Gas-phase electrochemistry: Measuring absolute potentials and investigating ion and electron hydration

2011 ◽  
Vol 83 (12) ◽  
pp. 2129-2151 ◽  
Author(s):  
William A. Donald ◽  
Evan R. Williams
Keyword(s):  
Gas Phase ◽  
Ion Solvation ◽  
Water Molecules ◽  
Hydrogen Electrode ◽  
Half Cell ◽  
Hydration Enthalpy ◽  
A Value ◽  
Hydrated Ions ◽  
Solvation Energies ◽  
The University

In solution, half-cell potentials and ion solvation energies (or enthalpies) are measured relative to other values, thus establishing ladders of thermochemical values that are referenced to the potential of the standard hydrogen electrode (SHE) and the proton hydration energy (or enthalpy), respectively, which are both arbitrarily assigned a value of 0. In this focused review article, we describe three routes for obtaining absolute solution-phase half-cell potentials using ion nanocalorimetry, in which the energy resulting from electron capture (EC) by large hydrated ions in the gas phase are obtained from the number of water molecules lost from the reduced precursor cluster, which was developed by the Williams group at the University of California, Berkeley. Recent ion nanocalorimetry methods for investigating ion and electron hydration and for obtaining the absolute hydration enthalpy of the electron are discussed. From these methods, an absolute electrochemical scale and ion solvation scale can be established from experimental measurements without any models.

scholarly journals Correlations in hydrochloride drugs with diverse pharmacological activities. Role of N-H…Cl bonds

2020 ◽  
Vol 10 (3) ◽  
pp. 5536-5547
Keyword(s):  
Dipole Moment ◽  
Gas Phase ◽  
Dipole Moments ◽  
Antihypertensive Agents ◽  
Water Molecules ◽  
Electrophilicity Index ◽  
Pharmacological Activities ◽  
Molecular Weights ◽  
Solvation Energies

In this work, the structural and vibrational properties of sixteen hydrochloride/hydrobromide drugs with different pharmacological activities have been compared and analysed in order to find some correlations among their properties and, mainly elucidate the role of N-H•••Cl bonds in them. Here, the properties of ten alkaloids: tropane, gramine, morphine, cocaine, methadone, naloxone, heroin and scopolamine as hydrochloride and hydrobromide including, the psychotropic 2-CB agent; three antihistaminic: diphenhydramine, cyclizine and promethazine and; three antihypertensive tolazoline, clonidine and guanfacine agents have been evaluated. All properties were predicted in gas phase and aqueous solution by using the hybrid B3LYP/6-31G* method and the same were evaluated in functions of their molecular weights. Here, stabilization and solvation energies, dipole moments and volumes in both media, atomic MK charges and bond N-H and N+Cl- lengths, N-H stretching modes of N-HCl bonds of hydrochloride and their cationic species and, frontier orbitals together with global electrophilicity and nucleophilicity descriptors were compared for those sixteen drugs. The results have shown that bonds N+Cl- lengths of all hydrochloride species are higher in solution, as compared with the values in gas phase. Hydrochloride species of alkaloids and antihistaminic agents in both media present higher positive MK values on the N atoms of N-HCl bonds while the species related to antihypertensive agents show higher negative MK values on the N atoms or low positive values. The species of guanfacine presents the higher number of donors and acceptors groups, higher dipole moment value in solution, low bond N-H lengths, higher negative charge on the N atom of N-HCl bond and, higher global electrophilicity index. Hydrochloride species of scopolamine and heroin present the more negative solvation energies while tolazoline the lower value. Hydrochloride species of 2-CB and diphendramine show the higher expansions volumes in solution while the species of naloxone, scopolamine and cocaine evidence volumes contractions in this medium. These studies show that the knowledge of hydration degrees, that is, the number of water molecules that hydrate the hydrochloride species are essential to understand the hydration process of these species in relation to the differences observed in solvation energies, volume variations and dipole moment values.

Ion solvation by dipolar aprotic solvents. An ab initio study

1987 ◽  
Vol 52 (1) ◽  
pp. 6-13 ◽  
Author(s):  
Petr Kyselka ◽  
Zdeněk Havlas ◽  
Ivo Sláma
Keyword(s):  
Ab Initio ◽  
Geometry Optimization ◽  
Molecular Structures ◽  
Dimethyl Sulphoxide ◽  
Ion Solvation ◽  
Interaction Energies ◽  
Ab Initio Study ◽  
Solvation Energies ◽  
Dipolar Aprotic Solvents ◽  
Complete Geometry Optimization

The paper deals with the solvation of Li+, Be2+, Na+, Mg2+, and Al3+ ions in dimethyl sulphoxide, dimethylformamide, acetonitrile, and water. The ab initio quantum chemical method was used to calculate the solvation energies, molecular structures, and charge distributions for the complexes water···ion, acetonitrile···ion, dimethyl sulphoxide···ion, and dimethylformamide···ion. The interaction energies were corrected for the superposition error. Complete geometry optimization was performed for the complex water···ion. Some generalizations are made on the basis of the results obtained.

Graduates giving back – a mentoring program for MBA students

2015 ◽  
Vol 4 (3) ◽  
pp. 200-212 ◽  
Author(s):  
Ann Darwin
Keyword(s):  
Higher Education ◽  
South Australia ◽  
Value Added ◽  
Master Of Business Administration ◽  
Mentoring Program ◽  
Education Students ◽  
Content Type ◽  
Mba Students ◽  
A Value ◽  
The University

Purpose – The purpose of this paper is to discuss the challenges and obstacles encountered in the implementation of a mentoring program for Master of Business Administration (MBA) students at the University of South Australia (UniSA) Business School. The paper starts with an exploration into the need for a mentoring program, the trial and subsequent four years of implementation. The paper also explores the network model of mentoring and the reasons why this, rather than a more traditional model, was chosen for the program’s implementation. Design/methodology/approach – This exploratory case study uses data from over 600 students and their alumni mentors over a five-year period to evaluate and improve the program as well as cultivating a critical community of adult learners. Findings – Feedback from students indicates that the mentoring program is regarded by most as a value-added feature of their early learning as it offers support, if and when it is required, from those who have been there before. Research limitations/implications – Results are limited to one institution. However, as research into mentoring for higher education students is thin on the ground, this study contributes to our understanding of the positive impacts of mentoring on student success. Practical implications – This paper emphasizes the importance of business leaders giving back to their alma mater through mentoring current MBA students. It shows how mentoring can support learning and management development. Originality/value – This is an original study which explores ways to increase the learning of higher education students for positive social outcomes.

scholarly journals Reflections on a measurement of the gravitational constant using a beam balance and 13 tons of mercury

2014 ◽  
Vol 372 (2026) ◽  
pp. 20140027 ◽  
Author(s):  
S. Schlamminger ◽  
R. E. Pixley ◽  
F. Nolting ◽  
J. Schurr ◽  
U. Straumann
Keyword(s):  
Gravitational Constant ◽  
Beam Balance ◽  
A Value ◽  
University Of Zurich ◽  
The University ◽  
Experimental Effort

In 2006, a final result of a measurement of the gravi- tational constant G performed by researchers at the University of Zürich, Switzerland, was published. A value of G =6.674252(122)×10 −11  m 3  kg −1  s −2 was obtained after an experimental effort that lasted over one decade. Here, we briefly summarize the measurement and discuss the strengths and weaknesses of this approach.

scholarly journals Bands in the secondary spectrum of hydrogen

1927 ◽  
Vol 114 (767) ◽  
pp. 293-313 ◽  
Keyword(s):  
Quantum Theory ◽  
Static Model ◽  
Moment Of Inertia ◽  
Initial Moment ◽  
A Value ◽  
Starting Point ◽  
Band Spectra ◽  
The University ◽  
Low Pressures ◽  
Complete Account

Fulcher’s discovery of bands in the secondary spectrum of hydrogen at low pressures proved the starting point of a number of investigations, including those, based on the valuable tables of Merton and Barratt, which have been carried out in the University of St. Andrews. The application of the quantum theory to these bands has been discussed by one of us (H. S. A.), by Curtis, and in particular by Richardson who, partly in association with Tanaka, has added greatly to the number of known regularities and done much to bring them into line with the theory of band spectra. Nevertheless, apart from the Fulcher system, of which Richardson has recently given a very complete account, there remains a very large number of lines which have not yet been classified. One of the present writers (I. S.) has been engaged in a study of the secondary spectrum at higher pressures, and among the regularities which have been selected by this method is a band with head at 4582·58 A. U. and shading towards the violet, which has been described in a recent communication. This band yielded an initial moment of inertia agreeing closely with a value deduced from a static model of triatomic hydrogen, H 3 . This band has since been found to be one of a large number of similar bands which it will be the purpose of this paper to describe. We shall refer to it for convenience as “Band II A , a .”

scholarly journals Universities under Pandemics of Management and COVID

Problemos ◽  
2020 ◽  
Vol 98 ◽  
pp. 107-112
Author(s):  
Jonas Dagys
Keyword(s):  
Academic Community ◽  
Academic Life ◽  
Effective Management ◽  
Unique Form ◽  
Community Based ◽  
University Development ◽  
A Value ◽  
Vilnius University ◽  
Societal Expectations ◽  
The University

The most urgent challenge of this year – the COVID-19 pandemic and measures of response to it – has sharpened and accelerated the process which was initially driven by bureaucratization and formalization: increasing depersonalization of academic life and the erosion of the university as a unique form of coexistence. The Assuming the concept of the university as a value category, this article aims to review and assess the changes in the self-perception of the academic community that have matured and acquired institutional forms in an attempt to adapt to rapidly shifting societal expectations and needs. Modern trends in university development are best expressed in terms such as “bureaucratization”, “formalization”, “depersonalization”, “instrumentalization of knowledge”, and “community fragmentation”. The pandemic of effective management that has affected Western universities and has gradually reached Vilnius University, no less than the pandemic of COVID-19 and administrative response to it, weakens the academic community based on autonomous and collegial decisions, which should be considered among the most important grounds of uniqueness of university as an institution.

Sign in / Sign up

Export Citation Format

Share Document