Instrument for Studying the Oxygen Transport in Capillaries

A possibility has been studied of the process of oxygen transfer to the tissues through the capillaries. Oxymetry principle is applied at the microscopic level. A prototype of the device has been designed and manufactured based on a measuring microscope and a spatially high-definition videocamera. Proposed and designed is the illumination schematic. The instrument structure is described including its parts, as well as the idea of image processing, the latter being acquired in different sections of the spectrum. In the studies, the narrow-band illumination was used in the regions of spectral lines 527 nm, 585 nm, and 650 nm, that were selected by the interference filters with transmission bandwidths 10-12 nm.

ESTIMATION OF ERRORS OF MEASUREMENT METHODS ON A UNIVERSAL MEASURING MICROSCOPE

The article presents the results of evaluating the errors of measurement methods on a universal measuring microscope, determines the causes of their occurrence and their impact on the measurement result, and also provides a comparative analysis of the resulting errors in comparison with other measuring microscopes.

Effect of different impression techniques and elastomeric impression materials on the dimensional accuracy of partially edentulous mandibular arch

Aim: Evaluate the dimensional accuracy of stone casts of a partially edentulous mandibular arch made by two impression techniques (1-step putty/light-body and 2-step putty/light-body) using addition and condensation silicones. Methods: A partially edentulous steel stainless cast with four markings on teeth 33, 37, 43, and 47 was used to obtain the impressions. The transverse (33-43 and 37-47) and anteroposterior (33-37 and 43-47) distances were measured by measuring microscope (30x magnification; 0.5μm accuracy). For the 1-step putty/light-body technique, both viscosities of the impression materials were handled together. For the 2-step putty/light-body technique, the impression materials of different viscosities were handled separately and a polypropylene spacer (2 mm thick) was used to create a relief. The same distances were measured om stone casts (n = 5). The values were submitted to normality test (Kolmogorov-Smirnov) and analyzed statistically by three-way ANOVA and Tukey’s (5%). Results: All distances showed shrinkage (negative linear changes). The addition silicones showed better accuracy than condensation silicones (p<0.05) and no significant difference was found between the impression techniques (p>0.05). The edentulous zone (43-47) presented worst dimensional accuracy results. Conclusions: The accuracy of the castsis more related to the impression material than impression technique.

Thread Measurement Algorithm Research and Software Development

The quality of thread will directly affect the reliability of mechanical system, and the accuracy grade of geometric parameters is the judgment standard to thread quality. Thus, its particularly important to detect the geometric parameters of thread. Its a pretty mature and widely used method to measure thread parameters with universal tool-measuring microscope, but it has many shortcomings, such as tedious operation, low efficiency and the reading error. In view of the above shortcomings, the paper does some simple refits to the existing 19JA universal tool-measuring microscope. In order to improve reading speed and accuracy, the grating rulers are installed on the operating platform in two directions. CCD camera is used to get external thread image instead of human eyes and the eyepiece, which is a non-contact measurement method. A software that based on MFC of VC + + 6.0 is written, which can deal with the thread image and get the thread parameters. The experimental results show that the method can not only effectively improve the measurement efficiency but also guarantee the accuracy of measurement.

Accuracy of Single-Step versus 2-Step Double-Mix Impression Technique

Objective. To investigate the accuracy of dies obtained from single-step and 2-step double-mix impressions. Material and Methods. Impressions (n=10) of a stainless steel die simulating a complete crown preparation were performed using a polyether (Impregum Soft Heavy and Light body) and a vinyl polysiloxane (Perfectim Blue Velvet and Flexi-Velvet) in two consistencies, in one or two (without relief) steps. Accuracy of the stone dies was accessed at a measuring microscope, using a metallic crown with perfect fit to the reference crown preparation. Data were submitted to 2-way ANOVA and Tukey test (α=0.05). Results. The single-step technique resulted in slightly larger dies, while the 2-step technique without relief produced significantly smaller dies, when compared to the original stainless steel die. Stone dies obtained from 2-step polyether impressions were significantly smaller when compared to dies obtained from 2-step vinyl polysiloxane impressions (Impregum 2-step: −290.94 ± 71.64 μm; Perfectim 2-step: −201.86 ± 28.58 μm). No significant differences were observed in dies obtained from either polyether or vinyl polysiloxane with the single-step technique (Impregum single-step: 63.52 ± 16.60 μm; Perfectim single-step: 79.40 ± 14.11 μm). Conclusion. Higher discrepancies were detected for the 2-step impression technique without relief for the investigated materials.