Photoluminescence spectra of porous silicon modified by copper phthalocyanine coating
In this paper we present photoluminescence (PL) spectra of porous silicon (PSi) coated with thin top layer of copper phthalocyanine (CuPc). PSi was by electrochemical anodisation method prepared. CuPc based thin organic film was using physical vapor deposition (PVD) in high vacuum on the top of fresh PSi deposited. PL was under pulsed excitation measured and samples were in vacuum enclosed. PSi/CuPc samples exhibit strong photoluminescence in visible region at room temperature. Observed PL spectra exhibit multiband structure and such structure changes in red region compared to “clean” PSi. Properties of PSi/organic luminescence can be explained by penetration of organic material into PSi skeleton and interaction between carriers in PSi and deposited material.
Time-of-flight repeller circuit application in laser ablation experiment
A proposed repeller circuit system of laser ablation apparatus is applied to analyse ions produced at the process of ablation. A repeller pulse gives the possibility of improving the resolution of the detection system based on the TOF spectrometer. Improvement of the system parameters is one of the advantages of the application of programmable logical devices. Moreover, application of such devices in high-resolution counting systems increases the flexibility of the system, increases the degree of the system integration and leads directly to increasing the system reliability.
Assessment of fractures in endodontically treated teeth restored with and without root canal posts using high-resolution cone beam computed tomography
Background Root fractures are a diagnostic challenge for dentists in endodontic treatment. This study aimed to determine the relationship between the characteristics of tooth fractures and the presence of root canal posts in endodontically treated teeth using high-resolution cone beam computed tomography (CBCT). Material and Methods Fifty high-resolution CBCT scans of endodontically treated teeth with a diagnosis of fracture were obtained, of which 30 were from women and 20 were from men. These scans were acquired with three Veraviewepocs 3D units and one 3D Accuitomo 170 unit, with a 40 × 40-mm field of view and 125 μm voxel size. The variables assessed included the type of fracture, extent of fracture, type of retention, post length, cause of endodontic failure, location of the lesion, and time required to detect the fracture (difficulty score). For data analysis, the chi-squared test, Student’s t-test, and multiple linear regression (α <0.05) were used. Results No association was found between the type of fracture and type of retention or between the type of fracture and its extent (P>0.05). On the other hand, the type of fracture significantly influenced the time required for its detection. Additionally, the most difficult plane for detecting the fracture and the difficulty score were associated, with statistically significant results. Conclusions The type of fracture in endodontically treated teeth was not associated with the type of post used for restoration. All of the CBCT systems used to detect tooth fracture showed the same efficiency. Key words:Cone-Beam CT, Tooth Fracture, Root Canal Post.