Entropy and Chemical Change. I. Characterization of Product (and Reactant) Energy Distributions in Reactive Molecular Collisions: Information and Entropy Deficiency

1972 ◽  
Vol 57 (1) ◽  
pp. 434-449 ◽  
Author(s):  
R. B. Bernstein ◽  
R. D. Levine
Keyword(s):  
Chemical Change ◽  
Molecular Collisions ◽  
Energy Distributions

scholarly journals Characterization of M dwarfs using optical mid-resolution spectra for exploration of small exoplanets

2020 ◽  
Author(s):  
Yohei Koizumi ◽  
Masayuki Kuzuhara ◽  
Masashi Omiya ◽  
Teruyuki Hirano ◽  
John Wisniewski ◽  
...  
Keyword(s):  
Sample Selection ◽  
Optical Spectra ◽  
Average Error ◽  
Spectral Energy ◽  
M Dwarfs ◽  
Energy Distributions ◽  
Fitting Procedures ◽  
Optical Region ◽  
Selection For

Abstract We present the optical spectra of 338 nearby M dwarfs, and compute their spectral types, effective temperatures (Teff), and radii. Our spectra were obtained using several optical spectrometers with spectral resolutions that range from 1200 to 10000. As many as 97% of the observed M-type dwarfs have a spectral type of M3–M6, with a typical error of 0.4 subtype, among which the spectral types M4–M5 are the most common. We infer the Teff of our sample by fitting our spectra with theoretical spectra from the PHOENIX model. Our inferred Teff is calibrated with the optical spectra of M dwarfs whose Teff have been well determined with the calibrations that are supported by previous interferometric observations. Our fitting procedures utilize the VO absorption band (7320–7570 Å) and the optical region (5000–8000 Å), yielding typical errors of 128 K (VO band) and 85 K (optical region). We also determine the radii of our sample from their spectral energy distributions. We find most of our sample stars have radii of <0.6 R⊙, with the average error being 3%. Our catalog enables efficient sample selection for exoplanet surveys around nearby M-type dwarfs.

scholarly journals Photometric characterization of multiple populations in star clusters: the impact of the first dredge-up

2020 ◽  
Vol 492 (3) ◽  
pp. 3459-3464 ◽  
Author(s):  
Maurizio Salaris ◽  
Chris Usher ◽  
Silvia Martocchia ◽  
Emanuele Dalessandro ◽  
Nate Bastian ◽  
...  
Keyword(s):  
Star Clusters ◽  
Light Element ◽  
Element Abundance ◽  
Spectral Energy ◽  
Spectral Energy Distributions ◽  
Energy Distributions ◽  
Multiple Populations ◽  
Red Giant ◽  
The Impact

ABSTRACT The existence of star-to-star light-element abundance variations (multiple populations, MPs) in massive Galactic and extragalactic star clusters older than about 2 Gyr is by now well established. Photometry of red giant branch (RGB) stars has been and still is instrumental in enabling the detection and characterization of cluster MPs, through the appropriate choices of filters, colours, and colour combinations that are mainly sensitive to N and – to a lesser degree – C stellar surface abundances. An important issue not yet properly addressed is that the translation of the observed widths of the cluster RGBs to abundance spreads must account for the effect of the first dredge-up on the surface chemical patterns, hence on the spectral energy distributions of stars belonging to the various MPs. We have filled this gap by studying theoretically the impact of the dredge-up on the predicted widths of RGBs in clusters hosting MPs. We find that for a given initial range of N abundances, the first dredge-up reduces the predicted RGB widths in N-sensitive filters compared to the case when its effect on the stellar spectral energy distributions is not accounted for. This reduction is a strong function of age and has also a dependence on metallicity. The net effect is an underestimate of the initial N-abundance ranges from RGB photometry if the first dredge-up is not accounted for in the modelling, and also the potential determination of spurious trends of N-abundance spreads with age.

scholarly journals Synthesis and characterization of some new tebufenozide analogues and study their toxicological effect against Spodoptera littoralis (Boisd.)

2022 ◽  
Vol 11 (1) ◽  
pp. 63-68 ◽  
Author(s):  
Omar M. Elhady ◽  
Erian. S. Mansour ◽  
M. M. Elwassimy ◽  
Sameh A. Zawam ◽  
Ali M. Drar
Keyword(s):  
Spodoptera Littoralis ◽  
Chemical Change ◽  
Cotton Leaf ◽  
Aromatic Rings ◽  
Toxicological Study ◽  
Toxicological Effect ◽  
Tert Butyl ◽  
Toxicological Activity ◽  
Concentration Levels

Many of mimic analogues synthesized before depending on the change in the structure of aromatic rings. In this work, the carbonyl group in the structure of compounds 1-4 converted to thiocarbonyl group, and then studying the toxicological activity due to chemical change in the active center of mimic analogues was performed for compounds N-tert-butyl-2,4-dichloro-N'-(2,4-dichlorobenzoyl)benzohydrazide (2) and N-tert-butyl-2,4-dichloro-N'-[(2,4-dichlorophenyl)carbonothioyl]benzenecarbothiohydrazide (6). The toxicological study was done by using 2nd and 4th instar larvae of the cotton leaf worm, Spodoptera littoralis (Boisd.). Five concentration levels (600, 300, 150, 75 and 37.5 ppm) of compounds (2) and (6) were applied on the fresh plant food to the newly grown (2nd and 4th) instar larvae.

Ion Bombardment in Silane VHF Deposition Plasmas

1997 ◽  
Vol 467 ◽  
Author(s):  
E. A. G. Hamers ◽  
J. Bezemer ◽  
H. Meiling ◽  
W.G.J.H.M. Van Sark ◽  
W. F. Van Der Weg
Keyword(s):  
Amorphous Silicon ◽  
Structural Properties ◽  
Threshold Energy ◽  
Energy Distributions ◽  
Ion Energy ◽  
Hydrogen Plasmas ◽  
Rf Glow Discharge ◽  
Ion Energy Distributions ◽  
Hydrogenated Amorphous

ABSTRACTThe measurement of mass resolved ion energy distributions at the grounded substrate in an RF glow discharge allows to determine the ion flux and the ion energy flux towards the surface of a growing hydrogenated amorphous silicon (a-Si:H) layer. This provides the means to study the influence of ions on the structural properties of a-Si:H. Here we focus on the α-γ’ transition as occurs in silane-hydrogen plasmas at an RF frequency of 50 MHz and a substrate temperature of 250 °C. The structural properties of the layers appear to depend on the kinetic energy of the arriving ions. This is supported by measurements of ion fluxes under other deposition conditions and by characterization of the corresponding layers. The influence of ions on the growth is discussed in terms of their flux, and the amount of delivered kinetic and potential energy to the growing film. The measurements suggest that a threshold energy of about 5 eV per deposited atom is needed for the construction of a dense amorphous silicon network.

The mapping of electronic energy distributions using experimental electron density

2002 ◽  
Vol 58 (4) ◽  
pp. 632-639 ◽  
Author(s):  
Vladimir G. Tsirelson
Keyword(s):  
Energy Density ◽  
Electron Density ◽  
Electronic Energy ◽  
Kinetic Energy Density ◽  
Energy Distributions ◽  
Structure Factors ◽  
Experimental Electron Density ◽  
Experimental Structure ◽  
Comprehensive Characterization

It is demonstrated that the approximate kinetic energy density calculated using the second-order gradient expansion with parameters of the multipole model fitted to experimental structure factors reproduces the main features of this quantity in a molecular or crystal position space. The use of the local virial theorem provides an appropriate derivation of approximate potential energy density and electronic energy density from the experimental (model) electron density and its derivatives. Consideration of these functions is not restricted by the critical points in the electron density and provides a comprehensive characterization of bonding in molecules and crystals.

Entropy and Chemical Change. II. Analysis of Product Energy Distributions: Temperature and Entropy Deficiency

1972 ◽  
Vol 57 (12) ◽  
pp. 5427-5447 ◽  
Author(s):  
A. Ben‐Shaul ◽  
R. D. Levine ◽  
R. B. Bernstein
Keyword(s):  
Chemical Change ◽  
Energy Distributions

scholarly journals Isolation, Identification, and Characterization of Polystyrene-Degrading Bacteria From the Gut of Galleria Mellonella (Lepidoptera: Pyralidae) Larvae

2021 ◽  
Vol 9 ◽  
Author(s):  
Shan Jiang ◽  
Tingting Su ◽  
Jingjing Zhao ◽  
Zhanyong Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Galleria Mellonella ◽  
Chemical Change ◽  
Water Contact ◽  
X Ray ◽  
Degrading Bacterium ◽  
Degrading Bacteria ◽  
Lepidoptera Pyralidae ◽  
Identification And Characterization

Polystyrene (PS) is a widely used petroleum-based plastic, that pollutes the environment because it is difficult to degrade. In this study, a PS degrading bacterium identified as Massilia sp. FS1903 was successfully isolated from the gut of Galleria mellonella (Lepidoptera: Pyralidae) larvae that were fed with PS foam. Scanning electron microscopy and X-ray energy dispersive spectrometry showed that the structure and morphology of the PS film was destroyed by FS 1903, and that more oxygen appeared on the degraded PS film. A water contact angle assay verified the chemical change of the PS film from initially hydrophobic to hydrophilic after degradation. X-ray photoelectron spectroscopy further demonstrated that more oxygen-containing functional groups were generated during PS degradation. After 30 days of bacterial stain incubation with 0.15 g PS, 80 ml MSM, 30°C and PS of Mn 64400 and Mw 144400 Da, the weight of the PS film significantly decreased, with 12.97 ± 1.05% weight loss. This amount of degradation exceeds or is comparable to that previously reported for other species of bacteria reported to degrade PS. These results show that Massilia sp. FS1903 can potentially be used to degrade PS waste.

SYNTHESIS AND CHARACTERIZATION OF COPPER NANO PARTICLES: APPLICATION, IN FIELD OF OXIDATION OF AROMATIC HYDROCARBONS CERIUM (IV) SULPHATE UNDER MICROWAVE IRRADIATION

2015 ◽  
Vol 1 (01) ◽  
pp. 06-16
Author(s):  
Manish Srivastava
Keyword(s):  
Copper Nanoparticles ◽  
Copper Catalyst ◽  
Chemical Change ◽  
Nano Particles ◽  
Oxidation Reactions ◽  
Experimental Conditions ◽  
Safe Alternative ◽  
Nano Powder ◽  
Environmentally Safe

The catalytic oxidation with Cerium (IV) in aqueous solution offers an economic and environmentally safe alternative for oxidation reactions performed in synthetic laboratories and chemical industry. In this paper we have shown that the size of the copper nanoparticle is responsible for the yield of chemical change. The copper catalyst (non-nano) powder showed 21% conversion of naphthalene to α-naphthol in 3 min under our experimental conditions. Same quantity of copper nanoparticles (size, ~ 60 nm diameter) ready by turn PVP-EG capping showed 33% conversion of  naphthalene to α-naphthol that inflated to concerning 43% when 8 nm diameter capped copper nanoparticles are used. Surprisingly, 5 nm size copper nanoparticles showed no change in the yield of about 41%. [Ce(IV)-Cu(II)sulphate] system in our experimental work shows 43%, 97%, and 96% yields for oxidation of naphthalene, phenanthrene, and anthracene respectively in the presence of copper nanoparticles.

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