bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimisation of Turbine Plant as Part of an Integrated Retrofit Project
Authors: Stephen Don , Baldwin Gary , Kienzle Conrad
Published: May 2009

In 2006 Eskom awarded a contract for the retrofitting of the boiler and turbine plant on 6 350MWe units in South Africa. The object of the project is to ensure that the continuous unit rating is increased to 400MWe whilst retaining as much of the existing plant as possible. In addition the plant life will be extended by twenty years. The optimisation process began with the development of various thermodynamic options which would allow a range of power increases. These were then integrated into an economic model which allowed the best option to be identified. In general, a key objective while retrofitting plant is to limit the extent of plant to be changed while still being able to meet the newly defined plant operation conditions, thus allowing for full utilisation of the current assets. This paper details the process followed in the development of the turbine plant retrofit solution. Particular attention is given to the successful Contractor’s Integrated Retrofit Project philosophy, which allows for full optimisation and integration of new components into the plant, while giving assurance of the suitability of the retained equipment.
Generator–Liquid Cooled Stator Skid Instrumentation/Runback Upgrades: Case Study
Authors: Clark James W. , Lake Les C. , Martindale Brian
Published: May 2009

In many cases after 25 plus years of service it may be time to look at the replacement/ upgrade of the instrumentation associated with the stator water cooling skid applicable to armature bars that need to operate in a high or low oxygenated environment. Standards, codes, consolidation, location, redundancy, obsolescence, environmental, safety concerns and runback functionality should be reviewed prior to the next outage or scheduled stator rewind and prudent instrumentation enhancements, if deficient from the list above, should be considered. At the time of instrumentation upgrades, consideration should be given to relocation and improvement of the runback system, e.g. timers, relays, power supplies, and system functionality. Field adjustments quantifying the runback circuit is operating correctly, from both the series of on-off pulses to the turbine reference motor causing a proper load reduction rate and the two trip timers activating at the time the runback begins, need to be verified for proper operation.
Residential Total Energy System Testing at the Canadian Centre for Housing Technology
Authors: Yang L. , Douglas M. A. , Gusdorf J. , Szadkowski F. , Limouse E. , Manning M. , Swinton M.
Published: May 2009

This paper outlines a demonstration project planned and implemented at the Canadian Centre for Housing Technology (CCHT) in 2006. The CCHT, located on the campus of the National Research Council (NRC) in Ottawa, Ontario, Canada maintains two identical, detached, single-family houses that have the capacity to assess energy and building technologies in side by side comparisons with daily simulated occupancy effects. The paper describes the residential integrated total energy system being installed in one of the homes at the CCHT for this demonstration, consisting of two one-ton ground source heat pumps, an air handler with supplemental/back-up hydronic heating capability, a natural gas fired storage type water tank, an indirect domestic hot water storage tank and a multistage thermostat capable of controlling the system. There is also a description of the bore-field, consisting of three vertical wells arranged to suit a typical suburban landscape. Two of the wells serve the heat pumps; the third well is arranged between the other two to sink the waste heat from a cogeneration unit. The 6 kWe cogeneration unit to be installed in May 2007 is also described. The heat pump system was deliberately sized to satisfy the cooling load in Canada’s heat dominated climate, leaving room in the operation of the system to accept waste heat from the cogeneration unit, either directly or indirectly through recycling the heat through the ground to the heat pumps. This paper presents and discusses preliminary testing results during the fall of 2006 and modeling work of the ground heat exchanger component of the system and therefore sets the stage for performance modeling work that is currently underway at Natural Resources Canada (NRCan).
Experimental Study to Test an Axial Flow Pump as a Turbine and Development of Performance Characteristics for Micro-Hydro Power Plant
Authors: Chattha Javed A. , Khan Mohammad S.
Published: May 2009

Standard centrifugal pumps are manufactured in a large number of sizes in order to cover a wide range of heads and flow rates. Conventional turbines, however, are not mass produced since they are custom designed and manufactured. Therefore, pumps are available in the market at comparatively lower cost and shorter delivery periods. In this paper an experimental study is presented in which the use of pumps as turbine (PAT) is explored for micro-hydro power generation. The objective of the study is to explore cheap alternate sources of energy production in remote locations of Pakistan. Extensive research has been carried out by Williams [1] in the field of using pumps as turbines. Only centrifugal pumps were studied to explore their use as turbines in that work. Since then quite a bit of advancement in this sector of technology has taken place. However, to the best of our knowledge, axial flow pumps have never been tested as turbines. The site conditions for micro-hydro power station usually find axial flow pumps to be more appropriate compared cross flow and pelton turbines. A commercially available axial flow pump was selected and test rig was designed and constructed in order to determine the performance characteristics of using the pump as a turbine. The test bed has a provision of simulating various head and flow rate conditions and dynamometer to measure the power output in order to determine the performance of the turbine. The simulated head and flow rates were varied for various typical conditions. Some minor modifications in the basic pump unit were made to accomplish these tests. The experimental study resulted in generating data for which head was varied from 4 to 12 m and flow rate from 700 to 900 m3/hr. For these conditions power developed ranged from 5–20 kW with a maximum efficiency of 70% corresponding to a head of 6.8 m and a flow rate of 800 m3/hr. Pump affinity laws and the data collected in this experimental study were then used to select a Kaplan turbine. This information was then used to choose a commercially available pump for typical low head and high flow rate conditions in Pakistan to generate about 100 kW of electric power, when running in turbine mode. This paper discusses the design and construction of the test rig to carry out experiments for testing pumps as turbines. Details of experimental procedure and results to determine performance characteristics are also presented. Finally selection procedure of a pump for a specific head and flow condition are also discussed in this paper.
On the Combustion Turbine Modeling: A Dynamic Approach
Authors: Brusca Sebastian , Lanzafame Rosario , Lo Trovato Maria Luisa
Published: May 2009

The present paper deals with the dynamic analysis of a heavy duty combustion turbine running on natural gas. Hence, a mathematical model of the power plant has been implemented. The model is able to simulate the engine behavior during steady state, as well as transient conditions. In order to test the model efficacy and accuracy, a dynamic analysis of a Siemens V94.3 A running as topper in a Combined Cycle (CC) complex has been carried out. Therefore, numerical results have been compared with experimental data extracted from the monitoring system of the plant for different running conditions. Comparison results analysis highlighted that the developed mathematical model is able to simulate correctly engine behavior in different combustion turbine conditions.
Numerical Study of Coal Gasification Using Eulerian-Eulerian Multiphase Model
Authors: Shi Shaoping , Guenther Christopher , Orsino Stefano
Published: May 2009

Gasification converts the carbon-containing material into a synthesis gas (syngas) which can be used as a fuel to generate electricity or used as a basic chemical building block for a large number of uses in the petrochemical and refining industries. Based on the mode of conveyance of the fuel and the gasifying medium, gasification can be classified into fixed or moving bed, fluidized bed, and entrained flow reactors. Entrained flow gasifiers normally feature dilute flow with small particle size and can be successfully modeled with the Discrete Phase Method (DPM). For the other types, the Eulerian-Eulerian (E-E) or the so called two-fluid multiphase model is a more appropriate approach. The E-E model treats the solid phase as a distinct interpenetrating granular “fluid” and it is the most general-purposed multi-fluid model. This approach provides transient, three-dimensional, detailed information inside the reactor which would otherwise be unobtainable through experiments due to the large scale, high pressure and/or temperature. In this paper, a transient, three-dimensional model of the Power Systems Development Facility (PSDF) transport gasifier will be presented to illustrate how Computational Fluid Dynamics (CFD) can be used for large-scale complicated geometry with detailed physics and chemistry. In the model, eleven species are included in the gas phase while four pseudo-species are assumed in the solid phase. A total of sixteen reactions, both homogeneous (involving only gas phase species) and heterogeneous (involving species in both gas and solid phases), are used to model the coal gasification chemistry. Computational results have been validated against PSDF experimental data from lignite to bituminous coals under both air and oxygen blown conditions. The PSDF gasifier geometry was meshed with about 70,000, hexahedra-dominated cells. A total of six cases with different coal, feed gas, and/or operation conditions have been performed. The predicted and measured temperature profiles along the gasifier and gas compositions at the outlet agreed fairly well.
How Vibratory Machines Can Improve Coal Handling and Processing
Authors: Dumbaugh George D.
Published: May 2009

All the different kinds of coal which are often non-flowable are successfully being “induced” to vertically flow and discharge from storage. This includes Bins, Silos, and Rail Cars which can completely empty. The Storage Piles are being made safe for added reclaim.
TUNNELING PERCOLATION MODEL OF THE ELECTRICAL CONDUCTIVITY OF PARTICULATE NANOCOMPOSITES
Authors: ZHU LIU-JUAN , CAI WEN-ZHONG , GU BO-QIN , TU SHAN-TUNG
Published: May 2009

The nanocomposites consisting of conducting nanoparticles and insulating matrix are studied. A tunneling percolation model is developed for their peculiar conduction behavior based on the equivalent-particle concept. It provides a clear microstructure-property correlation by combining many-particle statistics, effective-medium theory, and classical percolation theory. Its availability is assessed by available experimental data.
DESIGNING SUPERHARD MATERIALS BY INCORPORATING BORON INTO HEAVY TRANSITION METALS
Authors: LIANG YONGCHENG , LI ANHU , ZHAO JIANZHI , ZHANG WENQING
Published: May 2009

First-principles calculations on the incompressibility, elasticity and hardness of the Os , OsB2, Re , and ReB2materials have systematically been performed by the plane-wave basis pseudopotential method. Transition metals Os and Re , which have high bulk modulus but low hardness, can be converted into hard materials by combining them with small B atoms. Moreover, electronic and structural mechanisms of ReB2and OsB2are analyzed in detail and compared. It is shown that incorporating small B atoms into heavy transition metals should be a valid pathway to obtain new superhard materials.
HOJMAN CONSERVED QUANTITIES AND LIE SYMMETRIES OF DISCRETE NON-CONSERVATIVE SYSTEMS
Authors: FU JING-LI , CHEN BEN-YONG
Published: May 2009

This letter focuses on studying the theory of Hojman conserved quantity of the discrete non-conservative dynamical systems. The operators of discrete translation and discrete differentiation to the right and left are introduced in discrete non-conservative dynamical systems. The Hojman theorems, the determining equations and Hojman conserved quantities of the Lie symmetry are obtained for discrete non-conservative dynamical systems. Finally, an example is discussed to illustrate the application of the results.
A LOCAL INFORMATION-BASED ROUTING STRATEGY ON THE SCALE-FREE NETWORK
Authors: WANG XIANPENG , YU GANG , LU HONGTAO
Published: May 2009

The efficiency of a routing strategy on complex networks can be reflected by two measurements, i.e. the system capacity and the average data packets travel time. In this paper, we propose a new routing strategy which is only based on local information of network topology. This strategy integrated the delivering capability and packets queue length of nodes for enhancing the efficiency of traffic on scale-free networks. The probability that a given node i with delivering capability Ci receives packets from its neighbors is proportional to (Ni+1)/Ci and Ni is the packets queue length of the node i. Simulation results show that there exists an optimal value by maximizing the networks delivering capability and minimizing the packet travel time. We simulated the strategy on BA network with different m (connectivity density) values and the results show that our strategy is more efficient than other local information-based routing strategies.
THE TEMPERATURE-DEPENDENT VAPORIZATION ENTHALPY IN EQUILIBRIUM VAPOR–LIQUID PHASE TRANSITIONS: ITS UNIVERSAL BEHAVIOR FOR SIMPLE FLUIDS
Authors: TIAN JIANXIANG
Published: May 2009

In this paper, we study the universal behavior of the temperature-dependent vaporization enthalpy in equilibrium vapor–liquid phase transitions of simple fluids. We find that, under some reduction using critical data, the experimental curves of vaporization enthalpy versus the saturated temperature will overlap with each other, i.e. the universal behavior experimentally holds for the temperature-dependent vaporization enthalpy, in the temperature range from the triple point to the critical point, for simple fluids. An empirical correlation describing this universal behavior is proposed and compared with reference data and other correlations. Different from others, our correlation only needs the critical temperature as input parameters.
PREPARATION OF ODA-CLAY HYBRID FILMS BY LANGMUIR–BLODGETT TECHNIQUE
Authors: PAUL P. K. , HUSSAIN S. A. , BHATTACHARJEE D.
Published: May 2009

Hybrid monolayers of clay minerals (hectorite) and Octadecyamine (ODA) were prepared using the Langmuir–Blodgett (LB) technique. Surface pressure–area per molecule isotherm, FTIR and atomic force microscopy were used to confirm and analyze the ODA-hectorite hybrid films. The monolayer thickness is 2 nm and average height, length and width of individual clay platelets ranges between 1.5 to 2 nm, 500 to 1250 nm and 100 to 115 nm respectively. The surface coverage was more than 80%.
SENSITIVITY OF HYDROGENATED SILICON NANODOT ON SMALL POLAR MOLECULES
Authors: HE M. X. , ZHANG R. Q. , NIEHAUS T. A. , FRAUENHEIM TH. , LEE S. T.
Published: May 2009

The interactions of a hydrogenated silicon nanodot, Si 35 H 36, containing surface SiH and SiH 2 surface hydrides, with three representative small polar molecules, ethanol, NH 3, and H 2 O were comparatively studied using a self-consistent charge density-functional tight-binding method, complemented by an empirical van der Waals force correction. The binding energy of ethanol with the hydrogenated silicon dot was determined to be 0.39–0.78 eV with a positive sign, indicating that this adsorption process is endothermic and thermodynamically unfavorable. In contrast, the binding energies of H 2 O and NH3 were found to be about 0.15–0.53 eV with a negative sign, revealing exothermic and thermodynamically favorable reactions. Interestingly, these adsorptions are facilitated by H … H attraction, rather than by H … O or H … N H -bonding. The binding is mostly electrostatic and physical, with very little charge transfer occurring. All these adsorptions result in relatively small redshifts in optical absorption and emission spectra, according to additional time-dependent calculations, with little change in the IR peak position of their adsorbents and an almost perfect silicon surface.
MOLECULAR DYNAMIC SIMULATIONS ON THE FOLDING AND CONFORMATIONAL INSIGHTS OF THE TRUNCATED PEPTIDES
Authors: YANG GANG , WU XIAOMIN , ZU YUANGANG , YANG ZHIWEI , FU YUJIE , ZHOU LIJUN
Published: May 2009

A total of 120 ns molecular dynamics simulations was used to study the folding and conformational aspects of six peptides with different lengths (Pep19–25, Pep15–25, Pep1–25, Pep15–39, Pep1–40, and Pep1–50) truncated from the αβ-tubulin dimer. These truncated peptides were found to undergo distinct structural transitions, with Pep1–25 and Pep1–50 folding into their respective stable conformations whereas on the contrary for the others. All the six truncated peptides are more or less compact than the corresponding segments in the αβ-tubulin dimer. The most striking contraction was observed in Pep1–25, which folds in a similar manner of β-hairpin. Pep1–50 has the least contraction and its folded conformation is the closest to that in the αβ-tubulin dimer. Moreover, the same conversions of β12–β23 from helices to hydrogen-bonded turns were witnessed in both Pep1–50 and the αβ-tubulin dimer. The structural instabilities of Pep19–25, Pep15–25, Pep15–39, and Pep1–40 were caused by the lack of long-distance interactions or/and the absence of key residues, with the details given in the discussions. The folding and conformational divergences of six truncated peptides were also observed in their active peptide segments ( Ap 15–25). Ap 15–25 in Pep1–50 achieves the best agreements with the αβ-tubulin dimer, implying that the local structure of Ap 15–25 in the αβ-tubulin dimer can be well reserved in Pep1–50 rather than in the other truncated peptides. The long-distance interactions, especially the key residues (e.g. β48-Arg), play a crucial role in the correct folding of Ap 15–25. The correct folding into the stable conformations is a prerequisite for the peptides to implement their catalytic actions, and therefore the present results are helpful to the future designs of active peptides.
ESTIMATION ON THE INTRAMOLECULAR 8- AND 12-MEMBERED RING N–H…O=C HYDROGEN BONDING ENERGIES IN β-PEPTIDES
Authors: ZHANG YAN , WANG CHANG-SHENG , YANG ZHONG-ZHI
Published: May 2009

Computation of accurate hydrogen bonding energies in peptides is of great importance in understanding the conformational stabilities of peptides. In this paper, the intramolecular 8- and 12-membered ring N – H … O = C hydrogen bonding energies in β-peptide structures were evaluated. The optimal structures of the β-peptide conformers were obtained using MP2/6-31G(d) method. The MP2/6-311++G(d,p) calculations were then carried out to evaluate the single-point energies. The results show that the intramolecular 8-membered ring N – H … O = C hydrogen bonding energies in the five β-dipeptide structures β-di, β-di-R1, β-di-R2, β-di-R3, and β-di-R4 are -5.50, -5.40, -7.28, -4.94, and -6.84 kcal/mol with BSSE correction, respectively; the intramolecular 12-membered ring N – H … O = C hydrogen bonding energies in the nine β-tripeptide structures β-tri, β-tri-R1, β-tri-R2, β-tri-R3, β-tri-R4, β-tri-R1', β-tri-R2', β-tri-R3' and β-tri-R4' are -10.23, -10.32, -9.53, -10.30, -10.32, -10.55, -10.09, -10.51, and -9.60 kcal/mol with BSSE correction, respectively. Our calculation results further indicate that for the intramolecular 8-membered ring hydrogen bondings, the structures where the orientation of the side chain methyl group is "a–a" have stronger intramolecular hydrogen bondings than those where the orientation of the side chain methyl group is "e–e", while for the intramolecular 12-membered ring hydrogen bondings, the structures where the orientation of the side chain methyl group is "e–e" have stronger intramolecular hydrogen bondings than those where the orientation of the side chain methyl group is "a–a". The method is also applied to estimate the individual intermolecular hydrogen bonding energies in the dimers of amino-acetaldehyde, 2-amino-acetamide, 2-oxo-acetamide, and oxalamide, each dimer having two identical intermolecular hydrogen bonds. According to our method, the individual intermolecular hydrogen bonding energies in the four dimers are calculated to be -1.71, -1.50, -4.67, and -3.22 kcal/mol at the MP2/6-311++G(d,p) level, which are in good agreement with the values of -1.84, -1.72, -4.93, and -3.26 kcal/mol predicted by the supermolecular method.
DENSITY FUNCTIONAL THEORY STUDY ON THE IONIZATION POTENTIALS AND ELECTRON AFFINITIES OF ADENINE–FORMAMIDE COMPLEXES
Authors: TANG KE , SUN HAI-TAO , ZHOU ZHENG-YU , WANG ZHI-ZHONG
Published: May 2009

The effects of hydrogen bond interactions upon ionization potentials (IPs) and electron affinities (EAs) of adenine–formamide (AF) complexes have been investigated employing the density functional theory B3LYP. It is found that the hydrogen bond interactions between adenine and formamide play a more important role in the process of electron attachment than in the process of electron detachment. Meanwhile, the hydrogen bond interactions facilitate the adiabatical electron detachment and attachment but have different effects on the vertical electron detachment and attachment with different positions of formamide. Furthermore, when the complexes were dissociated to the free monomers, the processes AF - → A - + F and AF + → A + + F are energetically preferable for AF- and AF+, respectively.
THEORETICAL STUDY ON THE STRUCTURE TRANSFORMATIONS OF CRYPTOTANSHINONE AND TANSHINONE I WITH HYDRION OR HYDROXIDE ION
Authors: PING XIAOFAN , GUO YONG , ZHU HUA , XUE YING , XIE DAIQIAN
Published: May 2009

The effects of hydrion and hydroxide ions on the structure transformations of Cryptotanshinone and Tanshinone I were investigated using the density functional theory at the Becke three-parameter hybrid functional combined with Lee–Yang–Parr correlation functional B3LYP/6-31+G(d) level. The solvent effects were assessed using the polarized continuum model. Our results revealed that the furan ring of Tanshinone I and dihydrofuran ring of Cryptotanshinone could be opened with the attack of hydroxide ion. The reaction of furan ring-opening proceeds via two pathways, while the reaction of dihydrofuran ring-opening is reversible. In the case of hydrion, the furan or dihydrofuran ring could not be opened. All of the relevant Gibbs free energy barriers are increased with the increase of the polarity of the solvents. The results are in reasonable agreement with the experimental observation.
A MOLECULAR DYNAMICS SIMULATION STUDY OF CONFORMATIONAL CHANGES AND SOLVATION OF Aβ PEPTIDE IN TRIFLUOROETHANOL AND WATER
Authors: JALILI S. , AKHAVAN M.
Published: May 2009

Molecular dynamics (MD) simulations of amyloid beta peptide have been performed in aqueous solutions of trifluoroethanol with different concentrations. The amount of α-helical secondary structure increases when going from pure water to trifluoroethanol-rich solutions. The conformation obtained in 40% (v/v) trifluoroethanol solution is very similar to the experimental observations of beta peptide in sodium dodecyl sulfate micelle. In this solution, the peptide has two helical segments connected through a looped region. The C-terminal helix of beta peptide unfolds in pure water. The effect of trifluoroethanol on peptide's secondary structure has been explained using the properties calculated from MD trajectories.
Tacit Knowledge Sharing in Geographically Distributed Enterprise Resources Planning (ERP) Implementation: An Exploratory Multi-Site Case Study
Authors: Palanisamy Ramaraj
Published: May 2009

Organisations that implement Enterprise Resources Planning (ERP) software packages are making a big commitment in terms of both time and money. Realising the ERP benefits, some organisations have successfully implemented while others have struggled, settled for minimum returns, and abandoned the system. Especially in a Geographically Distributed Environment (GDE), ERP implementation is more risky. To mitigate the risks, a knowledge sharing framework is suggested to be put in place during ERP implementation phases. The ERP implementation requires more knowledge about business processes, transaction rules, organisational structure, and other related transactions. Based on findings in an extensive study of three Canadian organisations that have gone through ERP implementation phases, this study examines tacit knowledge sharing in design, configuration, and testing of ERP systems. The lessons learned and knowledge sharing activities are given by presenting a cross-comparison of the case studies.
Size-Dependent Resistivity in Nanoscale Interconnects
Authors: Josell Daniel , Brongersma Sywert H. , Tőkei Zsolt
Published: May 2009

As the dimensions of conductors shrink into the nanoscale, their electrical conductivity becomes dependent on their size even at room temperature. Although the behavior varies dramatically as temperatures increase from nanokelvins to hundreds of kelvins, the effect is generally to increase the resistivity above that of bulk material. As such, the underlying size-dependent phenomena have become increasingly important as advanced technologies have shifted their focus first from macro- to microscale and more recently from micro- to nanoscale dimensions. Indeed, the size-dependent increase of electrical resistivity that results from electron scattering on external and internal surfaces of copper conductors has already become technology limiting in modern microelectronics. This article summarizes the phenomena that underlie size effects, focusing on conduction in copper lines in particular. Attention is given to describing key innovations in both theoretical and experimental assessments that have significantly modified, facilitated, or advanced understanding.
The Genomes of Root-Knot Nematodes
Authors: Bird David McK. , Williamson Valerie M. , Abad Pierre , McCarter James , Danchin Etienne G.J. , Castagnone-Sereno Philippe , Opperman Charles H.
Published: May 2009

Plant-parasitic nematodes are the most destructive group of plant pathogens worldwide and are extremely challenging to control. The recent completion of two root-knot nematode genomes opens the way for a comparative genomics approach to elucidate the success of these parasites. Sequencing revealed that Meloidogyne hapla, a diploid that reproduces by facultative, meiotic parthenogenesis, encodes approximately 14,200 genes in a compact, 54 Mpb genome. Indeed, this is the smallest metazoan genome completed to date. By contrast, the 86 Mbp Meloidogyne incognita genome encodes approximately 19,200 genes. This species reproduces by obligate mitotic parthenogenesis and exhibits a complex pattern of aneuploidy. The genome includes triplicated regions and contains allelic pairs with exceptionally high degrees of sequence divergence, presumably reflecting adaptations to the strictly asexual reproductive mode. Both root-knot nematode genomes have compacted gene families compared with the free-living nematode Caenorhabditis elegans, and both encode large suites of enzymes that uniquely target the host plant. Acquisition of these genes, apparently via horizontal gene transfer, and their subsequent expansion and diversification point to the evolutionary history of these parasites. It also suggests new routes to their control.
Seed Pathology Progress in Academia and Industry
Authors: Munkvold Gary P.
Published: May 2009

Seed pathology involves the study and management of diseases affecting seed production and utilization, as well as disease management practices applied to seeds. In this paper, three aspects of seed pathology are discussed: research innovations in detection of seedborne pathogens and elucidation of their epidemiology; advances in development and use of seed treatments; and progress toward standardization of phytosanitary regulations and seed health testing methods. The application of nucleic-acid based detection methods in seed health testing has been facilitated by integrating conventional or real-time PCR with other technologies (e.g., BIO-PCR, IMS-PCR, MCH-PCR). PCR-based methods and pathogen marker technologies are being applied to epidemiological research on seedborne pathogens, e.g., seed transmission mechanisms, the influence of external biotic and abiotic factors on seed transmission, and tracking progress of seed-transmitted pathogens. Seed treatment use is discussed in terms of the revolutionary expansion in seed-applied insecticide use, impacts of new fungicide active ingredients, and the effects of some seed treatments on crop physiology. International seed trade has been affected significantly by changing phytosanitary regulations, not always based on science. Efforts are underway to revise phytosanitary regulations to reflect pest risk analysis outcomes and to develop standards for seed health testing methods that facilitate safe and efficient international trade in seeds.
The Biology of Viroid-Host Interactions
Authors: Ding Biao
Published: May 2009

Viroids are single-stranded, circular, and noncoding RNAs that infect plants. They replicate in the nucleus or chloroplast and then traffic cell-to-cell through plasmodesmata and long distance through the phloem to establish systemic infection. They also cause diseases in certain hosts. All functions are mediated directly by the viroid RNA genome or genome-derived RNAs. I summarize recent advances in the understanding of viroid structures and cellular factors enabling these functions, emphasizing conceptual developments, major knowledge gaps, and future directions. Newly emerging experimental systems and research tools are discussed that are expected to enable significant progress in a number of key areas. I highlight examples of groundbreaking contributions of viroid research to the development of new biological principles and offer perspectives on using viroid models to continue advancing some frontiers of life science.
Living-Cell Microarrays
Authors: Yarmush Martin L. , King Kevin R.
Published: May 2009

Living cells are remarkably complex. To unravel this complexity, living-cell assays have been developed that allow delivery of experimental stimuli and measurement of the resulting cellular responses. High-throughput adaptations of these assays, known as living-cell microarrays, which are based on microtiter plates, high-density spotting, microfabrication, and microfluidics technologies, are being developed for two general applications: (a) to screen large-scale chemical and genomic libraries and (b) to systematically investigate the local cellular microenvironment. These emerging experimental platforms offer exciting opportunities to rapidly identify genetic determinants of disease, to discover modulators of cellular function, and to probe the complex and dynamic relationships between cells and their local environment.
Comment on “Voltage‐Mode All‐Pass Filters Including Minimum Component Count Circuits”
Authors: Lahiri Abhirup
Published: May 2009

This comment is related to the recently published article
“Active and Passive Electronic Components” by S. Maheshwari
(2007), which presents single current differencing buffered
amplifier (CDBA) and current‐controlled current differencing
buffered amplifier‐ (CC‐CDBA‐) based first‐order voltage‐mode
(VM) all‐pass filtering (APF) sections. The paper is reviewed,
and additional first‐order APF realizations have been proposed.
Truths and Lies from the Polysomnography ECG Recording: An Electrophysiologist Perspective
Authors: Baranchuk Adrian , Quinlan Christina , Michael Kevin , Simpson Christopher S. , Redfearn Damian P. , Fitzpatrick Michael
Published: May 2009

Polysomnography remains the gold standard for diagnosis of Sleep Apnea (SA) and evaluation of the apnea/hypopnea index (AHI) which is used as the primary index of SA severity. The electrocardiogram (typically a single lead) obtained during the polysomnographic study is usually used to report the association between SA and cardiac rhythm disturbances. These findings help in guiding medical decisions but they could also represent a source for confusion. Electrophysiologists are frequently consulted to determine whether interventions need to be taken. We present 2 cases where the ECG during a polysomnography study required the intervention of an electrophysiologist to help with management.
Hyperfractionated Accelerated Radiotherapy versus Conventional Fractionation Both Combined with Chemotherapy in Patients with Locally Advanced Head and Neck Carcinomas
Authors: Welz Hanna , Pöttgen Christoph , Abu Jawad Jehad , Wierlemann Arne , Wittig Andrea , Stüben Georg , Budach Volker , Lehnerdt Goetz , Jahnke Klaus , Sack Horst , Stuschke Martin
Published: May 2009

Objective: Hyperfractionated accelerated radiotherapy (HART) has been combined with chemotherapy (CC) for locally advanced head and neck cancer, but no data from randomized trials are available for a comparison with conventionally fractionated radiotherapy (CFRT) and CC. Methods: This monoinstitutional retrospective study compares the results of both treatment schedules: 315 patients with locally advanced carcinoma (UICC stage III and IV) of the oral cavity and the orohypopharynx were treated from January 1990 to March 2006 with a radiochemotherapy combination based on mitomycin C and fluorouracil (HART-CC: 203 patients, CFRT-CC: 112 patients, total dose: 70–72 Gy) with curative intent. Results: Two- and 4-year survival was 60 and 42 (HART-CC) and 59 and 42% (CFRT-CC; p = 0.82, log-rank test), respectively. Using multivariate Cox regression, pretreatment hemoglobin level, N stage, tumor site but not the year of treatment, gender and T stage were significant prognosticators for survival. For locoregional control, only N stage was significant. The prognostic value of these pretreatment factors did not variate with the fractionation schedule used. Conclusions: In combination with CC, there was no trend towards an improved efficacy of HART in comparison with CFRT.
Fibrinogen Milano IV, Another Case of Congenital Dysfibrinogenemia with an Abnormal Fibrinopeptide A Release (Aα 16 Arg → His)
Authors: Bögli C. , Hofer A. , Baudo F. , Redaelli R. , Furlan M.
Published: May 2009

An abnormal fibrinogen, denoted as ‘fibrinogen Milano IV, has been found in a 36-year-old woman without any bleeding manifestations or thrombotic tendency. Routine coagulation studies revealed prolonged thrombin and reptilase clotting times, very low plasma fibrinogen concentration determined by the functional assay but a normal fibrinogen concentration measured by the immunologic assay. Turbidity curves, measured following addition of thrombin to purified fibrinogen Milano IV, both in presence of calcium or EDTA, were markedly delayed. Release of fibrinopeptide B by thrombin was normal, whereas only half the normal amount of fibrinopeptide A was cleaved. The fibrinopeptide A peak of fibrinogen was preceded by an abnormal fibrinopeptide A*. Both peaks were collected for amino acid analysis which showed an exchange of arginine by histidine in position 16 of the Aα chain of the fibrinopeptide A*.
Anticoagulant Mechanisms of Orgaran (Org 10172) and Its Fraction with High Affinity to Antithrombin III (Org 10849)
Authors: Ofosu F.A.
Published: May 2009

Orgaran (Org 10172), which has antithrombotic activity in man with apparently minimal bleeding side effects, is a mixture of low-molecular-weight heparan, dermatan, and chondroitin sulfates. The degrees to which the minimum concentrations of Orgaran, its fraction with high affinity for antithrombin III (Org 10849; AT III) and unfractionated heparin, which double the activated partial thromboplastin time (APTT) of pooled normal plasma, inhibit intrinsic activation of factor IX, factor X, and prothrombin were compared. Specific ELISAs were used to quantify the activation of each clotting factor. Factor IX activation, which began without a lag phase, preceded factor X and prothrombin activation by ∼ 15 and ∼ 25 s, respectively. When used at these functionally equivalent concentrations, heparin (2 µg/ml plasma), Orgaran (50 µg/ml plasma), and Org 10849 (20 µg/ml) could delay the onset of factor IX activation. Compared to control plasma, however, only Orgaran reduced the initial rate of factor IX activation. Heparin and Orgaran delayed the onset of factor X activation by 20 and 15 s, respectively, while Org 10849 could not delay the onset of factor X activation. In addition, each anticoagulant delayed the onset of prothrombin activation. Thus, at concentrations which double the APTT of normal plasma, the combined actions of heparan and dermatan sulfate present in Orgaran can apparently suppress factor IX activation more effectively than heparin, and delay the onset of factor X activation nearly as effectively as heparin. The coordinated inhibition of factor IX and factor X activation by Orgaran may contribute to its antithrombotic effectiveness.
Modulation der biochemischen Wirkung von 5-Fluorouracil (5-FU) durch Leucovorin (LCV) gemessen anhand der Thymidylat-Synthase-Aktivität und des Nucleosid-Einbaus in die DNS
Authors: Kau B. , Rieger M. , Sauer H.
Published: May 2009

Aus experimentellen Untersuchungen geht hervor, daß Leucovorin (LCV) die ZytotoxizitÄt von 5-Fluorouracil (5-FU) deutlich zu modulieren vermag. Durch den kombinierten Einsatz beider Substanzen kommt es zu einer anhaltenderen und ausgeprÄgteren Hemmung der DNS-Synthese via Blockade der Thymidylat-Synthase (TS). Dieser Effekt wird durch eine Stabilisierung des sog. ternÄren Komplexes bestehend aus 5-Fluoro-Deoxiuridinmonophosphat (5-FdUMP), der TS und NsNjo-Methylentetrariydrofolat (CH2FH4) bewirkt. An in vitro permanent wachsenden menschlichen Lymphoblasten (LS2) wurde die biochemische Wirkung einer Kombinationsbehandlung mit 5-FU und LCVmit zwei verschiedenen Methoden untersucht: a) Tritium-release-assay zur AktivitÄtsbestimmung der TS; b) Einbau von 3H-Deoxiuridin (3H-dUR) und 3H-Thymidin (3H -dTR) in die DNS zur Bestimmung der endogenen Nucleosid-PoolgrÖßen. Mit beiden Methoden wurden Ähnliche Ergebnisse erzielt. Weder mit der simultanen noch mit der sequentiellen Verabreichung beider Medikamente konnte an den LS2-Zellen eine signifikante Wirkungssteigerung gegenÜber der 5-FU Monotherapie registriert werden. Die relativ einfache Methodik bietet sich an zur biochemischen Charakterisierung von Zellpopulationen, bei denen die Kombination 5-FU + LCV nicht mehr Effekt zeigt als 5-FU alleine. Lymphoide Zellen und normales Knochenmark scheinen solche Populationen zu sein.
Antifungal Activity of Black Tea Polyphenols (Catechins and Theaflavins) against Candida Species
Authors: Sitheeque M.A.M. , Panagoda G.J. , Yau J. , Amarakoon A.M.T. , Udagama U.R.N. , Samaranayake L.P.
Published: May 2009

Background/Aims: The polyphenols catechins and theaflavins in black tea have been shown to possess many medicinal properties, including anticancer activity and some antifungal characteristics, but there have been few studies of their anti-Candida activity. In this paper we report the results of our study of the anti-Candida activity of tea polyphenols. Methods: The effects of 4 different concentrations of catechins and theaflavins were evaluated on 5 isolates each of 5 Candida species employing an agar diffusion growth inhibition assay. The minimum inhibitory concentration (MIC) of the polyphenols against C. albicans was determined. The post-antifungal effect (PAFE) of the polyphenols for C. albicans was investigated. C. albicans cells exposed to polyphenols were studied using a scanning electron microscope (SEM). Results: Both polyphenols showed anti-Candida activity against all tested Candida species and demonstrated a MIC of 6.25 mg/ml for C. albicans. C. glabrata was found to be the most sensitive species followed by C. parapsilosis, C. albicans, C. krusei and C. tropicalis (p < 0.05 for all). Significant intraspecies variations in sensitivity were noted among C. parapsilosis and C. tropicalis (p < 0.001) for both polyphenols. Theaflavins displayed standard PAFE while catechins showed a paradoxical PAFE with all isolates of C. albicans. SEM revealed considerable cell wall damage of C. albicans cells exposed to the polyphenols. Conclusion: The study reveals for the first time the anti-Candida properties of black tea polyphenols that may find therapeutic applications in future.
The Expression of RNA-Binding Protein HuR in Non-Small Cell Lung Cancer Correlates with Vascular Endothelial Growth Factor-C Expression and Lymph Node Metastasis
Authors: Wang Jun , Zhao Weipeng , Guo Yan , Zhang Bicheng , Xie Qichao , Xiang Debing , Gao Jianfei , Wang Baocheng , Chen Zhengtang
Published: May 2009

The expression levels of the RNA-binding protein Hu antigen (HuR) and vascular endothelial growth factor-C (VEGF-C) were examined immunohistochemically in 81 non-small cell lung cancers (NSCLC) and 15 benign human lung tissues. HuR showed a nuclear overexpression in 82.7% (67/81) of NSCLC specimens. Cytoplasmic immunoreactivity for HuR was observed in 45.7% (37/81) of NSCLC, while only nuclear expression of HuR was observed in 13.3% (2/15) of benign lung tissues. The expression of VEGF-C was present in a subgroup of 70.4% (57/81) of tumor cases. In the human NSCLC samples, cytoplasmic but not nuclear HuR expression was significantly associated with increased levels of VEGF-C and with clinicopathological variables, including high tumor grade, poor differentiation and lymph node metastasis. In vitro, HuR showed a predominantly nuclear staining in Lewis lung cancer cells, as seen by confocal microscopy. When lung cancer cells were treated with siRNA targeted against HuR, expression levels of the HuR and VEGF-C proteins were significantly reduced, as seen by Western blotting. Our findings indicate that there is a dysregulation of the cellular distribution of the mRNA stability factor HuR in a subset of NSCLC. Examination of cytoplasmic HuR in NSCLC tissues will allow for valuable prognostic diagnosis of lymph node metastasis, as HuR might be an important mediator regulating the expression of VEGF-C.
Primary Diffuse Leptomeningeal Gliomatosis
Authors: Jicha Gregory A. , Glantz Janel , Clarke Michelle J. , Lehwald Lenora M. , Russo David P. , Giannini Caterina , Wald John T. , Uhm Joon , Kumar Neeraj , Aksamit Allen J. , Wetmore Cynthia J.
Published: May 2009

Background: Primary diffuse leptomeningeal gliomatosis (PDLG) is a rare presentation of a primary central nervous system glial tumor. Methods: Four case reports of PDLG in young males aged 14–24 years are presented. These reports are discussed in the context of the existing literature. Results: The clinical presentation of 4 new cases of PDLG resembled chronic meningitis with and without polyradiculopathy. Spinal fluid studies are typically nondiagnostic, but characteristically show elevated opening pressure, an elevated protein level, and a relative paucity of cellular reaction. An accurate antemortem diagnosis required contrast-enhanced imaging and meningeal biopsy in all 4 of our cases. Treatment strategies including craniospinal radiation and chemotherapeutic approaches, alone or in combination, have not been proven to alter the course of the disease. Initial responses to temozolomide and radiation treatments in all 4 of our cases were promising, resulting in temporary stabilization of the disease and prolonging life expectancy over what was previously reported in the literature. Conclusion: Total neuroaxis contrast-enhanced MRI scanning is required for directing biopsy confirmation and detecting the extent of the disease. More effective therapeutic strategies are needed, but the combination of temozolomide and radiation therapy may slow disease progression.
Antithrombotic Effect of Argatroban on the Pial Vessels of the Rat: A Study with He-Ne Laser-Induced Thrombus Formation
Authors: Sasaki Y. , Morii S. , Yamashita T. , Yamamoto J.
Published: May 2009

The antithrombotic effect of the synthetic thrombin inhibitor (2R,4R)-4-methyl-1 -[N2-(3-methyl-1,2,3,4-tetrahydro-8-quin-olinesulfonyl)-L-arginyl]-2-piperidinecarboxylic acid mono-hydrate (argatroban) was investigated in cerebral vessels of the rat. An occlusive thrombus was formed in pial vessels using a He-Ne laser in a closed cranial window technique. Argatroban retarded the formation of thrombi in a dose-dependent manner. The antithrombotic effect of a single intravenous dose of argatroban at 0.5 mg/kg was diminished after 30 min in arterioles and after 50 min in venules, respectively. The antithrombotic activity was maintained, however, by continuous intravenous infusion (2 mg/kg/h).
Activation of Human Blood Platelets Induced by Nocloprost, a Stable Prostaglandin E2 Derivative
Authors: Glusa E. , Richter M. , Amon I.
Published: May 2009

Nocloprost, a 9β-chloro-16,16-dimethyl derivative of prostaglandin E2 (PGE2), belongs to the gastric cytoprotective agents that are used in the therapy of gastric ulcer. Since methylated derivatives of PGE2 are known to have proaggregatory effects the influence on platelets was studied. In platelet-rich citrated plasma, nocloprost ( > 0.1 μmol/l) caused aggregation with a biphasic course at higher concentrations. Aggregation induced by nocloprost (1 μmol/l) corresponded to that induced by adenosine diphosphate (ADP) (5 μmol/l). Activation of platelets by nocloprost was accompanied by formation of thromboxane A2 and an increase in cytosolic calcium in In do 1-loaded platelets. At 0.1 μmol/l it potentiated aggregation induced by low concentrations of ADP or adrenaline. The effect of nocloprost on platelets was blocked by iloprost, daltroban and indomethacin. PGE2, which was studied for comparison, at 0.1-1.0 μmol/l inhibited aggregation induced by 1 μmol/l nocloprost. The concentrations of nocloprost required for therapeutic use as antiulcer agent were lower by three orders of magnitude than those which induce human platelet aggregation.
Comparison of in vitro and in vivo Properties of rHirudin (HBW 023) and a Synthetic Analogous Peptide
Authors: Römisch Jürgen , Diehl Karl-Heinz , Hoffmann Dieter , Krahl-Mateblowski Ute , Reers Martin , Stüber Werner , Pâques Eric-Paul
Published: May 2009

Recombinant hirudin and a shortened synthetic analogue, with the amino acid sequence of D-Phe-Pro-Arg-Pro-(Gly)4-Asn-Gly-Asp-Phe-Glu-Glu-Ile-Pro-Glu-Glu-Tyr-Leu, are specific thrombin inhibitors which in a concentration-dependent manner inhibit thrombus formation as well as clot propagation both in vitro and in vivo. In comparison to the analogue, lower molar concentrations of rhirudin affected doubling of aPTT and TT as well as inhibition of thrombin amidolytic activity or thrombin-induced platelet aggregation in vitro. In the rat wire coil-induced thrombosis model, a 50% thrombo-protective effect may be brought about with doses of 0.043 μmol/kg of rhirudin and 1.43 μmol/kg of the synthetic peptide. However, doubling of bleeding times is caused, on average, by dosages of between 0.143 and 0.43 μmol/kg rhirudin or approximately 0.143 μmol/kg of the analogue. Treatment groups included animals revealing significant prolongation of bleeding times as well as nonresponders. Despite the 10-fold longer impact on aPTT after application of rhirudin, the extent of mean bleeding time prolongation is identical to that of the analogue.