Structural and substituent effects on the ketene infrared stretching frequency

1994 ◽  
Vol 72 (3) ◽  
pp. 882-887 ◽  
Author(s):  
Michael A. McAllister ◽  
Thomas T. Tidwell
Keyword(s):  
Negative Charge ◽  
Substituent Effects ◽  
Resonance Structure ◽  
Stretching Vibration ◽  
Structure Formula ◽  
Negative Charge Density ◽  
The Relationship ◽  
Absorption Frequencies ◽  
Modest Correlation ◽  
Good Agreement

The frequencies and intensities of the ketene asymmetric stretching vibration near 2100 cm−1 for a series of substituted ketenes and fulvenones have been calculated using ab initio molecular orbital methods. Comparisons of the calculated values with experimentally determined results show reasonably good agreement in most cases, with a typical deviation of ± 10 cm−1 between the measured and calculated values. A test of a correlation proposed by Gano and Jacob (Spectrochim. Acta, 43A, 1023 (1987)) of the frequencies with substituent field and resonance parameters F and R shows a modest correlation coefficient of 0.86, with no significant dependence on R. These results are consistent with enhancements of ketene infrared absorption frequencies by interaction of substituents with the negative charge density at Cβ of ketenes, as indicated by the resonance structure [Formula: see text] The calculated intensities I (km/mol) for non-π acceptor substituents are correlated with the group electronegativities X by the relationship I = 1841.6 − 305.7X (r = 0.94). The π-acceptor substituents show exaltations of the intensities, and the results are interpreted as showing an enhancement of intensities by electropositive substituents increasing the normal ketene dipole directed towards oxygen, and an opposite effect by π-acceptor substituents delocalizing the negative charge at Cβ.

Infrared spectra and substituent effects in 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones

1983 ◽  
Vol 48 (2) ◽  
pp. 586-595 ◽  
Author(s):  
Alexander Perjéssy ◽  
Pavol Hrnčiar ◽  
Ján Šraga
Keyword(s):  
Substituent Effects ◽  
Phenyl Group ◽  
Wave Number ◽  
Vibrational Coupling ◽  
Wave Numbers ◽  
Stretching Vibration ◽  
Stretching Vibrations ◽  
The Relationship ◽  
Derivatives Of ◽  
Effect Of Structure

The wave numbers of the fundamental C=O and C=C stretching vibrations, as well as that of the first overtone of C=O stretching vibration of 2-(3-, and 4-substituted phenylmethylene)-1,3-cycloheptanediones and 1,3-cycloheptanedione were measured in tetrachloromethane and chloroform. The spectral data were correlated with σ+ constants of substituents attached to phenyl group and with wave number shifts of the C=O stretching vibration of substituted acetophenones. The slope of the linear dependence ν vs ν+ of the C=C stretching vibration of the ethylenic group was found to be more than two times higher than that of the analogous correlation of the C=O stretching vibration. Positive values of anharmonicity for asymmetric C=O stretching vibration can be considered as an evidence of the vibrational coupling in a cyclic 1,3-dicarbonyl system similarly, as with derivatives of 1,3-indanedione. The relationship between the wave numbers of the symmetric and asymmetric C=O stretching vibrations indicates that the effect of structure upon both vibrations is symmetric. The vibrational coupling in 1,3-cycloheptanediones and the application of Seth-Paul-Van-Duyse equation is discussed in relation to analogous results obtained for other cyclic 1,3-dicarbonyl compounds.

scholarly journals Experimental studies on the transformation from firn to ice in the wet-snow zone of temperate glaciers

1997 ◽  
Vol 24 ◽  
pp. 181-185 ◽  
Author(s):  
Katsuhisa Kawashima ◽  
Tomomi Yamada
Keyword(s):  
Experimental Studies ◽  
Ice Formation ◽  
Compression Tests ◽  
Densification Rate ◽  
Overburden Pressure ◽  
Proportionality Constant ◽  
Wet Snow ◽  
Water Saturated ◽  
The Relationship ◽  
Good Agreement

The densification of water-saturated firn, which had formed just above the firn-ice transition in the wet-snow zone of temperate glaciers, was investigated by compression tests under pressures ranging from 0.036 to 0.173 MPa, with special reference to the relationship between densification rate, time and pressure. At each test, the logarithm of the densification rate was proportional to the logarithm of the time, and its proportionality constant increased exponentially with increasing pressure. The time necessary for ice formation in the firn aquifer was calculated using the empirical formula obtained from the tests. Consequently, the necessary time decreased exponentially as the pressure increased, which shows that the transformation from firn in ice can be completed within the period when the firn aquifer exists, if the overburden pressure acting on the water-saturated firn is above 0.12–0.14 MPa. This critical value of pressure was in good agreement with the overburden pressure obtained from depth–density curves of temperate glaciers. It was concluded that the depth of firn–ice transition was self-balanced by the overburden pressure to result in the concentration between 20 and 30 m.

Estimation of Interlayer Thickness in Inorganic Particulate-Filled Polymer Composites

2011 ◽  
Vol 24 (6) ◽  
pp. 777-788 ◽  
Author(s):  
J.Z. Liang
Keyword(s):  
Polymer Composites ◽  
Volume Fraction ◽  
Particle Diameter ◽  
Interfacial Structure ◽  
Interlayer Thickness ◽  
Filled Polymer ◽  
Mechanical And Physical Properties ◽  
The Relationship ◽  
Good Agreement

The structure of the interlayer between matrix and inclusions affect directly the mechanical and physical properties of inorganic particulate-filled polymer composites. The interlayer thickness is an important parameter for characterization of the interfacial structure. The effects of the interlayer between the filler particles and matrix on the mechanical properties of polymer composites were analyzed in this article. On the basis of a simplified model of interlayer, an expression for estimating the interlayer thickness ([Formula: see text]) was proposed. In addition, the relationship between the [Formula: see text] and the particle size and its concentration was discussed. The results showed that the calculations of the [Formula: see text] and thickness/particle diameter ratio ([Formula: see text]) increased nonlinearly with an increase of the volume fraction of the inclusions. Moreover, the predictions of [Formula: see text] and the relevant data reported in literature were compared, and good agreement was found between them.

TCAD Study of the Raised SiGe Source/Drain in 40nm PMOS

2015 ◽  
Vol 645-646 ◽  
pp. 70-74 ◽  
Author(s):  
Min Zhong ◽  
Yu Hang Zhao ◽  
Shou Mian Chen ◽  
Ming Li ◽  
Shao Hai Zeng ◽  
...  
Keyword(s):  
Computer Aided Design ◽  
Critical Role ◽  
Sige Layer ◽  
Strain Engineering ◽  
Effect Transistor ◽  
Simulation Results ◽  
Aided Design ◽  
The Relationship ◽  
Growth Experiments ◽  
Good Agreement

An embedded SiGe layer was applied in the source/drain areas (S/D) of a field-effect transistor to boost the performance in the p channels. Raised SiGe S/D plays a critical role in strain engineering. In this study, the relationship between the SiGe overfilling and the enhancement of channel stress was investigated. Systematic technology computer aided design (TCAD) simulations of the SiGe overfill height in a 40 nm PMOS were performed. The simulation results indicate that a moderate SiGe overfilling induces the highest stress in the channel. Corresponding epitaxial growth experiments were done and the obtained experimental data was in good agreement with the simulation results. The effect of the SiGe overfilling is briefly discussed. The results and conclusions presented within this paper might serve as useful references for the optimization of the embedded SiGe stressor for 40 nm logic technology node and beyond.

Phase stability, Debye temperature and hardness of semiconducting manganese tetraboride MnB4: First-principles investigations

2017 ◽  
Vol 31 (20) ◽  
pp. 1750131 ◽  
Author(s):  
Ming-Min Zhong ◽  
Cheng Huang ◽  
Chun-Ling Tian
Keyword(s):  
Debye Temperature ◽  
Phase Stability ◽  
First Principles ◽  
Formation Enthalpy ◽  
Structural Features ◽  
High Melting Point ◽  
Fundamental Understanding ◽  
New Perspective ◽  
The Relationship ◽  
Good Agreement

First-principles investigations are employed to provide a fundamental understanding of the structural features, phase stability, mechanical properties, Debye temperature, and hardness of manganese tetraboride. Eight candidate structures of known transition-metal tetraborides are chosen to probe. The calculated lattice parameters, elastic properties, Poisson’s ratio, and [Formula: see text] ratio are derived. It is observed that the monoclinic structure with [Formula: see text] symmetry (MnB4–MnB4) is the most stable in energy. The mechanical and thermodynamic stabilities of seven possible phases are confirmed by the calculated elastic constants and formation enthalpy. Moreover, the analysis on density of states demonstrates semiconducting behavior of MnB4–MnB4 and different metallic behaviors of other phases. The estimated hardness of MnB4–MnB4 is 38.3 GPa, which is in good agreement with experimental value. Furthermore, the relationship between hardness and Debye temperature is investigated and verifies that MnB4–MnB4 is a newly potential semiconducting ultrahard material with high melting point. It provides a new perspective of searching for semiconducting superhard materials to be applied in extreme conditions.

Estimating the influence of temperature on the survival of chinook salmon smolts (Oncorhynchus tshawytscha) migrating through the Sacramento – San Joaquin River Delta of California

1995 ◽  
Vol 52 (4) ◽  
pp. 855-863 ◽  
Author(s):  
Peter Fritz Baker ◽  
Franklin K. Ligon ◽  
Terence P. Speed
Keyword(s):  
Water Temperature ◽  
Chinook Salmon ◽  
Oncorhynchus Tshawytscha ◽  
Logistic Function ◽  
Laboratory Findings ◽  
Natural Systems ◽  
San Joaquin River ◽  
Influence Of Temperature On ◽  
The Relationship ◽  
Good Agreement

Data from the U.S. Fish and Wildlife Service are used to investigate the relationship between water temperature and survival of hatchery-raised fall-run chinook salmon (Oncorhynchus tshawytscha) smolts migrating through the Sacramento – San Joaquin Delta of California. A formal statistical model is presented for the release of smolts marked with coded-wire tags (CWTs) in the lower Sacramento River and the subsequent recovery of marked smolts in midwater trawls in the Delta. This model treats survival as a logistic function of water temperature, and the release and recovery of different CWT groups as independent mark–recapture experiments. Iteratively reweighted least squares is used to fit the model to the data, and simulation is used to establish confidence intervals for the fitted parameters. A 95% confidence interval for the upper incipient lethal temperature, inferred from the trawl data by this method, is 23.01 ± 1.08 °C This is in good agreement with published experimental results obtained under controlled conditions (24.3 ± 0.1 and 25.1 ± 0.1 °C for chinook salmon acclimatized to 10 and 20 °C, respectively): this agreement has implications for the applicability of laboratory findings to natural systems.

scholarly journals Fatigue Performance of Thin Laser Butt Welds in HSLA Steel

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1499
Author(s):  
Patricio G. Riofrío ◽  
Fernando Antunes ◽  
José Ferreira ◽  
António Castanhola Batista ◽  
Carlos Capela
Keyword(s):  
Fatigue Strength ◽  
Fatigue Behavior ◽  
Hsla Steel ◽  
High Strength ◽  
Butt Joints ◽  
Factors Affecting ◽  
Weld Profile ◽  
The Relationship ◽  
Good Agreement ◽  
Significant Factors

This work is focused on understanding the significant factors affecting the fatigue strength of laser-welded butt joints in thin high-strength low-alloy (HSLA) steel. The effects of the weld profile, imperfections, hardness, and residual stresses were considered to explain the results found in the S-N curves of four welded series. The results showed acceptable fatigue strength although the welded series presented multiple-imperfections. The analysis of fatigue behavior at low stress levels through the stress-concentrating effect explained the influence of each factor on the S-N curves of the welded series. The fatigue limits of the welded series predicted through the stress-concentrating effect and by the relationship proposed by Murakami showed good agreement with the experimental results.

scholarly journals Variation in rms charge radii of deuteron and helium nuclei with s\sqrt s

Nukleonika ◽  
2020 ◽  
Vol 65 (4) ◽  
pp. 211-215
Author(s):  
Sarwat Zahra ◽  
Bushra Shafaq ◽  
Bushra Kanwal ◽  
Nosheen Akbar
Keyword(s):  
Center Of Mass ◽  
Form Factors ◽  
Mass Energy ◽  
Charge Radii ◽  
Center Of Mass Energy ◽  
Theoretical Predictions ◽  
Dependent Form ◽  
Energy Dependent ◽  
The Relationship ◽  
Good Agreement

AbstractBy considering energy-dependent form factors extracted from generalized Chou–Yang model, root mean square (rms) charge radii of deuteron and helium nuclei (alpha) are predicted at different values of center of mass energy which are in good agreement with theoretical predictions and experimental results. The rms radius is inversely proportional to mass of nuclei. Besides, the relationship between radii and energy are also derived.

scholarly journals In-situ measurement of reactive hydrocarbons at Hohenpeissenberg with comprehensive gas chromatography (GCxGC-FID): use in estimating HO and NO<sub>3</sub>

2006 ◽  
Vol 6 (4) ◽  
pp. 8155-8188
Author(s):  
S. Bartenbach ◽  
J. Williams ◽  
C. Plass-Dülmer ◽  
H. Berresheim ◽  
J. Lelieveld
Keyword(s):  
Mean Value ◽  
Time Data ◽  
Night Time ◽  
Radical Species ◽  
Diurnal Cycles ◽  
Meteorological Observatory ◽  
Variate Analysis ◽  
The Relationship ◽  
Good Agreement

Abstract. During a field campaign at the Meteorological Observatory Hohenpeissenberg (MOHp) in July 2004, VOCs were measured using GCxGC-FID. Comparison to routinely made GC-MS measurements showed good agreement for a variety of anthropogenic and biogenic ambient VOCs ranging in concentration from below the detection limit (0.1 pmol mol−1) to 180 pmol mol−1. Pronounced diurnal cycles were found for both the biogenic and anthropogenic compounds, driven for the most part by the daily rise and fall of the boundary layer over the station. For the reactive compounds (lifetimes <2 days), a significant, non-zero dependency of the variability on lifetime was found, indicating that chemistry (as opposed to transport alone) was playing a role in determining the ambient VOC concentrations. The relationship was exploited using a single-variate analysis to derive a daytime mean value of HO (5.3±1.4×106 molecules cm−3), which compares well to that measured at the site, 3.2±2.3×106 molecules cm−3. The analysis was extended to the night time data to estimate concentrations for NO3 (1.47±0.2×108 molecules cm−3), which is not measured at the site. The feasibility of this approach for environments dominated by emissions of short-lived VOCs to estimate ambient levels of radical species is discussed.

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