Exact Wave Packet Dynamics of Singlet Fission in Unsubstituted and Substituted Polyene Chains within Long-Range Interacting Models

Singlet fission (SF) is a potential pathway for significant enhancement of efficiency in organic solar cells (OSC). In this paper, we study singlet fission in a pair of polyene molecules in two different stacking arrangements employing exact many-body wave packet dynamics. In the non-interacting model, the SF yield is absent. The individual molecules are treated within Hubbard and Pariser-Parr-Pople (PPP) models and the interaction between them involves transfer terms, intersite electron repulsions and site-charge--bond-charge repulsion terms. Initial wave packet is constructed from excited singlet state of one molecule and ground state of the other. Time development of this wave packet under the influence of intermolecular interactions is followed within the Schr\"odinger picture by an efficient predictor-corrector scheme. In unsubstituted Hubbard and PPP chains, $2{}^1A$ excited singlet state leads to significant SF yield while the $1{}^1B$ state gives negligible fission yield. On substitution by donor-acceptor groups of moderate strength, the lowest excited state will have sufficient $2{}^1A$ character and hence results in significant SF yield. Because of rapid internal conversion, the nature of the lowest excited singlet will determine the SF contribution to OSC efficiency. Furthermore, we find the fission yield depends considerably on the stacking arrangement of the polyene molecules.Comment: 13 pages, 8 figures, 4 table

Model for Triplet State Engineering in Organic Light Emitting Diodes

Engineering the position of the lowest triplet state (T1) relative to the first excited singlet state (S1) is of great importance in improving the efficiencies of organic light emitting diodes and organic photovoltaic cells. We have carried out model exact calculations of substituted polyene chains to understand the factors that affect the energy gap between S1 and T1. The factors studied are backbone dimerisation, different donor-acceptor substitutions and twisted geometry. The largest system studied is an eighteen carbon polyene which spans a Hilbert space of about 991 million. We show that for reverse intersystem crossing (RISC) process, the best system involves substituting all carbon sites on one half of the polyene with donors and the other half with acceptors.Comment: 7 Pages; 10 Figure

Geographical segment disclosure and capital market risk assessment of multinational enterprises

Abstract available : p.ii-ii

Knowledge and perception of extension workers towards ict utilization in agricultural extension service delivery in Gazipur district of Bangladesh

The primary purpose of the study was to assess the extent of knowledge and perception of extension workers towards ICT utilization and to determine the relationship between the selected characteristics of the respondents and knowledge and perception of extension workers towards ICT utilization in extension service delivery. The study was conducted in Gazipur district and comprised proportionate random sample of 90 extension workers from five upazila of Gazipur district. A pre-tested interview schedule was used to collect data from the respondents. To measure the knowledge on ICT utilization 35 statements were selected regarding 7 ICT with five possible answer of each tools and a score of one was given to the right answer and zero to the wrong answer alternatively to measure the perception of the respondents rated each of 10 statements ICT utilization in agriculture on a 5-point Likert type scale and the total of these ratings formed perception index. The result of the study showed that out of seven ICT tools the knowledge of extension workers was highest in case of MS Word this was followed by internet/ web service and the lowest knowledge was found in case of Geographical Information System. It is observed that an overwhelming majority (88.9%) of agricultural extension workers in the study area had low to medium knowledge towards ICT utilization. Findings reveal that the respondents had top most perception on the ICT utilization in respect of Extension work can be greatly enhanced by ICT followed by on The benefits of ICT use outweigh the financial burden involved. The result also indicated that more than fourth-fifth (84.4%) of the respondents had medium to high perception towards ICT utilization. There were significant relationship between service experience and use of the information sources of the respondents with their knowledge towards ICT utilization conversely innovativeness, cosmopoliteness and job satisfaction of the respondents showed positive significant relationship with their perception towards ICT utilization. DOI: http://dx.doi.org/10.3329/ijarit.v4i2.22647 Int. J. Agril. Res. Innov. & Tech. 4 (2): 46-52, December, 201

Systematic Literature review on the Use of Applications of Smartphones for Teaching English in EFL Contexts

This review paper provides an overview of the use of applications of smartphones, target language skills, methodology, and EFL contexts from the studies published between 2010 and January 2020. As per time frame and parameters followed by the PRISMA model, 45 of 2707 studies were retrieved from four reputable online databases, namely Springer link, Web of Science, Scopus, and ScienceDirect, were eligible for this study, All these studies (n=45) scrutinized and analyzed with NVIVO-12 for obtaining the objectives of this study. The findings showed that 25 applications of smartphones were employed, and the most used application was Short Message Service (SMS). Further, the findings reported that vocabulary was the most targeted language skills, the quantitative research methodology was the most popular and highest number of studies held in Iran employing smartphone apps in ELT. Based on the findings, the study would provide some implications and suggestions over the use of the applications of smartphones for facilitating teaching and learning language skills in the EFL contexts for educators and researchers

Project Based Approach Focusing on Students Speaking Skill Using Digital Storytelling

This paper describes the digital storytelling task applied in speaking class of second year students of English Study Program, including advantages students achieve from storytelling and technology integration as well as suggestions for classroom implementation. The necessity for students to use effective written communication and to be technologically literate remains strong. Meanwhile, English teachers charged with developing these skills are searching for ways to engage students in the writing process and integrate technology into daily learning activities. Digital storytelling aligns with both of these objectives. This strategy invites students into the writing process on a personal level and integrates several technologies into the final project. With careful planning and preparation, digital storytelling present students with a deeply meaningful learning experience. Many students readers and writers, will be highly motivated by the personal nature of storytelling and the integration of technology. An interactive technology can keep the students engaged into the material. As they build their stories, students will be reading for depth and understanding, and gaining proficiency with the vocabulary, structure and pronunciation of language. Finally, students will gain greater competence with technology as they refine their problem-solving skills. Sharing personal stories and engaging in this variety of thinking skills will prove to be a rewarding experience for both teachers and students. Keywords : Project based approach, digital storytelling, writing, literac

Classification and rating of strong-motion earthquake records

Ninety-two strong-motion earthquake records from the California region, U.S.A., have been statistically studied using principal component analysis in terms of twelve important standardized strong-motion characteristics. The first two principal components account for about 57 per cent of the total variance. Based on these two components the earthquake records are classified into nine groups in a two-dimensional principal component plane. Also a unidimensional engineering rating scale is proposed. The procedure can be used as an objective approach for classifying and rating future earthquakes

Spreading Fake News in the Virtual Realm in Bangladesh: Assessment of Impact

Fake news is false often sensational information disseminated under the guise of news reporting The upsurge of technological advancement especially social media has paved the way for spreading fake news The virtual realm spurs fake news as per the speed of air Nowadays fake news has been one of the social problems in the world along with Bangladesh Self-seeker groups use fake news as an atomic arsenal to disseminate their popular rhetoric with supersonic speed for fulfilling male purposes Fake news is usually rampant during any crisis elections and even in campaigns The hoaxers and fakers exploit the opportunity of the wavering psychology of the social media users and fake news becomes viral on social media Facebook Recently Bangladesh has faced an acute crisis of spreading fake news during the Movement of Nirapod Sarak Chai National election in December 2018 and very recent need child s head for Padma Bridge This study titled Spreading Fake News in the Virtual Realm in Bangladesh Assessment of Impact seeks the reasons for spreading fake news and its social impact in Bangladesh This paper is based on secondary literature The Rapid growth of online journalism most of the online portals are run by unskilled and less educated persons lack of news sense lack of national security act for controlling web portal lack of ethical knowledge of journalism lack of implementation of the law to punish criminals mistrust on existing justice mistrust on police who are detached from mass people taking revenge on political rivals derange social discipline creating a chaotic environment the suspicious mind of mass people lack of knowledge and mass awareness are the main reasons of spreading fake news in Banglades