Effects of Diode, CO2, Er : YAG, and Er and Cr : YSGG on Titanium Implant Surfaces by Scanning Electron Microscopy

This study aimed to determine the effects of various lasers on dental implants’ surface characteristics. Nine explanted dental implants were included. Two implants were randomly allocated to four intervention groups, namely, diode (2 W, 810 nm, 10 s), CO2 (2 W, 10600 nm, 10 s), Er : YAG (200 mJ/20 Hz, 2940 nm, 10 s), and Er, Cr : YSGG (200 mJ/20 Hz, 2780 nm, 10 s) groups and one control group. After laser irradiation, all implants were imaged with scanning electron microscopy. Qualitative changes on the surface of implants were evaluated. Quantitative surface changes at the threads and between the threads were assessed by software using depression and prominence plots. The paired t-test was used for statistical analysis. Diode laser irradiation showed the least surface changes while the Er : YAG group showed the greatest surface changes. Furthermore, CO2 and Er : YAG laser irradiation significantly altered the mean profile area at the threads ( p < 0.05 ), while CO2 and Er, Cr : YSGG laser irradiation significantly altered the mean profile area between the threads ( p < 0.05 ). Diode laser irradiation does not alter the implant surface characteristics. However, the use of CO2, Er : YAG, and Er, Cr : YSGG lasers on titanium implant surfaces is discouraged as they damage the titanium implant surfaces.

Morphological manifestations of experimental paclitaxel-induced sciatic neuropathy under correction of 2-ethyl-6-methyl-3-hydroxypyridine succinate

Paclitaxel is an effective chemotherapeutic agent for many cancers, but it has a number of limiting side effects that not only significantly reduce the quality of life of patients, but also limit their further treatment. Peripheral neuropathy is one of these, but there are currently no proven effective druHS for the prevention or treatment of paclitaxel-induced neuropathic pain (PINP) in particular, or chemotherapy-induced peripheral neuropathy (CIPN) in general. 2-ethyl-6-methyl-3-hydroxypyridine succinate (HS) is a derivative of succinic acid with neuroprotective, antihypoxic, membrane-protective, nootropic, sedative effects. The aim of the study was to study the effect of the neuroprotective agent HS on the pathomorphogenesis of the sciatic nerves under conditions of paclitaxel-induced peripheral neuropathy in the experiment. Materials and methods. The experiment was carried out on 80 white rats, which were injected intraperitoneally with paclitaxel (Actavis, Romania), previously dissolved in isotonic saline at a dose of 2 mg / kg of body weight four times every other day until a total dose of 8 mg / kg was reached. Then forty of these animals were injected intraperitoneally with 2-ethyl-6-methyl-3-hydroxypyridine succinate at a dose of 10 mg / kg (the remaining 40 rats received intraperitoneal water for injection). Morphological studies were carried out on the first, seventh, fifteenth, twenty-eighth, sixtieth, ninetieth and one hundred and twentieth days after the last injection of the drug. We investigated the pharmacological potential of HS in the prevention and treatment of CIPN at the level of sciatic nerve (SN) morphology. Results. The maximum value of the average profile area of myelinated nerve fibers with the use of HS is significantly lower than with uncorrected flow, and is (78.12±2.24) μm2 compared to (94.04±1.03) μm2 (p <0.001). The introduction of HS provides a stable content of the value of the ratio of the areas of the axial cylinder and the fiber within 0.39±0.01 (first day) - 0.44±0.01 (ninetieth day), and a rapid recovery of the indicator value to normal values during the final 30 days of the experiment. the maximum value of the index of the profile area of the myelin sheath with the introduction of HS is 1.4 times less than with an uncorrected flow, and is, respectively, (49.01±1.59) μm2 and (69.77±1.87) μm2 (p <0.001). HS provides a more intensive restoration of the indicator of the area of the myelin sheath during the 90th - 120th day of the experiment. Conclusions. Our results allow us to conclude that the introduction of HS creates a protective effect against paclitaxel-induced peripheral neuropathy (PIPN) by acting on both the axial cylinder and the myelin sheath of the heart failure. Due to the known pathophysiological mechanisms of the development of neuropathy, this method can be a promising therapeutic agent for the prevention and treatment of PIPN

Vancomycin heteroresistance in Staphylococcus haemolyticus: elusive phenotype

Aim: To determine the presence of vancomycin heteroresistance in Staphylococcus haemolyticus. Materials & methods: A total of 48 rifampicin-resistant S. haemolyticus isolates from bloodstream infections were included. Vancomycin heteroresistance was determined using the population analysis profile-area under curve (PAP-AUC) method. All the isolates were screened for the presence of mecA gene, mutations in the rpoB gene, staphylococcal cassette chromosome mec and multilocus sequence types. Results: Fifteen isolates were identified as heteroresistant vancomycin-intermediate S. haemolyticus using PAP-AUC method. Dual rpoB mutations (D471E and I527M) contributed for the rifampicin resistance. The sequence types of heteroresistant vancomycin-intermediate S. haemolyticus were highly diverse. Conclusion: These findings illustrate the potential of S. haemolyticus to develop heteroresistance, which emphasizes the need for routine surveillance of S. haemolyticus isolated from intensive care units for infection control practices.

SLEEP DEPRIVATION INTERFERES WITH JAK/STAT SIGNALING PATHWAY AND MYOGENESIS IN MASSETER MUSCLE OF RATS

jectives. This study evaluated the JAK/STAT signaling pathway and myogenesis on masseter muscle after sleep deprivation as well as to investigate the role of stress in this scenario. Subjetcts and Methods. A total of 18 male Wistar rats were distributed into the following groups: Control (CTRL; n=6): animals were not submitted to any procedures; Sleep Deprivation and Vehicle (PSD+V; n=6): animals were subjected to Paradoxical Sleep Deprivation for 96h and (PSD+MET; n=6): animals were subjected to Paradoxical Sleep Deprivation for 96h with administration of metyrapone. Paradoxal Sleep deprivation was performed by the Modified Multiple Platforms Method. Histopatological analysis, histomorphmetry and immunohistochemistry were performed. Results and Conclusion. The results showed the presence of inflammatory infiltrate in the PSD+V and PSD+MET groups and atrophy. Histomorphometry showed that Cellular Profile Area decreased while Cellular Density increased in both experimental groups. Expression of p-STAT 3, MyoD and MyoG increased in PSD+V group, while the PSD+MET group increased expression of IL-6 and p-STAT 3. Our results are consistent with notion that sleep deprivation induced inflammatory response and atrophy in masseter muscle of rats.

Analysis of product geometry formation at square billet stretching on profile matrix

There is considered square billet stretching in a cylindrical matrix. To ensure minimization of an inequality effect of billet ends in the matrix there was used a leading-in profile area. The investigation of matrix profile impact upon geometry of products manufactured is carried out. The efficient geometrical ratios of a tool allowing the achievement of a lesser inequality in the geometry of parts end area are revealed.

Effects of a combined hot-streak and swirl profile on cooled 1.5-stage turbine aerodynamics: an experimental and computational study

Recently developed lean-burn combustors offer reduced NOx emissions for gas turbines. The flow at exit of lean-burn combustors is dominated by hot-streaks and residual swirl, which have been shown–individually–to impact turbine aerodynamic performance. Studies have shown that residual swirl at inlet to the high-pressure (HP) stage predominantly affects the vane aerodynamics, while hot-streaks affect the rotor aerodynamics. Studies have also shown that these changes to the HP stage aerodynamics can affect the downstream intermediate-pressure (IP) vane aerodynamics. Yet, to date, there have been no published studies presenting experimental turbine test data with both swirl and hot-streaks simultaneously present at inlet. This paper presents the first experimental and computational investigation into the effects of combined hot-streaks and swirl on turbine aerodynamics. Measurements were conducted in the Oxford Turbine Research Facility, a short-duration rotating transonic facility that matches non-dimensional engine conditions. Two turbine inlet flows are considered. The first is uniform in total pressure, total temperature, and flow angle. The second features a non-uniform total temperature (hot-streak) profile featuring strong radial and weak circumferential variation superimposed on a swirling velocity profile. Area surveys of the flow were conducted throughout the turbine. Measurements and URANS predictions suggest that the inlet temperature non-uniformity was relatively well preserved upon being convected through the turbine, and relatively poor comparisons between URANS and experiment highlight the challenge of accurately predicting the complex IP vane flow.

Variation and artificial neural network prediction of profile areas during slant type taper profiling of triangle at different machining parameters on Hastelloy X by wire electric discharge machining

In the present research work, an in-house developed fixture is used to achieve taper profiles which avoids the disadvantages in convention tapering operation in wire electric discharge machining like wire bend, inaccuracies in taper, insufficient flushing, guide wear etc. A simple triangular profile was machined at 0°, 15° and 30° slant/taper angles. These taper profile areas are investigated for various machining parameters like wire guide distance, corner dwell time, wire offset and cutting speed override. It is observed that as the wire guide distance and cutting speed override increases, the profile area decreases. Whereas in case of wire offset, as offset increases the profile areas also increase. The corner dwell time parameter do not effect on the profile area. The taper profile areas measured highest at 30° followed by 15° and 0° slant angles. This is due to the workpiece placed at different angles during machining with the aid of fixture to obtain taper profile. The taper angle represents the angularity of slant triangular profiles. As the slant angle increases the variation in taper error also increases due to higher wire vibration. An artificial neural network model is developed for the prediction of these areas at a different slant angle. The model is validated experimentally where the errors in prediction ranged from 1% to 9%. In conclusion, it can be noticed that the machining parameters and slant angle influence on profiles irrespective of their dimensions.

The Influence of Laser Sintering Modes on the Conductivity and Microstructure of Silver Nanoparticle Arrays Formed by Dry Aerosol Printing

The demand for the development of local laser sintering of nanoparticle arrays is explained by the expanding needs for printed electronics for functional microstructure formation, on heat-sensitive substrates in particular. This work is based on the research into the sintering of arrays of silver nanoparticles synthesized in a spark discharge and deposited on a substrate by focused aerosol flow. The sintering was done by continuous and pulsed lasers with wavelengths 527, 980 and 1054 nm. Sintered samples were studied by measuring the resistivity, cross-section profile area and microstructure features. The highest average conductivity, equal to the half of the bulk silver conductivity, was achieved when sintering by continuous radiation with a wavelength 980 nm. The results showed that when using pulsed radiation the direct heating of nanoparticles in the sample surface layer dominates with the formation of a pore-free conductive layer of around 0.5 μm thick and crystallite of 70–80 nm size. It was found that laser sintering by radiation with a wavelength 527 nm required an order of magnitude lower specific energy costs as compared to the longwave laser radiation. The high energy efficiency of laser sintering is explained by special conditions for radiation absorption at plasmon resonance.