Positive and negative intramolecular nuclear Overhauser effects in an all-proton system

1968 ◽  
Vol 46 (21) ◽  
pp. 3421-3423 ◽  
Author(s):  
R. A. Bell ◽  
J. K. Saunders
Keyword(s):  
Relaxation Mechanism ◽  
Qualitative Explanation ◽  
Negative Effects ◽  
Dipole Relaxation ◽  
Positive Effects ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects

The Overhauser effects recorded for the alkaloid ochotensimine (1) show positive effects (area increases) for adjacent protons but negative effects (area decreases) for two protons separated by an intervening proton. A qualitative explanation based on the dominance of a dipole–dipole relaxation mechanism is advanced. The Overhauser effect between geminal protons on an sp2-carbon has been measured.

Relaxation Processes in the N-Methyl Group of 1,2,2,6,6-Pentamethylpiperidine

1990 ◽  
Vol 43 (2) ◽  
pp. 447 ◽  
Author(s):  
ID Rae ◽  
ML Woolcock
Keyword(s):  
Relaxation Times ◽  
Spin Rotation ◽  
Relaxation Processes ◽  
Methyl Group ◽  
Methyl Methyl ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects

Relaxation times (T1) and methyl-methyl nuclear Overhauser effects were measured for 1H, 13C and 2H nuclei in 1,2,2,6,6-pentamethylpiperidine and its N-CHD2 analogue which was synthesized by LiAlD4 reduction of the N-CHO compound. The relaxation pathways for hydrogens of the N-CH3 group were estimated to be as follows: spin-rotation 0.046 s-1, dipole-dipole within N-methyl 0.069 s-1, and dipole-dipole with the hydrogens of the C- methyls 0.027 s-1. The 1H{1H) Overhauser effect at the N-CH3 was 7.6%.

Variation of the nuclear Overhauser effect in dimethylformamide with temperature

1970 ◽  
Vol 48 (3) ◽  
pp. 512-513 ◽  
Author(s):  
J. K. Saunders ◽  
R. A. Bell
Keyword(s):  
High Field ◽  
Room Temperature ◽  
Nuclear Overhauser Effect ◽  
Low Field ◽  
Overhauser Effect ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects

The nuclear Overhauser effects at the formyl proton of dimethylformamide have been measured at and above room temperature. At 90° separate irradiation of the high field and low field methyl signals results in equal nuclear Overhauser effects from both methyls.

Analysis of short interproton distances in proline peptides as a guide in the interpretation of nuclear Overhauser effects

1988 ◽  
Vol 53 (11) ◽  
pp. 2801-2809 ◽  
Author(s):  
Chandrashekharan Ramakrishnan ◽  
Ramanathan Sowdhamini ◽  
Padmanabhan Balaram
Keyword(s):  
Nuclear Overhauser Effect ◽  
Model Systems ◽  
Pyrrolidine Ring ◽  
Ramachandran Map ◽  
Overhauser Effect ◽  
Ring Puckering ◽  
Nuclear Overhauser ◽  
Nuclear Overhauser Effects ◽  
Interproton Distances ◽  
Helical Region

The conformational dependence of interproton distances in model proline peptides has been investigated in order to facilitate interpretation of the results of Nuclear Overhauser Effect (NOE) studies on such peptides. For this purpose two model systems, namely, Ac-Pro-NHMe and Ac-Pro-X-NHMe have been chosen and used. In the former, short interproton distances detectable in NOE experiments permit a clear distinction between conformations with Pro ψ = -300 (helical region) and those in which ψ is around 1200 (polyproline region). For the latter, the variation of distances between the protons of methyl amide and the Pro ring have been studied by superimposing on the Ramachandran map in the (φ3, ψ3) plane. The results show that β-turns and non-β-turn conformations can be readily distinguished from NOE data and such long range NOEs should be detectable for specific non-β-turn conformations. NOEs involving Cβ and Cγ protons are particularly sensitive to the state of pyrrolidine ring puckering.

Undesirable Effects of Goal Setting on Perceived Fairness, Commitment, and Unethical Behavior

2018 ◽  
Vol 62 (2) ◽  
pp. 97-107 ◽  
Author(s):  
Nina Keith
Keyword(s):  
Goal Setting ◽  
Unethical Behavior ◽  
The United States ◽  
Goal Commitment ◽  
Management Technique ◽  
Long Term Effects ◽  
Perceived Fairness ◽  
Negative Effects ◽  
Positive Effects ◽  
And Performance

Abstract. The positive effects of goal setting on motivation and performance are among the most established findings of industrial–organizational psychology. Accordingly, goal setting is a common management technique. Lately, however, potential negative effects of goal-setting, for example, on unethical behavior, are increasingly being discussed. This research replicates and extends a laboratory experiment conducted in the United States. In one of three goal conditions (do-your-best goals, consistently high goals, increasingly high goals), 101 participants worked on a search task in five rounds. Half of them (transparency yes/no) were informed at the outset about goal development. We did not find the expected effects on unethical behavior but medium-to-large effects on subjective variables: Perceived fairness of goals and goal commitment were least favorable in the increasing-goal condition, particularly in later goal rounds. Results indicate that when designing goal-setting interventions, organizations may consider potential undesirable long-term effects.

Mobilizing for Some

2016 ◽  
Vol 28 (3) ◽  
pp. 123-135 ◽  
Author(s):  
Raffael Heiss ◽  
Jörg Matthes
Keyword(s):  
High School ◽  
Social Media ◽  
High School Students ◽  
Experimental Design ◽  
Collective Efficacy ◽  
Political Efficacy ◽  
Negative Effects ◽  
School Students ◽  
Positive Effects ◽  
Specific Factors

Abstract. This study investigated the effects of politicians’ nonparticipatory and participatory Facebook posts on young people’s political efficacy – a key determinant of political participation. We employed an experimental design, using a sample of N = 125 high school students (15–20 years). Participants either saw a Facebook profile with no posts (control condition), nonparticipatory posts, or participatory posts. While nonparticipatory posts did not affect participants’ political efficacy, participatory posts exerted distinct effects. For those high in trait evaluations of the politician presented in the stimulus material or low in political cynicism, we found significant positive effects on external and collective efficacy. By contrast, for those low in trait evaluations or high in cynicism, we found significant negative effects on external and collective efficacy. We did not find any effects on internal efficacy. The importance of content-specific factors and individual predispositions in assessing the influence of social media use on participation is discussed.

On the diversity of the effects of the state support for agriculture

2019 ◽  
pp. 59-73 ◽  
Author(s):  
Nikolai M. Svetlov ◽  
Renata G. Yanbykh ◽  
Dariya A. Loginova
Keyword(s):  
Agricultural Production ◽  
The State ◽  
Russian Regions ◽  
Negative Effects ◽  
State Support ◽  
Soft Budget Constraints ◽  
Institutional Conditions ◽  
Positive Effects ◽  
Production Factors ◽  
Corporate Farms

In this paper, we assess the effects of agricultural state support of corporate farms on their revenues from agricultural production sales in 14 Russian regions that differ in technology, environment and institutional conditions. In addition to the direct effect of the state support, the indirect effects via labor and capital are revealed. For this purpose, we identify production functions and statistical models of production factors for each of these regions separately. We find out diverse effects of the state support on revenues among the regions. Positive effects prevail. Negative effects are mainly caused by labor reductions that follow subsidy inflows. Another cause of negative effects is the soft budget constraints phenomenon.

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