Development of a handheld fiber-optic probe-based raman imaging instrumentation: raman chemlighter

Raman systems based on handheld fiber-optic probes offer advantages in terms of smaller sizes and easier access to the measurement sites, which are favorable for biomedical and clinical applications in the complex environment. However, there are several common drawbacks of applying probes for many applications: (1) The fixed working distance requires the user to maintain a certain working distance to acquire higher Raman signals; (2) The single-point-measurement ability restricts realizing a mapping or scanning procedure; (3) Lack of real-time data processing and a straightforward co-registering method to link the Raman information with the respective measurement position. The thesis proposed and experimentally demonstrated various approaches to overcome these drawbacks. A handheld fiber-optic Raman probe with an autofocus unit was presented to overcome the problem arising from using fixed-focus lenses, by using a liquid lens as the objective lens, which allows dynamical adjustment of the focal length of the probe. An implementation of a computer vision-based positional tracking to co-register the regular Raman spectroscopic measurements with the spatial location enables fast recording of a Raman image from a large tissue sample by combining positional tracking of the laser spot through brightfield images. The visualization of the Raman image has been extended to augmented and mixed reality and combined with a 3D reconstruction method and projector-based visualization to offer an intuitive and easily understandable way of presenting the Raman image. All these advances are substantial and highly beneficial to further drive the clinical translation of Raman spectroscopy as potential image-guided instrumentation

3D freeform surface measurement on coordinate measuring machine using photometric stereo method

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonSurface metrology has been widely used in manufacturing for many years. There has been a wide range of techniques applied for measuring surface topography. A photometric stereo technique is one of the best ways for the analysis of three-dimensional (3D) surface textural patterns. Many published works are concerned the developed approach for recovering the 3D profiles from surface normal. This research not only presents a methodology used to retrieve the profiles of surface roughness standards but also investigates the uncertainty estimation of textural measurement determined by the photometric stereo method. Various input quantities have been studied such as pixel error from recovered 3D surface textural patterns, the power of light source which involved with surface roughness average (Ra) value and the effect of room temperature. The surface roughness standards were utilized as the reference value. In term of increasing accuracy of the reference value, a contact method (stylus instrument) was used to calibrate them. Illumination angles of light source had some influence on the measurement results. A coordinate measuring machine (CMM) was used for holding the light source in order to study the effects of tilt and slant angles. The effect of tilt and slant angles were investigated. The results of these experiments successfully indicated that the angle used in photometric stereo method played an important role to the accuracy level of the roughness measurement results. The surface roughness specimen manufactured by a Computer Numerical Control (CNC) was applied to validate the capability of the photometric stereo system.The royal Thai government, ministry of sciences and technology and national institute of metrology Thailand (NIMT

Evaluation of the Sealing Ability of Gutta Percha with Bioroot RCS, MTA Fillapex and Sealapex: An SEM study

AIM OF THE STUDY: The aim of this in vitro study was to evaluate the sealing ability of three endodontic sealers, BioRoot RCS (a tricalcium silicate based sealer), MTA Fillapex (a salicylate resin based sealer) and Sealapex (a calcium hydroxide based sealer) with gutta-percha cones to the dentinal walls, using scanning electron microscopy. OBJECTIVES: To evaluate the sealing ability of BioRoot RCS, MTA Fillapex, Sealapex and ZOE sealers at the cervical, middle and apical thirds. To compare the sealing ability of BioRoot RCS, MTA Fillapex, Sealapex and ZOE root canal sealers based on the gap formation, as measured from SEM images. METHODOLOGY: Forty human mandibular premolars were selected and cleaned off the soft tissue debris. Access opening was done using endo access bur, working length determined with a #10K file. Chemomechanical preparation was done by crown technique using ProTaper Universal rotary system till F2 and irrigated using 3% sodium hypochlorite and 17% EDTA to remove the debris and final irrigation performed with 2ml normal saline. The teeth were dried with absorbent paper points and the sealers were mixed according to the manufacturer’s instructions. The teeth were divided into four groups of 10 (n=10) teeth each and obturated with; Group 1 – gutta percha with BioRoot RCS, Group 2 – gutta percha with MTA Fillapex, Group 3 – gutta percha with Sealapex, Group 4 – (control group) gutta percha with ZOE. Each tooth was sectioned at coronal, middle and apical thirds. The samples were then sputter coated with fine gold and subjected to SEM evaluation. The gap formed at the sealer- dentin interface was measured in μm. The collected data were analysed with IBM.SPSS statistics software 23.0 Version. RESULTS: The results of Oneway ANOVA shows that, the amount of gap formation between the sealer and root dentinal wall interface at the cervical, middle and apical thirds were highly significant (P < 0.01). The results obtained from multiple comparisons between various groups using Tukey’s post hoc test shows that, there is a highly significant difference between the control group of ZOE with the other 3 experimental groups at all the 3 levels. This shows that among the tested sealers, ZOE has shown more gap formation corresponding to minimal sealing ability with the dentinal wall followed by MTA Fillapex, Sealapex and BioRoot RCS at the cervical third. Whereas at the middle third, minimal sealing ability to the dentinal wall was shown by ZOE followed by Sealapex, MTA Fillapex and BioRoot RCS. In the apical third, ZOE has shown more gap formation with the dentinal wall followed by Sealapex, MTA Fillapex and BioRoot RCS. CONCLUSION: Within the limitations of this study, it can be concluded that minimum gap formation was seen for bioceramic sealers, with BioRoot RCS being better than MTA Fillapex. In the middle third, the calcium hydroxide based sealer, Sealapex showed better adaptation than MTA Fillapex sealer. Whereas in the cervical and apical thirds, MTA Filllapex exhibited lesser gap formation than Sealapex. All tested sealers showed significantly better adaptation and sealing ability at the cervical and middle thirds than in the apical third when compared to ZOE. Bioceramic sealers showed higher sealing ability at the apical third