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Purpose To adapt an evidence-based clinical practice guideline (CPG) for risk-based management of caries in 18–55 year-old Iranian adults. Methods A multidisciplinary adaptation team reviewed evidence-based guidelines such as the NICE, SIGN, and ADA according to the defined clinical questions. In addition, databases such as the PubMed and Google Scholar were searched and CPGs were screened and appraised using the AGREE II (Appraisal of Guidelines for Research and Evaluation II) tool. Clinical scenarios were developed and their level of evidence, clinical advantage and adaptability were assessed. Following a two-round ranking by experts, the final recommendations were selected using the RAND-UCLA appropriateness method. Results Of 17 CPGs, 5 were selected as the source guidelines for adaptation. To assess the risk of caries in the adult population, reduced Cariogram (without saliva tests) and CAMBRA were suggested as diagnostic tools. In addition, 53 risk-based recommendations on the preventive care (including the use of fluoride toothpaste, fluoride, and chlorhexidine mouthwash, at home and in-office fluoride gel, fluoride varnish, mouth buffering, and sealant), operative intervention threshold, and follow-up interval were adapted for Iranian adults. Conclusions A guideline was adapted for risk-based management of dental caries in Iranian adults. This helps local dentists in decision making and promoting oral health of adults. Further research is needed to assess the external validity and feasibility of the adapted guideline in the Iranian population.

In this experimental work, the effect of the drag-reducing polymer on the holdup and slip ratio of the oil-water flow in three different horizontal acrylic pipes was investigated. The internal diameters (IDs) of the pipes were 30.6-mm, 55.7-mm and 74.7-mm. The flow conditions of the oil-water flow consisted of 0.4–1.6 m/s mixture velocities and 0.1–0.9 input oil volume fractions. The master solution of the polymer (commercially known as AN 105-SH) was prepared at 2000 ppm concentration and injected into the water phase at controlled flow rates to provide 40 ppm concentration in the phase. The measurement of the holdup was carried out with help of quick closing valves after which the slip ratio was determined. The results showed that the water holdup and by extension, the slip ratio before the addition of the DRP increased with increase in the input oil volume fraction at low mixture velocity while the reverse was the case at high mixture velocity. The addition of the DRP increased the water holdup and the slip ratio only in water-dominated flow regions in all the three pipes. Finally, the increase in the pipe diameter also increased the water holdup and the slip ratio before and after the addition of the DRP in most of the flow conditions.

In this work, the results of the experimental investigations of oil-water flow in the absence and presence of water-soluble drag-reducing polymer in two different horizontal pipe diameters (55.7 and 74.67-mm ID) and their comparisons with the results in horizontal 30.6-mm ID pipe were presented. During the study, mixture velocity of the oil-water flow was varied from 0.1 to 1.6 m/s while the input oil volume fraction was varied from 0.05 to 0.9. At each experimental run, the polymer master solution of 2000 ppm concentration was injected into the flow at a controlled flow rate such that 40 ppm concentration of the polymer was achieved in the water phase. The six flow patterns previously observed in the 30.6-mm ID pipe reduced to four in the larger pipes. Although the presence of the polymer only affected the water-continuous flow patterns just like in the 30.6-mm ID pipe, the increase in the pipe diameter increased the regions of separated flow patterns before and after the addition of the polymer. Similarly, the frictional pressure gradients were significantly decreased by the polymer addition in all the three pipes resulting to huge drag reductions, which virtually decreased with increase in the pipe diameters.

An experimental investigation of the effect of various mixtures of different polymers on drag reduction was studied in a dispersed horizontal oil-water flow. The study was carried out in a horizontal pipe flow loop system of 30.6-mm ID and 24 m length. All the polymers are anionic water-soluble polymers prepared in 1000 ppm master solution and injected at different flow rates to achieve polymer concentrations in the range of 5 to 30 ppm in the water phase. As expected, the percentage drag reductions of the individual polymers and of the binary polymer mixtures increased with the increase in the mixture velocity but decreased with the increase in the oil fraction. It has been found that the drag reduction of the mixed polymer solution is higher than the drag reduction of the lower molecular weight polymer. In most of the cases, the drag reduction of the binary mixtures shows a positive deviation from the additive straight lines. The positive deviation is more dominant for the mixture of the high and low molecular weight polymers than the mixture of the high and medium molecular weight polymers. Also, the drag reductions of the mixture of the high and low molecular weight polymers are higher than the drag reductions of the mixture of the high and medium molecular weight polymers. Finally, although positive deviation was observed in this study, no synergism was obtained for all the investigated polymer-polymer mixtures conditions.

This study deals with development and evaluation of empirical correlation for predicting pressure gradients of oil-water flow after the addition of drag-reducing polymer. The experimental pressure gradient data used for the correlation were obtained from three different acrylic pipe diameters (30.6, 55.7 and 74.7 mm) at different inclination angles. The drag-reducing polymer (DRP) which was a water-soluble copolymer of polyacrylamide and 2-acryamido-2-methylpropane sulfonic acid, was injected at 40 ppm concentration into the water phase of the oil-water flow. The flow conditions of 0.4–1.6 m/s mixture velocities and 0.05–0.9 input oil volume fractions were imposed. The measured pressure gradient data after the addition of the DRP were used to develop a friction factor correlation as a function of mixture Reynolds number. The developed correlation when tested against the current and previously published experimental data showed a good performance. It also showed the best performance when compared with similar existing correlation and homogeneous model.

In this study, the influence of a drag-reducing polymer on oil–water flow patterns and pressure gradients was investigated in a downward-inclined pipe (−5°) and compared with the results obtained in a horizontal pipe for the same flow characteristics. Drag reduction was achieved by adding 40 ppm of polymer into an oil–water flow in an acrylic pipe of 0.0306 m ID flowing at 0.1–1.6 m/s mixture velocities and 0.05–0.9 input oil volume fractions. The downward inclination enhanced the mixing of the two phases and hence the boundaries between the dispersed and separated flows occurred at lower mixture velocities in downward flow than in horizontal flow. In both pipe orientations, the addition of the DRP affects the flow patterns and pressure gradients mainly in the water-dominated flow regions. Compared with those of the horizontal flow, the effect of polymer addition on flow pattern boundaries was generally lower at −5° inclination. The effect of the polymer on the pressure gradients was more pronounced at horizontal flow than at −5° flow, resulting in a maximum drag reduction of 64% and 55% at horizontal and −5° flows, respectively. Since the polymer used is water-soluble, there were no observable changes in the flow characteristics at the oil-dominated flow regions.

Five linear, water-soluble, sulfonated polyacrylamides of relatively high molecular weights were used to investigate drag reduction in oil–water multiphase flow through a horizontal, 30.6-mm pipe. The polymers were negatively-charged due to the presence of different density of the acrylamido tert-butyl sulfonic acid, ATBS, side groups along with acrylamide. They have different molecular weights and sulfonation degrees to investigate the effect of these polymer parameters in drag reduction during oil–water multiphase flow. Tap water was used as the aqueous phase and model oil with a density of 0.886 g/cm3 and a viscosity of 18.6 cP at 30 °C was used as the oil phase. The two phases were used in the tests at different oil fractions and mixture velocities to achieve a dispersed flow pattern. The maximum drag reduction was obtained for polymer concentrations higher than 20 ppm in the test section. Drag reduction effectiveness was negatively affected by the increase in oil fraction in the test section leading to negative drag reduction when the oil is initially the continuous phase. Moreover, drag reduction increased with the increase in mixture velocity especially above 1.0 m/s for polymer concentrations higher than 10 ppm. Using this family of polymers, it was concluded that flexibility (or rigidity) of polymer chains in solution is a primary factor in polymer's effectiveness as a drag reducing agent. In this study, drag reduction was higher for more flexible polymer chains, which was enhanced by using higher molecular weight polymers and lower charge density.

Experimental investigation of the effects of drag-reducing polymer on oil–water flow patterns, pressure drops, phase inversion and slip ratio in a horizontal acrylic pipe of 30.6-mm ID was carried out. The polymer which is a water-soluble, high-molecular-weight anionic copolymer of polyacrylamide and 2-Acrylamido-2-Methylpropane Sulfonic acid (AMPS) was prepared in 2000 ppm master solution and injected at controlled flow rates to provide 40 ppm of the polymer in the water phase. In the flow conditions of 0.1–1.6 m/s mixture velocity and 0.05–0.9 input oil volume fractions investigated, the addition of the polymer affected the flow characteristics especially at lower mixture velocities and input oil volume fractions. The stratified, dual continuous and dispersed oil in water and water layer flow patterns were extended to higher mixture velocities but the oil-continuous flow patterns were not affected by the addition of the polymer. There were significant reductions in the pressure drops after the addition of the polymer mainly in water-dominated flow regions and these reductions increased with increase in the mixture velocity and decrease in the input oil volume fraction, leading to maximum drag reduction of about 64% at the highest mixture velocity and at 0.05 input oil volume fraction. Again, the addition of the polymer eliminated or shifted the sharp increases in the pressure drops at the phase inversion points towards higher input oil volume fractions. Finally, the addition of the polymer increased the slip velocity ratios especially at lower mixture velocities.

All members of the Mycobacterium tuberculosis complex were assigned to one of the three principle genetic groups based on KatG463/GyrA95 polymorphism.A total of 202 isolates of M. tuberculosis consisting of 50 susceptible, 121 MDR (multidrug resistant) and 31 XDR (extensively drug resistant) isolated from culture-confirmed tuberculosis patients in different regions of Belarus and Iran (Tehran and Markazi province). Isolates were screened by sequencing and polymerase chain reaction restriction fragment length polymorphism (RFLP) assay, and were further divided into three principal genetic groups (PGG), based on Sreevatsan's pattern as polymorphisms in KatG463/GyrA95 codons.Among the 104 isolates, characterized as MDR from Belarus, 57 (54.8 ± 4.8%), 30 (28.8 ± 4.43%), 17 (16.3 ± 3.6), belonged to PGG 1, 2, and 3, respectively (p0.05). Thirty one XDR isolates from Belarus had a similar pattern as 15 (48.4%), 12 (38.7%), 4 (12.9%) PGG 1, 2, and 3, respectively. From Iranian samples, Markazi isolates (susceptible to drugs) had a pattern as 12 (36.5%), 15 (45.5%), 3 (6%), and Tehran samples were (selected MDR): 9 (53%), 6 (35.2%), 2 (11.8%) (PGG 1, 2, and 3, respectively). In a study of tuberculosis patients, who were in prison, no relation was found between PGG and resistance to isoniazid, but most of the identified isolates belonged to PGG 1 (45.5 ± 10.9%) (p0.05). Overall, the group 1 isolates showed more frequency in MDR and XDR rather than susceptible strains, and there aren't any relations to geographic region.

This study presents experimental investigation about the effect of polymer parameters on the performance of the drag reducing polymers in single-phase water flowing in a horizontal pipe of 30.6 mm ID. Master solutions (1000 ppm) of ten high-molecular weight polymers were injected at different flow rates to achieve polymer concentrations in the range of 2–40 ppm in the test section. The drag reduction increased with polymer concentration up to 10 ppm, above which it reached a plateau value. While the drag reduction at the plateau value increases with polymer molecular weight, the maximum drag reduction was not affected by the increase in polymer charge density up to 13%. For instance, the maximum drag reduction for anionic polymers with molecular weight 6–8 million Da. and charge density between 5 and 13% was around 60%, which decreased to around 38% for the polymer with charge density of 25%. Ionic polymers provided more drag reduction than nonionic ones. The overall conclusion is that drag reduction depends on polymer ability to form intermolecular associations and/or its flexibility, which can be enhanced by increasing molecular weight, decreasing charge density, and selecting smaller side groups in the main polymer backbone.