Animal feeding operations (AFOs) produce particulate matter (PM) and gaseous pollutants. Investigation of the chemical composition of PM
2.5
inside and in the local vicinity of AFOs can help to ...understand the impact of the AFO emissions on ambient secondary PM formation. This study was conducted on a commercial egg production farm in North Carolina. Samples of PM
2.5
were collected from five stations, with one located in an egg production house and the other four located in the vicinity of the farm along four wind directions. The major ions of NH
4
+
, Na
+
, K
+
, SO
4
2−
, Cl
−
, and NO
3
−
were analyzed using ion chromatography (IC). In the house, the mostly abundant ions were SO
4
2−
, Cl
−
, and K
+
. At ambient stations, SO
4
2−
, and NH
4
+
were the two most abundant ions. In the house, NH
4
+
, SO
4
2−
, and NO
3
−
accounted for only 10% of the PM
2.5
mass; at ambient locations, NH
4
+
, SO
4
2−
, and NO
3
−
accounted for 36-41% of the PM
2.5
mass. In the house, NH
4
+
had small seasonal variations indicating that gas-phase NH
3
was not the only major force driving its gas-particle partitioning. At the ambient stations, NH
4
+
had the highest concentrations in summer. In the house, K
+
, Na
+
, and Cl
−
were highly correlated with each other. In ambient locations, SO
4
2−
and NH
4
+
had a strong correlation, whereas in the house, SO
4
2−
and NH
4
+
had a very weak correlation. Ambient temperature and solar radiation were positively correlated with NH
4
+
and SO
4
2−
. This study suggests that secondary PM formation inside the animal house was not an important source of PM
2.5
. In the vicinity, NH
3
emissions had greater impact on PM
2.5
formation.
Implications
The chemical composition of PM
2.5
inside and in the local vicinity of AFOs showed the impact of the AFO emissions on ambient secondary PM
2.5
formation, and the fate and transport of air pollutants associated with AFOs. The results may help to manage in-house animal facility air quality, and to develop regional air quality control strategies and policies, especially in animal agriculture-concentrated areas.
b-Jet identification in the D0 experiment Adams, M.; Alton, A.; Askew, A. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2010, Letnik:
620, Številka:
2
Journal Article
Recenzirano
Odprti dostop
Algorithms distinguishing jets originating from b quarks from other jet flavors are important tools in the physics program of the D0 experiment at the Fermilab Tevatron
p
p
¯
collider. This article ...describes the methods that have been used to identify b-quark jets, exploiting in particular the long lifetimes of b-flavored hadrons, and the calibration of the performance of these algorithms based on collider data.
Organic sensitizers containing dithienopyrrole donor, benzotriazole or quinoxaline in the conjugation pathway, and cyanoacrylic acid acceptor featured in a donor–acceptor-π–acceptor configuration are ...reported. The effect of the nature of different conjugating bridges on photophysical, electrochemical and photovoltaic properties was systematically evaluated. The incorporation auxiliary acceptors broadened the absorption spectra and modulated the excited state energy levels. The DFT calculation unraveled a significant overlap of HOMO and LUMO orbitals in benzotriazole-containing dyes and the charge transfer character for the longer wavelength absorption. Among the dyes, a dye containing benzotriazole and thiophene in the conjugation pathway exhibited highest power conversion efficiency attributable to efficient electron injection and pronounced inhibition of electron recombination.
Studies by different groups on the rescue effect, where unirradiated bystander cells mitigated the damages in the irradiated cells, since its discovery by the authors' group in 2011 were first ...reviewed. The properties of the rescue effect were then examined using a novel experimental set-up to physically separate the rescue signals from the bystander signals. The authors' results showed that the rescue effect was mediated through activation of the nuclear factor-κB (NF-κB) response pathway in the irradiated cells, and that the NF-κB activation inhibitor BAY-11-7082 did not affect the activation of this response pathway in the irradiated cells induced by direct irradiation.
In a cell-free approach to regenerative therapeutics, transient application of paracrine factors in vivo could be used to alter the behavior and fate of progenitor cells to achieve sustained clinical ...benefits. Here we show that intramyocardial injection of synthetic modified RNA (modRNA) encoding human vascular endothelial growth factor-A (VEGF-A) results in the expansion and directed differentiation of endogenous heart progenitors in a mouse myocardial infarction model. VEGF-A modRNA markedly improved heart function and enhanced long-term survival of recipients. This improvement was in part due to mobilization of epicardial progenitor cells and redirection of their differentiation toward cardiovascular cell types. Direct in vivo comparison with DNA vectors and temporal control with VEGF inhibitors revealed the greatly increased efficacy of pulse-like delivery of VEGF-A. Our results suggest that modRNA is a versatile approach for expressing paracrine factors as cell fate switches to control progenitor cell fate and thereby enhance long-term organ repair.
This study aimed to compare 'cool' working memory (WM) and response inhibition and 'hot' (delay aversion) executive functions (EFs) in children with and without attention deficit hyperactivity ...disorder (ADHD).
A total of 100 ADHD children (45 with family history of ADHD and 55 with no family history) and 100 healthy controls, all medication free, were tested on tasks related to the 'hot' (i.e. two choice-delay tasks) and 'cool' domains of EF (i.e. Digits backward, Corsi Block Task backward, Go/No-Go Task, Stop-Signal Task, and the Stroop).
Compared with the controls, children with ADHD were found to perform significantly worse on one or more measures of response inhibition, WM, and delay aversion after controlling for co-morbidities and estimated IQ. In addition, comparisons between ADHD children with family history of ADHD and those with no family history found significant differences on measures of response inhibition and WM but not delay aversion. These results are largely supported by results of two logistic regressions.
ADHD was found to be associated with deficits on both cool and hot EFs. There is also evidence to suggest that cool EFs impairment is related to a family history of ADHD. Findings of this study have helped to elucidate the nature and extent of EF deficits in children with ADHD.
The interactions between a dicationic gemini surfactant with a six-hydrocarbon spacer (1,2-bis(dodecyldimethylammonio)hexane dibromide, C12C6C12Br2) and anionic polyelectrolyte DNA or ...sodium(polystyrene sulfonate) (NaPSS) at the air/solution interface have been studied and compared using neutron reflectometry together with surface tension. In the presence of the dichained cationic gemini surfactant, DNA and NaPSS display very different adsorption behaviors. The DNA/gemini mixtures show adsorption behavior very similar to that of DNA/C12TAB mixtures, with enhanced surfactant adsorption at low concentrations and thick structured layers at higher concentrations. However, for the NaPSS/gemini mixtures the amount of gemini at the surface is reduced relative to that in the absence of NaPSS at concentrations below the cmc. These differences in adsorption behavior are attributed to differences in the molecular structure and flexibility of the two polyanions. NaPSS is relatively hydrophobic and flexible enough to form bulk-phase polymer−micelle complexes with the gemini surfactant at low surfactant concentrations, whereas the adsorption of surface complexes is much less favorable because the dications on the gemini would require adjacent bulky pendant charges on the NaPSS to be oriented toward the surface. This would force the NaPSS to bend significantly whereas it is more favorable for the NaPSS to adopt an extended conformation at the surface. Thus, surfactant is actually removed from the surface to form bulk-phase complexes. In contrast with NaPSS, DNA has a far more rigid structure, and the charges on the backbone are at fixed intervals, factors that make the formation of surface DNA−monomer complexes much more favorable than bulk-phase DNA−micelle complexes. Finally, a short-chain sample of NaPSS consisting of only five to six segments adsorbs very strongly at the surface with the gemini to form more extensive layered structures than have previously been observed, consisting of approximately five sublayers.
Two new organic sensitizers featuring fluorenylidene decoration on the phenothiazine donor have been synthesized and characterized as sensitizers for nanocrystalline TiO
2
-based dye sensitized solar ...cells (DSSCs). The dyes possess cyanoacrylic acid as acceptor/anchoring group and a conjugation pathway composed of fluorene and thiophene. Introduction of the fluorenylidene moiety on phenothiazine enhances the optical density of the dyes while the extension of conjugation by thiophene insertion red-shifts the absorption peak originating from the intramolecular charge transfer from phenothiazine to cyanoacrylic acid. The ground and excited state oxidation potentials of the fluorenylidene-containing dyes are upwardly shifted when compared to the parent dyes indicating a π-delocalized donor segment. The electronic properties were supported by density functional theoretical computations. Among the DSSCs fabricated, the dye (
5a
) having fluorene and thiophene in the spacer resulted higher power conversion efficiency (3.31 %) than the corresponding bithiophene analog (
5b
, 2.83 %) attributable to the relatively high electron life time and enhanced resistance for recombination in the former.
A novel process involving hot rolling and air cooling followed by dynamic carbon partitioning is proposed to design a low density Fe-Mn-Al-C steel with high strength-high ductility combination. The ...low density alloy 0.25C-3Mn-2Al (wt%) steel was designed to control the phase transformation and achieve dynamic carbon partitioning, thereby obtaining bainite/martensite matrix embedded with nano-sized retained austenite (RA). The effect of different air-cooling finish temperatures on the microstructures and mechanical properties is elucidated in the study described here. Multi-phase microstructures of ferrite, martensite/bainite and RA were obtained during air-cooling in the temperature range of 360–510 °C. It was interesting that bainite matrix was obtained at finish temperature of 400 °C, while the martensite matrix including lath and twin martensite was obtained on air cooling temperature to 510 °C. The twin martensite resulted in higher tensile strength of ~1096 MPa in sample air cooled to 510 °C. The RA in samples subjected to dynamic partitioning was high, significantly approaching 27.3%. Additionally, RA was characterized into two types, film and blocky. A large amount of blocky RA in sample air cooled to 510 °C led to 21.4% transformed RA during uniform deformation. Consequently, excellent combination of high tensile strength of ~1096 MPa and uniform elongation of ~16% was attained in sample air cooled to 510 °C. The study simplifies the existing processes and breaks the constraint for quenching and partitioning treatment limited by quenching temperature below Ms. It has important implications for developing the new generation hot rolled high strength steels.
Full understanding of the thermomechanical behaviors of materials at high strain rates and high temperatures are of great importance from not only scientific meaning but also practical value in ...engineering structure design and safety assessment. Great efforts have been made for abilities of operation the split Hopkinson bars, the most popular technique for experimental determination of mechanical behaviors of materials over the strain rates from 10
2
to 10
4
s
−1
over the past 70 years, at high temperatures since 1960s. A review of experiment work is presented in this paper to give an overview of the development of experimental techniques at high temperatures based on Hopkinson bar systems. The principles of the split Hopkinson bar requires the loading bars avoiding temperature gradient or keeping relatively low temperature when performing high temperature testing. Techniques such as performing temperature gradient corrections, rapid heating or using special designed automatically assembled systems were proposed by researchers to enable the operation of the split Hopkinson bars at temperature as high as possible. Moreover, to the application of high speed photographic technique for capturing the dynamic deformation process of the specimen in high temperature Hopkinson bar testing, some key issues of eliminating the strong thermal radiation induced lights oversaturation and de-blurring of images due to insufficient exposure at high temperature and high strain rate condition, as well as fabrication of high contrast speckle pattern for high temperature digital image correlation measurement were also proposed. The technique can now enable the split Hopkinson bar testing to be performed at high temperature up to 1873 K under the loading conditions of compression or tension with the in situ observation and full field measurement of deformation as well. The paper concludes with summaries of the most important achievements and highlighting of the prospects, trends and remaining challenges for future research.
Graphic abstract
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