bluuebunny/crossref_metadata_2025_split huggingface dataset:
Simulation of Intermediate-Temperature SOFC for 60%+ Efficiency Distributed Generation
Authors: Mastropasqua Luca , Campanari Stefano , Iora Paolo , Romano Matteo Carmelo 
Published: October 2015

This work proposes a process simulation of high efficiency intermediate-temperature (660–730°C) SOFC systems for promising applications in the foreseeable future distributed power generation sector. Two case-studies have been considered: the kW-scale unit proposed by Ceramic Fuel Cell Limited (CFCL), which reaches up to 68% stack DC efficiency, and the FuelCell Energy (FCE) SOFC system, where a 65% DC efficiency has been verified on a 10 kW module. Both systems can be applied to distributed generation, yielding 60%+ net electric efficiency (LHV basis) from natural gas at small scale.
This study aims at calibrating the two considered SOFC balance of plants with the Politecnico di Milano in-house software GS. Throughout a zero-dimensional model of the complete system a validation of the manufacturer’s claimed performance is possible. The general module configuration is made up of a natural gas pre-treating processor, a SOFC stack, an anodic spent fuel combustor and a waste heat recovery system for CHP applications. A pre-reforming adiabatic reactor has been proven to be an efficient choice to reduce the higher hydrocarbon chains content in the fuel stream and therefore to lessen the burden on the anodic channel, especially in terms of solid carbon deposition. The fuel is then pre-heated and, in the FCE case-study, mixed with the anodic outlet recycle; this last solution is regarded as of utmost importance for the attainment of the high overall fuel utilisation (≈80–85%) factors necessary to reach the proposed high efficiency targets, as well as to provide the steam required by the internal reforming process.
Both the considered fuel cell systems performance have been verified and their extremely high efficient operation proven, according to those reported by their manufacturers.
In addition to the process simulation, the work lays the foundations for a more thorough SOFC stack modelling throughout a 2D in-house developed software. This analysis gives valuable insights on the geometry characterisation and on the flow arrangement, as well as on their effects on cell internal temperature and composition profiles. In particular, the proposed analysis focuses on the case of a planar cross-flow arrangement, representative of the latter of the two case-studies. The understanding of the internal behaviour of the systems provides useful information to optimise the cell performance and design.
Influence of Excess Air Factor on NOx Emissions From a 200 kW Swirl Burner
Authors: Ahmed Abdallah , Khalil Essam E. , Kayed Hatem , Hassan Mohamed M. A. 
Published: October 2015

NOx formation during the combustion process occurs mainly through the oxidation of nitrogen in the combustion air (thermal NOx) and through oxidation of nitrogen with the fuel (prompt NOx). The present study aims to investigate numerically the problem of NOx pollution using a model of combustion chamber with 200 kW swirl burner utilizing propane as fuel. The importance of this problem is mainly due to its relation to the pollutants produced by boiler furnaces and gas turbines, which used widely in thermal industrial plants. Governing conservation equations of mass, momentum and energy, and equations representing the transport of species concentrations, turbulence, combustion and radiation modeling in addition to NOx modeling equations were solved together to present temperature and OH distribution inside the combustion chamber, and the NOx concentration at the combustion chamber exit, at various operating conditions of fuel to air ratio.
In particular, the simulation provided more insight on the correlation between the peak flame temperature and the thermal NOx concentration. The results have shown that the peak flame temperature and NOx concentration decrease as the excess air factor λ increases. When considering a fixed value of mass flow rate of fuel, the results show that increasing λ results in a maximum value of thermal NOx concentration at the exit of the combustion chamber at λ = 1.05. As the combustion air temperature increases, and the thermal NOx concentration increases sharply. However, when λ exceeds this value NOx concentration starts to decrease due to the combustion air temperature decrease.
Successful Implementation of Methanol Firing at 50 MW Gas Turbine for Long Term Operation
Authors: Chudnovsky B. , Reshef M. , Keren M. , Baitel S. 
Published: October 2015

Recently methanol’s use as a fuel is becoming more attractive. Firstly, because of the prices of NG (the main feedstock for methanol production) are now at record low. This has prompted consideration of other alternative energy sources that are not oil dependent. A second key issue has been growing global concern for environment and emphasis being placed on the use of fuels with lower SO2, NOx and particulates emissions. Methanol offers these advantages, being a derivative of natural gas which partly de-linked from oil, and is a clean burning fuel.
In this manner full scale test of methanol firing at FT4C TWIN PAC 50 MWe GT designed by Pratt & Whitney was performed. The obtained results clearly show that with minor low cost fuel system retrofit methanol firing leads to significant NOx, SO2 and particulates emission reduction. NOx emissions were reduced by more than 75% and are equal 75 mg/dNm3 at 15%O2. It is less then required standard even with water injection operation mode (the standard is 86 mg/dNm3 at 15%O2 of NOx emission). SO2 emissions were reduced to zero with methanol firing. Particulate emissions vary from 1.3 to 1.6 mg/dNm3 at 15% O2 with methanol firing, while with LFO this parameter was 13–37 mg/dNm3 at 15% O2.
However, it should be noted that methanol has a significantly lower calorific value, which is, for example, half of diesel oil and requires therefore some specific modification in gas turbine equipment. First, the existing fuel nozzles are too small for the higher volumetric methanol flow and should be replaced by high flow fuel nozzles. The existing fuel supplying pump should also be upgraded to the higher methanol flow. Modulating valve was also replaced due to the same reason.
The paper first gives an overview of some of the key technical considerations of the gas turbine conversion from diesel oil to methanol firing, and results of long term operation of gas turbine fired by methanol.
Based on the obtained results one may conclude that methanol is an attractive alternative fuel for meeting the energy needs of niche markets in an economic and environmentally sustainable manner, utilizing existing and/or new power generation units.
Gallium Potentiates the Antibacterial Effect of Gentamicin against Francisella tularensis
Authors: Lindgren Helena , Sjöstedt Anders 
Published: October 2015

ABSTRACTThe reasons why aminoglycosides are bactericidal have not been not fully elucidated, and evidence indicates that the cidal effects are at least partly dependent on iron. We demonstrate that availability of iron markedly affects the susceptibility of the facultative intracellular bacteriumFrancisella tularensisstrain SCHU S4 to the aminoglycoside gentamicin. Specifically, the intracellular depots of iron were inversely correlated to gentamicin susceptibility, whereas the extracellular iron concentrations were directly correlated to the susceptibility. Further proof of the intimate link between iron availability and antibiotic susceptibility were the findings that a ΔfslAmutant, which is defective for siderophore-dependent uptake of ferric iron, showed enhanced gentamicin susceptibility and that a ΔfeoBmutant, which is defective for uptake of ferrous iron, displayed complete growth arrest in the presence of gentamicin. Based on the aforementioned findings, it was hypothesized that gallium could potentiate the effect of gentamicin, since gallium is sequestered by iron uptake systems. The ferrozine assay demonstrated that the presence of gallium inhibited >70% of the iron uptake. Addition of gentamicin and/or gallium to infected bone marrow-derived macrophages showed that both 100 μM gallium and 10 μg/ml of gentamicin inhibited intracellular growth of SCHU S4 and that the combined treatment acted synergistically. Moreover, treatment ofF. tularensis-infected mice with gentamicin and gallium showed an additive effect. Collectively, the data demonstrate that SCHU S4 is dependent on iron to minimize the effects of gentamicin and that gallium, by inhibiting the iron uptake, potentiates the bactericidal effect of gentamicinin vitroandin vivo.
Cardiac Effects of Echinocandins in Endotoxemic Rats
Authors: Koch Christian , Wolff Matthias , Henrich Michael , Weigand Markus A. , Lichtenstern Christoph , Uhle Florian 
Published: October 2015

ABSTRACT

Echinocandins are known as effective and safe agents for the prophylaxis and treatment of different cohorts of patients with fungal infections. Recent studies revealed that certain pharmacokinetics of echinocandin antifungals might impact clinical efficacy and safety in special patient populations. The aim of our study was to evaluate echinocandin-induced aggravation of cardiac impairment in septic shock. Using an
in vivo
endotoxemic shock model in rats, we assessed hemodynamic parameters and time to hemodynamic failure (THF) after additional central-venous application of anidulafungin (2.5 mg/kg of body weight [BW]), caspofungin (0.875 mg/kg BW), micafungin (3 mg/kg BW), and control (0.9% sodium chloride). In addition, echinocandin-induced cytotoxicity was evaluated in isolated rat cardiac myocytes. THF of the animals in the caspofungin group (
n
= 7) was significantly reduced compared to that in the control (
n
= 6) (136 min versus 180 min;
P
= 0.0209). The anidulafungin group (
n
= 7) also showed a trend of reduced THF (136 min versus 180 min; log-rank test
P
= 0.0578). Animals in the micafungin group (
n
= 7) did not show significant differences in THF compared to those in the control. Control group animals and also micafungin group animals did not show altered cardiac output (CO) during our experiments. In contrast, administration of anidulafungin or caspofungin induced a decrease in CO. We also revealed a dose-dependent increase of cytotoxicity in anidulafungin- and caspofungin-treated cardiac myocytes. Treatment with micafungin did not cause significantly increased cytotoxicity. Further studies are needed to explore the underlying mechanism.
A Two-Year Surveillance in Five Colombian Tertiary Care Hospitals Reveals High Frequency of Non-CG258 Clones of Carbapenem-Resistant Klebsiella pneumoniae with Distinct Clinical Characteristics
Authors: Ocampo Ana M. , Chen Liang , Cienfuegos Astrid V. , Roncancio Gustavo , Chavda Kalyan D. , Kreiswirth Barry N. , Jiménez J. Natalia 
Published: October 2015

ABSTRACTThe global spread of carbapenem-resistantKlebsiella pneumoniae(CR-Kp) has been largely associated with sequence type 258 (ST258) and its related variants (clonal group 258 [CG258]). Here we describe the molecular epidemiology of CR-Kp from five tertiary care hospitals in Medellín, the second largest city in Colombia. All CR-Kp-infected patients admitted from June 2012 to June 2014 were included (n= 193). Patients' clinical information was obtained from medical records. Carbapenemase KPC, VIM, IMP, NDM, and OXA-48 genes were detected by PCR. A CG258-tonB79cluster-specific real-time PCR (targeting the multilocus sequence type [MLST]tonB79allele), pulsed-field gel electrophoresis (PFGE), and MLST analysis were performed for typing. Remarkably, 62.2% (n= 120) of isolates were from STs unrelated to CG258 (non-CG258). KPC-3 predominated in CG258 isolates (86.3%), while KPC-2 prevailed in non-CG258 isolates (75.5%) (P< 0.001). Multidrug resistance (MDR) frequency was significantly higher in CG258 strains (91.4% versus 56.1%;P< 0.001). ST512 (a single-locus variant of ST258) is the main ST in CG258 (96.3%), and isolates in this group showed closely related pulsotype and similar resistance gene profiles, suggesting the clonal spread of this strain. In contrast, high heterogeneity of STs (34/54), including eight novel STs, was found in non-CG258 isolates. Among non-CG258 isolates, ST14 (13.3%;n= 16) and ST307 (14.2%;n= 17) were the most frequent, and they showed distinct molecular and clinical characteristics in comparison to CG258 isolates. Our results suggest that the dissemination of carbapenem resistance in Medellín is due to heterogeneousK. pneumoniaeclones, likely the result of horizontal transmission of KPC in different unrelated lineages, further highlighting the challenge in CR-Kp infection control and the need for a multifocal intervention.
Novobiocin Inhibits the Antimicrobial Resistance Acquired through DNA Damage-Induced Mutagenesis in Acinetobacter baumannii
Authors: Jara Luis M. , Pérez-Varela María , Corral Jordi , Arch Marta , Cortés Pilar , Bou Germán , Aranda Jesús , Barbé Jordi 
Published: October 2015

ABSTRACT

Acinetobacter baumannii
, a worldwide emerging nosocomial pathogen, acquires antimicrobial resistances in response to DNA-damaging agents, which increase the expression of multiple error-prone DNA polymerase components. Here we show that the aminocoumarin novobiocin, which inhibits the DNA damage response in Gram-positive bacteria, also inhibits the expression of error-prone DNA polymerases in this Gram-negative multidrug-resistant pathogen and, consequently, its potential acquisition of antimicrobial resistance through DNA damage-induced mutagenesis.
Intracellular Activation of Tenofovir Alafenamide and the Effect of Viral and Host Protease Inhibitors
Authors: Birkus Gabriel , Bam Rujuta A. , Willkom Madeleine , Frey Christian R. , Tsai Luong , Stray Kirsten M. , Yant Stephen R. , Cihlar Tomas 
Published: October 2015

ABSTRACT

Tenofovir alafenamide fumarate (TAF) is an oral phosphonoamidate prodrug of the HIV reverse transcriptase nucleotide inhibitor tenofovir (TFV). Previous studies suggested a principal role for the lysosomal serine protease cathepsin A (CatA) in the intracellular activation of TAF. Here we further investigated the role of CatA and other human hydrolases in the metabolism of TAF. Overexpression of CatA or liver carboxylesterase 1 (Ces1) in HEK293T cells increased intracellular TAF hydrolysis 2- and 5-fold, respectively. Knockdown of CatA expression with RNA interference (RNAi) in HeLa cells reduced intracellular TAF metabolism 5-fold. Additionally, the anti-HIV activity and the rate of CatA hydrolysis showed good correlation within a large set of TFV phosphonoamidate prodrugs. The covalent hepatitis C virus (HCV) protease inhibitors (PIs) telaprevir and boceprevir potently inhibited CatA-mediated TAF activation (50% inhibitory concentration [IC
50
] = 0.27 and 0.16 μM, respectively)
in vitro
and also reduced its anti-HIV activity in primary human CD4
+
T lymphocytes (21- and 3-fold, respectively) at pharmacologically relevant concentrations. In contrast, there was no inhibition of CatA or any significant effect on anti-HIV activity of TAF observed with cobicistat, noncovalent HIV and HCV PIs, or various prescribed inhibitors of host serine proteases. Collectively, these studies confirm that CatA plays a pivotal role in the intracellular metabolism of TAF, whereas the liver esterase Ces1 likely contributes to the hepatic activation of TAF. Moreover, this work demonstrates that a wide range of viral and host PIs, with the exception of telaprevir and boceprevir, do not interfere with the antiretroviral activity of TAF.
Development of an Intracellular Screen for New Compounds Able To Inhibit Mycobacterium tuberculosis Growth in Human Macrophages
Authors: Sorrentino Flavia , Gonzalez del Rio Ruben , Zheng Xingji , Presa Matilla Jesus , Torres Gomez Pedro , Martinez Hoyos Maria , Perez Herran Maria Esther , Mendoza Losana Alfonso , Av-Gay Yossef 
Published: October 2015

ABSTRACT
Here we describe the development and validation of an intracellular high-throughput screening assay for finding new antituberculosis compounds active in human macrophages. The assay consists of a luciferase-based primary identification assay, followed by a green fluorescent protein-based secondary profiling assay. Standard tuberculosis drugs and 158 previously recognized active antimycobacterial compounds were used to evaluate assay robustness. Data show that the assay developed is a short and valuable tool for the discovery of new antimycobacterial compounds.
Staphylococcus aureus Strain USA300 Perturbs Acquisition of Lysosomal Enzymes and Requires Phagosomal Acidification for Survival inside Macrophages
Authors: Tranchemontagne Zachary R. , Camire Ryan B. , O'Donnell Vanessa J. , Baugh Jessfor , Burkholder Kristin M. 
Published: October 2015

ABSTRACTMethicillin-resistantStaphylococcus aureus(MRSA) causes invasive, drug-resistant skin and soft tissue infections. Reports thatS. aureusbacteria survive inside macrophages suggest that the intramacrophage environment may be a niche for persistent infection; however, mechanisms by which the bacteria might evade macrophage phagosomal defenses are unclear. We examined the fate of theS. aureus-containing phagosome in THP-1 macrophages by evaluating bacterial intracellular survival and phagosomal acidification and maturation and by testing the impact of phagosomal conditions on bacterial viability. Multiple strains ofS. aureussurvived inside macrophages, and in studies using the MRSA USA300 clone, the USA300-containing phagosome acidified rapidly and acquired the late endosome and lysosome protein LAMP1. However, fewer phagosomes containing live USA300 bacteria than those containing dead bacteria associated with the lysosomal hydrolases cathepsin D and β-glucuronidase. Inhibiting lysosomal hydrolase activity had no impact on intracellular survival of USA300 or otherS. aureusstrains, suggesting thatS. aureusperturbs acquisition of lysosomal enzymes. We examined the impact of acidification onS. aureusintramacrophage viability and found that inhibitors of phagosomal acidification significantly impaired USA300 intracellular survival. Inhibition of macrophage phagosomal acidification resulted in a 30-fold reduction in USA300 expression of the staphylococcal virulence regulatoragrbut had little effect on expression ofsarA,saeR, orsigB. Bacterial exposure to acidic pHin vitroincreasedagrexpression. Together, these results suggest thatS. aureussurvives inside macrophages by perturbing normal phagolysosome formation and that USA300 may sense phagosomal conditions and upregulate expression of a key virulence regulator that enables its intracellular survival.
The LasB Elastase of Pseudomonas aeruginosa Acts in Concert with Alkaline Protease AprA To Prevent Flagellin-Mediated Immune Recognition
Authors: Casilag Fiordiligie , Lorenz Anne , Krueger Jonas , Klawonn Frank , Weiss Siegfried , Häussler Susanne 
Published: October 2015

ABSTRACT

The opportunistic pathogen
Pseudomonas aeruginosa
is capable of establishing severe and persistent infections in various eukaryotic hosts. It encodes a wide array of virulence factors and employs several strategies to evade immune detection. In the present study, we screened the Harvard Medical School transposon mutant library of
P. aeruginosa
PA14 for bacterial factors that modulate interleukin-8 responses in A549 human airway epithelial cells. We found that in addition to the previously identified alkaline protease AprA, the elastase LasB is capable of degrading exogenous flagellin under calcium-replete conditions and prevents flagellin-mediated immune recognition. Our results indicate that the production of two proteases with anti-flagellin activity provides a failsafe mechanism for
P. aeruginosa
to ensure the maintenance of protease-dependent immune-modulating functions.
Fimbria-Encoding Gene
yadC
Has a Pleiotropic Effect on Several Biological Characteristics and Plays a Role in Avian Pathogenic Escherichia coli Pathogenicity
Authors: Verma Renu , Rojas Thaís Cabrera Galvão , Maluta Renato Pariz , Leite Janaína Luisa , da Silva Livia Pilatti Mendes , Nakazato Gerson , Dias da Silveira Wanderley 
Published: October 2015

ABSTRACT

The extraintestinal pathogen termed avian pathogenic
Escherichia coli
(APEC) is known to cause colibacillosis in chickens. The molecular basis of APEC pathogenesis is not fully elucidated yet. In this work, we deleted a component of the Yad gene cluster (
yadC
) in order to understand the role of Yad in the pathogenicity of the APEC strain SCI-07.
In vitro
, the transcription level of
yadC
was upregulated at 41°C and downregulated at 22°C. The
yadC
expression
in vivo
was more pronounced in lungs than in spleen, suggesting a role in the early steps of the infection. Chicks infected with the wild-type and mutant strains presented, respectively, 80% and 50% mortality rates. The Δ
yadC
strain presented a slightly decreased ability to adhere to HeLa cells with or without the
d
-mannose analog compared with the wild type. Real-time PCR (RT-PCR) assays showed that
fimH
was downregulated (
P
< 0.05) and
csgA
and
ecpA
were slightly upregulated in the mutant strain, showing that
yadC
modulates expression of other fimbriae. Bacterial internalization studies showed that the Δ
yadC
strain had a lower number of intracellular bacteria recovered from Hep-2 cells and HD11 cells than the wild-type strain (
P
< 0.05). Motility assays in soft agar demonstrated that the Δ
yadC
strain was less motile than the wild type (
P
< 0.01). Curiously, flagellum-associated genes were not dramatically downregulated in the Δ
yadC
strain. Taken together, the results show that the fimbrial adhesin Yad contributes to the pathogenicity and modulates different biological characteristics of the APEC strain SCI-07.
Real-Time Imaging of Interactions of Neutrophils with Cryptococcus neoformans Demonstrates a Crucial Role of Complement C5a-C5aR Signaling
Authors: Sun Donglei , Zhang Mingshun , Liu Gongguan , Wu Hui , Zhu Xiaoping , Zhou Hong , Shi Meiqing 
Published: October 2015

ABSTRACTNeutrophils have been shown to efficiently killCryptococcus neoformans, a causative agent of meningoencephalitis. Here, using live-cell imaging, we characterize the dynamic interactions of neutrophils withC. neoformansand the underlying mechanisms in real time. Neutrophils were directly seen to chaseC. neoformanscells and then rapidly internalize them. Complement C5a-C5aR signaling guided neutrophils to migrate to the yeast cells, resulting in optimal phagocytosis and subsequent killing of the organisms. The addition of recombinant complement C5a enhanced neutrophil movement but did not induce chemotaxis, suggesting that the C5a gradient is crucial. Incubation withC. neoformansresulted in enhanced activation of Erk and p38 mitogen-activated protein (MAP) kinases (MAPKs) in neutrophils. Inhibition of the p38 MAPK pathway, but not the Erk pathway, significantly impaired neutrophil migration and its subsequent killing ofC. neoformans. Deficiency of CD11b or blocking of CD11b did not affect the migration of neutrophils towardC. neoformansbut almost completely abolished phagocytosis and killing of the organisms by neutrophils. C5a-C5aR signaling induced enhanced surface expression of CD11b. Interestingly, the original surface expression of CD11b was essential and sufficient for neutrophils to attach toC. neoformansbut was unable to mediate phagocytosis. In contrast, the enhanced surface expression of CD11b induced by C5a-C5aR signaling was essential for neutrophil phagocytosis and subsequent killing of yeast cells. Collectively, this is the first report of the dynamic interactions of neutrophils withC. neoformans, demonstrating a crucial role of C5a-C5aR signaling in neutrophil killing ofC. neoformansin real time.