Dataset Information

An experimental comparative study of drilling efficiency and temperature elevation with unmodified and modified medical drills in pig tibia bone.

ABSTRACT:

Background

There are no medical drill specifications capable of achieving bone drilling in a short time under low-thrust and low-speed drilling. Gekkou-drill® is an industrial drill that enables drilling with low cutting resistance by its characteristic point design. Our aims were to develop Gekkou-modified drills by processing to the points of currently available medical drills and to verify whether these modified drills enable less invasive drilling procedure for bone tissue in thermal exposure compared with unmodified medical drills.

Materials and methods

Two commercially available 3.2-mm drills were compared before and after Gekkou modification. Drilling of pig tibias was performed at speeds of 300, 800, and 1,500 rpm and a uniform thrust force of 10 N. Temperature at the entry point for bone drilling was measured using a digital thermometer system. The feed rates were calculated using cortical thickness and monitoring data of the digital force gauge.

Results

Two unmodified drills could not penetrate the cortical bone on the near side at 300 rpm, even after 5 min of drilling. The maximum temperatures with modified drills were 54.6 °C and 46.2 °C at 300 rpm. At medium to high speeds, those were statistically significantly lower than with unmodified drills (58.5 °C vs. 90.5 °C at 800 rpm, 62.6 °C vs. 80.8 °C and 73.9 °C vs. 104.6 °C at 1,500 rpm). The feed rates for modified drills were 4.9-6.9 times as high as unmodified drills at 800 rpm, and 3.4 to 4.5 times at 1,500 rpm. On the other hand, the feed rates of modified drills at 300 rpm were equal to or higher than those of unmodified drills at 1500 rpm.

Conclusion

Gekkou-modified drills clearly suppressed the temperature rise and increased the feed rate compared with conventional drills. Furthermore, it was notable that these modified drills had higher performance even at conditions of low thrust and low speed.

SUBMITTER: Enokida M

PROVIDER: S-EPMC6690560 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Similar Datasets

Project description:According to the Canadian Food Inspection Agency and Health Canada, genetically modified crops are considered safe if they are substantially equivalent to a conventional crop in regards to agronomic, physiological and compositional characteristics. A recurring issue in safety assessment of genetically modified crops is the paucity of analytical methods to detect unintended or unexpected outcomes of genetic modification. Traditional targeted compound comparative analyses are limited in scope and capacity to detect unintended changes in chemical composition. This study explored the potential of using microarray technology to assess the substantial equivalence of gene expression profiles between genetically modified and conventional soybean cultivars. Different pre processing methods were applied to the raw expression data from the arrays, and clustering methods were used to try and differentiate the genetically modified cultivars from the conventional cultivars. Results showed that more variation existed between different strains of conventional cultivars than between conventional and genetically modified cultivars. For more information, please see: Cheng, K.C., Beaulieu, J., Iquira, E., Belzile, F.J., Fortin, M.G. and StrÃ¶mvik, M.V. (2008). âEffect of transgenes on global gene expression in soybean is within the natural range of variation of their conventional counterparts.â Journal of Agricultural and Food Chemistry (in press) Experiment Overall Design: Five samples (biological replicates) of total RNA from each of the five different soybean varieties were selected for hybridization to Affymetrix Soybean GeneChips, for a total of 25 chips (following total RNA integrity assessment). Spike controls B2, bio-B, bio-C, bio-D and Cre-x were added to each hybridization cocktail. Arrays were washed and stained in an Affymetrix Fluidics Station prior to scanning on the Affymetrix GeneChip Scanner 3000. Image acquisition and processing was done with the Affymetrix Microarray Analysis Suite 5.0.

Project description:Petroleum well drilling fluids are one of the most significant constituents in the subterranean drilling processes to meet an increasing global demand for oil and gas. Drilling fluids experience exceptional wellbore conditions, e.g. high temperature and high pressure that adversely affect the rheology of these fluids. Gas and oil well drilling operations have to adjourn due to changes in fluid rheology, since the drilling fluids may lose their effectiveness to suspend heavy particles and to carry drilled cuttings to the surface. The rheological properties of drilling fluids can be controlled by employing viscosifiers that should have exceptional stability in downhole environments. Here, we have developed next-generation viscosifiers-organically modified magnesium silicates (MSils)-for reservoir drilling fluids where organic functionalities are directly linked through the Si-C bond, unlike the industry's traditional viscosifier, organoclay, that has electrostatic linkages. The successful formation of covalently-linked hexadecyl and phenyl functionalized magnesium silicates (MSil-C16 and MSil-Ph) were confirmed by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and thermogravimetric analysis (TGA). Identical drilling fluid formulations were designed for comparison using MSils and a commercial viscosifier. The rheological properties of fluids were measured at ambient conditions as well as at high temperatures (up to 150 °C) and high pressure (70 MPa). Owing to strong covalent linkages, drilling fluids that were formulated with MSils showed a 19.3% increase in yield point (YP) and a 31% decrease in apparent viscosity (AV) at 150 °C under 70 MPa pressure, as compared to drilling fluids that were formulated with traditional organoclay. The higher yield point and lower apparent viscosity are known to facilitate and increased drilling rate of penetration of the fluids and an enhanced equivalent circulation density (ECD), the dynamic density condition, for efficient oil and gas wells drilling procedures.