Sharif Digital Repository

Flagella is the organelle involved in motility of Salmonella and plays an important role in colonization of Salmonella. Flagellins is the structural subunits of flagellar filament that is known as an adjuvant. Recombinant production of flagellin of S. enteritidis is advantageous due to the removal of pathogenic microorganism from the production process and improved process safety. E.coli is an appropriate host for the expression of recombinant proteins. However, its major obstacle is the formation of inclusion bodies. Inclusion bodies are aggregated inactive proteins and the recovery of proteins in the active form from these aggregates usually has a low yield. Therefore, the objective of our... 

Over the past two decades, the interest in exploring consumers' behavior has risen to popularity. Nowadays, it is necessary for marketers to reach out to the right consumers at the right time and with the right message. Even though the positive impact of tracking consumers throughout their purchase journey and its managerial implications have been emphasized several times by academics, There is still a lack of practical research on how to discern the consumers' stage in the purchase journey from a holistic point of view. In this study, we develop several machine learning models, including RNNs (GRU and LSTM), Transformers, and XGBoost, by utilizing historical data of Yektanet (the leading... 

Recently, the advent of online platforms as an intermediary tool has provided an opportunity for service providers and manufacturers to offer their services/products to consumers. Ride-hailing platforms are an example of these businesses where independent drivers and passengers are matched via an online platform. One of the most significant challenges faced by these companies is the emergence of strategic behaviors on both the demand and the supply side, which might affect the performance and profitability of the platform.In this thesis, we study the strategic behavior of drivers and its impact on their performance, using the data of one of the largest ride-hailing companies in Iran. We use... 

There are always some unpredictable phenomena happen in the process of constructing of a downstream petrochemichal plant resulting to delays that increase the cost compared with the benefits or sometimes cancelation of the projects that abodones the investors from the returns at all. On of the reasons that these issues can dwibdles the benefits is that most of Iranian’s downstream companies do not prepare suitable and sufficient capabilitities to cope with such a risks. In this thesis, at first, influensive risks on the downstream oil and gas projects in Iran have been studied based on a comprehensive litreture review, secondly using a questionnaire, these extracted risks have been assessed... 

This research examines the attributes, themes, and topics discussed in electronic word-of-mouth (e-WOM) generated in TripAdvisor for robotic hotels in comparison to traditional ones. The first objective is to explore the themes and topics within TripAdvisor negative e-WOMs for both types of hotels and analyze how these topics differ between the two types of hotels, using the Latent Dirichlet Allocation (LDA) method. The research shows that which topics are mostly discussed in TripAdvisor negative e-WOMs for both types of hotels. Additionally, the research explores whether different themes, topics, and attributes have varying effects on user ratings in traditional hotels versus robotic ones,... 

This study explores topics discussed in positive eWOM of robotic and conventional hotels through a comprehensive analysis of online reviews using Latent Dirichlet Allocation (LDA). LDA is an advanced topic modeling technique. To uncover topics discussed in eWOM of robotic hotels and conventional hotels, and then compare them to see if there are any meaningful statistical differences between them, three separate LDA models were implemented on reviews of robotic hotels, conventional hotels, and the overall rereviews of all hotels, respectively. The results reveal that “service quality and overall atmosphere” is the most common topic discussed considering both hotel types, with key themes... 

This thesis examines the impact of electronic word-of-mouth (e-WOM) on product demand forecasting, specifically in the context of video game consoles. This study examines the importance of emotion-based topics and their impact on demand forecasting at two stages of the product life cycle: pre-launch and post-launch. Using sentiment analysis and topic modeling, this study uncovers product sales drivers and captures evolving consumer sentiment throughout the product lifecycle. By integrating insights from diffusion theory and consumer information search theory, this research contributes to the field of demand forecasting using social media data. This research shows that by using the topics... 

Residential satisfaction plays a pivotal role in shaping liveable cities, profoundly influencing individuals' health and well-being. In contrast, dissatisfaction in living environments often triggers relocation intentions, leading to significant vacancy costs for landlords and property managers. While previous studies predominantly relied on traditional methods like surveys and interviews, our research adopts a novel, bottom-up approach, analysing this phenomenon through the lens of residents themselves. Leveraging a custom-developed Python-based web scraper, we meticulously gathered 195,000 online reviews from apartments.com. This comprehensive dataset spans the most populous cities and... 

In recent years, Internet advertising has become increasingly customized to individual users. As advertising carry on refining its capacities, it is more likely to be seen as insightful and useful by everyone. Consumers, particularly Gen Y and older members of Gen Z, are becoming more accepting of relevant advertising as digital acquaintance. Consumers now welcome active advertising that responds and reflects social activity, location, and brand and product preferences in real-time. This ability to be agile within the consumer’s connected experience is an emerging revenue driver and will continue to grow as ad platforms and ad presentations become smarter. But more personalization results in... 

Nowadays, one of the most popular methods of advertising is online advertising, which is commonly used by many businesses. In the meantime, targeting the right person at the right moment to show an advertisement is always a major concern of advertisers and other players in this field. One of the areas of study in the literature in this field is the investigation of factors affecting the effectiveness of targeted advertising. The purpose of the upcoming research is to investigate the impact of the advertised product involvement in targeted online advertising. This level of effectiveness is measured by considering click intention as a measure of effectiveness and examining the impact of... 

Nowadays, the brain drain problem has become a challenge for countries of origin (COO) and a blessing for countries hosting student migrants. This issue has been studied in many domestic and international types of research. These studies' results can lead to the ability to identify the causes and discover methods to solve this problem. For several decades, the human capital flight has been one of the most challenging educational-economic-social problems in Iran and has grown significantly in recent years. The waste of the country's resources, the ineffectiveness of the education provided to students to improve the country's condition and its construction, the social and psychological... 

With the easy access to internet and connected devices ubiquities, Today more than 50 million people use online education platforms to improve their skills and broaden their knowledge. In this research we tend to answer two questions based on data from Iranian students from top domestic universities.First question is which factors would these users consider in choosing their online education platform. This would be especially interesting to know in context of Iran’s cultural and job market situations.Second question we are interested in the same context is what are the factors that make users of these platforms to stop using them. This is very important since stoppage rate of online... 

From the beginning of current decade, ride souring in two sided platforms started its activities in Iran and after few years could reach to 10 billion Tomans turnover per year. Now a day Ride sourcing has more than 30 million users in Iran. These days there are more than 5 million price checks in ride sourcing mobile applications from passenger side but, only in half of them passengers and drivers get match. In this situation, one of the biggest challenges of ride sourcing companies is driver’s acceptance rate. Improving acceptance rate could make market bigger, increase utilization and driver satisfaction rate. According to explained need, this study with cooperating of the ride sourcing... 

Health influencers leveraged social networks to connect with people and society during the Covid-19 crisis. Platforms like Twitter served as suitable channels for disseminating published messages through word-of-mouth communication. In times of crises like Covid-19, individuals and organizations involved in managing the situation harnessed this capability, contingent upon the quantity and quality of word-of-mouth exchanges. During public crises, public polarity and sentiment toward the issue and the maintenance of public morale hold paramount significance. Consequently, crafting messages that garner positive word-of-mouth communication became a focal point for health influencers. In this... 

In this research, we will examine the emotions in the comments recorded about the tweets that have gone viral on the Twitter social media. We use Ekman's emotion classification model to classify emotions. Also, we choose the desired brands from the international brands of the fashion and clothing industry. These brands are divided into 2 luxury and non-luxury categories. Finally, we select 10 luxury brands and 9 non-luxury brands and extract all their tweets in a period of 6 months. Tweets that have been published more than a certain amount are considered as viral tweets, and using a machine learning model designed for this purpose, the emotions in the comments of users are analyzed and...