bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Uniformity of Catalytic Burner for Off-Gas Combustion of Molten Carbonate Fuel Cell
Authors: Yu Sangseok , Im Seokyeon , Lee Young Duk , Ahn Kook Young , Lee Sangmin
Published: March 2012

A catalytic combustor is a device to burn out the fuel by surface combustion that is used for the combustion of anode off-gas of molten carbonate fuel cell. By employing the catalytic combustor, the purified exhaust gas is able to be recirculated into the cathode channel for CO2 supply to improve thermal efficiency. The design of catalytic combustor depends on many parameters but the flow uniformity is particularly important during the emergency shut-down of fuel cell stack. Right before the temperature control of catalytic combustor is not yet activated, the catalytic combustor should burn out more than two times of rated amount of fuel flow rate. At the over-loaded condition, assurance of flow uniformity at the inlet of catalytic combustor can reduce the damage of catalytic burner caused by local hot zone. In this study, the flow uniformity of the catalytic combustor is investigated in two steps such as preliminary step with model combustor and main analysis step with practical 250 kW catalytic combustor. The 0.5 kW and 5 kW class combustors are applied for preliminary step. In preliminary step, the model combustor is used to determine supporting matters for the flow uniformity. Inlet direction of mixing chamber below the catalytic combustor is also examined in the preliminary step. In the main analysis step, flow uniformity of scale-up combustor has been examined with selected supporting matter and inlet direction into mixing chamber. Geometric and operating parameters are investigated. In particular, the flow rate at off-design operating condition has been examined.
Three-Dimensional Numerical Study of Circular-Fin Tube Heat Exchanger for UAV
Authors: Sung Haejung , Kang Sanggyu , Kim Hanseok , Choi Hangseok , Park Hunchae , Ahn Kook Young
Published: March 2012

The proton exchange membrane fuel cell (PEMFC) has been regarded as promising alternative power sources for unmanned aerial vehicle (UAV). The temperature of PEMFC stack should be maintained an optimal range around 60∼80°C to prevent stack membrane damages at high temperature or low efficiency of stack at low temperature. Therefore, thermal management is crucial to maximize the performance of the PEMFC. Generally, the thermal management system (TMS) of PEMFC is composed of heat exchanger (HEX), fan, and pump. In this work, since the weight of UAV is one of the main factors to affect the UAV flight, the fan is eliminated. That means only the air flowing through the UAV is used to cool down the stack coolant water. Therefore a design optimization of HEX is important to get the best performance of PEMFC for UAV. The three dimensional numerical modeling has been developed by using the commercial code of STAR-CCM+®. In this simulation, the UAV body, circular-fin tube HEX, and duct are considered. Since the cruise velocity of the UAV is 40km/h, the air velocity at the duct inlet is set to be 40km/h. Heat exchanger is located at the top of the UAV, and the coolant water from the pump is flowing through the header and divided several tubes to increase the surface area of heat rejection rate or decrease the pressure drop. The mass flow rate of air flowing into each fin of HEX is determined by fluid analysis. In order to validate this model, the simulation results are compared with the experimental data, which is obtained at various coolant inlet temperatures, and coolant flow rates. And the parametric study of HEX model was conducted with various UAV velocities and air temperatures. One reference data point is selected to tune several unknown parameters in the model, and once established, the same parameter values are used for all other conditions. The simulation results are in good agreement with the experimental data. This model can be helpful to develop the optimal design of heat exchanger for UAV.
Design and Performance Analysis of a 1 MW Solid Oxide Fuel Cell System for Combined Production of Heat, Hydrogen, and Power
Authors: Becker William L. , Braun Robert J. , Penev Michael
Published: March 2012

SOFC systems with co-generation exhibit high overall efficiency. Fuel cell-based co-generation studies have typically focused on electricity and heat; pure hydrogen gas can also be generated in these systems as an energy co-product resulting in the combined production of heat, hydrogen, and power (CHHP). Co-locating a distributed generation SOFC CHHP plant with fueling stations for fuel cell vehicles enables use of lower scale (200 kg/day) hydrogen production and leverages the capital investment among all co-products, thereby lowering the unit cost of hydrogen and offering a potentially promising transition pathway to a hydrogen economy. This work focuses on the design and performance estimation of a methane-fueled 1 MW SOFC CHHP system operating at steady-state. System design and modeling are carried out employing Aspen Plus™ software where performance characteristics of the SOFC and the balance-of-plant are estimated from industry and literature sources. Analysis of the SOFC CHHP system indicates that the SOFC electrochemical performance is independent of the heat recovery and hydrogen production processes because the latter two subsystems are downstream of the SOFC power module. The system is configured such that it can preferentially produce hydrogen or low-temperature thermal energy (80 °C) as needed. Two methods of hydrogen purification and recovery from the SOFC tail-gas were analyzed: pressure swing adsorption (PSA) and electrochemical hydrogen separation (EHS). The recovered hydrogen is compressed to 425 bar for storage. The SOFC electrical efficiency at rated power is estimated at 48.1% (LHV) and the overall CHHP efficiency is 84.4% (LHV) for the EHS design concept. The amount of hydrogen recovery (85–90%) with EHS is higher than PSA for typical SOFC effluent gas compositions. The hydrogen separation energy requirement of 2.7 kWh/kg H2 for EHS is found to be about three times lower than PSA in this system. Increasing the amount of hydrogen production can be independently controlled by flowing excess methane into the system, effectively decreasing SOFC fuel utilization yet still reforming the fuel to a hydrogen-rich syngas. A case study for hydrogen overproduction is given. Operating the system to produce excess hydrogen increases the efficiency for both hydrogen separation design concepts.
Fuel Flexible and Reversible Operation of Yttrium-Doped Strontium Titanate Anode Supported SOFC
Authors: Zhao Li , Brouwer Jacob
Published: March 2012

The performance of novel yttrium-doped SrTiO3 (Sr0.86Y0.08TiO3, SYT) anode materials for an anode supported SOFC have been evaluated in terms of fuel flexibility and reversible operation at intermediate temperature (800°C). The SYT anode supported PEN structures were fabricated using tape casting, dip coating and screen printing for the anode substrate, electrolyte and cathode, respectively. Overall performance of SYT-YSZ composite anode supported cells indicates that this anode material set is not likely to be an outstanding performer, mainly due to the significant anode polarization losses and relatively high ohmic losses. With careful processing of the anode during cell fabrication, major parts of the ohmic losses introduced by the SYT anode can be reduced. The results also indicate that Ni infiltration of the SYT anode can lead to smaller polarization losses, thus achieving better cell performance.
Full Field Imaging of Nickel Oxidation States in Solid Oxide Fuel Cell Anode Materials by Xanes Nanotomography
Authors: Harris William M. , Nelson George J. , Izzo John R. , Grew Kyle N. , Chiu Wilson K. S. , Chu Yong S. , Yi Jaemock , Andrews Joy , Liu Yijin , Pianetta Piero
Published: March 2012

A greater understanding of nickel reduction-oxidation cycling (redox) mechanisms at the microstructural level can enhance SOFC performance and reliability. Transmission x-ray microscopy (TXM) provides several techniques for exploring oxidation states within SOFC electrode microstructure. X-ray nanotomography and full field x-ray absorption near edge structure (XANES) spectroscopy are new TXM techniques that have been applied in tandem to study samples of varying nickel (Ni) and nickel oxide (NiO) compositions. The imaged samples are treated as mock SOFC anodes containing distinct Ni and NiO regions. XANES spectra for the individual materials provide a basis for the processing and analysis of these mixed samples. Images of composite samples obtained using x-ray nanotomography are treated using numerical image processing steps including: scaling, tomographic reconstruction, and image alignment and subtraction. The distinct nickel and nickel oxide phases have been uniquely identified using full field XANES nanotomography. Applications to SOFC anodes are discussed.
Design and construction of the SuperKEKB vacuum system
Authors: Suetsugu Yusuke , Kanazawa Ken-ichi , Shibata Kyo , Ishibashi Takuya , Hisamatsu Hiromi , Shirai Mitsuru , Terui Shinji
Published: March 2012

A two-ring electron-positron collider with asymmetric energies—called the SuperKEKB—has been designed by the High Energy Accelerator Research Organization (KEK) as an upgrade of the KEKB B-factory (KEKB), which completed 12 years of operation in 2010. It is anticipated that the SuperKEKB will reach a luminosity of 8 × 1035 cm−2 s−1, which is approximately 40 times larger than that of the original KEKB. The upgrade of the vacuum system is a key factor that will allow the SuperKEKB to achieve unprecedented high performance. Most of the beam pipes, especially in the positron ring, are newly manufactured to manage the electron cloud effect, and to reduce beam impedance, which is essential to keep the low-emittance beam stable. Our design of the vacuum system implements recent technologies and draws on various experiences and studies during the operation of the original KEKB. The basic design is near completion, and manufacturing of beam pipes and the major vacuum components, such as bellows chambers, gate valves and supports, are in progress. The installation of these components will start in 2013 with the aim of commissioning the SuperKEKB in 2014.
Motion tracking in undergraduate physics laboratories with the Wii remote
Authors: Tomarken Spencer L. , Simons Dallas R. , Helms Richard W. , Johns Will E. , Schriver Kenneth E. , Webster Medford S.
Published: March 2012

We report the incorporation of the Wiimote, a light-tracking remote control device, into two undergraduate-level experiments. We provide an overview of the Wiimote’s basic functions and a systematic analysis of its motion tracking capabilities. We describe the Wiimote’s use in measuring conservation of linear and angular momentum on an air table, and measuring the gravitational constant with the classic Cavendish torsion pendulum. Our results show that Wiimote is a simple and affordable way to streamline the data acquisition process and produce results that are generally superior to those obtained with conventional techniques.
The creation and propagation of radiation: Fields inside and outside of sources
Authors: Olbert Stanislaw , Belcher John , Price Richard H.
Published: March 2012

We present an algorithm for computing the electromagnetic fields due to currents inside and outside of finite sources with a high degree of spatial symmetry for arbitrary time-dependent currents. The solutions for these fields do not involve the time derivatives of the currents but involve only the currents and their time integrals. We give solutions for moving planar sheets of charge, and a rotating spherical shell carrying a uniform charge density. We show that the general solutions reduce to the standard expressions for magnetic dipole radiation for slow time variations of the currents. If the currents are turned on very quickly, the general solutions show that the amount of energy radiated equals the magnetic energy stored in the static fields a long time after current creation. We give three problems which can be used in undergraduate courses and one problem suitable for graduate courses. These problems illustrate that because the generation of radiation depends on what has happened in the past, a system of currents can radiate even during time intervals when the currents are constant due to radiation associated with earlier acceleration.
New Range of Vectors with a Stringent 5-Fluoroorotic Acid-Based Counterselection System for Generating Mutants by Allelic Replacement in Staphylococcus aureus
Authors: Redder Peter , Linder Patrick
Published: March 2012

We have developed a range of vectors for allelic replacements in
Staphylococcus aureus
to facilitate genetic work in this opportunistic pathogen. The central feature of the vector range is a selection/counterselection system that takes advantage of the 5-fluoroorotic acid (FOA) resistance and pyrimidine prototrophy caused by the loss and gain, respectively, of the
pyrF
and
pyrE
genes. This system allows for stringent counterselection of the vectors during the second homologous recombination of a classic allelic replacement. The basic vector pRLY2, which contains the
pyrFE
genes from
Bacillus subtilis
, was combined with chloramphenicol, erythromycin, and tetracycline resistance genes and four different versions of nonreplicative or conditionally replicative origins of replication. The choice between these 12 different pRLY vectors allows for high versatility and ensures that the vectors can be used in virtually any genetic background. Finally, as proof of concept, we present six deletions or modifications of components in the
S. aureus
degradosome as well as the operon containing the
cshB
DEAD box helicase.
Genetic Analysis of the Cronobacter sakazakii O4 to O7 O-Antigen Gene Clusters and Development of a PCR Assay for Identification of All C. sakazakii O Serotypes
Authors: Sun Yamin , Wang Min , Wang Quan , Cao Boyang , He Xin , Li Kun , Feng Lu , Wang Lei
Published: March 2012

The Gram-negative bacterium
Cronobacter sakazakii
is an emerging food-borne pathogen that causes severe invasive infections in neonates. Variation in the O-antigen lipopolysaccharide in the outer membrane provides the basis for Gram-negative bacteria serotyping. The O-antigen serotyping scheme for
C. sakazakii
, which includes seven serotypes (O1 to O7), has been recently established, and the O-antigen gene clusters and specific primers for three
C. sakazakii
serotypes (O1, O2, and O3) have been characterized. In this study, the
C. sakazakii
O4, O5, O6, and O7 O-antigen gene clusters were sequenced, and gene functions were predicted on the basis of homology.
C. sakazakii
O4 shared a similar O-antigen gene cluster with
Escherichia coli
O103. The general features and anomalies of all seven
C. sakazakii
O-antigen gene clusters were evaluated and the relationship between O-antigen structures and their gene clusters were investigated. Serotype-specific genes for O4 to O7 were identified, and a molecular serotyping method for all
C. sakazakii
O serotypes, a multiplex PCR assay, was developed by screening against 136 strains of
C. sakazakii
and closely related species. The sensitivity of PCR-based serotyping method was determined to be 0.01 ng of genomic DNA and 10
3
CFU of each strain/ml. This study completes the elucidation of
C. sakazakii
O-antigen genetics and provides a molecular method suitable for the identification of
C. sakazakii
O1 to O7 strains.
Anaerobic Metabolism of Indoleacetate
Authors: Ebenau-Jehle Christa , Thomas Markus , Scharf Gernot , Kockelkorn Daniel , Knapp Bettina , Schühle Karola , Heider Johann , Fuchs Georg
Published: March 2012

The anaerobic metabolism of indoleacetate (indole-3-acetic acid [IAA]) in the denitrifying betaproteobacterium
Azoarcus evansii
was studied. The strain oxidized IAA completely and grew with a generation time of 10 h. Enzyme activities that transformed IAA were present in the soluble cell fraction of IAA-grown cells but were 10-fold downregulated in cells grown on 2-aminobenzoate or benzoate. The transformation of IAA did not require molecular oxygen but required electron acceptors like NAD
+
or artificial dyes. The first products identified were the enol and keto forms of 2-oxo-IAA. Later, polar products were observed, which could not yet be identified. The first steps likely consist of the anaerobic hydroxylation of the N-heterocyclic pyrrole ring to the enol form of 2-oxo-IAA, which is catalyzed by a molybdenum cofactor-containing dehydrogenase. This step is probably followed by the hydrolytic ring opening of the keto form, which is catalyzed by a hydantoinase-like enzyme. A comparison of the proteome of IAA- and benzoate-grown cells identified IAA-induced proteins. Owing to the high similarity of
A. evansii
with strain EbN1, whose genome is known, we identified a cluster of 14 genes that code for IAA-induced proteins involved in the early steps of IAA metabolism. These genes include a molybdenum cofactor-dependent dehydrogenase of the xanthine oxidase/aldehyde dehydrogenase family, a hydantoinase, a coenzyme A (CoA) ligase, a CoA transferase, a coenzyme B
12
-dependent mutase, an acyl-CoA dehydrogenase, a fusion protein of an enoyl-CoA hydratase and a 3-hydroxyacyl-CoA dehydrogenase, a beta-ketothiolase, and a periplasmic substrate binding protein for ABC transport as well as a transcriptional regulator of the GntR family. Five predicted enzymes form or act on CoA thioesters, indicating that soon after the initial oxidation of IAA and possibly ring opening, CoA thioesters are formed, and the carbon skeleton is rearranged, followed by a CoA-dependent thiolytic release of another CoA thioester. We propose a scheme of an anaerobic IAA metabolic pathway that ultimately leads to 2-aminobenzoyl-CoA or benzoyl-CoA.
Organizational Requirements of the SaeR Binding Sites for a Functional P1 Promoter of the
sae
Operon in Staphylococcus aureus
Authors: Cho Hoonsik , Jeong Do-Won , Li Chunling , Bae Taeok
Published: March 2012

In
Staphylococcus aureus
, the SaeRS two-component system controls the expression of multiple virulence factors. Of the two promoters in the
sae
operon, P1 is autoinduced and has two binding sites for the response regulator SaeR. In this study, we examined the organizational requirements of the SaeR binding sites in P1 for transcription activation. Mutational studies showed that both binding sites are essential for binding to phosphorylated SaeR (P-SaeR) and transcription activation. When the 21-bp distance between the centers of the two SaeR binding sites was altered to 26 bp, 31 bp, 36 bp, or 41 bp, only the 31-bp mutant retained approximately 40% of the original promoter activity. When the −1-bp spacing (i.e.,1-bp overlap) between the primary SaeR binding site and the −35 promoter region was altered, all mutant P1 promoters failed to initiate transcription; however, when the first nucleotide of the −35 region was changed from A to T, the mutants with 0-bp or 22-bp spacing showed detectable promoter activity. Although P-SaeR was essential for the binding of RNA polymerase to P1, it was not essential for the binding of the enzyme to the alpha-hemolysin promoter. When the nonoptimal spacing between promoter elements in P1 or the coagulase promoter was altered to the optimal spacing of 17 bp, both promoters failed to initiate transcription. These results suggest that SaeR binding sites are under rather strict organizational restrictions and provide clues for understanding the molecular mechanism of
sae
-mediated transcription activation.
Pop hole use by hens with different keel fracture status monitored throughout the laying period
Authors: Richards G. J. , Wilkins L. J. , Knowles T. G. , Booth F. , Toscano M. J. , Nicol C. J. , Brown S. N.
Published: March 2012

The aim of this work was to study the effect of keel fractures on the extent to which free‐range hens access the range through pop holes. Over two consecutive laying periods (two production years) a total of 1100 individual birds from one half of a house, divided into four separated flocks, were caught at 25, 35, 45, 55 and 65 weeks, palpated to assess the prevalence and severity of keel fractures and tagged with RFID transponders. Their use of pop holes was subsequently monitored in some cases from week 25 to end of lay at 68 to 70 weeks. At regular intervals (every 10 weeks), the tagged birds were re‐caught to assess changes in keel fracture prevalence and severity. The average percentage of birds with fractured keels at 25, 35, 45, 55, 65 and at end of lay (68 to 70 weeks of age) was 5.5, 25.5, 49, 63, 66.5 and 78.5, respectively, across both production years. The effect of keel score on pop hole use was modelled statistically, adjusting for weather conditions and age of the birds. There were significant effects of most of the weather variables recorded, as well as age of the bird, on use of pop holes and also a significant effect of keel score. Higher keel scores resulted in a reduction in pop hole use. A significant statistical interaction between keel score and ambient temperature revealed an accelerated reduction in use as the temperature decreased and keel score increased. It is concluded that the occurrence of keel fractures may affect the birds' ability or willingness to utilise the outdoor range provided by free‐range housing systems, thereby reducing the potential welfare advantages of this type of housing.
Regional increase in extracellular potassium can be arrhythmogenic due to nonuniform muscle contraction in rat ventricular muscle
Authors: Miura Masahito , Hattori Taiki , Murai Naomi , Nagano Tsuyoshi , Nishio Taichi , Boyden Penelope A. , Shindoh Chiyohiko
Published: March 2012

In the ischemic myocardium, extracellular potassium ([K+]o) increases to ≥20 mmol/l. To determine how lethal arrhythmias occur during ischemia, we investigated whether the increased spatial pattern of [K+]o, i.e., a regional or a global increase, affects the incidence of arrhythmias. Force, sarcomere length, membrane potential, and nonuniform intracellular Ca2+([Ca2+]i) were measured in rat ventricular trabeculae. A “regional” or “global” increase in [K+]owas produced by exposing a restricted region of muscle to a jet of 30 mmol/l KCl or by superfusing trabeculae with a solution containing 30 mmol/l KCl, respectively. The increase in [Ca2+]i(CaCW) during Ca2+waves was measured (24°C, 3.0 mmol/l [Ca2+]o). A regional increase in [K+]ocaused nonuniform [Ca2+]iand contraction. In the presence of isoproterenol, the regional increase in [K+]oinduced sustained arrhythmias in 10 of 14 trabeculae, whereas the global increase did not induce such arrhythmias. During sustained arrhythmias, Ca2+surged within the jet-exposed region. In the absence of isoproterenol, the regional increase in [K+]oincreased CaCW, whereas the global increase decreased it. This increase in CaCWwith the regional increase in [K+]owas not suppressed by 100 μmol/l streptomycin, whereas it was suppressed by 1) a combination of 10 μmol/l cilnidipine and 3 μmol/l SEA0400; 2) 20 mmol/l 2,3-butanedione monoxime; and 3) 10 μmol/l blebbistatin. A regional but not a global increase in [K+]oinduces sustained arrhythmias, probably due to nonuniform excitation-contraction coupling. The same mechanism may underlie arrhythmias during ischemia.
Cyclin-Dependent Kinase 7/9 Inhibitor SNS-032 Abrogates FIP1-like-1 Platelet-Derived Growth Factor Receptor α and Bcr-Abl Oncogene Addiction in Malignant Hematologic Cells
Authors: Wu Yongbin , Chen Chun , Sun Xiaoyong , Shi Xianping , Jin Bei , Ding Ke , Yeung Sai-Ching Jim , Pan Jingxuan
Published: March 2012

Purpose: The “gate-keeper” mutations T674I platelet—derived growth factor receptor α (PDGFRα) in hypereosinophilic syndrome (HES) and T315I Bcr-Abl in chronic myeloid leukemia (CML) are resistant to imatinib and the second-generation small-molecule tyrosine kinase inhibitors (TKI). However, to combat acquired resistance to imatinib, an alternative approach is to decrease the expression of the addicted gene to efficiently kill resistant malignant hematologic cells. The purpose of this study was to evaluate the strategy of shutting down the transcription and expression of FIP1-like-1 (FIP1L1)–PDGFRα and Bcr-Abl with SNS-032, an inhibitor of cyclin-dependent kinase 7 (CDK7) and CDK9 in phase I clinical trials.

Experimental Design: The effects of SNS-032 on PDGFRα and Bcr-Abl signaling pathways, apoptosis, and cell cycling were analyzed in TKI-resistant cells of HES and CML. The in vivo antitumor activity of SNS-032 was assessed with xenografted BaF3-T674I FIP1L1-PDGFRα and KBM5-T315I Bcr-Abl cells in nude mouse models.

Results: SNS-032 inhibited the phosphorylation on Ser5 and Ser2 of RNA polymerase II. SNS-032 decreased both the mRNA and protein levels of FIP1L1-PDGFRα and Bcr-Abl and inhibited the proliferation of malignant cells expressing FIP1L1-PDGFRα or Bcr-Abl. It also decreased the phosphorylation of downstream molecules. It induced apoptosis by triggering both the mitochondrial pathway and the death receptor pathway.

Conclusions: This CDK7/9 inhibitor potently inhibits FIP1L1-PDGFRα–positive HES cells and Bcr-Abl–positive CML cells regardless of their sensitivity to imatinib. SNS-032 may have potential in treating hematologic malignancy by abrogating oncogene addiction. Clin Cancer Res; 18(7); 1966–78. ©2012 AACR.
Technology-neutral green procurement in practice – an example from Swedish waste management
Authors: Arvidsson Anders , Stage Jesper
Published: March 2012

Green public procurement has been criticized for its excessive reliance on detailed technology specifications, which can distort incentives in the short term and discourage innovation in the longer term. Economists therefore tend to prefer technology-neutral procurement, which rewards outcomes rather than technologies. However, technology-neutral procurement can also be problematic in practice. The present study investigated green public procurement of waste management, a rapidly growing field. In one of the most sophisticated models for technology-neutral procurement applied in Sweden in recent years, different environmental impacts were assigned weights, but no weight was given to the particular technology employed. Even here, however, potential inefficiencies were found where the scoring rule could have led to arbitrary, and presumably unwanted, outcomes. Explicitly assigning monetary surcharges to desirable and undesirable environmental effects may be a better way to reach environmental targets.
Folic acid supplementation increases survival and modulates high risk HPV-induced phenotypes in oral squamous cell carcinoma cells and correlates with p53 mRNA transcriptional down-regulation
Authors: Moody Michael , Le Oanh , Rickert Megan , Manuele Jeremy , Chang Sarah , Robinson Gary , Hajibandeh Jeffrey , Silvaroli John , Keiserman Mark A , Bergman Christine J , Kingsley Karl
Published: March 2012

Background

Although the primary risk factors for developing oral cancers are well understood, less is known about the relationship among the secondary factors that may modulate the progression of oral cancers, such as high-risk human papillomavirus (HPV) infection and folic acid (FA) supplementation. This study examined high-risk HPV and FA supplementation effects, both singly and in combination, to modulate the proliferative phenotypes of the oral cancer cell lines CAL27, SCC25 and SCC15.

Results

Using a comprehensive series of integrated in vitro assays, distinct effects of HPV infection and FA supplementation were observed. Both high-risk HPV strains 16 and 18 induced robust growth-stimulating effects in CAL27 and normal HGF-1 cells, although strain-specific responses were observed in SCC25 and SCC15 cells. Differential effects were also observed with FA administration, which significantly altered the growth rate of the oral cancer cell lines CAL27, SCC15, and SCC25, but not HGF-1 cells. Unlike HPV, FA administration induced broad, general increases in cell viability among all cell lines that were associated with p53 mRNA transcriptional down-regulation. None of these cell lines were found to harbor the common C677T mutation in methylenetetrahydrofolate reductase (MTHFR), which can reduce FA availability and may increase oral cancer risk.

Conclusion

Increased FA utilization and DNA hypermethylation are common features of oral cancers, and in these cell lines, specifically. The results of this study provide further evidence that FA antimetabolites, such as Fluorouracil (f5U or 5-FU) and Raltitrexed, may be alternative therapies for tumors resistant to other therapies. Moreover, since the incidence of oral HPV infection has been increasing, and can influence oral cancer growth, the relationship between FA bioavailability and concomitant HPV infection must be elucidated. This study is among the first pre-clinical studies to evaluate FA- and HPV-induced effects in oral cancers, both separately and in combination, which provides additional rationale for clinical screening of HPV infection prior to treatment.
Ethylene Films Adsorbed onto Purified HiPco Single Walled Carbon Nanotubes: A Comparison with Ethane and Longer Alkanes
Authors: Rawat Dinesh S. , Migone Aldo D.
Published: March 2012

The results of adsorption isotherm measurements for ethylene on purified HiPco SWNTs conducted at 11 different temperatures (between 110 K and 220 K) are reported, together with a comparison with the results we have obtained for ethane on the same substrate. Two groups of distinct binding sites were observed for ethylene on bundles of carbon nanotubes; this is in agreement with previously reported observations for ethane on this same sorbent. In addition, a consistent value of the specific surface area of the substrate was obtained from the ethylene and ethane data measured at approximately the same temperature. We have also determined the coverage dependence of the isosteric heat of adsorption for ethylene on the HiPco nanotube bundles. The reported experimental isosteric heat results are compared with simulation results for ethane and ethylene.
Removal of Cadmium Ions from Water by Synthetic Niobia
Authors: Melo Érika S. , Carvalho Kele T.G. , Oliveira Luiz C.A.
Published: March 2012

The feasibility of using synthetic niobia, both pure and modified with H2O2, as adsorbents for the removal of Cd2+ ions from aqueous solution has been studied. Different adsorption isotherms were obtained using Cd2+ ion concentrations ranging from 10 mg/ℓ to 500 mg/ℓ. At an initial pH value of 4.5, the Cd2+ ion adsorption capacity of synthetic niobia at 298 K was estimated as 182 mg/g. The Freundlich adsorption isotherm model gave the better fit to the equilibrium adsorption data for Cd2+ ions. The thermodynamic parameters for the studied system showed that the adsorption process was spontaneous and endothermic. The results obtained suggest that niobia may be employed as an efficient material for the removal of Cd2+ ions from aqueous solution.
Investigation of the Benefits of Application of Earthquake Action on the Design of Double Layer Barrel Vaults
Authors: Sadeghi Arjang , Amani Shapour
Published: March 2012

Space structures are generally light and rich in redundancy. These two characteristics caused this assumption for a while that these structures are aseismic. However, some events like Kobe 1995 earthquake, Japan, showed that although the space structures are safer than ordinary structures, but are not aseismic. A lot of research based on the seismic behavior of the space structures are carried out since then [1, 2, 3 and 4], however few of the is lead to practical results. Sadeghi in 2004 have established some formula for assessing the equivalent static earthquake action on the double layer barrel vaults. In the current work, those formulae are considered in the design of six double layer barrel vaults with different rise to span ratios and support conditions. Then the seismic behavior of these double layer barrel vaults are compared with corresponding barrel vaults which are designed without considering the seismic actions. To do this, the finite element package of ANSYS is utilized. The results show that these formulae are practically useful and versatile and application of them on the barrel vaults improves the structures' seismic safety significantly.
Shaping and Ultimate Loading of Space Trusses, Shaped by Post-Tensioning Technique
Authors: Karbaschi M. E. , Dehdashti G.
Published: March 2012

By means of post-tensioning technique, planar space trusses, particularly the single chord space trusses can be formed into curved forms. This novel process of the shape formation results in the architecturally interesting forms with the sufficient structural stability and stiffness, and with the additional advantage of being economical due to eliminating the need to use scaffolding or heavy cranes for their construction.

This paper deals with the shape formation and loading tests as well as analyses of the single chord space trusses shaped by post-tensioning technique. To validate analyses and investigate effect of curvature of the shaped models on the results, two models are included; a gently curved dome-shape and a sharply curved barrel-vault. First, shape formation analysis is carried out and next, buckling load of shaped models in loading analyses are determined and findings are compared with the experimental results. Also, effect of the residual stresses of shape formation step on the results of loading analysis is investigated.
Ladder form Rib-Ring Type of Spherical Reticulated Shells: A Novel Type of Latticed Shells
Authors: Zhang Zhi-hong , Li Zhi-qiang , Dong Shi-lin , Jian-xin  , Liu
Published: March 2012

A novel ladder form rib-ring type of spherical reticulated shell is put forward in the present paper. There are only circular members on the upper chord and only radial members on the lower chord. A triangular shear-force key composed of a horizontal and a vertical paunch bar connects the upper and the lower chord. Automatically parametric modeling of their lattices is given out in details. Structural performance of this kind of reticulated shells are analyzed and summarized. Comparison with corresponding single-layer reticulated shells is also carried out. Ladder form rib-ring type of reticulated shells in application to a practical roof system of Jiangyin swimming arena comes true.
Integration of Wind and Hydropower Systems: Results of IEA Wind Task 24
Authors: Acker Thomas L. , Robitaille André , Holttinen Hannele , Piekutowski Marian , Tande John Olav Giæver
Published: March 2012

In May of 2004, the IEA Wind Implementing Agreement (IA) established R&D Task 24, “Integration of Wind and Hydropower Systems.” Australia, Canada, Finland, Norway, Sweden, Switzerland, and the United States joined Task 24 with the goal of collaborating in the study of wind integration in a variety of electrical system configurations (load, generation, and transmission); hydro system configurations and characteristics; and market and operational configurations. Representing these countries were utilities and research organizations with the intent to understand the potential for and limiting factors in integrating wind into systems with hydropower. Case studies that analyze the feasibility, benefits, detriments, and costs of specific wind-hydro integration projects were the mechanism through which the goals of the task were addressed. The purpose of this article is to summarize the framework within which these studies were performed, and to present the key results and the general conclusions of the Task.
Planning and Operation of Large Offshore Wind Farms in Areas with Limited Power Transfer Capacity
Authors: Tande John Olav Giæver , Korpås Magnus , Uhlen Kjetil
Published: March 2012

At many locations with excellent wind conditions the wind farm development is hindered by grid issues. Conservative assumptions are often applied that unnecessarily limits the wind power installation. This paper shows that significantly more wind power can be allowed by taking proper account of the wind power characteristics and facilitating coordinated power system operation.

A systematic approach is developed for assessing grid integration of wind farms subject to grid congestions. The method is applied to a case of connecting offshore wind farms to regional grid with hydro generation (380 MW) and loads (75–350 MW). The tie to the main grid is via a corridor with limited capacity (420 MW). With conservative assumptions (i.e. no changes in scheduled hydro generation or control of wind power output) the wind power installation is limited to 115 MW.

The system operation is simulated on an hourly basis for multiple years taking into account the stochastic variations of wind speed and hydro inflow as well as the geographical distribution of wind farms. The simulation uses a control strategy for coordinated power system operation that maximises wind penetration. By using the developed methodology the wind power capacity can be increased from 115 MW to at least 600 MW with relatively little income reduction from energy sales compared to a case with unlimited grid capacity.

It is concluded that coordinated operation allows for the integration of surprisingly large amounts of wind power. In order to realize the increase in transfer capability, it is essential to take account of the power system flexibility and the stochastic and dispersed nature of wind power. The presented methodology facilitates this and represents a rational approach for power system planning of wind farms.
Wind Integration Impacts on Hydropower and System Balancing Operations in the Grant County PUD
Authors: Acker Thomas L. , Buechler Jason T. , Knitter Keith , Conway Kevin J. , Noteboom Rod
Published: March 2012

The Public Utility District No. 2 of Grant County, Washington, USA, in collaboration with the National Renewable Energy Laboratory and Northern Arizona University, conducted an analysis of the impact wind integration on their hydropower dominant generation system. Wind power penetration levels of 12 MW (2.0%), 63.7 MW (10.4%) and 150 MW (24.6%) were considered. For the 2006 study year, a statistical summary of the changes in the regulation and load following requirements expected due to wind variability was conducted. The results demonstrated that the impact of wind power upon minute-to-minute regulation requirements is small, and small to modest on the load following requirements. However, changes in the distribution of load following hourly changes could result in infringement upon system constraints. A chronological simulation of preschedule (i.e. day ahead) planning was therefore conducted indicating an increased incidence of constraint “exceedences.” The nature of the increase in exceedences is presented and discussed.
The Centrifugal Instability of a Slender Rotating Cone
Authors: Hussain Z. , Stephen S. O. , Garrett S. J.
Published: March 2012

In this study, we provide a mathematical description of the onset of counter-rotating circular vortices observed for a family of slender rotating cones (of half-angles 15° or less) in quiescent fluid. In particular, we apply appropriate scalings in order to simplify the basic-flow profiles, which are subsequently perturbed, accounting for the effects of streamline curvature. A combined large Reynolds number and large vortex wavenumber analysis is used to obtain an estimate for the asymptotic right-hand branch of neutral stability for a slender rotating cone. Our results confirm our earlier predictions pertaining to the existence of the new Görtler mode and capture the effects of the governing centrifugal instability mechanism. Meanwhile, favourable comparisons are drawn with existing numerical neutral stability curve results.
Fast Signature Scheme for Network Coding
Authors: Yang Mingxi , Yan Wenjie , Fang Huajing
Published: March 2012

It has been proven that network coding can provide significant benefits to networks, but such systems are very vulnerable to pollution attacks. In recent years, many schemes have been designed to prevent these attacks. But most of them are based on expensive operation, such as discrete logarithms and Weil pairing operations on elliptic curves, these schemes are inefficient in verifying the integrity of messages and not suitable for those scenarios with low computing capability such as mobile Ad hoc networks and wireless sensor networks. In this paper, we proposed a novel signature scheme for network coding based on a homomorphic public cryptography. This scheme can detect those polluted messages and discard them. What's more, replaying attacks are also infeasible in this scheme. The most important feature of this scheme is the improvement of the authentication efficiency with a fast computation, that is, the time complexity of the verification in our signature scheme is much less than those in the existing algorithms.
Surgical Engineering in Cranio‐Maxillofacial Surgery: A Literature Review
Authors: Olszewski Raphael
Published: March 2012

A systematic review of the literature concerning surgical engineering in cranio‐maxillofacial surgery was performed. APubMed search yielded 1721 papers published between 1999 and 2011. Based on the inclusion/exclusion criteria, 1428 articles were excluded after review of titles and abstracts. Atotal of 292 articles were finally selected covering the following topics: finite element analysis (n = 18), computer‐assisted surgery (n = 111), rapid prototyping models (n = 41), preoperative training simulators (n = 4), surgical guides (n = 23), image‐guided navigation (n = 58), augmented reality (n = 2), video tracking (n = 1), distraction osteogenesis (n = 19), robotics (n = 8), and minimal invasive surgery (n = 7). The results show that surgical engineering plays a pivotal role in the development and improvement of cranio‐maxillofacial surgery. Some technologies, such as computer‐assisted surgery, image‐guided navigation, and three‐dimensional rapid prototyping models, have reached maturity and allow for multiple clinical applications, while augmented reality, robotics, and endoscopy still need to be improved.
Experimental Impact Characterization on a Structurally Dissipating Rock-Shed (SDR) Structure
Authors: Boukria Z. , Perrotin P. , Bennani A. , Limam A.
Published: March 2012

The estimate load by direct measures for structures that are in actual use is in practice very difficult or even impossible because the impact location is inaccessible, or the projectile is deformable so can not be instrumented. The problem of identifying impact force on mechanical structures is the inverse of the direct problem: the use of measured responses on a given structure to try to identify the causes, i.e. the impact forces that are at the origin.

In this study, we developed an experimental method to identify the impact force on a reinforced concrete slab. A transfer function obtained experimentally between the acceleration response and the force history applied to a point of the structure was used. To regularize the solution obtained with this inverse problem, we used the Tikhonov method. To locate the impact force, we used an experimental method based on the minimization of an objective function created from the transfer functions between several impact locations, forming a mesh structure, and several measuring points. Characterizing the impact means locating the impactor and identifying the load.
Incompatibility Between X Chromosome Factor and Pericentric Heterochromatic Region Causes Lethality in Hybrids Between Drosophila melanogaster and Its Sibling Species
Authors: Cattani M Victoria , Presgraves Daven C
Published: March 2012

The Dobzhansky–Muller model posits that postzygotic reproductive isolation results from the evolution of incompatible epistatic interactions between species: alleles that function in the genetic background of one species can cause sterility or lethality in the genetic background of another species. Progress in identifying and characterizing factors involved in postzygotic isolation in Drosophila has remained slow, mainly because Drosophila melanogaster, with all of its genetic tools, forms dead or sterile hybrids when crossed to its sister species, D. simulans, D. sechellia, and D. mauritiana. To circumvent this problem, we used chromosome deletions and duplications from D. melanogaster to map two hybrid incompatibility loci in F1 hybrids with its sister species. We mapped a recessive factor to the pericentromeric heterochromatin of the X chromosome in D. simulans and D. mauritiana, which we call heterochromatin hybrid lethal (hhl), which causes lethality in F1 hybrid females with D. melanogaster. As F1 hybrid males hemizygous for a D. mauritiana (or D. simulans) X chromosome are viable, the lethality of deficiency hybrid females implies that a dominant incompatible partner locus exists on the D. melanogaster X. Using small segments of the D. melanogaster X chromosome duplicated onto the Y chromosome, we mapped a dominant factor that causes hybrid lethality to a small 24-gene region of the D. melanogaster X. We provide evidence suggesting that it interacts with hhlmau. The location of hhl is consistent with the emerging theme that hybrid incompatibilities in Drosophila involve heterochromatic regions and factors that interact with the heterochromatin.
Frequência e distribuição de Helicobacter spp. na mucosa gástrica de cães
Authors: Vieira Fernanda de Toledo , Silva João Carlos Pereira da , Viloria Marlene Izabel Vargas , Vieira Marcel de Toledo , Pereira Carlos Eduardo Real
Published: March 2012

A associação das helicobacterias com doença gástrica em humanos e em alguns animais domésticos e selvagens sugere a participação dessas na patogênese da gastrite em cães. Neste artigo procurou-se verificar a presença de Helicobacter spp. na mucosa gástrica de cães e avaliar sua associação com os achados macro e microscópicos, considerando a idade. Coletaram-se amostras das regiões cárdica, fúndica, do corpo e pilórica dos estômagos de 60 cães para a realização de exame histopatológico, utilizando-se as colorações pela hematoxilina-eosina (HE) e carbolfucsina (CF). Tais exames revelaram Helicobacter spp. em 96,7% dos animais, sendo observados infiltrados inflamatórios, predominantemente mononucleares (100%), hiperplasia de nódulos linfoides (98,3%), erosões/ulcerações (6,7%), hemorragia (5%) e hiperemia (95%) em amostras coradas por HE. Não houve correlação da infecção por helicobacter spp. com a idade do animal e da idade com alterações inflamatórias na presença da bactéria. As amostras das regiões do corpo e pilórica apresentaram maior presença de bactérias a histopatologia (CF) (ambos 95%), em seguida vindo as regiões fúndica (91,7%) e cárdica (56,7%). Houve correlação do número de Helicobacter spp. com o de células inflamatórias e nódulos linfoides nessas regiões, sugerindo que as bactérias encontradas na mucosa gástrica dos cães poderiam ser responsáveis pelas alterações que caracterizam a gastrite.