bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Fuel Oilpremix Burner for Gas Turbines: Development and Initial Operating Experience
Authors: Schetter Bernhard , Schabbehard Hans Wilhelm , Josefson Ulf , Ahlberg Anders 
Published: February 2015

Premix combustion of natural gas in Siemens hybrid burners has been carried out successfully in gas turbine power plant since 1986 and has enabled NOx emissions below 10 ppm to be achieved without additional water or steam injection.
Based on this experience, the hybrid burner has been further developed for the premix combustion of fuel oil and is now in commercial operation in a Siemens Model V94.2 gas turbine at the Halmstad power plant in Sweden. The final testing of the new burners on site was carried out from January to September 1993 by courtesy of and in a fruitful cooperation with the client, SYDKRAFT AB.
This paper sets out a number of requirements for successful premix combustion of fuel oil, describes how these requirements have been met and concludes with the results of site measurements of NOx and CO emissions.
Base load NOx emissions were reduced to less than a quarter of their previous values without additional water or steam injection.
CFD Modelling of an Advanced 1600 K Reverse-Flow Combustor
Authors: Martino P. Di , Colantuoni S. , Cirillo L. , Cinque G. 
Published: February 2015

A fully-elliptic three dimensional computational fluid dynamic (CFD) code based on pressure-correction techniques has been used in the design of an advanced turbine single annular reverse-flow combustor (AR1600) under development at Alfa Romeo Avio (ARA).
Fuel injection was handled using a Lagrangian liquid droplet spray model coupled to the gas phase equations, which are solved in an Eulerian frame of reference. Turbulent transport is described by the standard k-ε model. The combustion model utilizes a conserved scalar formulation and an assumed shape probability density function to account for chemistry-turbulence interaction.
The numerical algorithm employs structured nonorthogonal curvilinear grids, node-centered variable arrangement and Cartesian velocity components.
The code was validated on a similar combustor (AR318 turboprop engine of 600 SHP). The numerical results agree well with the test measurements available for this chamber.
The aerothermal design of AR1600 (1600K exit temperature) has the same gemetrical constraints of AR318 (tip and root diameters for compressor outlet and turbine inlet), but the lenght is shorter to reduce surface area for less cooling and to utilize the excess air for more efficient mixing and combustion.
Casing Boundary Layer Control by Recess Vaned Casing for a Twin-Rotor Contra-Rotating Axial Flow Fan Unit
Authors: Roy Bhaskar , Agrawal Lokesh 
Published: February 2015

In axial compressor or fan one of the major sources of losses is uncontrolled development of casing boundary layer and its interaction with the rotating blades. These losses are aggravated in an axial compressor or fan with low aspect ratio blades due to strong secondary flow development.
The recess vaned Casing treatment has been used in a low speed contra-rotating axial flow fan unit with low aspect ratio blades. The casing treatment aims at removing casing boundary layer from near the second fan tip and inject the flow back near the first fan tip. The treatment works on a principle of automatic suction and injection. The boundary layer control mechanism is expected to be automatically adjusted by axial static pressure gradient across the vanes.
The recess vaned casing treatment has yielded significant improvement in contra-rotating fan unit performance, and has increased the surge margin, essentially through fluid flow control near the casing.
The Performance of a Low Speed One and a Half Stage Axial Turbine With Varying Rotor Tip Clearance and Tip Gap Geometry
Authors: Morphis G. , Bindon J. P. 
Published: February 2015

The performance of a low speed axial turbine followed by a second stage nozzle is measured with particular reference to the understanding of tip clearance effects in a real machine and to possible benefits of streamlined low loss rotor tips.
A radiused pressure edge was found to improve the performance of b single stage and of a one and a half stage turbine at the small tip clearance levels for which the radius was selected. This is in contrast to cascade results where mixing loss reduced the benefits of such tips. Clearance gap flow appears therefore to be just like other turbine flow where the loss mechanism of separation must be avoided. Loss formation within and downstream of a rotor are more complex than previously realized and do not obey the simple rules that have been used to design for minimum tip clearance loss. For example, approximately 48% of the tip leakage mass flow within a rotor appears to be a flat wall jet rather than a wrapped up vortex.
The second stage nozzle efficiency was found to be significantly higher than for the first stage and to even increase with tip clearance. This is a surprising result since it means that not only is there a reduction in secondary flow loss but also that rotor leakage and rotor secondary flows do not generate downstream mixing loss.
Gas Turbine Units for Pipeline Compressor Stations: Environmental Update Problems
Authors: Sudarev A. V. , Zakharov Y. I. , Vinogradov E. D. , Vesely S. , Poslushny G. 
Published: February 2015

The exhaust of nitrogen oxides into atmosphere is the most stringent environmental challenge in the operation of gas pipeline gas turbine plants. In 1991–1993 NITI EM along with EKOL retrofitted over 170 GTK-10 and GT-750-6 type gas turbine combustors of the “Tyumentransgas” and “Transit” (Czech Republic) gas transmission enterprises. Operations were carried out directly at the gas pumping stations.
Emissions of the retrofitted units are within a range of 135–175 mg/Nm3 of oxides of nitrogen (NOx) referred to 15% O2 and carbon monoxide (CO) content of the exhaust gases does not exceed 100 mg/Nm3, at 15% O2.
Image quality dependency on system configuration and tube voltage in chest tomosynthesis—A visual grading study using an anthropomorphic chest phantom
Authors: Söderman Christina , Asplund Sara , Allansdotter Johnsson Åse , Vikgren Jenny , Rossi Norrlund Rauni , Molnar David , Svalkvist Angelica , Gunnar Månsson Lars , Båth Magnus 
Published: February 2015

Purpose:To investigate the potential benefit of increasing the dose per projection image in chest tomosynthesis, performed at the current standard dose level, by reducing the angular range covered or the projection image density and to evaluate the influence of the tube voltage on the image quality.Methods:An anthropomorphic chest phantom was imaged using nine different projection image configurations and ten different tube voltages with the GE VolumeRAD tomosynthesis system. The resulting image sets were representative of being acquired at the same total effective dose. This was achieved partly by applying a simulated dose reduction to the projection images due to restrictions concerning the tube load settings on the VolumeRAD system. Four observers were included in a visual grading study where the reconstructed tomosynthesis section images were rated according to a set of image quality criteria. Image quality was evaluated relative to the default configuration and default tube voltage on the VolumeRAD system.Results:Overall, the image quality decreased with decreasing projection image density. Regarding angular range covered by the projection images, the image quality increased with decreasing angular range for two of the criteria, whereas for a criterion related to the depth resolution in the section images the reduced angular ranges resulted in inferior image quality as compared to the default configuration. The image quality showed little dependence on the tube voltage.Conclusions:At the standard dose level of the VolumeRAD system, the potential benefits from increasing the dose per projection do not fully compensate for the negative effects resulting from a reduction in the number of projection images. Consequently, the default configuration consisting of 60 projection images acquired over 30° is a good alternative. The tube voltage used in tomosynthesis does not have a large impact on the image quality.
Antileishmanial Effect of 18β-Glycyrrhetinic Acid Is Mediated by Toll-Like Receptor-Dependent Canonical and Noncanonical p38 Activation
Authors: Gupta Purnima , Das Pijush K. , Ukil Anindita 
Published: February 2015

ABSTRACT18β-Glycyrrhetinic acid (GRA), a natural immunomodulator, greatly reduced the parasite load in experimental visceral leishmaniasis through nitric oxide (NO) upregulation, proinflammatory cytokine expression, and NF-κB activation. For the GRA-mediated effect, the primary kinase responsible was found to be p38, and analysis of phosphorylation kinetics as well as studies with dominant-negative (DN) constructs revealed mitogen-activated protein kinase kinase 3 (MKK3) and MKK6 as the immediate upstream regulators of p38. However, detection of remnant p38 kinase activity in the presence of both DN MKK3 and MKK6 suggested alternative pathways of p38 activation. That residual p38 activity was attributed to an autophosphorylation event ensured by the transforming growth factor β-activated kinase 1 (TAK1)-binding protein 1 (TAB1)-p38 interaction and was completely abolished upon pretreatment with SB203580 in DN MKK3/6 double-transfected macrophage cells. Further upstream signaling evaluation by way of phosphorylation kinetics and transfection studies with DN constructs identified TAK1, myeloid differentiation factor 88 (MyD88), interleukin 1 receptor (IL-1R)-activated kinase 1 (IRAK1), and tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) as important contributors to GRA-mediated macrophage activation. Finally, gene knockdown studies revealed Toll-like receptor 2 (TLR2) and TLR4 as the membrane receptors associated with GRA-mediated antileishmanial activity. Together, the results of this study brought mechanistic insight into the antileishmanial activity of GRA, which is dependent on the TLR2/4-MyD88 signaling axis, leading to MKK3/6-mediated canonical and TAB1-mediated noncanonical p38 activation.
The Mu Subunit of Plasmodium falciparum Clathrin-Associated Adaptor Protein 2 Modulates
In Vitro
Parasite Response to Artemisinin and Quinine
Authors: Henriques Gisela , van Schalkwyk Donelly A. , Burrow Rebekah , Warhurst David C. , Thompson Eloise , Baker David A. , Fidock David A. , Hallett Rachel , Flueck Christian , Sutherland Colin J. 
Published: February 2015

ABSTRACT

The emergence of drug-resistant parasites is a serious threat faced by malaria control programs. Understanding the genetic basis of resistance is critical to the success of treatment and intervention strategies. A novel locus associated with antimalarial resistance,
ap2-mu
(encoding the mu chain of the adaptor protein 2 [AP2] complex), was recently identified in studies on the rodent malaria parasite
Plasmodium chabaudi
(
pcap2-mu
). Furthermore, analysis in Kenyan malaria patients of polymorphisms in the
Plasmodium falciparum
ap2-mu
homologue,
pfap2-mu
, found evidence that differences in the amino acid encoded by codon 160 are associated with enhanced parasite survival
in vivo
following combination treatments which included artemisinin derivatives. Here, we characterize the role of
pfap2-mu
in mediating the
in vitro
antimalarial drug response of
P. falciparum
by generating transgenic parasites constitutively expressing codon 160 encoding either the wild-type Ser (Ser160) or the Asn mutant (160Asn) form of
pfap2-mu
. Transgenic parasites carrying the
pfap2-mu
160Asn allele were significantly less sensitive to dihydroartemisinin using a standard 48-h
in vitro
test, providing direct evidence of an altered parasite response to artemisinin. Our data also provide evidence that
pfap2-mu
variants can modulate parasite sensitivity to quinine. No evidence was found that
pfap2-mu
variants contribute to the slow-clearance phenotype exhibited by
P. falciparum
in Cambodian patients treated with artesunate monotherapy. These findings provide compelling evidence that
pfap2-mu
can modulate
P. falciparum
responses to multiple drugs. We propose that this gene should be evaluated further as a potential molecular marker of antimalarial resistance.
Eravacycline (TP-434) Is Efficacious in Animal Models of Infection
Authors: Grossman Trudy H. , Murphy Timothy M. , Slee Andrew M. , Lofland Denene , Sutcliffe Joyce A. 
Published: February 2015

ABSTRACT

Eravacycline is a novel broad-spectrum fluorocycline antibiotic being developed for a wide range of serious infections. Eravacycline was efficacious in mouse septicemia models, demonstrating 50% protective dose (PD
50
) values of ≤1 mg/kg of body weight once a day (q.d.) against
Staphylococcus aureus
, including tetracycline-resistant isolates of methicillin-resistant
S. aureus
(MRSA), and
Streptococcus pyogenes
. The PD
50
values against
Escherichia coli
isolates were 1.2 to 4.4 mg/kg q.d. In neutropenic mouse thigh infection models with methicillin-sensitive
S. aureus
(MSSA) and
S. pyogenes
, eravacycline produced 2 log
10
reductions in CFU at single intravenous (i.v.) doses ranging from 0.2 to 9.5 mg/kg. In a neutropenic mouse lung infection model, eravacycline administered i.v. at 10 mg/kg twice a day (b.i.d.) reduced the level of tetracycline-resistant MRSA in the lung equivalent to that of linezolid given orally (p.o.) at 30 mg/kg b.i.d. At i.v. doses of 3 to 12 mg/kg b.i.d., eravacycline was more efficacious against tetracycline-resistant
Streptococcus pneumoniae
in a neutropenic lung infection model than linezolid p.o. at 30 mg/kg b.i.d. Eravacycline showed good efficacy at 2 to 10 mg/kg i.v. b.i.d., producing up to a 4.6 log
10
CFU reduction in kidney bacterial burden in a model challenged with a uropathogenic
E. coli
isolate. Eravacycline was active in multiple murine models of infection against clinically important Gram-positive and Gram-negative pathogens.
Avibactam and Inhibitor-Resistant SHV β-Lactamases
Authors: Winkler Marisa L. , Papp-Wallace Krisztina M. , Taracila Magdalena A. , Bonomo Robert A. 
Published: February 2015

ABSTRACT

β-Lactamase enzymes (EC 3.5.2.6) are a significant threat to the continued use of β-lactam antibiotics to treat infections. A novel non-β-lactam β-lactamase inhibitor with activity against many class A and C and some class D β-lactamase variants, avibactam, is now available in the clinic in partnership with ceftazidime. Here, we explored the activity of avibactam against a variety of characterized isogenic laboratory constructs of β-lactamase inhibitor-resistant variants of the class A enzyme SHV (M69I/L/V, S130G, K234R, R244S, and N276D). We discovered that the S130G variant of SHV-1 shows the most significant resistance to inhibition by avibactam, based on both microbiological and biochemical characterizations. Using a constant concentration of 4 mg/liter of avibactam as a β-lactamase inhibitor in combination with ampicillin, the MIC increased from 1 mg/liter for
bla
SHV-1
to 256 mg/liter for
bla
SHV S130G
expressed in
Escherichia coli
DH10B. At steady state, the
k
2
/
K
value of the S130G variant when inactivated by avibactam was 1.3 M
−1
s
−1
, versus 60,300 M
−1
s
−1
for the SHV-1 β-lactamase. Under timed inactivation conditions, we found that an approximately 1,700-fold-higher avibactam concentration was required to inhibit SHV S130G than the concentration that inhibited SHV-1. Molecular modeling suggested that the positioning of amino acids in the active site of SHV may result in an alternative pathway of inactivation when complexed with avibactam, compared to the structure of CTX-M-15–avibactam, and that S130 plays a role in the acylation of avibactam as a general acid/base. In addition, S130 may play a role in recyclization. As a result, we advance that the lack of a hydroxyl group at position 130 in the S130G variant of SHV-1 substantially slows carbamylation of the β-lactamase by avibactam by (i) removing an important proton acceptor and donator in catalysis and (ii) decreasing the number of H bonds. In addition, recyclization is most likely also slow due to the lack of a general base to initiate the process. Considering other inhibitor-resistant mechanisms among class A β-lactamases, S130 may be the most important amino acid for the inhibition of class A β-lactamases, perhaps even for the novel diazabicyclooctane class of β-lactamase inhibitors.
A Novel Tricyclic Ligand-Containing Nonpeptidic HIV-1 Protease Inhibitor, GRL-0739, Effectively Inhibits the Replication of Multidrug-Resistant HIV-1 Variants and Has a Desirable Central Nervous System Penetration Property
In Vitro
Authors: Amano Masayuki , Tojo Yasushi , Salcedo-Gómez Pedro Miguel , Parham Garth L. , Nyalapatla Prasanth R. , Das Debananda , Ghosh Arun K. , Mitsuya Hiroaki 
Published: February 2015

ABSTRACT

We report here that GRL-0739, a novel nonpeptidic HIV-1 protease inhibitor containing a tricycle (cyclohexyl-
bis
-tetrahydrofuranylurethane [THF]) and a sulfonamide isostere, is highly active against laboratory HIV-1 strains and primary clinical isolates (50% effective concentration [EC
50
], 0.0019 to 0.0036 μM), with minimal cytotoxicity (50% cytotoxic concentration [CC
50
], 21.0 μM). GRL-0739 blocked the infectivity and replication of HIV-1
NL4-3
variants selected by concentrations of up to 5 μM ritonavir or atazanavir (EC
50
, 0.035 to 0.058 μM). GRL-0739 was also highly active against multidrug-resistant clinical HIV-1 variants isolated from patients who no longer responded to existing antiviral regimens after long-term antiretroviral therapy, as well as against the HIV-2
ROD
variant. The development of resistance against GRL-0739 was substantially delayed compared to that of amprenavir (APV). The effects of the nonspecific binding of human serum proteins on the anti-HIV-1 activity of GRL-0739 were insignificant. In addition, GRL-0739 showed a desirable central nervous system (CNS) penetration property, as assessed using a novel
in vitro
blood-brain barrier model. Molecular modeling demonstrated that the tricyclic ring and methoxybenzene of GRL-0739 have a larger surface and make greater van der Waals contacts with protease than in the case of darunavir. The present data demonstrate that GRL-0739 has desirable features as a compound with good CNS-penetrating capability for treating patients infected with wild-type and/or multidrug-resistant HIV-1 variants and that the newly generated cyclohexyl-
bis
-THF moiety with methoxybenzene confers highly desirable anti-HIV-1 potency in the design of novel protease inhibitors with greater CNS penetration profiles.
Characterization of a Large Cluster of Influenza A(H1N1)pdm09 Viruses Cross-Resistant to Oseltamivir and Peramivir during the 2013-2014 Influenza Season in Japan
Authors: Takashita Emi , Kiso Maki , Fujisaki Seiichiro , Yokoyama Masaru , Nakamura Kazuya , Shirakura Masayuki , Sato Hironori , Odagiri Takato , Kawaoka Yoshihiro , Tashiro Masato 
Published: February 2015

ABSTRACT

Between September 2013 and July 2014, 2,482 influenza 2009 pandemic A(H1N1) [A(H1N1)pdm09] viruses were screened in Japan for the H275Y substitution in their neuraminidase (NA) protein, which confers cross-resistance to oseltamivir and peramivir. We found that a large cluster of the H275Y mutant virus was present prior to the main influenza season in Sapporo
/
Hokkaido, with the detection rate for this mutant virus reaching 29% in this area. Phylogenetic analysis suggested the clonal expansion of a single mutant virus in Sapporo
/
Hokkaido. To understand the reason for this large cluster, we examined the
in vitro
and
in vivo
properties of the mutant virus. We found that it grew well in cell culture, with growth comparable to that of the wild-type virus. The cluster virus also replicated well in the upper respiratory tract of ferrets and was transmitted efficiently between ferrets by way of respiratory droplets. Almost all recently circulating A(H1N1)pdm09 viruses, including the cluster virus, possessed two substitutions in NA, V241I and N369K, which are known to increase replication and transmission fitness. A structural analysis of NA predicted that a third substitution (N386K) in the NA of the cluster virus destabilized the mutant NA structure in the presence of the V241I and N369K substitutions. Our results suggest that the cluster virus retained viral fitness to spread among humans and, accordingly, caused the large cluster in Sapporo/Hokkaido. However, the mutant NA structure was less stable than that of the wild-type virus. Therefore, once the wild-type virus began to circulate in the community, the mutant virus could not compete and faded out.
Amplification of
pfmdr1
,
pfcrt
,
pvmdr1
, and K13 Propeller Polymorphisms Associated with Plasmodium falciparum and Plasmodium vivax Isolates from the China-Myanmar Border
Authors: Feng Jun , Zhou Daili , Lin Yingxue , Xiao Huihui , Yan He , Xia Zhigui 
Published: February 2015

ABSTRACT

Malaria in the China-Myanmar border region is still severe; local transmission of both falciparum and vivax malaria persists, and there is a risk of geographically expanding antimalarial resistance. In this research, the
pfmdr1
,
pfcrt
,
pvmdr1
, and K13-propeller genotypes were determined in 26
Plasmodium falciparum
and 64
Plasmodium vivax
isolates from Yingjiang county of Yunnan province. The
pfmdr1
(11.5%),
pfcrt
(34.6%), and
pvmdr1
(3.1%) mutations were prevalent at the China-Myanmar border. The indigenous samples exhibited prevalences of 14.3%, 28.6%, and 14.3% for
pfmdr1
N86Y,
pfcrt
K76T, and
pfcrt
M74I, respectively, whereas the samples from Myanmar showed prevalences of 10.5%, 21.1%, and 5.3%, respectively. The most prevalent genotypes of
pfmdr1
and
pfcrt
were Y
86
Y
184
and M
74
N
75
T
76
, respectively. No
pvmdr1
mutation occurred in the indigenous samples but was observed in two cases coming from Myanmar. In addition, we are the first to report on 10 patients (38.5%) with five different K13 point mutations. The F446I allele is predominant (19.2%), and its prevalence was 28.6% in the indigenous samples of Yingjiang county and 15.8% in samples from Myanmar. The present data might be helpful for enrichment of the molecular surveillance of antimalarial resistance and useful for developing and updating guidance for the use of antimalarials in this region.