bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sensitivity Analysis on Brayton Cycle Gas Turbine Performance
Authors: Negri di Montenegro G. , Peretto A. 
Published: January 2015

This paper evaluates the performance of a Brayton cycle gas turbine, in terms of power output and conversion efficiency.
Sensitivity on this performance due to the realistic value of each input variable considered is analyzed.
Sensitivity is evaluated by introducing a parameter, defined as the ratio between the logarithmic differential of the power output or efficiency functions and the logarithmic differential of each variable considered. These analytical functions and their derivatives correspond to a gas turbine model developed by the Authors.
The above-mentioned sensitivity parameter can be also evaluated by means of a numerical procedure utilizing a common gas turbine power plant computational model.
The values calculated with the two procedures turn out to be substantially the same.
Finally, the present analysis permits the determination of the weight of the input variable and of its value on the obtainable numerical performance. Such weights are found to be less important for some variables, while they are of marked significance for others, thus indicating those input parameters requiring a very precise verification of their numerical values.
25MW Class Modern Industrial Gas Turbine Suitable for Wide Range of Applications in CoGen/CC Power Plants
Authors: Stankiewicz Chuck , van der Linden Septimus 
Published: January 2015

The GT10 25MW class industrial gas turbine from ABB has seen a rapid success in power as well as heat generation for utilities, district heating plants, refineries, communities, universities, paper & food, cement and petrochemical industries.
This broad application attests to the versatility of a modern gas turbine benefiting from advanced technology concepts in combustion, as well as turbine component efficiencies. The paper will review these developments and some interesting applications that could benefit dispersed industrial power plants in the fast developing economies of South East Asia.
Modified Rankine HRSG Beats Triple-Pressure System
Authors: Eisenkolb Peter , Pogoreutz Martin , Halozan Hermann 
Published: January 2015

Gas-fired combined cycle power plants (CCP) are presently the most efficient systems for producing electricity with fossil fuels. Gas turbines have been and are being improved remarkably during the last years; presently they achieve efficiencies of more than 38% and gas turbine outlet temperatures of up to 610°C.
These high outlet temperatures require modifications and improvements of heat recovery steam generators (HRSG). Presently dual pressure HRSGs are most commonly used in combined cycle power stations. The next step seems to be the triple-pressure HRSG to be able to utilise the high gas turbine outlet temperatures efficiently and to reduce exergy losses caused by the heat transfer between exhaust gas and the steam cycle. However, such triple-pressure systems are complicated considering parallel tube bundles as well as start up operation and load changes.
For that reason an attempt has been made to replace such multiple pressure systems by a modified Rankine cycle with only a single-pressure level. In the case of the same total heat transfer surfaces this innovative single-pressure system achieves approximately the same efficiency as the triple-pressure system. By optimising the heat recovery from the exhaust gas to the steam/water cycle, i.e. minimising exergy losses, the stack temperature is much higher. Increasing the heat transfer surfaces means a decrease of the stack temperature and a further improvement of the overall CCP-efficiency.
Therefore one has to be aware that the proposed system offers advantages not only in the case of a foreseeable increase of gas turbine outlet temperatures but also for presently available gas turbines. Using existing highly efficient gas turbines and subcritical steam conditions, power plants with this proposed Eisenkolb Single Pressure (ESP_CCP) heat recovery steam generator achieve thermal efficiencies of about 58.7% (LHV).
Advanced Combined Cycle Alternatives With the Latest Gas Turbines
Authors: Dechamps P. J. 
Published: January 2015

The last decade has seen remarkable improvements in industrial gas turbine size and performances. There is no doubt that the coming years are holding the promises of even more progress in these fields.
As a consequence, the fuel utilization achieved by combined cycle power plants has been steadily increased. This is however also because of the developments in the heat recovery technology.
Advances on the gas turbine side justify the development of new combined cycle schemes, with more advanced heat recovery capabilities. Hence, the system performance is spiralling upwards.
In this paper, we look at some of the heat recovery possibilities with the newly available gas turbine engines, characterized by a high exhaust temperature, a high specific work, and the integration of some gas turbine cooling with the boiler.
The schemes range from classical dual pressure systems, to triple pressure systems with reheat in supercritical steam conditions. For each system, an optimum set of variables (steam pressures, etc) is proposed. The effect of some changes on the steam cycle parameters, like increasing the steam temperatures above 570°C are also considered. Emphasis is also put on the influence of some special features or arrangements of the heat recovery steam generators, not only from a thermodynamic point of view.
Propulsion Integration Aspects in Advanced Military Aircraft
Authors: Herrmann P. 
Published: January 2015

Back in history, propulsion integration into an aircraft was mainly related to physical aspects requiring only a low degree of sophistication.
Today propulsion integration has become a major task split between airframe and engine engineers. It now includes performance, functional and physical aspects all needing to be integrated to meet specific requirements.
The aircraft and engine configurations are therefore optionised simultaneously at a very early stage of development. Some of the major interfaces influencing configuration, performance and operability will be discussed, ie. Intake/Engine/Afterbody; Electronic Controls Integration including monitoring; Performance optimisation; Systems; Installation.
Characterization of High-Level Daptomycin Resistance in Viridans Group Streptococci Developed upon
In Vitro
Exposure to Daptomycin
Authors: Akins Ronda L. , Katz Bradley D. , Monahan Catherine , Alexander Dylan 
Published: January 2015

ABSTRACT

Viridans group streptococci (VGS) are part of the normal flora that may cause bacteremia, often leading to endocarditis. We evaluated daptomycin against four clinical strains of VGS (MICs = 1 or 2 μg/ml) using an
in vitro
-simulated endocardial vegetation model, a simulated bacteremia model, and kill curves. Daptomycin exposure was simulated at 6 mg/kg of body weight and 8 mg/kg every 24 h for endocardial and bacteremia models. Total drug concentrations were used for analyses containing protein (albumin and pooled human serum), and free (unbound) drug concentrations (93% protein bound) were used for analyses not containing protein. Daptomycin MICs in the presence of protein were significantly higher than those in the absence of protein. Despite MICs below or at the susceptible breakpoint, all daptomycin regimens demonstrated limited kill in both pharmacodynamic models. A reduction of approximately 1 to 2 log
10
CFU was seen for all isolates and dosages except daptomycin at 6 mg/kg, which achieved a reduction of 2.7 log
10
CFU/g against one strain (
Streptococcus gordonii
1649) in the endocardial model. Activity was similar in both pharmacodynamic models in the presence or absence of protein. Similar activity was noted in the kill curves over all multiples of the MIC. Regrowth by 24 h was seen even at 8× MIC. Postexposure daptomycin MICs for both pharmacodynamic models increased to >256 μg/ml for all isolates by 24 and 72 h. Despite susceptibility to daptomycin by standard MIC methods, these VGS developed high-level daptomycin resistance (HLDR) after a short duration following drug exposure not attributed to modification or inactivation of daptomycin. Further evaluation is warranted to determine the mechanism of resistance and clinical implications.
Staphylococcal Persistence Due to Biofilm Formation in Synovial Fluid Containing Prophylactic Cefazolin
Authors: Dastgheyb Sana S. , Hammoud Sommer , Ketonis Constantinos , Liu Andrew Yongkun , Fitzgerald Keith , Parvizi Javad , Purtill James , Ciccotti Michael , Shapiro Irving M. , Otto Michael , Hickok Noreen J. 
Published: January 2015

ABSTRACT

Antibiotic prophylaxis is standard for patients undergoing surgical procedures, yet despite the wide use of antibiotics, breakthrough infections still occur. In the setting of total joint arthroplasty, such infections can be devastating. Recent findings have shown that synovial fluid causes marked staphylococcal aggregation, which can confer antibiotic insensitivity. We therefore asked in this study whether clinical samples of synovial fluid that contain preoperative prophylactic antibiotics can successfully eradicate a bacterial challenge by pertinent bacterial species. This study demonstrates that preoperative prophylaxis with cefazolin results in high antibiotic levels. Furthermore, we show that even with antibiotic concentrations that far exceed the expected bactericidal levels,
Staphylococcus aureus
bacteria added to the synovial fluid samples are not eradicated and are able to colonize model implant surfaces, i.e., titanium pins. Based on these studies, we suggest that current prophylactic antibiotic choices, despite high penetration into the synovial fluid, may need to be reexamined.
Identification of Metal Dithiocarbamates as a Novel Class of Antileishmanial Agents
Authors: Pal Dhiman Sankar , Mondal Dipon Kumar , Datta Rupak 
Published: January 2015

ABSTRACT

Dithiocarbamates have emerged as potent carbonic anhydrase (CA) inhibitors in recent years. Given that CAs are important players in cellular metabolism, the objective of this work was to exploit the CA-inhibitory property of dithiocarbamates as a chemotherapeutic weapon against the
Leishmania
parasite. We report here strong antileishmanial activity of three hitherto unexplored metal dithiocarbamates, maneb, zineb, and propineb. They inhibited CA activity in
Leishmania major
promastigotes at submicromolar concentrations and resulted in a dose-dependent inhibition of parasite growth. Treatment with maneb, zineb, and propineb caused morphological deformities of the parasite and
Leishmania
cell death with 50% lethal dose (LD
50
) values of 0.56 μM, 0.61 μM, and 0.27 μM, respectively. These compounds were even more effective against parasites growing in acidic medium, in which their LD
50
values were severalfold lower. Intracellular acidosis leading to apoptotic and necrotic death of
L. major
promastigotes was found to be the basis of their leishmanicidal activity. Maneb, zineb, and propineb also efficiently reduced the intracellular parasite burden, suggesting that amastigote forms of the parasite are also susceptible to these metal dithiocarbamates. Interestingly, mammalian cells were unaffected by these compounds even at concentrations which are severalfold higher than their antileishmanial LD
50
s). Our data thus establish maneb, zineb, and propineb as a new class of antileishmanial compounds having broad therapeutic indices.
CD4+T Cell Hyporesponsiveness after Repeated Exposure to Schistosoma mansoni Larvae Is Dependent upon Interleukin-10
Authors: Prendergast Catriona T. , Sanin David E. , Cook Peter C. , Mountford Adrian P. 
Published: January 2015

ABSTRACTThe effect that multiple percutaneous exposures toSchistosomalarvae has on the development of early CD4+lymphocyte reactivity is unclear, yet it is important in the context of humans living in areas where schistosomiasis is endemic. In a murine model of multiple infections, we show that exposure of mice to repeated doses (4×) ofSchistosoma mansonicercariae, compared to a single dose (1×), results in CD4+T cell hyporesponsiveness within the skin-draining lymph nodes (sdLN), manifested as reduced CD4+cell proliferation and cytokine production. FoxP3+CD4+regulatory T cells were present in similar numbers in the sdLN of 4× and 1× mice and thus are unlikely to have a role in effecting hyporesponsiveness. Moreover, anergy of the CD4+cell population from 4× mice was slight, as proliferation was only partly circumvented through thein vitroaddition of exogenous interleukin-2 (IL-2), and thein vivoblockade of the regulatory molecule PD1 had a minimal effect on restoring responsiveness. In contrast, IL-10 was observed to be critical in mediating hyporesponsiveness, as CD4+cells from the sdLN of 4× mice deficient for IL-10 were readily able to proliferate, unlike those from 4× wild-type cohorts. CD4+cells from the sdLN of 4× mice exhibited higher levels of apoptosis and cell death, but in the absence of IL-10, there was significantly less cell death. Combined, our data show that IL-10 is a key factor in the development of CD4+T cell hyporesponsiveness after repeated parasite exposure involving CD4+cell apoptosis.
BaeSR, Involved in Envelope Stress Response, Protects against Lysogenic Conversion by Shiga Toxin 2-Encoding Phages
Authors: Imamovic Lejla , Martínez-Castillo Alexandre , Benavides Carmen , Muniesa Maite 
Published: January 2015

ABSTRACT

Infection and lysogenic conversion with Shiga toxin-encoding bacteriophages (Stx phages) drive the emergence of new Shiga toxin-producing
Escherichia coli
strains. Phage attachment to the bacterial surface is the first stage of phage infection. Envelope perturbation causes activation of envelope stress responses in bacterial cells. Although many external factors are known to activate envelope stress responses, the role of these responses in the phage-bacterium interaction remains unexplored. Here, we investigate the link between three envelope signaling systems in
E. coli
(RcsBC, CpxAR, and BaeSR) and Stx2 phage infection by determining the success of bacterial lysogenic conversion. For this purpose,
E. coli
DH5α wild-type (WT) and mutant strains lacking RcsBC, CpxAR, or BaeSR signaling systems were incubated with a recombinant Stx2 phage (933W). Notably, the number of lysogens obtained with the BaeSR mutant was 5 log
10
units higher than with the WT, and the same differences were observed when using 7 different Stx2 phages. To assess whether the membrane receptor used by Stx phages, BamA, was involved in the differences observed,
bamA
gene expression was monitored by reverse transcription-quantitative PCR (RT-qPCR) in all host strains. A 4-fold-higher
bamA
expression level was observed in the BaeSR mutant than in the WT strain, suggesting that differential expression of the receptor used by Stx phages accounted for the increase in the number of lysogenization events. Establishing the link between the role of stress responses and phage infection has important implications for understanding the factors affecting lysogenic conversion, which drives the emergence of new pathogenic clones.
An Electrostatic Interaction between BlpC and BlpH Dictates Pheromone Specificity in the Control of Bacteriocin Production and Immunity in Streptococcus pneumoniae
Authors: Pinchas Marisa D. , LaCross Nathan C. , Dawid Suzanne 
Published: January 2015

ABSTRACTTheblplocus ofStreptococcus pneumoniaesecretes and regulates bacteriocins, which mediate both intra- and interspecific competition in the human nasopharynx. There are four major alleles of the geneblpH, which encodes the receptor responsible for activating theblplocus when bound to one of four distinct peptide pheromones (BlpC). The allelic variation ofblpHis presumably explained by a need to restrict cross talk between competing strains. The BlpH protein sequences have polymorphisms distributed throughout the sequence, making identification of the peptide binding site difficult to predict. To identify the pheromone binding sites that dictate pheromone specificity, we have characterized the four major variants and two naturally occurring chimeric versions ofblpHin which recombination events appear to have joined two distinctblpHalleles together. Using these allelic variants, a series of laboratory-generated chimericblpHalleles, and site-directed mutants of both the receptor and peptide, we have demonstrated that BlpC binding to some BlpH types involves an electrostatic interaction between the oppositely charged residues of BlpC and the first transmembrane domain of BlpH. An additional recognition site was identified in the second extracellular loop. We identified naturally occurring BlpH types that have the capacity to respond to more than one BlpC type; however, this change in specificity results in a commensurate drop in overall sensitivity. These natural recombination events were presumably selected for to balance the need to sense bacteriocin-secreting neighbors with the need to turn on bacteriocin production at a low density.IMPORTANCEBacteria use quorum sensing to optimize gene expression to accommodate for local bacterial density and diffusion rates. To prevent interception of quorum-sensing signals by neighboring strains, the genomes of single species often encode strain-specific signal/receptor pairs. Theblplocus inStreptococcus pneumoniaethat drives bacteriocin secretion is controlled by quorum sensing that involves the interaction of the signal/receptor pair BlpC/BlpH. We show that the pneumococcal population can be divided into several distinct BlpC/BlpH pairs; however, there are examples of naturally occurring chimeric receptors that can bind to more than one BlpC type. The trade-off for this broadened specificity is a loss of overall receptor sensitivity. This suggests that under certain conditions, the advantage of signal interception can trump the requirements for self-induction.
Deletion of a 77-Base-Pair Inverted Repeat Element Alters the Synthesis of Surface Polysaccharides in Porphyromonas gingivalis
Authors: Bainbridge Brian W. , Hirano Takanori , Grieshaber Nicole , Davey Mary E. 
Published: January 2015

ABSTRACT

Bacterial cell surface glycans, such as capsular polysaccharides and lipopolysaccharides (LPS), influence host recognition and are considered key virulence determinants. The periodontal pathogen
Porphyromonas gingivalis
is known to display at least three different types of surface glycans: O-LPS, A-LPS, and K-antigen capsule. We have shown that PG0121 (in strain W83) encodes a DNABII histone-like protein and that this gene is transcriptionally linked to the K-antigen capsule synthesis genes, generating a large ∼19.4-kb transcript (PG0104-PG0121). Furthermore, production of capsule is deficient in a PG0121 mutant strain. In this study, we report on the identification of an antisense RNA (asRNA) molecule located within a 77-bp inverted repeat (77bpIR) element located near the 5′ end of the locus. We show that overexpression of this asRNA decreases the amount of capsule produced, indicating that this asRNA can impact capsule synthesis
in trans
. We also demonstrate that deletion of the 77bpIR element and thereby synthesis of the large 19.4-kb transcript also diminishes, but does not eliminate, capsule synthesis. Surprisingly, LPS structures were also altered by deletion of the 77bpIR element, and reactivity to monoclonal antibodies specific to both O-LPS and A-LPS was eliminated. Additionally, reduced reactivity to these antibodies was also observed in a PG0106 mutant, indicating that this putative glycosyltransferase, which is required for capsule synthesis, is also involved in LPS synthesis in strain W83. We discuss our finding in the context of how DNABII proteins, an antisense RNA molecule, and the 77bpIR element may modulate expression of surface polysaccharides in
P. gingivalis
.

IMPORTANCE
The periodontal pathogen
Porphyromonas gingivalis
displays at least three different types of cell surface glycans: O-LPS, A-LPS, and K-antigen capsule. We have shown using Northern analysis that the K-antigen capsule locus encodes a large transcript (∼19.4 kb), encompassing a 77-bp inverted repeat (77bpIR) element near the 5′ end. Here, we report on the identification of an antisense RNA (asRNA) encoded within the 77bpIR. We show that overexpression of this asRNA or deletion of the element decreases the amount of capsule. LPS structures were also altered by deletion of the 77bpIR, and reactivity to monoclonal antibodies to both O-LPS and A-LPS was eliminated. Our data indicate that the 77bpIR element is involved in modulating both LPS and capsule synthesis in
P. gingivalis
.
High-Throughput Metagenomic Technologies for Complex Microbial Community Analysis: Open and Closed Formats
Authors: Zhou Jizhong , He Zhili , Yang Yunfeng , Deng Ye , Tringe Susannah G. , Alvarez-Cohen Lisa 
Published: January 2015

ABSTRACT
Understanding the structure, functions, activities and dynamics of microbial communities in natural environments is one of the grand challenges of 21st century science. To address this challenge, over the past decade, numerous technologies have been developed for interrogating microbial communities, of which some are amenable to exploratory work (e.g., high-throughput sequencing and phenotypic screening) and others depend on reference genes or genomes (e.g., phylogenetic and functional gene arrays). Here, we provide a critical review and synthesis of the most commonly applied “open-format” and “closed-format” detection technologies. We discuss their characteristics, advantages, and disadvantages within the context of environmental applications and focus on analysis of complex microbial systems, such as those in soils, in which diversity is high and reference genomes are few. In addition, we discuss crucial issues and considerations associated with applying complementary high-throughput molecular technologies to address important ecological questions.
Psychogenic polydipsia, hyponatremia and osmotic myelinolysis
Authors: Penders Thomas M , Stanciu Cornel N , Ganpat Peter , Ingersoll Jennifer A 
Published: January 2015

ObjectiveDescription of a case of osmotic myelinolysis associated with hyponatremia produced as a consequence of compulsive water drinking.MethodCase report and review of relevant literature.ResultsCompulsive water drinking or psychogenic polydipsia is a common cause of hyponatremia among individuals with chronic mental illness. Central pontine myelinolysis and extrapontine myelinolysis are serious neurological complications resulting from rapid correction of serum sodium and associated changes in serum osmolality. A case of extrapontine myelinolysis confirmed by characteristic MRI findings following an episode of extreme hyponatremia caused by psychogenic polydipsia is described involving a patient with an adult lifelong history of chronic mental illness diagnosed as schizoaffective disorder. With supportive care the related cognitive deficits and balance difficulties resolved completely.ConclusionsClinicians should be aware of the potential for hyponatremia resulting from compulsive water drinking to cause myelinolysis with delayed development of cognitive and gait symptoms that responds to supportive care if identified early.