Showing 4 results for Yaqubi
Volume 9, Issue 3 (Summer 2018)
Abstract
Aims: Hepatitis B is a viral infection, which can cause serious liver problems. Hepatitis B surface antigen (HBsAg), which is produced as recombinant, is used to produce the Hepatitis B vaccine. The aim of this study was to detect DNA aptamer with high affinity against HBsAg by Systematic Evolution of Ligands by Exponential Enrichment (SELEX).
Materials and Methods: In the present experimental study, SELEX method was used to isolate and sequence a DNA aptamer with high affinity against HBsAg. The affinity of this monoclonal nucleotide sequence was calculated by fluorimetric method. The difference of initial absorption and residual value as a measure for the number of associated sequences were calculated with Prism 5 software by nonlinear regression method, Binding-saturation and one site-total model were performed, and the amount of electron affinity (Kd) was determined.
Findings: After performing the SELEX procedure and evaluating the amplified sequence with agarose gel, the result was positive control sample containing a bond in the range of 72nucleotides, indicating successful amplification of the selected sequence, using selective primers. During cloning steps from existing colonies of PCR reaction with aptamer specific primers, the presence of aptamer was confirmed in Escherichia coli bacteria. The reported aptamer had a stable secondary structure with a free energy of ΔG of less than -6.9kJ and Tm higher than 45°C.
Conclusion: The selected DNA aptamer has a high affinity to the target protein (HbsAg) and can be considered as an alternative for mAbs in chromatography column.
Volume 14, Issue 3 (July & August 2023 (Articles in English & French) 2023)
Abstract
This study was conducted to examine learners’ attitudes and perceptions toward the efficacy of task repetition: whether or not they appreciated task repetition as an effective classroom strategy for enhancing their oral performance. To this end, a multiple case study approach was adopted in which six intermediate English as a Foreign Language (EFL) learners were investigated over a four-month period in an intact class. Four data collection tools were used: (1) multiple interview sessions, (2) learner diaries, (3) participant observation, and (4) classroom portfolios. In addition, 20 hours of the learners’ audio-recorded task performances across sessions were transcribed and analyzed for signs of improvements in qualities of oral performance. Results indicated that despite the fact that repeating reciprocal narrative tasks led to gains in oral performance, learners viewed task repetition as a futile activity that did not affect their performances over time. The findings are discussed, and implications are provided in the context of education.
Volume 21, Issue 3 (12-2017)
Abstract
Work engagement is a psychological state experiencing energy, absorption and dedication at work. The purpose of this study is to investigate impact of psychological empowerment and its components on work engagement. This cross sectional study was practical in terms of goal and descriptive-correlational in terms of nature. The statistical population was several public organizations in Mashhad, Iran. A simple random sampling method was applied. Krejcie and Morgan table showed that the suitable sample size is 384. Then, 420 questionnaires were distributed, led to 389 collected completed questionnaires. To measure the work engagement, Schaufeli, Bakker, and Salanova scale, and to measure psychological empowerment, Spreitzer scale were used. Using confirmatory factor analysis, the validity of measures were approved. The results of path analysis in LISREL software showed that psychological empowerment explains 73 percent of the employees' work engagement. While, competence’s effect on work engagement was not statistically significant, other components of psychological empowerment such as meaning, self-determination, and impact, had 48 percent, 33 percent and 38 percent positive and significant effect on the work engagement, respectively. Therefore, psychological empowerment is a significant predictor for work engagement. The results indicate that the organization performs interventions to increase employees' psychological empowerment. The pivot of these interventions should focused on sense of meaning for the tasks, self-determination, and impact.
Volume 28, Issue 4 (9-2021)
Abstract
The purpose of this article is to contribute to studies on counterfactuals by exploring counterfactual conditions in Persian. Here, counterfactual sentences in Persian have been studied based on typological findings of the same in different languages. In order to study the typology, two main parameters are examined: symmetrical and asymmetrical morphological patterns of counterfactual conditional sentences and the range of TAM (Tense Aspect Mood) values in protasis and apodosis. The main concepts of counterfactual conditionals, including the construction of complex sentences, imagined conditions that have not occurred, false events, and the two above parameters were taken into account. This is a library-based research and the required data was extracted from the Persian Linguistic Database (PLDB). Findings show that the counterfactual conditions in Persian have a complex sentence construction and protasis acts as a subordinate clause and in typological classifications, Persian has counterfactual conditionals for past, present and future and counterfactual conditionals have both symmetrical and asymmetrical patterns. Also in the TAM spectrum, counterfactual conditions have both symmetrical and asymmetric morphological patterns. In these patterns, both protasis and apodosis are used in the past continuous and past perfect tenses. In all three types of counterfactual conditions, the past tense is used, with either perfective or imperfective appearance.
