Method of measuring angular position based on a new class ofoptoelectronic sensors

У овој докторској дисертацији извршен је преглед постојећих метода мерења угаоног положаја и дат је предлог нове методе за мерење апсолутног угаоног положаја. Предложена мерна метода заснива се на примени трансформације боје објекта из Декартовог RGB простора боја у неки од цилиндричних, кориснички оријентисаних, простора боја (HSV, HSI, HLS). На бази предложене мерне методе конструисан је сензор апсолутног угаоног положаја који се састоји од три оптичка рефлексиона сензора и штампаног шаблона са сивом скалом. Тачност, поновљивост и резолуција мерења, постигнути приликом тестирања сензора су ±1 °, ±0,3 ° и 0,1 °.U ovoj doktorskoj disertaciji izvršen je pregled postojećih metoda merenja ugaonog položaja i dat je predlog nove metode za merenje apsolutnog ugaonog položaja. Predložena merna metoda zasniva se na primeni transformacije boje objekta iz Dekartovog RGB prostora boja u neki od cilindričnih, korisnički orijentisanih, prostora boja (HSV, HSI, HLS). Na bazi predložene merne metode konstruisan je senzor apsolutnog ugaonog položaja koji se sastoji od tri optička refleksiona senzora i štampanog šablona sa sivom skalom. Tačnost, ponovljivost i rezolucija merenja, postignuti prilikom testiranja senzora su ±1 °, ±0,3 ° i 0,1 °.In this doctoral thesis a review of existing methods for angular position measurement is conducted and a new method for measuring absolute angular position is proposed. The proposed measurement method is based on the use of object color transformation from Cartesian RGB color space to one of the user-oriented cylindrical color space (HSV, HSI, HLS). Оn the basis of the proposed measurement method, absolute angular position sensor consisting of three optical reflective sensors and a grayscale printed pattern is constructed. Accuracy, repeatability and resolution of measurement using proposed sensor were ± 1 °, ± 0.3 ° and 0.1 °

Examination of the effects of X-ray phase contrast imaging dose on DNA in mesenchymal stem cells by comet assay

INTRODUCTION: Imaging techniques based on X-ray phase-contrast (XPC) have shown tremendous promise for applications involving biomaterials and soft tissue formation [1,2].XPC imaging can be applied at higher energy offering the potential for lower dose imaging. Essential to the development of this technique and its routine use is an understanding of the potential damage of X-ray dose on cells and tissues. EXPERIMENTAL: In this study the comet assay, a sensitive assay for DNA damage, was used to evaluate DNA damage on mesenchymal stem cells (MSCs) exposedto X-ray irradiation. We examined the effects of early (immediately following irradiation) and delayed (24h post-irradiation) X-ray effects caused by low (15mGy) and intermediate (150mGy and 1.5 Gy) exposure on MSCs during a monitoring period of 4 weeks (five irradiations, one weekly). Cells were submitted to apolychromatic X-ray source (Thermo Fisher PXS10 conditions: voltage 45 kV, source current 160A, source power 7.2 W, source spot size 9 um, photon flux on the sample 7.66106photonss-1mm-2irradiation).Statistical analysis was performedby using Two-way analysis of variance (ANOVA) with Tukey’s multiple comparisons posttest in GraphPad Prism 5.0.A difference at p< 0.05 was considered statistically significant.RESULTS AND DISCUSSION: Resultsof the DNA comet assay indicated that early effects of low-and intermediate-dose of XPC induced an increase in the number of cells with DNA damage after each irradiation, where intermediate-dose (150 mGy and 1.5 Gy) produced significantly higher damage relative to controls. DNA damage induced by low and intermediate doses returned to the control value 24h after the irradiation exposure, suggesting a strong protection of MSCs at the tested doses of XPC irradiation. CONCLUSIONS: The data presented in this studyshows that 24 h after the last of five weekly low and intermediate doses XPC irradiation, the harmful effects on DNA in MSCs were notdetected. The current study reinforces the need of investigating consequences of low and intermediate doses of X-ray PC irradiation in the field of tissue engineering and provide new basis for MSCs using in the clinics.ExcellMater Conference 2024: Innovative Biomaterials for Novel Medical Devices, Belgrade, Serbia, April 10-12, 2024

Activity of combined gemcitabine therapy on treatment of planocellular carcinoma: A pilot study

BACKGROUND: Drug-orientated, pilot study was conducted to estimate the activity of gemcitabine on treatment of head and neck and lung planocellular carcinoma in combination with either radiotherapy or chemotherapy. METHODS There were 22 patients treated with gemcitabine for planocellular carcinoma of head and neck (9 patients) and lung (13 patients). Combined gemcitabine-radiotherapy was applied in 10 patients while gemcitabine-chemotherapy in 12 patients. Eligible and evaluable patients (22) were with either locally advanced (14 patients) or metastatic (8 patients) stage of the disease. In gemcitabine-radiotherapy group, gemcitabine was given IV, 1000 mg/ m2, on day 1, 8, and 15 during the radiotherapy course as radiopotentiator (65 Gy in 32 fractions for head and neck, and 55 Gy in 20 fractions, split course one month for lung cancer patients). In gemcitabine-chemotherapy group the same dose of gemcitabine was given (4-week schedule) in combination with platinum based cytotoxic drugs. We analyzed response rate and toxicity. RESULTS: Among patients treated for head and neck planocellular carcinoma, there were 67% complete responders while there was 15% complete responders treated for lung cancer. Also, 80% of patients treated in gemcitabine-radiotherapy group had complete response while 50% of those treated in gemc- itabine-chemotherapy group. Actuarial survival as function of tumor control was 52% for lung and 88% for head and neck cancer 12 months after the initiation of treatment. In gemcitabine-radiotherapy group of patients treated for head and neck carcinoma, the radiation mucositis grade III was observed in 80% while in gemcitabine - chemotherapy group of patients the most common side effect (60% of patients) was neutropenia grade II (40%)/III (20%). CONCLUSION: There was no statistically significant difference regarding response rate between two groups of patients (head and neck vs. lung cancer, and gemcitabine- radiotherapy vs. gemcitabine - chemotherapy). However, better clinical results were achieved for head and neck cancer patients, particularly in gemcitabine - radiotherapy group but with significant toxicity due to high gemcitabine dose

Comparative Analysis of Deformation Determination by Applying Fiber-optic 2D Deflection Sensors and Geodetic Measurements

In the paper the description of an experiment for a comparative analysis of two different methods for deformation determination, geodetic and 2D deflection sensors based on fiber-optic curvature sensors (FOCSs) is given. The experiment is performed by a using specially designed assembly which makes it possible to apply both methods. For performing geodetic measurements, a geodetic micro-network is established. Measurements by applying a 2D deflection sensor and three total stations are carried out for comparison. The data processing comprises graphical and numerical analysis of the results. Based on the presented results the potential of 2D deflection sensor application in structural health monitoring (SHM) procedures is indicated. The analysis of the measurement results also indicates the importance of integrating various types of sensors for obtaining more accurate and more reliable deformation measurements results

Surface-modified TiO2 nanoparticles with ascorbic acid: antioxidant properties and efficiency against DNA damage

Ascorbic acid (AA) is a standard antioxidant and its radical scavenging properties also appear to be responsible for its antigenotoxic properties. Nanoparticle-mediated delivery of antioxidant compounds is intended to increase their bioavailability while maintaining their effectiveness. Colloids consisting of the 45-Å TiO2 nanoparticles (NPs) with anatase crystal structure were prepared by acidic hydrolysis of TiCl4. The synthesized TiO2 NPs were characterized using transmission electron microscopy and X-ray diffraction analysis. The charge transfer (CT) complex formation between surface Ti atoms and AA is indicated by immediate appearance of red color. The aim of this study was to compare, for the first time, the antioxidant and antigenotoxic effects of AA attached to the surface of TiO2 NPs with free AA in a wide concentration range. For evaluation of antigenotoxic properties whole blood cells were first treated with 50 μM H2O2 to induce DNA damage, and then exposed to 3 different concentrations of free AA (1.3×10-2, 2.6×10-2, and 3.9×10-2 M) and the same concentrations of AA attached to TiO2 NPs (0.05, 0.1, and 0.15 M) for 30 min at 37 0C. The level of DNA damage was evaluated by comet assay method. For evaluation of antioxidant properties, total antioxidant capacity (TAC), total antioxidative status (TAS) and prooxidative-antioxidative balance (PAB) were determined in human serum pool during 2 and 24 h incubation at 37 °C, without and with terc-buthyl-hydroperoxide (TBH) as exogenously added oxidant. As expected, the results of DNA damage showed that the increase of AA concentration leads to a reduction of DNA damage. The similar concentration dependence was observed for surface-modified TiO2 NPs with AA. So, no significant differences between the antigenotoxic properties of free AA and AA attached to the TiO2 NPs were noticed, but only the highest concentrations showed significant effect in both experimental treatments. Regarding short-term oxidative balance in biological material (serum), during 2h, by measuring the TAC we have showed that the complex NP and AA, so as ascorbic acid showed a significant increase in TAC capacity, compared to native serum. This increase of antioxidative capacity couldn’t be abrogated even with a powerful oxidant, terc-buthylhydroperoxide presence (TBH). After 24h hour incubation the TAC level in both samples decreased towards the baseline level. About the TOS, which measures all oxidative components in plasma such as hydrogen-peroxide and lipid hydroperoxide, the complex of NP and AA versus AA alone showed inconsistent results. Prooxidative-antioxidative balance (PAB) measuring equilibrium between oxidants and antioxidants remains low, almost imponderable after 2h and after 24h serum incubation with the two substances. To summarize, we suggest that surface-modified TiO2 NPs with AA and/or similar compounds can be used to improve their bioavailability while maintaining its beneficial activities.3rd International Congress on Occupational & Environmental Toxicology - ICOETox 2016 and 3rd Ibero-American Meeting on Toxicology and Environmental Health International (IBAMTOX 2016), 21-23 June 2016 | Port

Acute toxicity study in mice of orally administrated TiO2 nanoparticles functionalized with caffeic acid

The acute toxicity of surface-modified TiO2 nanoparticles (NPs) with caffeic acid (CA) was compared with those of its separate constituents (free CA and bare TiO2 NPs) upon their oral administration in laboratory mice. Prior to in vivo experiments, the interfacial charge transfer (ICT) complex between surface Ti atoms and CA is thoroughly characterized. Composition and stability constants of ICT complex were determined using Job's method and Banesi-Hildebrand analysis, respectively. The experimental data were supported with quantum chemical calculations based on density functional theory (DFT). Acute toxicity signs, including biochemical alterations and extensive histopathological changes in the liver tissue of mice were detected 14 days after oral administration of bare TiO2 NPs. However, the clinical signs of toxicity, the fractional contribution of organs, biochemical parameters of liver and kidney function, and histopathological changes in liver upon treatment with surface-modified TiO2 NPs with CA were not observed. Also, the genotoxic potential of the ICT complex and its constituents were evaluated in leukocytes of whole blood cells in vivo by comet assay. Both, bare and surface-modified TiO2 NPs did not display DNA damaging effect in time frame of 24 h upon their oral administration in mice

Surface-modified TiO2 nanoparticles with ascorbic acid: Antioxidant properties and efficiency against DNA damage in vitro

The antigenotoxic and antioxidative properties of surface-modified TiO2 nanoparticles (NPs) with ascorbic acid (AA) were compared with those of constituents (free AA and bare TiO2 NPs). Colloids consisting of the TiO2 NPs with anatase crystal structure were prepared by acidic hydrolysis of TiCl4. The synthesized TiO2 NPs were characterized using transmission electron microscopy and X-ray diffraction analysis. The charge transfer (CT) complex formation between surface Ti atoms and AA is indicated by immediate appearance of red color. Composition and stability constants of CT complex were determined using Job's method and Banesi-Hildebrand analysis, respectively. The surface structure of CT complex was determined from infra-red spectra of free and bound AA to the surface Ti atoms. The experimental data were supported with quantum chemical calculations based on density functional theory (DFT). The antigenotoxic potential of CT complex was evaluated in leukocytes of whole blood cells in vitro by comet assay method. For evaluation of antioxidant properties, total antioxidant status (TAS) and total oxidant status (TOS) were determined in human serum pool in vitro. The presented results indicate that bare TiO2 NPs have more pronounced antigenotoxic effects in comparison with either surface-modified TiO2 NPs with AA or free AA. No significant differences between the antigenotoxic and antioxidative properties of free and bound AA on the TiO2 NPs were noticed in the investigated concentration range. It seems that surface-modified TiO2 NPs with AA and/or similar compounds can be used to maintain its beneficial activities