary challenge, did not correlate with the protection observed upon secondary challenge with wild-type spores. A correlation was observed between survival after secondary challenge and rapid anamnestic responses directed against toxin proteins. Taken together, these studies indicate that anthrax toxins are required for dissemination of bacteria beyond the draining lymphoid tissue, leading to full virulence in the mouse aerosol challenge model, and that primary and anamnestic immune responses to toxin proteins provide protection against subsequent lethal challenge. These results provide support for the utility of the mouse aerosol challenge model for the study of inhalational anthrax.
Substrains of 129 Mice Are Resistant to
Yersinia pestis
KIM5: Implications for Interleukin-10-Deficient Mice
Authors: Turner Joshua K. , Xu John L. , Tapping Richard I.
Published: October 2008

Interleukin-10 (IL-10)-deficient mice are resistant to several pathogens, including
Yersinia pestis
. Surprisingly, we observed that heterozygous IL-10
+/−
mice also survive high-dose intravenous infection with
Y. pestis
KIM5 (Pgm
−
). Analysis of commercial IL-10
−/−
mice revealed that at least 30 cM of genomic DNA from the original 129 strain remains, including a functional Slc11a1 (Nramp1) gene. Interestingly, two substrains of 129 mice were resistant to high-dose
Y. pestis
KIM5. Resistance does not appear to be recessive, as F
1
mice (C57BL/6J × 129) also survived a high-dose challenge. A QTL-based genetic scan of chromosome 1 with 35 infected F
1
backcrossed mice revealed that resistance to KIM5 maps to a region near IL-10. Two novel IL-10
+/+
mouse strains which each possess most of the original 30-cM stretch of 129 DNA maintained resistance to high-dose infection with
Y. pestis
KIM5 even in a heterozygous state. Conversely, a novel IL-10
−/−
mouse strain in which most of the 129 DNA has been crossed out exhibited intermediate resistance to KIM5, while the corresponding IL-10
+/−
strain was completely susceptible. Taken together, these results demonstrate that 129-derived genomic DNA near IL-10 confers resistance to
Yersinia pestis
KIM5 and contributes to the observed resistance of IL-10
−/−
mice.
Effet d’un assèchement édaphique sur la croissance, l’allocation de biomasse et les relations hydriques chez Casuarina glauca
Authors: Béjaoui Zoubeir , Albouchi Ali , Lamhamedi Mohammed S. , El Aouni Mohamed Hédi
Published: October 2008

Tunisia has vast land tracts that are marginal, arid, semiarid, or desert (about three quarters of the surface of the country). Reforestation of these regions is one of the methods being used to rehabilitate degraded areas. Casuarina glauca Sieber, a fast-growing tree species that is widely used outside of its native range, was tested in the present study with respect to its degree of acclimatization and hardening in response to drought. Three water regimes, simulating the conditions of the reforestation sites, were applied to C. glauca seedlings. These regimes included a control treatment (T : predawn water potential Ψb = –0.2 MPa), a moderate stress treatment (M : Ψb = –0.5 MPa), and a severe stress treatment (S : Ψb = –1.0 MPa). Water relations parameters, estimated by pressure–volume curves through a repeat pressurization method, as well as accumulated dry mass were measured at the beginning of the experiment and 2, 4, and 6 months following treatment imposition. The total dry mass of M and S plants was significantly affected by the treatments. However, water stress favoured dry mass allocation to roots and decreased the shoot turgid mass / dry mass ratio (TM/DM). The evolution of water relations parameters under M or S regimes revealed an adaptive capacity of C. glauca seedlings, as expressed by a significant decrease of the osmotic potentials at full turgor (Ψπ100) and at the turgor loss point (Ψπ0), an osmotic adjustment in water-stressed plants reaching 0.31 and 0.56 MPa, and a significant increase in εmax reaching 26 % and 68 % of that of the control plants, respectively, at the end of the drought period. A reduction in shoot TM/DM combined with increases in εmax during water stress suggests the presence of a cell wall adjustment. These effects were more pronounced under the severe stress. Our results suggest that preconditioning seedlings to drought under nursery conditions by applying a moderate or severe stress, depending on the conditions of the planting site, for 4 months prior to outplanting, possibly will allow the seedlings to adapt morphologically and physiologically and improve their chance of survival in arid and semiarid zones.
Effects of nutrient distribution pattern and aboveground competition on size of individuals inIpomoea tricolorpopulations
Authors: Nakamura Ryoji , Kachi Naoki , Suzuki Jun-Ichirou
Published: October 2008

We investigated whether the distribution pattern of soil nutrients interacted with aboveground competition to affect plant size in Ipomoea tricolor Cav. populations. Six plants per pot were grown in a factorial experiment with combinations of heterogeneous or homogeneous nutrient distribution pattern and presence or absence of aboveground competition. Plants were harvested and ranked by their aboveground biomasses. In analyses of plant sizes in all ranks simultaneously, mean plant size was significantly affected by nutrient distribution pattern, aboveground competition, and their interaction. In analyses of plant sizes of each rank, aboveground competition affected plant size, which was found in all ranks. Nutrient distribution pattern affected plant size in the higher ranks, but not in the lowest rank. Selective root placement into nutrient-rich patches under heterogeneous conditions was observed. Our results suggest that the magnitude of the effect of nutrient distribution pattern on plant size changed among ranks owing to changes in aboveground competition and size-dependent growth rate. Size-dependent growth rate could explain the significant effect of nutrient distribution pattern independent of the effect of aboveground competition. Nutrient distribution pattern would then interact with aboveground competition and consequently affect size structure in a population.
Relationships between leaf life span, leaf mass per area, and leaf nitrogen cause different altitudinal changes in leaf δ13C between deciduous and evergreen species
Authors: Takahashi K. , Miyajima Y.
Published: October 2008

We examined the variability in stable carbon isotope ratio (δ13C) in leaves of two deciduous broad-leaved species and two evergreen conifer species along an altitudinal gradient in central Japan. The δ13C of the two deciduous species decreased with altitude, except near the upper distribution limit. The two evergreen species, however, showed no clear altitudinal trends for δ13C. The δ13C of the two deciduous species was positively correlated with leaf mass per area (LMA), indicating that the altitudinal variation in δ13C was controlled by LMA. Leaf nitrogen per mass (as a proxy of assimilation capacity, Nmass) was negatively correlated with LMA for the two deciduous species, while it was not correlated with LMA for the two evergreen species. Leaf life span of the two deciduous species decreased with altitude, whereas that of the two evergreen species increased. Thus, the two deciduous species had shorter-lived thinner leaves with higher Nmass at higher altitudes, and the two evergreen species had longer-lived leaves. These changes contribute to the positive carbon balance at higher altitudes. Therefore, the different changes in δ13C with altitude between the deciduous and evergreen species are ascribed to the different altitudinal changes in the leaf traits for carbon balance.
Whole-Lake Radiocarbon Experiment in an Oligotrophic Lake at the Experimental Lakes Area, Northwestern Ontario
Authors: Hesslein R. H. , Broecker W. S. , Quay P. D. , Schindler D. W.
Published: October 2008

To gain more insight into the nature of carbon cycling in lakes and to provide a check on estimates of carbon fluxes obtained by more conventional means, 1 Ci (= 37 GBq) of C14 as NaHCO3 was added to the epilimnion of Lake 224, a dimictic, oligotrophic lake of the Canadian Shield near Kenora, Ontario. The dominant loss from the dissolved inorganic carbon (DIC) pool was via C14O2 evasion to the overlying atmosphere. The next most important loss from the DIC pool was by photosynthetic fixation of inorganic carbon by epilimnetic phytoplankton. About half of the C14 thus incorporated into the particulate organic carbon (POC) pool was converted into soluble organic molecules which became part of the epilimnetic dissolved organic carbon-14 (DOC) pool. Since the amount of C14 lost to the sediments of the epilimnion, to the hypolimnion, and to periphyton biomass was not significant to the C14 mass balance over the duration of the experiment, the rate of gas exchange can be calculated by measuring the decrease in epilimnetic C14 inventory (DIC14 + POC14 + DOC14) over a specific time period. Using the stagnant boundary model and pCO2 values calculated from pH, temperature and DIC data a range of stagnant film thicknesses of 212–316 μm was obtained. To provide a check on the film thickness calculated from C14 inventories 10 mCi if Ra226 was also added to the epilimnion of L224. Measurements of Rn222, the gaseous daughter product of Ra226, allowed an independent estimate of the film thickness. The average value of 200 μm obtained in this way is consistent with that obtained for C14O2 evasion. A simplified model was also constructed to describe the behavior of the POC and DOC pools. This model produced results in excellent agreement with the photosynthetic rate averaging 65 mg C∙m−1∙d−1 measured using C14 and the Fee incubator technique. The model also suggests that only about 10% of the POC + DOC pool is active in the photosynthetic process on the time scale of 30 d.Key words: whole-lake radiocarbon experiment, gas exchange, primary production, radium226, radon222, carbon14, carbon in lakes
Density-Dependent Juvenile Mortality in Marine Demersal Fish
Authors: Myers Ransom A. , Cadigan Noel G.
Published: October 2008

We examine the hypothesis that population variability is created and regulated in the juvenile stage for demersal marine fish. Juvenile mortality is examined for 17 populations of Atlantic cod (Gadus morhua), haddock (Melanogrammus aeglefinus), whiting (Merlangius merlangus), plaice (Pleuronectes platessa), yellowtail flounder (Pleuronectes ferrugineus), and sole (Solea vulgaris) in the North Sea, Irish Sea, Barents Sea, Baltic Sea, and Northwest Atlantic. A latent variable covariance analysis of recruitment time series with measurement error is used to test hypotheses. We found strong evidence of density-dependent mortality within cohorts during the juvenile stage for cod, plaice, sole, and whiting; density-dependent mortality appears to be related to the log of juvenile abundance. There is evidence of negative autocorrelation between adjacent cohorts of cod; this pattern is consistent with density-dependent mortality between adjacent cohorts. The autocorrelations are positive for the flatfish examined. It is possible to obtain estimates of estimation error variances for populations if there are multiple research surveys of the same population. We conclude that the juvenile stage is very important for population regulation in most species but that the source of the variability in year class strength is in the larval stage or very early juvenile stage.
Relationship between Juvenile Growth and the Onset of Sexual Maturity of Female North Sea Plaice,Pleuronectes platessa
Authors: Rijnsdorp A. D.
Published: October 2008

The relationship between juvenile growth and the onset of sexual maturation of female North Sea plaice, Pleuronectes platessa, is explored on the individual and population level by analysing individual growth curves back-calculated from otoliths of immature and mature fish and by analysing maturity–length ogives of individual cohorts sampled between 1960 and 1990 from commercial landings from three areas in the North Sea. Back-calculated growth rate of females sampled as mature fish was higher than that of immature females up to 3 yr prior to sampling but lower in the last year. The probability of maturation was significantly related to the length reached as well as to the growth rate in previous years. Maturity–length relationships from market samples showed significant differences in slopes and intercepts between age groups, geographical areas, and year classes. Length at maturation (Lmat) decreased with age and increased with latitude. The differences in Lmatof individual year-classes corresponded to differences in the growth rate and temperature during early life. Both the evidence obtained from the individual and population analysis suggest a 2- to 3-yr maturation time. A model of the juvenile–adult transition process is proposed that provides a consistent interpretation of the observations.
Spatial Model for the Population Dynamics and Exploitation of the Western Australian Rock Lobster, Panulirus cygnus
Authors: Walters Carl J. , Hall Norm , Brown Rhys , Chubb Chris
Published: October 2008

There is concern about whether long-standing regulatory measures (size and effort limits) are adequate to protect spawning stocks of the Western Australian rock lobster, Panulirus cygnus, and assure the highest average yields. Virtual population analysis and tagging studies indicate that exploitation rates are extremely high (possibly exceeding 70%/yr) on younger, mainly immature lobsters. To predict the efficacy of alternative regulatory schemes, it has been necessary to explicitly model the spatial and temporal dynamics of lobster abundance and fishing effort. Puerulus settlement (at age 9–11 mo) is mainly into shallow-water (< 40 m) areas, and at 3–5 yr of age in most areas, there is a migration into deeper water where the animals mature after a further 1–2 yr. The size at migration (70–90 mm carapace length) ensures that at least some animals will have a chance to reach the breeding grounds offshore, where fishing effort has historically been lower than inshore, before they reach the minimum legal size (76 mm carapace length). By explicitly modelling the effort distribution as well as lobster movement and stock distribution, we hope to anticipate some consequences of changes in management policy that could not be predicted from biological assessments alone.
Hormonal Control of Hepatic Glycogen Metabolism in Food-deprived, Continuously Swimming Coho Salmon (Oncorhynchus kisutch)
Authors: Vijayan M. M. , Maule A. G. , Schreck C. B. , Moon T. W.
Published: October 2008

The plasma cortisol concentration and liver cytosolic glucocorticoid receptor activities of continuously swimming, food-deprived coho salmon (Oncorhynchus kisutch) did not differ from those of resting, fed fish. Plasma glucose concentration was significantly higher in the exercising, starved fish, but there were no significant differences in either hepatic glycogen concentration or hepatic activities of glycogen phosphorylase, glycogen synthase, pyruvate kinase, or lactate dehydrogenase between the two groups. Total glucose production by hepatocytes did not differ significantly between the two groups; glycogen breakdown accounted for all the glucose produced in the resting, fed fish whereas it explained only 59% of the glucose production in the exercised animals. Epinephrine and glucagon stimulation of glucose production by hepatocytes was decreased in the exercised fish without significantly affecting hepatocyte glycogen breakdown in either group. Insulin prevented glycogen breakdown and enhanced glycogen deposition in exercised fish. The results indicate that food-deprived, continuously swimming coho salmon conserve glycogen by decreasing the responsiveness of hepatocytes to catabolic hormones and by increasing the responsiveness to insulin (anabolic hormone).
Influence of the Size of Enclosures on the Swimming Characteristics of Juvenile Brook Trout (Salvelinus fontinalis)
Authors: Tang Ming , Boisclair Daniel
Published: October 2008

We tested the hypothesis that swimming characteristics of an active planktivorous fish, brook trout (Salvelinus fontinalis), are significantly influenced by the size of enclosure and the time of day. Swimming characteristics of 0+ brook trout kept in 1,- 8,- and 27-m3enclosures were recorded with an underwater videocamera system between 06:00 and 20:00. Enclosure size had a significant influence on swimming characteristics. Median speed (range = 6.4–11.1 cm/s) and associated variance observed in the 27-m3enclosure were approximately twice those estimated in the 1- and 8-m3enclosures. Variance of acceleration rates varied three- to fourfold among enclosures. Median turning rates (range = 11.8–19.8°/s) and corresponding variances tended to decrease as enclosure size increased. Our analyses suggest that models of spontaneous swimming costs developed using respirometry experiments performed in small aquaria may not appropriately represent the complexity of swimming patterns, and consequently, the costs of spontaneous swimming in large enclosures or in the field.
DAMAGE AS Γ-LIMIT OF MICROFRACTURES IN ANTI-PLANE LINEARIZED ELASTICITY
Authors: SCARDIA LUCIA
Published: October 2008

A homogenization result is given for a material having brittle inclusions arranged in a periodic structure. According to the relation between the softness parameter and the size of the microstructure, three different limit models are deduced via Γ-convergence. In particular, damage is obtained as limit of periodically distributed microfractures.