Background and Objectives. Tooth decay is an infectious disease of microbial origin. Considering the increasing prevalence of antibiotic resistance due to their overuse and also their side effects, medicinal plants are now considered for use against bacterial infections. This study aimed to assess the effects of different concentrations of Zingiber officinale extract on proliferation of Streptococcus mutans and Streptococcus sanguinis in vitro. Materials and Methods. In this experimental study, serial dilutions of the extract were prepared in two sets of 10 test tubes for each bacterium (total of 20). Standard amounts of bacterial suspension were added; 100ƛ of each tube was cultured on prepared solid agar plates and incubated at 37°C for 24 hours. Serial dilutions of the extract were prepared in another 20 tubes and 100ƛ of each tube was added to blood agar culture medium while being prepared. The mixture was transferred to the plates. The bacteria were inoculated on plates and incubated as described. Results. The minimum inhibitory concentration (MIC) was 0.02 mg/mL for S. mutans and 0.3 mg/mL for S. sanguinis. The minimum bactericidal concentration (MBC) was 0.04 mg for S. mutans and 0.6 mg for S. sanguinis. Conclusion. Zingiber officinale extract has significant antibacterial activity against S. mutans and S. sanguinis cariogenic microorganisms.

Carbonated water (CW) and low salinity (LS) injection processes are among the most widely investigated method during the past decade due to their unique advantages. Although the results revealed rather efficiency of these two methods, it is reported that using the combination of these two methods can introduce new insight about the smart and newly developed enhance oil recovery processes. Respect to these facts, the current work is aimed to investigate the swelling behavior of heavy crude oil in carbonated water at the presence of Na2SO4 and Mg2SO4. In this way, one of the main effective mechanisms through the carbonated water injection which is swelling factor is examined in the presence of two different salts, namely, Na2SO4 and Mg2SO4, under different pressures (500–4000 psi) and temperatures (30–80 °C). The results obtained in this investigation are compared with the previously reported results regarding the carbonated brine (CB) solutions consisted of different salts such as KCl, NaCl, CaCl2, and MgCl2 with the same concentration of 15,000 ppm. The results not only reveal the possible mechanism behind the swelling factor variation, but also reveal that crude oil and ion type as well as temperature besides the solubility of CO2 in aqueous phase can introduce tremendous influence on the mobility of CO2 molecules and their partitioning from aqueous phase towards the oil phase. Also, the obtained results reveal that the presence of divalent ions can directly affect the crossover pressure toward lower values.

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Using drilling fluids with optimum density is one of the most important approaches to stabilize the pressure of the bottom formation and prevent blowout through the drilling process. One of the common methods for this purpose is adding some additives with high specific gravity to the drilling fluid to tune its density. Among the possible chemicals, barite and hematite with the density of 4.2 and 5.2 g/cc are the most common additives. Unfortunately, although the application of these additives is advantageous, they have some drawbacks which the most important one is separation and settlement of solid phase called barite sag. The barite sag comes from barite, or other dense materials particles deposition resulted in undesired density fluctuations in drilling fluid can lead to mud loss, well control problems, poorly cementing and even pipe sticking which occurs in severe cases. With respect to these concerns, the current investigation is concentrated to obtain the relation between the dynamic conditions such as flow rate (0.308 and 0.19 l/s) and deviation angles of 30°,45°,60° and 90° and barite sag phenomenon through a flow loop equipment. Besides, the effect of drilling string rotational speed (70 rpm) on the barite deposition is investigated. The results not only indicate that increasing the flow rate from 0.19 l/s to 0.308 l/s can reduce the deposition rate, but also increasing the deviation angle from 45 to 60 o enhance the barite deposition to its maximum value. Graphic abstract

Background: Multidrug-resistant tuberculosis (MDR-TB) is one of the main challenges to TB control, particularly in developing countries such as Iran. Continuous TB drug resistance surveillance is required for the effective management of TB patients. Methods: The antibiotic susceptibility patterns of clinical Mycobacterium tuberculosis isolates were retrospectively analyzed from April 2012 to March 2018. Conventional and molecular methods were used for the identification and drug susceptibility testing (DST) of M. tuberculosis isolates. Results: A total of 3,012 clinical specimens were collected form TB-suspected patients. Of them, 100 (3.3%) were culture-positive and assigned as M. tuberculosis by phenotypic and molecular methods. According to DST, 17 (17%) isolates were MDR-TB. Conclusions: Improved diagnosis and treatment of MDR-TB may lead to better control of the disease in Iran.

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