## 3 Results and Discussion
### Authors, Institutions, and Countries Collaboration Networks  
Collaboration is one of the crucial factors that drives research forward and increases productivity, as it enhances networks among researchers that are conducting similar studies \begin{table}
\begin{tabular}{c c c c c c} \hline
**Country** & **Articles** & **Freq** & **SCP** & **MCP** & **MCP\_Ratio** \\ \hline USA & 160 & 0.50314 & 122 & 38 & 0.237 \\ China & 20 & 0.06289 & 11 & 9 & 0.45 \\ Germany & 19 & 0.05975 & 12 & 7 & 0.368 \\ Italy & 16 & 0.05031 & 10 & 6 & 0.375 \\ Brazil & 15 & 0.04717 & 10 & 5 & 0.333 \\ Spain & 11 & 0.03459 & 7 & 4 & 0.364 \\ India & 10 & 0.03145 & 9 & 1 & 0.1 \\ Japan & 8 & 0.02516 & 6 & 2 & 0.25 \\ United Kingdom & 7 & 0.02201 & 4 & 3 & 0.429 \\ France & 5 & 0.01572 & 3 & 2 & 0.4 \\ Korea & 5 & 0.01572 & 4 & 1 & 0.2 \\ Canada & 4 & 0.01258 & 4 & 0 & 0 \\ Australia & 3 & 0.00943 & 1 & 2 & 0.667 \\ Czech & 3 & 0.00943 & 0 & 3 & 1 \\ Republic & 2 & 0.00629 & 0 & 2 & 1 \\ Colombia & 2 & 0.00629 & 1 & 1 & 0.5 \\ Denmark & 2 & 0.00629 & 2 & 0 & 0 \\ Kuwait & 2 & 0.00629 & 1 & 1 & 0.5 \\ Mexico & 2 & 0.00629 & 1 & 1 & 0.5 \\ Poland & 2 & 0.00629 & 2 & 0 & 0 \\ \hline \end{tabular}
\end{table} 
Table 7: The 20 most contributing countries by corresponding authors between 2011 and 2020.  
locally and internationally. It gives room for inter and intra-disciplinary sharing/exchange of ideas and helps to boost cooperation at different levels among scientists who are involved in related investigations [69]. In fact, such collaboration is now attracting support and approval from funding agencies, governments, and policymakers across the globe. Scientific collaborations also boost the output quality of such research and contribute impressively to the speed at which the process is accomplished [70]. Other benefits of scientific collaborations among authors, institutions, and countries with respect to research include accessibility of funds, equipment, and human resources and ease of solving difficult problems by bringing together different skills among experts [71; 72]. Figure 2 shows details about the inter-country collaborations among authors in general (including the first, corresponding, and as co-authors of articles) using various colors to indicate their clusters of cooperation. Altogether, six clusters were observed in the map. The node representing each country and the lines (links) that connect them with other countries have different sizes and thicknesses, respectively, indicating their relevance and the strength of collaborations that exist among them. The names of the countries involved are by default written in small letters [73]. The USA was observed to be the lead country with the biggest node, having the highest number of links with different countries of the world, including China, Canada, France, India, Denmark, Mexico, Japan, Spain, Korea, Luxembourg, and Australia. Hence, it is obvious that the top-rated countries in this field of research exhibit strong cooperation with each other. It could be seen that developed countries dominate the research field, and this indicates the significance of the subject being understudied. Besides, scientific research leaders are mainly from the developed countries of the world. Figure 2: Collaboration among countries from 2011 to 2020. Similarly, the cooperation among the top authors and institutions in this research field is depicted in Figures 3 and 4. The following researchers exhibited strong collaboration as depicted in Figure 3: [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], [PERSON], and [PERSON] This is revealed in the thickness of the lines that connect them. They are all among the top 20 authors as shown in Table 2, except [PERSON] The five of them (5 nodes) belong to the same cluster. There are about 14 clusters altogether on the map, as shown by the different colors representing each cluster of collaboration. Authors with the same color are in the same cluster (i.e., working closely together or having intimate collaboration) [74].