Revolution Per Minutes Research Articles

Developing hybrid ELM-ALO, ELM-LSO and ELM-SOA models for predicting advance rate of TBM

Accurate prediction of TBM performance is very important for efficient completion of TBM construction tunnel project. This paper aims to predict the advance rate (AR) of tunnel boring machine (TBM) using three hybrid models by combining three swarm intelligence optimization algorithm (Ant Lion Optimizer (ALO), Loin swarm optimization (LSO) and Seagull optimization algorithm (SOA)) and the Extreme learning machine (ELM) model, namely ELM-ALO, ELM-LSO and ELM-SOA model respectively. The dataset consists of 1, 286 samples from the Pahang Selangor Raw Water Transfer (PSRWT) tunnel project in Malaysia, and containing six parameters (rock quality designation (RQD), uniaxial compressive strength (UCS), rock mass rating (RMR), Brazilian tensile strength (BTS), thrust force per cutter (TFC) and revolution per minutes (RPM)) from rock mass and machines. In order to evaluate the prediction performance of different hybrid models, the root mean square error (RMSE), the mean absolute error (MAE), the mean square error (MSE), the determination coefficient (R2), the sum of square error (SSE), and the variance accounted for (VAF) were adopted as the performance indicators. The results show that ELM-LSO is the best model to predict AR. Sensitivity analysis shows the importance of all considerations to AR. TFC, RPM and RMR are the three most important parameters. But this is not absolute, more parameters need to be taken into account in AR prediction. Meanwhile, the ELM-LSO model proposed in this paper can be used as a new method to predict AR.

In vitro analysis of gallstone formation in the presence of bacteria.

In our previous study, we have isolated different genera of bacteria from gallstones and this intrigued us to study their role in gallstone formation. The isolates exhibited certain biliary activities like urease activity, slime production, and β-glucuronidase production. We aimed to investigate the role of these factors in the formation of gallstone in in vitro conditions at a supersaturated concentration of cholesterol. To mimic bile in in vitro state, Brilliant Green Bile Broth (BGBB) media having a composition similar to human bile was used. Four different experimental sets were prepared, each having nine flasks with varying concentrations of cholesterol and CaCO3 (calcium carbonate). Test sets I, II, III, and IV were inoculated with Salmonella, Enterococcus, Helicobacter, and Neisseria respectively, which were isolated from gallstone itself. Out of these four bacteria, only Helicobacter did not possess slime activity. A control set was also established which was devoid of bacteria. The control also had nine flasks with different concentrations of cholesterol and CaCO3. All the sets were incubated in the incubator shaker at 37 °C and 80 revolution per minutes (RPM) for 20 days. It was observed that the sets having bacteria had a less nucleation time as compared to the control (F = 5.274; p < 0.001). Solidification of gallstone was observed only in the set with bacteria having slime activity (sets I, II, and IV). The slime activity of bacteria leads to solidification of gallstones, whereas the other activities accelerate the nucleation of gallstone formation enhancing the severity of the disease.

Spectrophotometric analysis evaluating apical microleakage in retrograde filling using GIC, MTA and biodentine: an in-vitro study

BackgroundThe present study compares the apical microleakage of three different root-end filling materials in which the retrograde cavity is prepared by two different burs.MethodsEighty extracted single rooted maxillary and mandibular premolars were taken. Root canal treatment was completed. Apical 3 mm of all the teeth were resected with diamond disk. The tooth were divided into four groups with two subgroups for each group containing 10 tooth (N = 10) as: Group IA (Negative Control and IB (Positive Control); Group IIA and IIB: Prepared with round carbide bur and round diamond bur respectively, filled with GIC; Group IIIA and IIIB: Prepared with round carbide bur and round diamond bur respectively, filled with MTA; Group IVA and IVB: Prepared with round carbide bur and round diamond bur, filled with Biodentine. After applying two coats of nail varnish leaving apical 3 mm (except for negative control group) all teeth were immersed in 2% methylene blue for 3 days and again in 65% nitric acid for next 3 days for extraction of dye. The obtained solution was then transferred to eppendorf tube and centrifuged in microcentrifuges at 14,000 revolution per minutes (RPM) for 5 min. Optical density or absorbance of the supernatant solution was measured with UV spectrophotometer at 550 nm.ResultsThe absorbance of the supernatant solution after dye extraction is decreasing in the order of positive control> GIC > MTA > Biodentine> negative control group. The significant difference was observed between GIC and MTA (p = 0.0001) and GIC and Biodentine (p = 0.0001) with two different burs but statistically non-significant difference was observed between MTA and Biodentine with Carbide bur (p = 0.127) and Diamond bur (p = 0.496) respectively.ConclusionsWithin the limitations of the present study, it can be concluded that Biodentine and MTA showed less microleakage as compared to GIC. There is no significant difference between mean microleakage of MTA and Biodentine. However, the mean OD of the Biodentine was least of all evaluated materials. Preparation of the root-end using round carbide bur as well as round diamond burs showed comparable microleakage for all three filling materials.