Study on the dynamic behavior of cylindrical steel liquid storage tanks using finite element method

Dynamic behavior of ground supported cylindrical storage tanks (CST) is of crucial importance because of its applications in industrial complexes. Seismic behavior of tanks is greatly affected by the height to diameter ratio, fluid height and fluid type. Five CSTs with different height to diameter ratios, three CSTs with the same height and diameters but various fluid heights and one CST with two different fluid types are selected to determine the effect of height to diameter ratio, fluid heights, and fluid type on the seismic behavior of the tanks respectively. Static, modal, response spectrum, and time history analyses are used in this study for the selected CSTs using ANSYS finite element software. In the time history analysis method, the Tabas, Kobe and Cape Mendocino earthquake records have been utilized on the first five CSTs to ascertain the effect of height to diameter ratio and the Tabas earthquake record is used for the rest of CSTs. Results show that an increase in fluid height lead to a corresponding increase in the base shear. Based on observations, 100 percent increase in the diameter showed 63 percent increase in sloshing under the response spectrum and 70 percent under time history analyses. Based on static and response spectrum analyses, the highest values of displacements are obtained at the lowest part of the tanks, while in time history analysis, the highest is obtained at the top of the tanks. All analyses showed that the maximum stress occurred at the height of 1 to 2 meter from the bottom of the tanks

EXAMINING PERFORMANCE OF STABILIZATION PONDS OF AHVAZ'S SLAUGHTERHOUSE

A waste stabilization pond (WSP) is a hole in which household wastewater and other types of sewage are stored for long periods of time so that organic materials existing in them are deposited, decomposed and stabilized through exposure to light and heat and growth of algae and microorganisms.  In WSPs, deposition and stabilization processes take place simultaneously.  Such features make WSPs suitable for treating industrial sewage such as wastewaters produced by slaughterhouses, dairy plants and canned food factories. The present study sampled wastewaters collected and treated by the treatment plant of a slaughterhouse in Ahvaz and compared the relevant measured parameters with the standards set by the Environmental Protection Organization of Iran in order to determine the efficiency of WSPs in treating wastewaters and making them usable for irrigation purposes.  The results indicate that Turbidity, BOD5, PH, COD, TDS, and TSS values for the treated wastewaters stood at 1000 NTU, 912 mg/lit, 8.78, 1520 mg/lit, 1052 mg/lit, and 2180 mg/lit respectively. A comparison of these values with the standard values set by the Environmental Protection Organization of Iran revealed a significant difference. This finding shows that the wastewater treatment plant under study had a poor productivity and performance and that wastewater treated by that facility could not be used for irrigation or pumped into surface waters. Therefore, environmental management programs and solutions have been suggested in order to help control and reduce the adverse effects of treated wastewater

EFFECT OF HEIGHT ON THE STATIC STABILITY OF HETEROGENEOUS EMBANKMENT DAMS

The main objective in designing an embankment dam is to achieve a structure that keeps water and in addition prevents seepage in downstream that has piping and rupture. Therefore, the present study examined the effect of height on upstream and downstream slope stability of heterogeneous embankment dams with the same characteristics but with different heights at the end of construction and Steady-State Seepage and Rapid Drawdown. To investigate the effects of height, two dams with a height of 62 meters and 133 meters and 6 meters crest width were modeled in Geostudio software. The embankment dam is composed of 14 different areas with different characteristics. To analyze the dam stability, SLOP/W and to model the movement of water in dam due to presence of water behind the dam in a Rapid Drawdown and Steady-State, seepage SEEP/W in Geostudio was used. Finally, the obtained safety factors in two dams with different height are compared with each other and the obtained safety factor was compared with USBR safety factor. This research showed that the safety factor is safer for 62 meters dam. The safety factor in shorter dam is safer than long dam

Restorative dentistry considerations in the geriatric dentistry : systematic review

BACKGROUND AND AIM: As the number of elderly people visiting dental clinics increases, it is essential to have sufficient information on the correct treatment as well as the appropriate treatment plan for these patients. Therefore, the present study aimed at reviewing the most important restorative considerations for the elderly.METHOD: In this systematic review study, databases such as Pubmed, Embase, Web of Science, Scopus, ProQuest, Google scholar, as well as Iranian databases were searched with the keywords of elderly dentistry and restorative considerations. Inclusion criteria were original articles and reviews related to restorative dentistry considerations for the elderly without a time limit and being written in either English or Persian. In order to combine the results of the research, a thematic content analysis method was applied.RESULTS: The total number of documents recovered was 4208, the number of duplicate documents was 2042, and the number of documents reviewed was 17. The most important considerations related to the elderly included giving due attention to medical and social conditions, medication use, type of restorative teeth, level of restoration involved, use of dentures, age and gender, oral cancer screening, tooth decay education and prevention, and oral hygiene. The most important considerations related to restorative methods and materials were applying minimally invasive methods such as ART, more durable restorative materials, and giving due attention to the aesthetic and non-aesthetic needs of the elderly in choosing restorative materials. The most important considerations related to dentists were the differences in applying restorative methods and materials by experienced dentists in comparison younger dentists and the rate of referral of elderly people to dental centers.CONCLUSION: The most important dental considerations of the elderly are using minimally invasive methods and restorative materials with easy maintenance which are washable according to their social, economic, medical, gender, and age conditions. It is also necessary to consider the prevention of tooth decay and provide the required training for families and their caregivers in nursing homes. The elderly people are also required to avoid change their dentists frequently to maintain their oral health.peer-reviewe

Cell Toxicity and inhibitory effects of Cyperus rotundus extract on Streptococcus mutans, Aggregatibacter actinomycetemcomitans and Candida albicans

Periodontitis and tooth decay are common dental diseases. There are some bacterial risk factors such as Streptococcus mutans, Aggregatibacter actinomycetemcomitans and Candida albicans fungi. Considering the increasing resistance of bacteria and fungi to antibiotics and their complications, tubers of Cyperus rotundus was used to determine the antimicrobial effect of alcoholic and aqueous extracts and essential oil on Streptococcus mutans, Aggregatibacter actinomycetemcomitans and Candida albicans, as well as an examination cytotoxicity on gingival fibroblast cells. Alcoholic and aqueous extracts and essential oil prepared from tubers of Cyperus rotundus. After bacterial and fungal cultures, the inhibition zone, Minimum inhibitory concentrations (MIC), and Minimum Bactericidal Concentration (MBC), were studied. Cytotoxicity was also evaluated using the Methyl tetrazolium test (MTT).The results showed that Cyperus rotundus alcoholic extract had the greatest effect on inhibition of growth and death of Streptococcus mutans, Aggregatibacter actinomycetemcomitans. According to the present study, Cyperus rotundus extract can be considered as a suitable candidate for the treatment and prevention of periodontitis and tooth decay

Anaphothrips sineconus and Hyalopterothrips brunneus, two new species of Anaphothrips genus-group (Thysanoptera) from Iran

Alavi, Jalil, Yazdanian, Mohsen, Minaei, Kambiz (2018): Anaphothrips sineconus and Hyalopterothrips brunneus, two new species of Anaphothrips genus-group (Thysanoptera) from Iran. Zootaxa 4388 (3): 437-443, DOI: https://doi.org/10.11646/zootaxa.4388.3.1

Seismic Vulnerability of Cylindrical Steel Liquid Storage Tanks for an Oil Industry Plant

Liquid storage tanks are quite important structures that are widely used in different industrial plants. Because of their recent performance along sever earthquakes; there is a strong possibility that these structures are under possible danger of devastating damages. Hence, in this study, the seismic behavior of these structures with an emphasis on their vulnerability under different condition is analyzed. For this purpose, an oil industry plant in the south of Iran is considered and five different tanks with different dimension are chosen. Three significant parameters which are usually taken into account for evaluation of tanks are investigated. These Criterions are including: 1) Sliding, 2) Elasto-Plastic buckling (Elephant foot buckling), 3) Tank roof damage. Finally, the results show that al the studied tanks are quite safe for Elephant foot buckling criteria. However, for the two other criteria the results was not like Elephant foot buckling criteria

The current markers of cancer stem cell in oral cancers

Head and neck cancer (HNC) constitute 5 of all reported cancers. Among all, the oral cavity cancer is the most frequent type of HNC which accounts for over half of HNC cases. Mouth cancer ranks the sixth leading cause of cancer-related mortality. Generally, conventional chemotherapy has shown success at decreasing relapse and metastasis rates and improves the overall prognosis. Recently, target therapy and targeted drug delivery systems have been introduced as promising treatments. The elimination of efficiency of current therapeutic strategies due to the spared cancer stem cells that cause chemotherapy resistance, relapse and metastasis. Inefficiency methodologies in the elimination of all cancer cells in the body are a major problem that remained to be resolved before to confront the new cancer therapies. Many studies imply to cancer stem cell markers as important agents for targeted anti-cancer as well as improving chemotherapy efficiencies. The potentials of targeted cancer therapy led us to search for novel markers in the mouth cancer stem cells especially in rare cancers. The aimed of this research was, first a comprehensive critical review of the previous studies on the markers of cancer stem cells in oral cancers including oral squamous cell carcinoma, salivary gland cancers, and to highlight the most common cancer stem cell markers which have potential to be exploited as indicators for the preneoplastic lesion malignancy, oral cancer progression, and/or treatment prognosis

Retrospective Evaluation of Common Dentistry Errors in Selected Dental Clinics of the Armed Forces, Iran

Background & Aims: The occurrence of errors in dental practice is an inevitable factor resulting in a reduction in the quality of medical services. These errors can prompt adverse complications, weaken the patient's trust in the dentist, and induce financial losses to the health care system. The purpose of this study was to investigate the common overt and covert errors that can be detected from medical records in selected clinics of the Armed Forces, Iran. Materials & Methods: In this study, we evaluated 3248 dental records, documented in seven selected dental clinics of the Armed Forces, Iran. The dental files were reviewed to detect flaws in the process of documentation, treatment protocols, and results. The patient and practitioner demographics were also extracted for further statistical analyses. Results: Among the studied documents, 14% of the dental records were incomplete and 17% of dental treatments showed at least one deviation from the standard treatment protocols. Also, there was a significant relationship between the occurrence of these errors and some demographic variables such as the dentist’s age, academic degree, and work experience. The prevalence of dental errors was 14%, 20%, and 30% in 1st, 2nd, and 3rd-grade dental clinics, respectively. Conclusion: Deficiencies in completing medical records and errors in the treatment process are common in Armed Forces clinics, Iran. Many of these errors can be identified through periodic evaluations and review of medical records to reduce the likelihood of recurrence

Current natural bioactive materials in bone and tooth regeneration in dentistry: a comprehensive overview

Tissue regeneration is a vital phenomenon in the skeletal system of human beings during their life span. The structure of bony architecture and teeth are highly dependent to this ongoing procedure to maintain their functional form. Regarding the fundamental function of our skeletal system, all the involved components are at constant risk for injuries and deformations throughout the life. Therefore, in modern medicine, promotion of bone and tooth regeneration has become a critical counter measure to correct these acquired defects. There are numerous ways to address the bone and tooth related erosive pathologies but utilization of natural compounds has gained immense popularity in recent years. These materials provide a broad spectrum of therapeutic agents with a variety of biological characteristics. In this review, a comprehensive exploration has been implemented to extract and categorize the relevant scientific evidence on this issue, based on the source of natural candidates and the potential clinical indications. Database searching presented a considerable data pool with more than 300 references in this field. According to the results, all the proposed items can be categorized in two major groups including scaffolding and osteogenesis (or dentinogenesis) induction. The clinical applicability of a number of them is properly demonstrated in clinical trials but for the rest, more examinations are required to reach a conclusive decision