scholarly journals Discovery of the acetyl cation, CH3CO+, in space and in the laboratory

2021 ◽  
Vol 646 ◽  
pp. L7 ◽  
Author(s):  
J. Cernicharo ◽  
C. Cabezas ◽  
S. Bailleux ◽  
L. Margulès ◽  
R. Motiyenko ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Theoretical Calculations ◽  
Protonated Form ◽  
Abundance Ratio ◽  
Dense Cores ◽  
High Proton Affinity ◽  
High Proton ◽  
Symmetric Rotor ◽  
Stable Product ◽  
High Level

Using the Yebes 40 m and IRAM 30 m radiotelescopes, we detected two series of harmonically related lines in space that can be fitted to a symmetric rotor. The lines have been seen towards the cold dense cores TMC-1, L483, L1527, and L1544. High level of theory ab initio calculations indicate that the best possible candidate is the acetyl cation, CH3CO+, which is the most stable product resulting from the protonation of ketene. We have produced this species in the laboratory and observed its rotational transitions Ju = 10 up to Ju = 27. Hence, we report the discovery of CH3CO+ in space based on our observations, theoretical calculations, and laboratory experiments. The derived rotational and distortion constants allow us to predict the spectrum of CH3CO+ with high accuracy up to 500 GHz. We derive an abundance ratio N(H2CCO)/N(CH3CO+) ∼ 44. The high abundance of the protonated form of H2CCO is due to the high proton affinity of the neutral species. The other isomer, H2CCOH+, is found to be 178.9 kJ mol−1 above CH3CO+. The observed intensity ratio between the K = 0 and K = 1 lines, ∼2.2, strongly suggests that the A and E symmetry states have suffered interconversion processes due to collisions with H and/or H2, or during their formation through the reaction of H3+ with H2CCO.

scholarly journals Discovery of HC3O+ in space: The chemistry of O-bearing species in TMC-1

2020 ◽  
Vol 642 ◽  
pp. L17
Author(s):  
J. Cernicharo ◽  
N. Marcelino ◽  
M. Agúndez ◽  
Y. Endo ◽  
C. Cabezas ◽  
...  
Keyword(s):  
Laboratory Experiments ◽  
Theoretical Calculations ◽  
Rotational Constant ◽  
Protonated Form ◽  
Abundance Ratio ◽  
Radio Telescopes ◽  
Neutral Species ◽  
High Proton Affinity ◽  
High Proton ◽  
High Level

Using the Yebes 40m and IRAM 30m radio telescopes, we detected a series of harmonically related lines with a rotational constant B0 = 4460.590 ± 0.001 MHz and a distortion constant D0 = 0.511 ± 0.005 kHz towards the cold dense core TMC-1. High-level-of-theory ab initio calculations indicate that the best possible candidate is protonated tricarbon monoxide, HC3O+. We have succeeded in producing this species in the laboratory and observed its Ju − Jl = 2–1 and 3–2 rotational transitions. Hence, we report the discovery of HC3O+ in space based on our observations, theoretical calculations, and laboratory experiments. We derive an abundance ratio N(C3O)/N(HC3O+) ∼ 7. The high abundance of the protonated form of C3O is due to the high proton affinity of the neutral species. The chemistry of O-bearing species is modelled, and predictions are compared to the derived abundances from our data for the most prominent O-bearing species in TMC-1.

scholarly journals Formation of C-A-S-H phases from the interaction between concrete or cement and bentonite

Clay Minerals ◽  
2016 ◽  
Vol 51 (2) ◽  
pp. 223-235 ◽  
Author(s):  
Raúl Fernández ◽  
Ana Isabel Ruiz ◽  
Jaime Cuevas
Keyword(s):  
Calcium Silicate Hydrate ◽  
Laboratory Experiments ◽  
Pore Scale ◽  
Lime Mortar ◽  
Cement Interface ◽  
Argillaceous Rocks ◽  
Deep Geological Disposal ◽  
Engineered Barriers ◽  
High Level ◽  
Increasing Temperature

AbstractConcrete and bentonite are being considered as engineered barriers for the deep geological disposal of high-level radioactive waste in argillaceous rocks. Three hydrothermal laboratory experiments of different scalable complexity were performed to improve our knowledge of the formation of calcium aluminate silicate hydrates (C-A-S-H) at the interface between the two materials: concretebentonite transport columns, lime mortar-bentonite transport columns and a portlandite- (bentonite and montmorillonite) batch experiment. Precipitation of C-A-S-H was observed in all experiments. Acicular and fibrous morphologies with certain laminar characteristics were observed which had smaller Ca/Si and larger Al/Si ratios with increasing temperature and lack of accessory minerals. The compositional fields of these C-A-S-H phases formed in the experiments are consistent with Al/(Si+Al) ratios of 0.2– 0.3 described in the literature. The most representative calcium silicate hydrate (C-S-H) phase from the montmorillonite–cement interface is Al-tobermorite. Structural analyses revealed a potential intercalation or association of montmorillonite and C-A-S-H phases at the pore scale.

Mechanisms responsible for the niche shift of brook charr, Salvelinus fontinalis Mitchill, when living sympatrically with creek chub, Semotilus atromaculatus Mitchill

1984 ◽  
Vol 62 (8) ◽  
pp. 1548-1555 ◽  
Author(s):  
Pierre Magnan ◽  
Gérard J. FitzGerald
Keyword(s):  
Laboratory Experiments ◽  
Salvelinus Fontinalis ◽  
Niche Shift ◽  
Intraspecific Aggression ◽  
Brook Charr ◽  
Semotilus Atromaculatus ◽  
High Level ◽  
Gill Raker ◽  
Creek Chub ◽  
Study Laboratory

When brook charr, Salvelinus fontinalis Mitchill, are in allopatry in oligotrophic Québec lakes, they feed largely on macrobenthic invertebrates. However, when brook charr cooccur with creek chub, Semotilus atromaculatus Mitchill, they feed largely on zooplankton. In the present study, laboratory experiments showed that creek chub were more effective than brook charr in searching for hidden, patchily distributed prey. The searching efficiency of an individual chub feeding in a group was improved through social facilitation. In contrast, the high level of intraspecific aggression observed in brook charr prevents the formation of such feeding groups. In the laboratory, brook charr were able to displace creek chub from the food source because of interspecific aggression. Data are presented showing that chub are morphologically better adapted than charr to feed on benthos (subterminal orientation of the mouth and protrusible premaxillae), while the charr are better adapted than chub to feed on zooplankton (gill raker structure). Differences in feeding behaviour, morphology, and relative abundance between these species appear to be important in the observed niche shift of brook charr in nature.

scholarly journals Molecular Fingerprints of Hemoglobin on a Nanofilm Chip

Sensors ◽  
2018 ◽  
Vol 18 (9) ◽  
pp. 3016 ◽  
Author(s):  
Yeşeren Saylan ◽  
Adil Denizli
Keyword(s):  
Real Time ◽  
Theoretical Calculations ◽  
Essential Element ◽  
Hemoglobin Concentration ◽  
Ammonium Persulfate ◽  
Detection Methods ◽  
Molecular Fingerprints ◽  
Molecularly Imprinted ◽  
On Chip ◽  
High Level

Hemoglobin is an iron carrying protein in erythrocytes and also an essential element to transfer oxygen from the lungs to the tissues. Abnormalities in hemoglobin concentration are closely correlated with health status and many diseases, including thalassemia, anemia, leukemia, heart disease, and excessive loss of blood. Particularly in resource-constrained settings existing blood analyzers are not readily applicable due to the need for high-level instrumentation and skilled personnel, thereby inexpensive, easy-to-use, and reliable detection methods are needed. Herein, a molecular fingerprints of hemoglobin on a nanofilm chip was obtained for real-time, sensitive, and selective hemoglobin detection using a surface plasmon resonance system. Briefly, through the photopolymerization technique, a template (hemoglobin) was imprinted on a monomeric (acrylamide) nanofilm on-chip using a cross-linker (methylenebisacrylamide) and an initiator-activator pair (ammonium persulfate-tetramethylethylenediamine). The molecularly imprinted nanofilm on-chip was characterized by atomic force microscopy and ellipsometry, followed by benchmarking detection performance of hemoglobin concentrations from 0.0005 mg mL−1 to 1.0 mg mL−1. Theoretical calculations and real-time detection implied that the molecularly imprinted nanofilm on-chip was able to detect as little as 0.00035 mg mL−1 of hemoglobin. In addition, the experimental results of hemoglobin detection on the chip well-fitted with the Langmuir adsorption isotherm model with high correlation coefficient (0.99) and association and dissociation coefficients (39.1 mL mg−1 and 0.03 mg mL−1) suggesting a monolayer binding characteristic. Assessments on selectivity, reusability and storage stability indicated that the presented chip is an alternative approach to current hemoglobin-targeted assays in low-resource regions, as well as antibody-based detection procedures in the field. In the future, this molecularly imprinted nanofilm on-chip can easily be integrated with portable plasmonic detectors, improving its access to these regions, as well as it can be tailored to detect other proteins and biomarkers.

PC-Based Computer Modeling of Combustion Processes

1999 ◽  
Author(s):  
Greg W. Gmurczyk ◽  
Ashwani K. Gupta
Keyword(s):  
Numerical Simulations ◽  
Computer Modeling ◽  
Numerical Experiments ◽  
Laboratory Experiments ◽  
Combustion Process ◽  
Numerical Algorithms ◽  
Computer Hardware ◽  
Simplifying Assumptions ◽  
High Level ◽  
Analytical Approaches

Abstract Constant and significant progress in both computer hardware and numerical algorithms, in recent years, have made it possible to investigate complex phenomena in engineering systems using computer modeling and simulations. Advanced numerical simulations can be treated as an extension of traditional analytical-theoretical analyses. In such cases, some of the simplifying assumptions can usually be dropped and the nonlinear interactions between various processes can be captured. One of the most complex engineering processes encountered in industry is a combustion process utilized either for power/thrust generation or incineration. However, even nowadays, because of the high level of complexity of the general problem of a combustion process in practical systems, it is not currently possible to simulate directly all the length and time scales of interest. Simplifying assumptions still need to be made, but they can be less drastic than in analytical approaches. Therefore, another view of numerical simulations is as a tool to simulate idealized systems and conduct numerical experiments. Such numerical experiments can be complementary to laboratory experiments and can also provide more detailed, nonintrusive diagnostics. Therefore, simulations, along with theory and laboratory experiments, can provide a more complete picture and better understanding of a combustion process. As an example of computer modeling of industrial combustion systems, an enclosed spray flame was considered. Such a flame can frequently be encountered in power generation units, turbine engines, and incinerators. Both the physical and mathematical models were formulated based on data from earlier laboratory studies and results obtained for open air spray flames. The purpose of this study was to use those data as model input to predict the characteristics of a confined flame and provide a means of optimizing the system design with a PC computer.

Towards high-level theoretical studies of large biodiesel molecules: an ONIOM/RRKM/Master-equation approach to the isomerization and dissociation kinetics of methyl decanoate radicals

2019 ◽  
Vol 21 (9) ◽  
pp. 5232-5242 ◽  
Author(s):  
Qinghui Meng ◽  
Yicheng Chi ◽  
Lidong Zhang ◽  
Peng Zhang ◽  
Liusi Sheng
Keyword(s):  
Theoretical Calculations ◽  
Theoretical Studies ◽  
Equation Approach ◽  
Dissociation Kinetics ◽  
Master Equation Approach ◽  
High Layer ◽  
High Level ◽  
Kinetics Of ◽  
Oniom Method ◽  
Methyl Decanoate

The isomerization and dissociation reactions of methyl decanoate (MD) radicals were theoretically investigated by using high-level theoretical calculations based on a two-layer ONIOM method, employing the QCISD(T)/CBS method for the high layer and the M06-2X/6-311++G(d,p) method for the low layer.

scholarly journals ESI-MS spectra of 3-cyano-4-(substituted phenyl)-6-phenyl-2(1H)-pyridinones

2009 ◽  
Vol 74 (3) ◽  
pp. 223-235
Author(s):  
Aleksandar Marinkovic ◽  
Tatjana Vasiljevic ◽  
Mila Lausevic ◽  
Bratislav Jovanovic
Keyword(s):  
Proton Affinity ◽  
Phenyl Ring ◽  
Steric Effect ◽  
Proton Acceptor ◽  
Tandem Mass ◽  
High Proton Affinity ◽  
High Proton ◽  
Negative Electrospray Ionization ◽  
Cn Radicals ◽  
Fragmentation Processes

Twelve 3-cyano-4-(substituted phenyl)-6-phenyl-2(1H)-pyridinones were investigated by tandem mass spectrometry using positive as well as negative electrospray ionization. The influence of the electron affinity of the substituent and the steric effect on the fragmentation is discussed. Pyridinones with a substituent of low proton affinity show loss of water, HCN or benzene from the pyridinone ring in the first step of MS2 fragmentations. Oppositely, if a substituent with high proton affinity is present on the phenyl ring in the 4-position of pyridinone, the fragmentation paths are complex, depending mainly on the substituent proton acceptor ability. Elimination of neutral molecules CO, HCN, H2O, PhH (benzene) or Ph and CN radicals are fragmentation processes common for all compounds in the subsequent steps of the fragmentations.

The Slug Design of Multi-Slug and Equi-Fluidity Oil Displacement with Binary Flooding

2015 ◽  
Vol 733 ◽  
pp. 144-147 ◽  
Author(s):  
Jiang Min Zhao ◽  
Tian Ge Li
Keyword(s):  
Synergistic Effect ◽  
Oil Recovery ◽  
Laboratory Experiments ◽  
Theoretical Calculations ◽  
Water Flooding ◽  
Oil Displacement ◽  
Remaining Oil ◽  
Heterogeneous Cores

This paper optimizes the design of the nature of each slug and the combination of slugs through theoretical calculations and laboratory experiments, which is the key to tremendously enhance the oil recovery with the oil-displacing method of multiple multi-slug combinations. When oil-displacing experiments with multiple multi-slug combinations are conducted on heterogeneous cores in the laboratory, it is necessary that each injected slug be designed rationally in their viscosity, volume, etc., with the view to guarantee the synchronous equi-fluidity mobility of each slug after water flooding. With the synergistic effect of a variety of oil-displacing agents, the remaining oil in each permeability layer can be dug, driven by overall piston.

Quasi-steady states in natural displacement ventilation driven by periodic gusting of wind

2012 ◽  
Vol 707 ◽  
pp. 1-23 ◽  
Author(s):  
Richard W. Mott ◽  
Andrew W. Woods
Keyword(s):  
Laboratory Experiments ◽  
Temporal Variations ◽  
The Body ◽  
Buoyancy Flux ◽  
Shopping Mall ◽  
Displacement Ventilation ◽  
Geometric Properties ◽  
Two Layer Model ◽  
High Level ◽  
Continuous Source

AbstractWe investigate the natural displacement ventilation of a space connected to a body of warm fluid through high- and low-level vents. The space is subject to discrete periodic gusts of wind entering at high level from a cold exterior. The cold exterior air entering the space produces buoyancy differences between the space and the body of warm fluid, driving a ventilation flow. Initially we examine the case of a series of identical gusts of wind modelled as turbulent buoyant thermals. New laboratory experiments show that an approximately two-layer stratification is established and the height of the interface is quasi-steady if the period between thermals is much less than the draining time of the space but longer than the fall time of individual thermals. Experiments also show that the interface height depends on the average buoyancy flux associated with the wind gusts, the time between thermals as well as the geometric properties of the vents. This contrasts with the case of a continuous source of buoyancy where the interface height depends only on the geometric properties of the vents and is independent of the buoyancy flux. We develop a quasi-steady two-layer model of the flow based on the classical theory of turbulent thermals and show that it is consistent with our new experimental data. We generalize the model to explore the sensitivity of the results to temporal variations in the size of thermals. We then extend the model to explore the effects of longer interval times between successive thermals and find a two-layer stratification still develops but that the interface height now varies cyclically in time. We then discuss the implications of these results for the ventilation of a shopping mall subject to gusts of wind.

The H13CN/HC15N Abundance Ratio in Dense Cores: Possible Source‐to‐Source Variation of Isotope Abundances?

2002 ◽  
Vol 575 (1) ◽  
pp. 250-256 ◽  
Author(s):  
Masafumi Ikeda ◽  
Tomoya Hirota ◽  
Satoshi Yamamoto
Keyword(s):  
Abundance Ratio ◽  
Dense Cores ◽  
Source Variation
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