scholarly journals Solid State NMR for Nonexperts: An Overview of Simple but General Practical Methods

Solids ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 139-154
Author(s):  
Ilya G. Shenderovich ◽  
Hans-Heinrich Limbach
Keyword(s):  
Noncovalent Interactions ◽  
Theoretical Calculations ◽  
Heterogeneous Systems ◽  
Organometallic Compounds ◽  
Ease Of Use ◽  
Specific System ◽  
Main Research ◽  
Specialized Equipment ◽  
Technical Simplicity ◽  
Analytical Tools

There are varieties of methods available for the exploration of solids using nuclear magnetic resonance (NMR) spectroscopy. Some of these methods are quite sophisticated, others require specialized equipment. This review is addressed to those for whom NMR is not the main research method. It discusses simple methods that can be applied to solids with little or no adaptation to a specific system. Despite their technical simplicity and ease of use, these methods are powerful analytical tools that provide unique insights into the structure, dynamics, and noncovalent interactions in homo- and heterogeneous systems. Particular attention is paid to the characterization of porous materials and solids containing phosphorus. 31P NMR of organometallic compounds has been used as an example of how theoretical calculations can help in deeper analysis of experimental data.

scholarly journals A theoretical and experimental study of the adsorptive removal of hexavalent chromium ions using graphene oxide as an adsorbent

2020 ◽  
Vol 18 (1) ◽  
pp. 936-942
Author(s):  
Ardhmeri Alija ◽  
Drinisa Gashi ◽  
Rilinda Plakaj ◽  
Admir Omaj ◽  
Veprim Thaçi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Hexavalent Chromium ◽  
Adsorption Energy ◽  
Density Functional ◽  
Noncovalent Interactions ◽  
Theoretical Calculations ◽  
Chemical Oxidation ◽  
Chromium Ions ◽  
Adsorption Sites ◽  
Vis Spectroscopy

AbstractThis study is focused on the adsorption of hexavalent chromium ions Cr(vi) using graphene oxide (GO). The GO was prepared by chemical oxidation (Hummers method) of graphite particles. The synthesized GO adsorbent was characterized by Fourier transform infrared spectroscopy and UV-Vis spectroscopy. It was used for the adsorption of Cr(vi) ions. The theoretical calculations based on density functional theory and Monte Carlo calculations were used to explore the preferable adsorption site, interaction type, and adsorption energy of GO toward the Cr(vi) ions. Moreover, the most stable adsorption sites were used to calculate and plot noncovalent interactions. The obtained results are important as they give molecular insights regarding the nature of the interaction between GO surface and the adsorbent Cr(vi) ions. The found adsorption energy of −143.80 kcal/mol is indicative of the high adsorptive tendency of this material. The adsorption capacity value of GO toward these ions is q = 240.361 mg/g.

scholarly journals Bimetallic nanocatalysts PtCu and PtNi for fuel cells

2020 ◽  
Vol 21 (2) ◽  
pp. 211-214
Author(s):  
O. M. Chernikova ◽  
Y. V. Ogorodnik
Keyword(s):  
Density Functional ◽  
Bimetallic Catalyst ◽  
Theoretical Calculations ◽  
Catalyst Activity ◽  
Main Research ◽  
Heterogeneous Catalytic ◽  
Physical Mechanisms ◽  
Oxidation Of Methanol ◽  
The Density Functional Theory ◽  
Bimetallic Nanocatalysts

We review the physical mechanisms of heterogeneous catalytic oxidizing reactions methanol oxidation using bimetallic film layered mechanically strained PtNi and PtCu-based catalysts. The main research methods are theoretical calculations based on the density functional theory and the ˝ab initio˝ pseudopotential method. The work illustrates that the mechanical stress and the presence of dissociated oxygen have the greatest impact on increasing electron bimetallic catalyst activity during the oxidation of methanol with using bimetallic layered mechanically strained PtNi and PtCu-based catalysts. The compression of the platinum film pushes the electron density outside the film and it gives the density an elongated form and increases the chemical and absorption activity of the film.

Noncovalent Interactions in Organometallic Compounds: Formation of an Intramolecular Metal–Carbon Ion Pair in Zirconium Borate Betaines

1997 ◽  
Vol 36 (24) ◽  
pp. 2771-2774 ◽  
Author(s):  
Jörn Karl ◽  
Gerhard Erker ◽  
Roland Fröhlich ◽  
Frank Zippel ◽  
Friedrich Bickelhaupt ◽  
...  
Keyword(s):  
Noncovalent Interactions ◽  
Organometallic Compounds ◽  
Ion Pair ◽  
Carbon Ion

scholarly journals Smallholder: an inconvenient label in the adoption of water pumping technologies?

2020 ◽  
Author(s):  
Juan Carlo Intriago Zambrano ◽  
Ruben van Dijk ◽  
Martin van Beusekom ◽  
Jan-Carel Diehl ◽  
Maurits W. Ertsen
Keyword(s):  
Decision Making ◽  
Q Methodology ◽  
Field Work ◽  
Ease Of Use ◽  
External Support ◽  
Farm Size ◽  
Adoption Process ◽  
Structured Interviews ◽  
Main Research ◽  
Water Pumping

<p>Use of water pumping technologies (WPTs) to drive pressurized systems in smallholder irrigation schemes is one of the key interventions to secure water, hence to increase yields and to potentially alleviate poverty, as well as to foster local and global good security. Whichever the chosen WPT, smallholders face many decision-making variables when considering them: finances, information, technical performance, ease of use, market characteristics, and even environmental concerns are amongst them. We will present evidence that suggests that the way smallholders deal with those factors cannot be predicted based on mere land size-based classifications that are used in many existing policy studies and actual policies. As there are not many specific studies that focus on understanding the influence that the aforementioned variables, directly and indirectly, have on smallholders’ adoption of WPTs, we conducted field work in three different contexts—Nepal, Indonesia and Malawi—to identify the multidimensional gaps and relations between farmer and technology.</p><p>Due to the nature of the study, which comprised several (subjective) variables across a number of contexts and individuals, a triangulation of data collection techniques (e.g. direct observations, semi-structured interviews, surveys) was preferred. The main research method was Q-methodology, an increasingly popular inverted technique of factor analysis that combines the strengths of qualitative and quantitative research. Furthermore, one of its main advantages is that representativeness of the subjectivity does not depend on large samples of respondents but rather on their diversity.</p><p>By this process, it became evident that clustering farmers under the “smallholders” label—in line with the traditional farm size-based approach—did not reflect their heterogeneity in the WPTs’ adoption process. As a matter of fact, some smallholders are willing (and able, at times) to make substantial investments in WPTs for agricultural irrigation, thus moving away from the “external support-reliant-farmer” image. In conclusion, smallholder’s behaviour, thus decision making, is highly contextualized and cannot be underpinned by solely and simplistically looking at the holding size.</p>

Evaluating the Factors Affecting DSS Usage by Senior Managers in Local Authorities in Egypt

2006 ◽  
pp. 283-307 ◽  
Author(s):  
Ibrahim Elbeltagi ◽  
Neil McBride ◽  
Glenn Hardaker
Keyword(s):  
Technology Acceptance ◽  
Developed Countries ◽  
Ease Of Use ◽  
Perceived Usefulness ◽  
Perceived Ease Of Use ◽  
Senior Managers ◽  
Specific System ◽  
Local Authorities ◽  
Management Approaches ◽  
Acceptance Model

The study of factors influencing the adoption and use of information systems in less-developed countries is an important area to address since differences in culture, social structure, and business approaches may have significant effects on the benefits derived from importing Western-influenced IT technology, concepts, and management approaches. This study examines the usage of a decision support system (DSS) in Egyptian local authorities using an adapted Technology Acceptance Model (TAM). The centrally-developed DSS had been rolled out to 27 governorates in Egypt for use by chief executive officers. The results demonstrated that TAM could be applied to a specific system within a developing country. Both perceived ease of use (PEU) and perceived usefulness (PU) had a significant direct effect on DSS usage. PEU dominated over PU whose effect on DSS usage was negative.

Antecedents and consequences of e-shopping: an integrated model

2015 ◽  
Vol 25 (2) ◽  
pp. 184-217 ◽  
Author(s):  
Weng Marc Lim
Keyword(s):  
Structural Equation ◽  
Perceived Value ◽  
Integrated Model ◽  
Ease Of Use ◽  
Perceived Usefulness ◽  
Equation Modeling ◽  
Perceived Ease Of Use ◽  
Content Type ◽  
Main Research ◽  
Antecedents And Consequences

Purpose – The purpose of this paper is to present an integrated information systems–consumer behavior (IS-CB) model for e-shopping to examine the antecedents and consequences of e-shopping and usage behavior. Design/methodology/approach – The study tests 320 usable responses collected from e-shoppers against the integrated model using structural equation modeling. Findings – The main research results support the use of antecedents of e-shopping acceptance and usage by drawing from unified knowledge of IS and CB underpinnings. The findings show the significance of perceived value, social factors, perceived ease of use, perceived usefulness, entertainment gratification (EG), web irritation (WI), emotional state, and web atmospherics (WA) in the process of e-shopping. Practical implications – The results suggest that e-retailers should establish positive perceived value in consumers’ minds and uphold trust to foster favorable attitudes and intentions toward e-shopping and actual e-shopping purchase. Proper and good construction of WA can lead to useful and easy-to-use e-shopping sites, EG, and minimization of WI. Capitalizing on online social influences also would be an advantage. Originality/value – This paper bridges a gap in the studies of IS and CB, contributing to a more comprehensive understanding of the influence of IS and CB antecedents on acceptance and usage of e-shopping.

scholarly journals THE NORTHERN SEA ROUTE: A SCIENTOMETRIC ANALYSIS OF INFORMATION ARRAYS IN WEB OF SCIENCE AND SCOPUS DATABASES

2021 ◽  
Vol 11 (1) ◽  
pp. 77-86
Author(s):  
Valentina V. Rykova
Keyword(s):  
Web Of Science ◽  
Publication Activity ◽  
Scientometric Analysis ◽  
Urgent Problem ◽  
International Database ◽  
Main Research ◽  
Research Fields ◽  
Northern Sea Route ◽  
Analytical Tools ◽  
Practical Implications

The article traces main trends of the scientific research development on the Northern Sea Route using the international database Web of Science by Clarivate Analytics and Scopus by Elsevier. Using a scientometric analysis and analytical tools of DBs, the author shows countries, institutions and organizations that study this problem, as well as funds financing them; names productive periodicals and authors with high publication activity. In conclusion, the author notes that the study of the Northern sea Route development is an urgent problem for the entire world society, not only for the northern countries. Objective – to carry on a scientometric analysis of information arrays (IA) in the international scientific citation indices devoted to studying the Northern Sea Route development. Methods: scientometric analysis. Results: countries, institutions and organizations that study this problem are represented, as well as funds financing them; productive periodicals and authors with high publication activity are designated; the main research fields are revealed. Practical implications: the study should be used as an information base for further research of scientists and specialists on various aspects of the Northern Sea Route development.

scholarly journals Psychological Burnout among Tutors in Colleges of Education in the Ashanti Region, Ghana

2020 ◽  
pp. 12-21
Author(s):  
Kennedy Nyeseh Ofori ◽  
Eunice Agyeiwaa Kyere ◽  
Lydia Boateng Berko
Keyword(s):  
Quantitative Research ◽  
Cluster Sampling ◽  
Colleges Of Education ◽  
Main Research ◽  
Ashanti Region ◽  
Study Approach ◽  
Teacher Trainee ◽  
Significant Difference ◽  
Lack Of Commitment ◽  
Analytical Tools

This paper identifies the antecedents of psychological burnout and its influence on tutors’ job stress in Colleges of Education in the Ashanti Region of Ghana. The study adopted a case study approach because it probes four specific Colleges of Education (COE) in the Ashanti Region of Ghana. Quantitative research method was employed. Cluster sampling was used in selecting 120 tutors and then stratified on the basis of gender. The study used questionnaire as the main research instrument for gathering the data from participants. Cronbach’s Alpha was used to test the sample reliability, which yielded coefficient 0f 0.84. Data were analyzed using inferential statistics, with Pearson Product Moment Correlation and multiple regression models as analytical tools. Hypothesis was tested at a significant level of 0.01 and 0.05. Results revealed that lack of job satisfaction (96 %) and delay in payment of salary (88%) were the leading antecedents of psychological burnout among the tutors. Again, the findings showed that lack of commitment to work (92%) and transferring of aggression to teacher trainees were the top most effects of stress on Tutors. Results of hypothesis tested revealed no significant difference on the expression on both the causes and effects of psychological burnout among tutors on the basis of gender.  It was concluded that inadequate or complete lack of academic facilities did not only impair academic productivity, but also exerted undue stress on tutors and available facilities. The study recommended among others, the development priorities of the colleges should be Tutor –teacher trainee oriented.

Confluent Modeling of Heterogeneous Safety and Operational Instrumentation and Control Systems

2020 ◽  
Vol 6 (3) ◽  
Author(s):  
Mithil Parekh ◽  
Yuan Gao ◽  
Mariana Jockenhoevel-Barttfeld ◽  
Karl Waedt
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Critical Infrastructure ◽  
Heterogeneous Systems ◽  
Legacy Systems ◽  
Security Measures ◽  
Product Families ◽  
Or Groups ◽  
Specialized Equipment ◽  
Commercial Off The Shelf

Abstract Individual systems or groups of systems related to the safety and operational instrumentation & control (I&C), and electrical systems are gradually replaced in existing nuclear power plants (NPPs) as part of modernization projects. Modernizations are usually scheduled over multiple years. Different automation platform generations and safety-related product families are deployed to progressively replace legacy systems. Typically, each of the new I&C platforms and products have their own set of engineering tools. One challenge for the modernization of installed systems is the safety and security approval of these heterogeneous systems by regulatory bodies. An NPP consists of systems manufactured by different vendors, which target different application domains, like category A according to IEC 61226 for a reactor protection system, category C for some control room data processing systems or nonclassified for auxiliary systems. Thus, replacing a legacy system by introducing a new one might bring in unknown risks, especially when the new system has more complex interfaces, e.g., when replacing an analog system by a digital system. Moreover, considering the time and budget limitations, commercial-off-the-shelf (COTS) hardware and software are also involved in modernization projects. In contrast to specialized equipment, vulnerabilities for COTS are widespread. On the other hand, existing security measures/mitigations are also required to reflect the system's changes, e.g., mitigations for known vulnerabilities of COTS systems. In order to make an overall and integrated safety analysis after a system change in the frame of a modernization project, it is necessary to jointly consider these I&C systems targeting different application domains, in addition to the physical aggregates, like sensors, pumps, and valves that interact with the physical processes. The restrictive deployment of wireless technologies may also be modeled and analyzed. While wireless is not deployed by legacy systems, it is being covered by new nuclear IEC standards, as some utilities intend to simplify selected I&C maintenance procedures that involve temporary data collection. The key modeling concepts consider new developments in the critical infrastructure and industrial automation domain. With the integrated modeling approach, different disciplines can be addressed, like probabilistic and deterministic safety analyses, security assessments, need for testing and specialized trainings.

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