Charge distributions and Chemical effects. XII. A unifying concept

1976 ◽  
Vol 54 (18) ◽  
pp. 2839-2846 ◽  
Author(s):  
Sándor Fliszár
Keyword(s):  
Positive Charge ◽  
Recent Literature ◽  
Atomic Charges ◽  
Charge Distributions ◽  
Chemical Effects ◽  
Carbonium Ions ◽  
Inductive Effects ◽  
Definition Of ◽  
C Nmr

Major inconsistencies which are currently acknowledged in discussions involving atomic charges, inductive effects, 13C nmr shifts, and stability of carbonium ions are removed (i) by the use of an appropriate definition of charges and (ii) by the recognition that in alkanes and alkyl carbonium ions any decrease in positive charge at carbon atoms results in a downfield 13C shift. Methyl appears to be less electron withdrawing than hydrogen, and stability of carbonium ions is associated with dispersion of positive charge at the carbonium center, in line with the more traditional views which are repeatedly challenged in recent literature.

Charge Distributions and Chemical Effects. III. A Comparison with PCILO and CNDO/2 Calculations

1973 ◽  
Vol 51 (7) ◽  
pp. 991-996 ◽  
Author(s):  
S. Fliszár ◽  
J. Sygusch
Keyword(s):  
Excellent Agreement ◽  
Qualitative Agreement ◽  
Charge Distributions ◽  
Chemical Effects ◽  
Inductive Effects ◽  
Pcilo Method ◽  
Chemical Character ◽  
Quantitative Chemical

The PCILO charge distributions of a number of alkanes are in excellent agreement with charge distributions derived on the assumption that the inductive effects can be described in a Taft-like manner. This agreement with "quantitative chemical intuition" stresses the strong chemical character of the PCILO method. The CNDO/2 results are only in qualitative agreement with "chemical expectancy" and suffer apparently from the same difficulties as PCILO used with zero C—C and C—H polarities.

Defining and assessing walkability: a concept for an integrated approach using surveys, biosensors and geospatial analysis

2019 ◽  
Vol 62 (1) ◽  
pp. 5-15 ◽  
Author(s):  
Linda Dörrzapf ◽  
Anna Kovács-Győri ◽  
Bernd Resch ◽  
Peter Zeile
Keyword(s):  
Spatial Planning ◽  
Recent Literature ◽  
Integrated Approach ◽  
Measurement Methods ◽  
Transport Mode ◽  
Positive Effects ◽  
Spatial Environment ◽  
Planning Processes ◽  
Valuable Complement ◽  
Definition Of

AbstractWalking as a transport mode is still often underrepresented in the overall transport system. Consequently, pedestrian mobility is usually not recorded statistically in the same manner as it is performed for motorised traffic which leads to an underestimation of its importance and positive effects on people and cities. However, the integration of walkability assessments is potentially a valuable complement in urban planning processes through considering important quantitative and qualitative aspects of walking in cities. Recent literature shows a variety of approaches involving discrepancies in the definition of walkability, the factors which contribute to it, and methods of assessing them. This paper provides a new understanding of the concept of walkability in the European context. Our approach relies on the extension of methodological competence in transportation, spatial planning and geography by linking new measurement methods for evaluating walkability. We propose an integrated approach to assessing walkability in a comprehensive methodology that combines existing qualitative and GIS-based methods with biosensor technologies and thus captures the perceptions and emotions of pedestrians. This results in an increased plausibility and relevance of the results of walkability analysis by considering the spatial environment and its effect on people.

Social media and consumer engagement: a review and research agenda

2016 ◽  
Vol 10 (4) ◽  
pp. 268-287 ◽  
Author(s):  
Victor Barger ◽  
James W. Peltier ◽  
Don E. Schultz
Keyword(s):  
Social Media ◽  
Recent Literature ◽  
Future Research ◽  
Consumer Engagement ◽  
Research Directions ◽  
Content Type ◽  
Future Research Directions ◽  
Antecedents And Consequences ◽  
Area Of Concern ◽  
Definition Of

Purpose In “Social media’s slippery slope: challenges, opportunities and future research directions”, Schultz and Peltier (2013) asked “whether or how social media can be used to leverage consumer engagement into highly profitable relationships for both parties”. The purpose of this article is to continue this discussion by reviewing recent literature on consumer engagement and proposing a framework for future research. Design/methodology/approach The paper reviews the marketing literature on social media, paying particular attention to consumer engagement, which was identified as a primary area of concern in Schultz and Peltier (2013). Findings A significant amount of research has been conducted on consumer engagement since 2010. Lack of consensus on the definition of the construct has led to fragmentation in the discipline, however. As a result, research related to consumer engagement is often not identified as such, making it difficult for academics and practitioners to stay abreast of developments in this area. Originality/value This critical review provides marketing academics and practitioners insights into the antecedents and consequences of consumer engagement and offers a conceptual framework for future research.

A Didactic Dilemma in Emerging Societies: Devaluing Journal Club in Medical Working out

2021 ◽  
Vol 2 (4) ◽  
pp. 01-05
Author(s):  
Saeed Shoja Shafti
Keyword(s):  
Developing Countries ◽  
Recent Literature ◽  
Journal Club ◽  
Academic Misconduct ◽  
Critical Reading ◽  
Clinical Issues ◽  
Journal Clubs ◽  
Reading Abilities ◽  
Definition Of ◽  
Working Out

A journal club is a scholastic conference in which a group of persons discuss issued articles, providing an opportunity for a shared effort to keep up with the current writings. The emphasis of journal clubs has supposedly shifted over the years. What was once a setting in which the world's recent literature was analyzed became a setting for talking over clinical issues raised by the writings and, most recently, a setup for learning critical reading abilities to physicians or other associated authorities. Nevertheless, so far there is no generally accepted definition of journal club, even though this academic method has been around for more than a century and has evolved basically during this period. In the present paper, conceptual and applied features of journal club, especially in developing countries, is surveyed, to discuss an apparent underrating of journal club in some medical departments, which could be due to misunderstanding of new philosophies, or to talk about the necessity of modification of an academic misconduct, which could be attributable to didactic unawareness.

Wallach rearrangement of azoxypyridines and azoxypyridine N-oxides — Charge distributions and dramatic reactivity differences

2008 ◽  
Vol 86 (4) ◽  
pp. 298-304 ◽  
Author(s):  
Erwin Buncel ◽  
Sam-Rok Keum ◽  
Srinivasan Rajagopal ◽  
Eric Kiepek ◽  
Robin A Cox
Keyword(s):  
Sulfuric Acid ◽  
Positive Charge ◽  
Theoretical Calculations ◽  
Medium Effect ◽  
Mulliken Charge ◽  
Reaction Intermediates ◽  
Charge Distributions ◽  
First Time ◽  
Acid Region

Extension of our studies of the generic Wallach rearrangement (of azoxybenzene to 4-hydroxyazobenzene) to the heteroaromatic series (azoxypyridines and axoxypyridine N-oxides) has revealed some dramatic reactivity differences, particularly for the α and β compounds. We have studied the 3-isomers and the 4-isomers in each series, each with α and β forms, eight compounds in all, in the 100 wt% sulfuric acid region of acidity. In those cases in which a product could be observed, the α and β isomers both give the same one, the corresponding 4′-hydroxyazo compounds. All the compounds react much more slowly than does azoxybenzene itself, presumably because of the extra positive charge present in the substrates, but the β isomers have half-lives of seconds and the α isomers half-lives of hundreds of hours in the 100 wt% H2SO4 acidity region. The α compounds have measurable pKBH+ values, but the β compounds do not, exhibiting only a medium effect in the acidity region in which the α compounds protonate. This means that for the β compounds, the protonated intermediates must be much less stable and the postulated reaction intermediates must be much more stable than for the α compounds. To clarify this, we have obtained Mulliken charge distributions for the various species concerned, calculating the charge carried by each half of the molecule, larger charge separations being taken to indicate lesser stability. As far as we can establish, this is the first time that this technique has been used to indicate the stabilities of carbocationic species.Key words: azoxypyridines, azoxypyridine N-oxides, Wallach rearrangement, excess acidity, basicities, theoretical calculations, charge distributions, reactivities.

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