Coronavirus by one kind of its surface proteins (spike protein) locks onto the human cells surface receptors and after entering and replication of its RNA in the host cells causes immune responses. Briefly, a vaccine which may be weakened or inactivated virus, provokes the immune system to be ready to fight an invasive pathogen. So far, various technologies have been applied to develop vaccines against SARS-CoV-2 all over the world. Such vaccines including “, Nucleic acid vaccines”, , “, Viral-vector vaccines”,and protein-based vaccines”, .

BACKGROUND AND OBJECTIVE: Mechanical preparation of root canal system is an important objective of root canal therapy. Many rotary devices have been produced to decrease instrumentation time and improve its quality. The purpose of this study was to compare apical transportation in root canal treatment with three methods of hand, reciprocal and rotary (Race) instrumentation.METHODS: In this experimental study 45 extracted human mandibular first molar were selected. The crown was cut at CEJ. The roots were mounted in acrylic resin material. The roots had a 20-40 degree canal curvature. Teeth were randomly divided into 3 groups. Group one was prepared with hand method and NiTi files, group two was prepared with Endogripper handpiece and NiTi files, group three was prepared with Race rotary system. By superimposing the initial file and MAF radiography the apical transportation was evaluated (double exposure radiography method(.FINDINGS: Race rotary system (group 3) had prepared canals without transportation and deviation in the original shape of canals. NiTi hand files (group 1) had prepared canals with 8 apical transportations out of 15 root canals. Reciprocal handpiece with NiTi files had prepared canals with 7 apical transportations. Race rotary system was prepared canals with significant the least apical transportations than other groups (p<0.05).CONCLUSION: The results showed that original canal shape in apical region had minimum transportation with Race rotary system compare with hand or reciprocal preparation.

Introduction: Successful treatment of root depends on complete elimination of debris and bacteria's from root canal system and appropriate shaping of canal in obturation canal preparation is the most difficult and time consuming stage during root canal treatment. This stage especially in curved and narrow canals always causes some problems for students, general dentist and specialist. Following placement of file in curved root canals, some faces are introduced to instrument which tends to straighten it. This leads to removing of much dentin from curvature of canal. Then a phenomenon which is called "apical displacement" will take place and canal will be widened more than usual.Objective: The aim of this study is comparison of preparation of root canal using NiTi hand & Race rotary instrument.Materials &Methods: In this study 40 acrylic blocks with canal curvature 75 degree divided in two groups of 20 in each were used with passive step back technique. Canals in first group were cleaned and shaped using NiTi hand files and second group with Race rotary ones. Rate of transportation in 1/3 apical of root and file fracture was under investigation and statistical analyzed.Results: In this investigation there was no relationship between transportation and file fracture during two methods of preparation. This study showed that the canal preparation using Race rotary file can be as efficient as NiTi hand files.

Digital marketing can be considered a modern approach, which has accompanied today's businesses with a technological revolution. On the other hand, the world of modern industry and technology needs minerals more and more every day. For this reason, the present study has evaluated the digital marketing strategies of mining companies in Bushehr province and also provided suggestions in this regard, in order to assess the current state of the digital marketing in this sector, to take steps to modernize the companies in the province. This descriptive-applied research has collected information in the field, using tools such as questionnaires and interviews, has analyzed the data quantitatively, and has adopted a correlation and survey strategy. The statistical population of the study is all 172 mining companies in the province, and by sampling based on the criteria of "activation" and "use of the digital marketing", 11 companies have been selected as a sample. Data analysis was performed with SPSS and Smart-PLS software. Findings show that the digital marketing strategy of the province's mining companies is not in a good condition, and companies in 4 dimensions of this strategy, namely "PLAN, REACH, ACT (CONVERT) and ENGAGE" did not receive a appropriate score. Therefore, the present study to improve this situation provides practical suggestions for the digital marketing of the mining companies in Bushehr province.

As a significance process, identity is not a constant but a fluid and changing issue. The basic components of identity are being changed by passing time and under some events and thoughts. As an identity-building component, the Aria Race has been added to other identity components for Iranians in two recent centuries, particularly during the World War I and the years after that. This article has examined the backgrounds and quality of constructing Iranian identity on the basis of Race component by using analytical-documentary method. The findings indicate that the propounding of Race component as an identity-building one or Iranians is one of achievements of Orientalism. The World War I has affected this process due to the socio-political conditions of Iran and its relation with the Germans.