scholarly journals Experimental and Theoretical Investigation on the Thermochemistry of 3-Methyl-2-benzoxazolinone and 6-Nitro-2-benzoxazolinone

Molecules ◽  
2021 ◽  
Vol 27 (1) ◽  
pp. 24
Author(s):  
Ana L. R. Silva ◽  
Vânia M. S. Costa ◽  
Maria D. M. C. Ribeiro da Silva
Keyword(s):  
Gas Phase ◽  
Structural Characteristics ◽  
Enthalpies Of Formation ◽  
Calvet Microcalorimetry ◽  
Static Bomb ◽  
High Level ◽  
The Relationship ◽  
Related Compounds ◽  
Enthalpies Of Sublimation

The determination of the reliable thermodynamic properties of 2-benzoxazolinone derivatives is the main goal of this work. Some correlations are established between the energetic properties determined and the structural characteristics of the title compounds, and the reactivity of this class of compounds is also evaluated. Static-bomb combustion calorimetry and high-temperature Calvet microcalorimetry were used to determine, respectively, the standard molar enthalpies of formation in the solid state and the standard molar enthalpies of sublimation, both at T = 298.15 K. Using the results obtained for each compound, the respective gas-phase standard molar enthalpy of formation was derived. High-level quantum chemical calculations were performed to estimate the same property and the results evidence good accordance. Moreover, the gas-phase relative thermodynamic stability of 2-benzoxazolinone derivatives was also evaluated using the respective gas-phase standard molar Gibbs energy of formation. In addition, the relationship between the energetic and structural characteristics of the benzoxazolinones is presented, evidencing the enthalpic increments associated with the presence of a methyl and a nitro groups in the molecule, and this effect is compared with similar ones in other structurally related compounds.

scholarly journals Energetic and Structural Studies of Two Biomass-Derived Compounds: 6- and 7-hydroxy-1-indanones

2020 ◽  
Vol 10 (23) ◽  
pp. 8512
Author(s):  
Ana Luisa Ribeiro da Silva ◽  
Maria D. M. C. Ribeiro da Silva
Keyword(s):  
Gas Phase ◽  
Computational Study ◽  
Intramolecular Proton Transfer ◽  
Molecular Structures ◽  
Experimental Techniques ◽  
Hydroxyl Group ◽  
Enthalpies Of Formation ◽  
Calvet Microcalorimetry ◽  
Computational Calculations ◽  
High Level

The energetic study of 6-hydroxy-1-indanone and 7-hydroxy-1-indanone was performed using experimental techniques and computational calculations. The enthalpies of combustion and sublimation of the two compounds were determined and allowed to derive the corresponding gas-phase standard molar enthalpies of formation. For this purpose, static-bomb combustion calorimetry and drop-method Calvet microcalorimetry were the experimental techniques used. Further, the enthalpy of fusion of each compound was obtained from scanning differential calorimetry measurements. Additionally, the gas-phase standard molar enthalpies of formation of these compounds were calculated through high-level ab initio calculations. The computational study of the molecular structures of the indanones was carried out and two possible conformers were observed for 6-hydroxy-1-indanone. Furthermore, the energetic effects associated with the presence of one hydroxyl group as a substituent on the benzenic ring of 1-indanone were also evaluated. Both experimental and theoretical methods show that 7-hydroxy-1-indanone is thermodynamically more stable than the 6-isomer in the gaseous phase and these results provide evidence for the existence of a strong intramolecular H-bond in 7-hydroxy-1-indanone. Finally, the intramolecular proton transfer in 7-hydroxy-1-indanone has been evaluated and as expected, it is not energetically favorable.

Influence of the functional groups −NH2, −OCH3, and −OH on the thermochemistry of indanes

2019 ◽  
Vol 97 (11) ◽  
pp. 788-794
Author(s):  
Ana L.R. Silva ◽  
Paula M.V. Gama ◽  
Maria D.M.C. Ribeiro da Silva
Keyword(s):  
Enthalpy Of Formation ◽  
Gaseous Phase ◽  
Molar Enthalpy ◽  
Enthalpies Of Formation ◽  
Condensed State ◽  
Calvet Microcalorimetry ◽  
Energy Of Combustion ◽  
Experimental Values ◽  
Enthalpies Of Sublimation

This work is a contribution to the thermochemical characterization of bicyclic hydrocarbons, reporting the study of six indane derivatives: 4-aminoindane, 5-aminoindane, 5-methoxyindane, 1-indanol, 2-indanol, and 5-indanol. The combustion calorimetry technique was used to measure the massic energy of combustion of each compound in the condensed state, which has been used to derive the corresponding standard (p° = 0.1 MPa) molar enthalpy of formation, at 298.15 K. The standard molar enthalpies of sublimation or vaporization of the compounds were determined by high-temperature Calvet microcalorimetry. For each indane derivative, the results obtained for those two properties, allowed to derive the respective value of standard molar enthalpy of formation, in the gaseous phase. Additionally, a theoretical study at the G3(MP2)//B3LYP level has been carried out, and the calculated enthalpies of formation have been compared with the experimental values. The values of the enthalpy of formation, in the gaseous phase, were analysed in terms of correlations between the structural (different substituents in the indane core) and energetics characteristics.

scholarly journals The Relationship between Hope and Perceived Stress in Teacher Candidates

2019 ◽  
Vol 8 (2) ◽  
pp. 1
Author(s):  
Serdar Sucan
Keyword(s):  
Perceived Stress ◽  
Personnel Selection ◽  
Teacher Candidates ◽  
Negative Effects ◽  
Positive Effects ◽  
Preparatory Course ◽  
High Level ◽  
The Relationship

The long-term and uncontrollable stress of KPSS (Personnel Selection Examination) candidates disrupts their psychology, weakens thinking and decision-making, and thus decreases academic achievement. The aim of this study is; It is the determination of the relationship between the level of hope and perceived stress of teacher candidates prepared for KPSS.A total of 382 teacher candidates participated in a special KPSS preparatory course in Kayseri. Candidate teachers who graduated from different departments and universities are between the ages of 21-25 in 41.6%. When we look at socio-demographic characteristics; 68.4% male; 59.9% single and 51.5% were at medium income level. Perceived Stress Scale (PSS-10) and Adult Hope Scale (AHS) were administered to the participants. The mean AHS score of the teacher candidates was 27.73±1.92. This shows the high level of hope of the participants. Perceived Stress level was found to be medium at 53.6%. As a result of the analysis, a significant a negative correlation was found between level of hope and perceived stress (p <0.01). According to regression analysis, level of hope in teacher candidates showed a statistically significant positive effect on perceived stress (p <0.01).As a result, negative relationships were found between hope and perceived stress. It is thought that highly hopeful people perceive stress lower and life satisfaction increases. Therefore, in order to increase the level of hope and to reduce the negative effects of stress, educators should support KPSS candidates. Programs related to the high level of hope to be implemented in schools may have positive effects on individuals' low stress and examinations.

scholarly journals Hydrogen Storage: Thermodynamic Analysis of Alkyl-Quinolines and Alkyl-Pyridines as Potential Liquid Organic Hydrogen Carriers (LOHC)

2021 ◽  
Vol 11 (24) ◽  
pp. 11758
Author(s):  
Sergey P. Verevkin ◽  
Sergey P. Safronov ◽  
Artemiy A. Samarov ◽  
Sergey V. Vostrikov
Keyword(s):  
Liquid Phase ◽  
Gas Phase ◽  
Wood Preservation ◽  
Enthalpies Of Formation ◽  
Vapor Pressures ◽  
Liquid Phase Hydrogenation ◽  
Substituted Quinolines ◽  
Attractive Option ◽  
Substituted Pyridines ◽  
High Level

The liquid organic hydrogen carriers (LOHC) are aromatic molecules, which can be considered as an attractive option for the storage and transport of hydrogen. A considerable amount of hydrogen up to 7–8% wt. can be loaded and unloaded with a reversible chemical reaction. Substituted quinolines and pyridines are available from petroleum, coal processing, and wood preservation, or they can be synthesized from aniline. Quinolines and pyridines can be considered as potential LOHC systems, provided they have favorable thermodynamic properties, which were the focus of this current study. The absolute vapor pressures of methyl-quinolines were measured using the transpiration method. The standard molar enthalpies of vaporization of alkyl-substituted quinolines and pyridines were derived from the vapor pressure temperature dependencies. Thermodynamic data on vaporization and formation enthalpies available in the literature were collected, evaluated, and combined with our own experimental results. The theoretical standard molar gas-phase enthalpies of formation of quinolines and pyridines, calculated using the quantum-chemical G4 methods, agreed well with the evaluated experimental data. Reliable standard molar enthalpies of formation in the liquid phase were derived by combining high-level quantum chemistry values of gas-phase enthalpies of formation with experimentally determined enthalpies of vaporization. The liquid-phase hydrogenation/dehydrogenation reaction enthalpies of alkyl-substituted pyridines and quinolines were calculated and compared with the data for other potential liquid organic hydrogen carriers. The comparatively low enthalpies of reaction make these heteroaromatics a seminal LOHC system.

scholarly journals A relação entre litogia e morfologia das encostas das montanhas Tucson, Arizona

2008 ◽  
Vol 31 (1) ◽  
pp. 30-42
Author(s):  
Kamel Khanchoul ◽  
Robert Altschul
Keyword(s):  
Arid Region ◽  
Structural Characteristics ◽  
Size Analysis ◽  
Slope Length ◽  
Mountain Front ◽  
Semi Arid Region ◽  
The Relationship ◽  
Semi Arid

The relationship between lithology and slope morphology is investigated at eight sites on granitic, andesitic, and sedimentary hillslopes in the Tucson Mountains, Arizona. Several methods are used in the study. Topographic profiles are constructed. Skewness indices, slope length, and mean slope angles of the different slope profiles are computed and compared with each other. Debris size analysis has permitted for some profiles, the determination of hillfront/piedmont junctions. The nature and structural characteristics of the bedrock are the ones that determine the hillslope morphology in this semi-arid region. There are, as a matter of fact, variations in profiles on the same bedrock nature but differently exposed. More precise morphologic studies have been also done in comparing the different lithologic pairs. They have permitted to show some similarities in shapes. The granitic-andesitic slopes and andesiic-sedimentary slopes are the best comparisons which show the relationship between lithology and slope morphology. The granitic-sedimentary slope relationship is shown in the hillfront concavities, mountain front and piedmont mean slope angles.

Gas-Phase Infrared Spectroscopy for Determination of Double-Bond Configuration of Some Polyunsaturated Pheromones and Related Compounds

1995 ◽  
Vol 67 (9) ◽  
pp. 1558-1567 ◽  
Author(s):  
Athula B. Attygalle ◽  
Ales. Svatos ◽  
Charles. Wilcox ◽  
Simon. Voerman
Keyword(s):  
Infrared Spectroscopy ◽  
Double Bond ◽  
Gas Phase ◽  
Related Compounds

scholarly journals KEPUASAN KERJA DITINJAU DARI BEBAN KERJA KARYAWAN YANG BERLATARBELAKANG PENDIDIKAN TIDAK SESUAI DENGAN PEKERJAAN

2020 ◽  
Vol 14 (2) ◽  
pp. 71-82
Author(s):  
Zuraida Zuraida
Keyword(s):  
Job Satisfaction ◽  
Negative Relationship ◽  
Significant Negative Correlation ◽  
Educational Background ◽  
Educational Backgrounds ◽  
Analysis Technique ◽  
High Workload ◽  
High Level ◽  
The Relationship

Employees who are placed in positions that are not in accordance with educational backgrounds will experience a high workload so that they will feel dissatisfied at work. This study aims to examine the relationship between job satisfaction in terms of the workload of employees whose educational background is not appropriate for their work. Job satisfaction and workload variables are measured using a scale. The subjects of this study were 50 employees who work not according to educational background, with the determination of the sample based on accidental sampling. The analysis technique used in this research is quantitative analysis using Karl Pearson's product moment with the SPSS version 20 for Windows program. Based on the research results, it is known that job satisfaction has a negative relationship with the workload of employees with educational backgrounds that are not suitable for their work. There is a significant negative correlation (r-0.769 with sig <0.05) between the variable job satisfaction and the workload of employees whose educational background is not in accordance with their work, namely 0.000 and the significance value is below / smaller 0.05, this means that the lower the job satisfaction, then the higher the workload and vice versa, the higher the job satisfaction, the lower the workload. . Job satisfaction has the most low categories with a contribution of 56% and the workload at most has a high level category with a contribution of 58%.

Modified factor analysis of the circular dichroism spectra, applied to a series of cyclodipeptides containing L-proline

1979 ◽  
Vol 44 (4) ◽  
pp. 1296-1311 ◽  
Author(s):  
Petr Pančoška ◽  
Ivo Frič ◽  
Karel Bláha
Keyword(s):  
Mathematical Model ◽  
Factor Analysis ◽  
Hilbert Spaces ◽  
Principal Components ◽  
Structural Characteristics ◽  
Cd Spectra ◽  
Modified Method ◽  
Minimum Number ◽  
Related Compounds

A mathematical model has been developed which uses the theory of Hilbert spaces and the modified method of the principal components of the factor analysis to the determination of the minimum number of subspectra sufficient to describe a set of experimental CD curves of a series of structurally related compounds. The use of this method has been demonstrated on the CD spectra of nine cyclodipeptides containing (besides L-proline) glycine, L or D alanine, L or D valine, L or D leucine, and L or D tert-leucine, measured in acetonitrile and 2,2,2-trifluoroethanol. Relation is discussed between the calculated subspectra and the structural characteristics of the measured systems.

MEANING OF LIFE AS THE BASIS FOR THE CONSTRUCTION OF AT THE AGE OF ADULTHOOD

2021 ◽  
pp. 53-56
Author(s):  
O. Karabanova ◽  
Ye. Zakharova ◽  
Yu. Starostina
Keyword(s):  
Self Determination ◽  
Family Role ◽  
Professional Career ◽  
Career Plans ◽  
Professional Careers ◽  
The Family ◽  
The Individual ◽  
High Level ◽  
The Relationship

The aim of the study was to explore the relationship between the meaningfulness of life and the career plans of an individual in the professional and family spheres at the age stage of emerging adulthood. A family career represents a sequential change in conventional family role positions and the development of relevant competencies in accordance with the life cycle of the family and self-determination of the individual. We used the test of meaningful life orientations and the author's questionnaire of family and professional careers. The sample consisted of 167 students aged 17-22. The results allowed us to identify three groups of respondents, differing in the level of meaningfulness of life. It was found that a high level of life meaningfulness is combined with a certainty of career plans in the sphere of family and profession and a high level of their consistency. Respondents with a low level of meaningfulness in life are characterized by an insufficient balance of professional and family career plans. Orientation towards a professional career with insufficient attention to life plans in the family sphere is combined with an external locus of control.

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