Feasibility study of a current mode gamma radiation dosimeter based on a commercial pin photodiode and a custom made auto-ranging electrometer

An experimental study has been conducted to evaluate the feasibility of a current mode gamma radiation dosimeter, consisting of a commercial PIN photodiode as a radiation sensor, and a custom made auto-ranging electrometer for real-time measurement of the PIN photodiode’s response under radiation exposure. The radiation induced direct current response for single PIN photodiodes with different active areas, as well as for multiple PIN photodiodes connected in parallel, has been investigated. Three types of commercial silicon PIN photodiodes have been chosen for evaluation - S1223, BPW34, and PS100-6-CER2 PIN. During the experiment, five samples have been tested - three samples made of single PIN photodiodes (one sample of each photodiode type) and two samples formed by connecting multiple photodiodes in parallel (two BPW34 photodiodes in parallel and four BPW34 photodiodes in parallel). The samples have been irradiated with a 60Co gamma ray source and the relations between the induced photocurrent and the dose rate, and between the accumulated charge and the absorbed dose, have been determined. For measuring the photodiodes response, a custom made auto-ranging electrometer controlled by a personal computer, and capable of measuring direct currents from 50 pA to 10 mA with relative error less than 2.5%, has been used. Obtained results have shown very good linearity between the dose rate and the induced photocurrent for dose rates ranging from 0.93 Gy/h to 67 Gy/h. Also, very good linearity has been observed between the accumulated charge and the absorbed dose for all tested samples, within the investigated range of absorbed doses from 472 mGy to 3.3 Gy. On the basis of the obtained results, a simple model has been derived, enabling the estimation of the photodiode’s current response as a function of the dose rate and the photodiode’s geometry (active area and depletion layer width). [Projekat Ministarstva nauke Republike Srbije, br. 43011

Estimation of laser-Doppler anemometry measuring volume displacement in cylindrical pipe flow

Laser-Doppler anemometry application in measurements of the 3-D swirl turbulent flow velocity in the cylindrical pipe, behind the axial fan, have been analysed. This paper presents a brief overview of uncertainty sources in the laser-Doppler anemometry measurements. Special attention is paid to estimation of laser-Doppler anemometry measuring volume positioning in cylindrical pipe flow due to optical aberrations, caused by the pipe wall curvature. The hypothesis, that in the central part of the pipe (r/R < 0.6) exists a small, or negligible pipe wall influence on laser- -Doppler anemometry measuring position, is investigate. The required corrections, for measurements of axial, tangential, and radial velocity components such: shift of measuring volume and its orientation are analyzed and determined for used test rig and for some other pipe geometries. [Projekat Ministarstva nauke Republike Srbije, br. TR 35046

Laser doppler velocimetry and confined flows

Finding the mode, in which two component laser Doppler velocimetry can be applied to flows confined in cylindrical tubes or vessels, was the aim of this study. We have identified principle issues that influence the propagation of laser beams in laser Doppler velocimetry system, applied to flow confined in cylindrical tube. Among them, the most important are influences of fluid and wall refractive indices, wall thickness and internal radius ratio and beam intersection angle. In analysis of the degrees of these influences, we have applied mathematical model, based on geometrical optics. The separation of measurement volumes, that measure different velocity components, has been recognized as the main drawback. To overcome this, we propose a lens with dual focal length primary focal length for the measurement of one velocity component and secondary focal length for the measurement of the other velocity component. We present here the procedure for calculating the optimal value of secondary focal length, depending on experimental set-up parameters. The mathematical simulation of the application of the dual focal length lens, for chosen cases presented here, confirmed the accuracy of the proposed procedure

Genetic variability of maize landraces (zea mays l.) assessed by molecular markers

Agronomski biodiverzitet je širok pojam koji uključuje sve komponente biološkog diverziteta od značaja za hranu i poljoprivredu. On predstavlja rezultat interakcije između genetičkih resursa, životne sredine i upravljanja sistemima i prakse koji čine poljoprivrednu proizvodnju. Biljni genetički resursi, smatraju se izuzetno značajnim u obezbeđivanju dovoljne količine hrane neophodne za ljudsku ishranu. Procenjuje se da danas ukupno 30 useva obezbeđuju 95% čovekovih potreba za hranom. Kukuruz je jedna od najznačajnijih useva koja se gaji širom sveta. Iako poseduje izuzetno veliku genetičku varijabilnost, u komercijalnoj upotrebi se nalazi svega oko 5% ukupne germplazme kukuruza, koja obezbeđuje visoke prinose. Banka gena Instituta za kukruz „Zemun Polje“ održava kolekciju od 2217 lokalnih populacija kukuruza klasifikovanih u 18 agroekoloških grupa, sakupljenih na prostoru bivše Jugoslavije. Ispitivanje diverziteta lokalnih populacija predstavlja osnovni preduslov za njihovu efikasnu klasifikaciju, čuvanje i korišćenje, i ima za cilj procenu genetičke raznovrsnosti i strukture populacija Ispitana je genetička varijabilnost 54 lokalne (po tri populacije svake agroekološke grupe) i 6 introdukovanih populacija kukuruza (po dve iz Francuske, Gruzije i Kine). Za ispitivanje genetičke varijabilnosti populacija korišćeno je 18 morfoloških osobina i 10 RAPD (Random Amlified Polymorphic DNA) i 10 SSR (Simple Sequence Repeat) markera. Na osnovu morfoloških osobina urađena je analiza varijanse i uočene su značajne razlike kod svih osobina za različite izvore variranja što govori o visokom stepenu fenotipskog diverziteta između populacija. Takođe, dobijene su visoke vredosti heritabilnosti u širem smislu (preko 0,6) za skoro sve osobine, osim dužine granatog dela metlice. Rezultati PCA analize su ukazali da lokalne populacije kukuruza mogu biti okarakterisane pomoću osobina kao što su rast biljke, osobine metlice i karakteristike zrna, a zapaženo je i veće grupisanje tvrdunaca/polutvrdunaca, odnosno poluzubana/zubana. Na osnovu morfoloških osobina i molekularnih markera, pomoću UPMGA metode dobijeni su klasteri, koristeći NTSYSpc statistički program. Morfološka, SSR i RAPD analiza nisu dovele do jasnog grupisanja lokalnih populacija prema poreklu, ali je uočeno delimično poklapanje između grupa populacija povezanih u kastere/subklaste i putevima introdukcije, odnosno njihovog nastanka od originalnih populacija...Agricultural biodiversity is a broad term which includes all components of biological diversity of relevance to food and agriculture. It represents the result of interaction between genetic resources, environmental protection and both management systems and practices that make agricultural production. Plant genetic resources are considered to be very important in providing sufficient amounts of food for human consumption. It is estimated that today a total of 30 crops provide 95% of human needs for food. Corn is one of the most important crops that are grown around the world. Although it has a very high genetic variability, only about 5% of the germplasm is in the commercial use, which provides high yields. Maize Research Institute „Zemun Polje“ genebank maintains a collection of 2217 maize landraces classified into 18 agro-ecological groups, collected in the former Yugoslavia. Evaluation of genetic diversity of the local population represents basic precondition for their effective classification, storage and use. It aims to assess the genetic diversity and population structure. Assessment of genetic variability was done on 54 maize landraces (three landraces from each agro-ecological group) and six introduced maize landraces (two of each from France, Georgia and China). In order to analyze genetic variability of maize landraces, 18 morphological traits, 10 RAPD (Random Amplified Polymorphic DNA) and 10 SSR (Simple Sequence Repeat) markers were used. Analysis of variance was performed for evaluate morphological traits. Significant differences were observed for all traits for different sources of variation which indicates a high degree of phenotypic diversity between populations. Also, high broad-sense heritability (over 0.6) were obtained for almost all the traits except branched tassel length. The results of PCA analysis indicated that local maize populations can be characterized by traits such as plant growth, tassel traits and kernel characteristics. It was also observed the larger grouping of flint/semi-flint respectively to semident/dent. Unweighted Pair Group Method with Arithmetic Mean (UPGMA) method was applied for cluster analysis. All marker data analyses were performed using NTSYSpc statistical program..

A use of Cournot's competition model in oligopolistic markets in the terms of limited capacities

Cilj ovog rada je da teorijski utemelji primenu Kurnoovog modela kao skraćene forme dvostepene konkurencije na oligopolskim tržištima u uslovima ograničenih kapaciteta. Razvijen je model koji predstavlja prečicu za analizu potencijalnih efekata na blagostanje horizontalnih spajanja preduzeća. Model mogu upotrebiti komisije za zaštitu konkurencije kao simulacioni model pri kontroli horizontalnih spajanja preduzeća. Pokazano je da se ishod modela dvostepene konkurencije, gde se preduzeća obavezuju na određene nivoe kapaciteta, pre konkurencije cenama, poklapa sa ishodom Kurnoovog modela količinske konkurencije. Šta više, ispostavlja se da ovaj rezultat važi kako za tržišta homogenih proizvoda tako i za tržišta diferenciranih proizvoda. To protivreči gotovo standardnom stavu da je količina strateška varijabla isključivo na tržištima homogenih proizvoda. Robusnost ovog rezultata proverava se kako za simetrični oligopol, što predstavlja standardno polazište svih modela iz ove klase, tako i za okolnost asimetričnog oligopola. Asimetrija se uvodi kroz internalizaciju konkurencije izazvanu spajanjem dva simetrična preduzeća na tržištu diferenciranih proizvoda. Komisijama za zaštitu konkurencije je predložen algoritam za primenu modela simulacija. U skladu sa definisanim koracima, sprovedene su simulacije spajanja na realnom primeru, primenom Kurnoovog modela konkurencije u uslovima ograničenih kapaciteta. Na osnovu rezultata simulacija, komisijama su date praktične preporuke za sprovođenje kontrole koncentracija.The objective of the thesis is to examine the Cournot model as a reduced form of the two-stage competition in oligopolistic markets with limited capacities. A short-cut model for analysing welfare effects of potential horizontal mergers is developed. The model can be used by Anti-trust commissions as a simulation model in the process of horizontal merger assessment. It is shown that the outcome of the two-stage competition, where firms had been conditioned by their level of capacities even before the price competition has started, coincide with the outcome of the Cournot quantity competition model. Moreover, it turns out that this result is valid for both the homogeneous product markets and the markets of differentiated products. This contradicts an almost universal belief that the quantity is a strategic variable exclusively within the homogeneous product markets. The robustness of this result is examined both for symmetric oligopoly, which is a starting point for all models in the class, and for the asymmetric oligopoly. The asymmetry is introduced through the internalisation of competition due to a merger of two symmetric firms in the differentiated products market. The implementation algorithm of the simulation model is suggested to the Anti-trust commissions. In accordance with defined steps, merger simulation can be carried out in the real world by using the Cournot model of competition with limited firm capacities. Based on the simulation results, practical recommendations for the merger control policies are offered to the commissions

The influence of chronic pre-conditioning of phosphodiesterase 1 inhibitors alone and in combination with physical activity on functional recovery of an isolated heart of rats

Uvod: Redovna fizička aktivnost umerenog intenziteta se smatra neophodnom zdravstvenom merom kao osnovom nefarmakološke terapije kardiovaskularnih bolesti. Cilj ove studije je bio da proceni efekte PDEIs na kardiodinamske parametre i sistemski redoks status, nakon farmakološkog i fizičkog prekondicioniranja miokarda Materijal i metode: Studija je sprovedena na 96 mužjaka Wistar albino pacova, podeljenih u sledeće grupe sa i bez fizičkog treninga (12 po grupi): sedentarna kontrola, Nikardipin (6 mg/kg/dan), Vinpocetin (10 mg/kg/dan), Nimodipin (10 mg/kg/dan), trening umerenog intenziteta kontrolna grupa (MIT), Nikardipin (MIT + 6 mg/kg/dan leka), Vinpocetin (MIT + 10 mg/kg/dan leka), Nimodipin (MIT + 10 mg/kg/dan leka). Od kardidinamskih parametara praćeni su: dp/dt max, dp/dt min, SLVP, DLVP, frekvenca srca i koronarni protok. U koronarnom efluentu kao i u hemolizatu eritrocita životinja određivani su parametri oksidacionog stresa i antioksidacione zaštite: nitriti (NO2 – ), superoksidni anjonski radikal (O2), vodonik-peroksid (H2O2), indeks lipidne peroksidacije, superoksid dismutaza, katalaza i redukovani glutation. Rezultati: Prekondicioniranje PDE1 inhibitorima i treningom umerenog intenziteta povećavaju parametre kontraktilnosti srca, sa dominantnijim povećanjem dp/dt min i max kao i SPLK nakon primene vinpocetina i nimodipina i smanjuje oslobađanje pro-oksidanasa. Zaključak: Fizički trening umerenog inteziteta dovoljnog trajanja samostalno ili u kombinaciji sa PDE1 inhibitorima dovodi do razvijanja pozitivnih protektivnih adaptivnih mehanizama koji se manifestvuju smanjenjem oksidacionog stresa i poboljšanjem hemodinamskih parametara., a time i ukupne sposobnosti organizma.Introduction: Regular physical activity of moderate intensity is considered a necessary health measure as a basis for non-pharmacological therapy of cardiovascular diseases. The aim of this study was to evaluate the effects of PDEIs on cardiodynamic parameters and systemic redox status, after pharmacological and physical myocardial preconditioning Material and methods: The study was performed on 96 male Wistar albino rats, divided into the following groups with and without physical training (12 per group): sedentary control, Nicardipine (6 mg/kg/day), Vinpocetine (10 mg/kg/day), Nimodipine (10 mg/kg/day), moderate intensity training control group (MIT), Nicardipine (MIT + 6 mg/kg/day), Vinpocetine (MIT + 10 mg/kg/day), Nimodipine (MIT) + 10 mg/kg/day). The following parameters were monitored: dp/dt max, dp/dt min, SLVP, DLVP, HR, CF and parameters of oxidative stress and antioxidant protection: nitrites (NO2 – ), superoxide anion radical (O2),hydrogen peroxide (H2O2), lipid peroxidation index (suzaroxide dismuta) , catalase (CAT) and reduced glutathione (GSH). Results: Preconditioning with PDE1 inhibitors and moderate-intensity training increase cardiac contractility parameters, with a more dominant increase in dp/dt min and max as well as SLVP after administration of vinpocetine and nimodipine, and decrease pro-oxidant release. Conclusion: Physical training of moderate intensity of sufficient duration alone or in combination with PDE1 inhibitors leads to the development of positive protective adaptive mechanisms which are manifested by reduction of oxidative stress and improvement of hemodynamic parameters, and thus the overall ability of the organism

The effect of structural changes on magnetic permeability of amorphous powder Ni80Co20

The structural changes of Ni80Co20 amorphous powder were tested during heating. The alloy was obtained by electrolysis from ammonia solution sulfate of cobalt and nickel on the titanium cathode. The differential scanning calorimetry (DSC) method was used to detect that the crystallization process of powder occurred in two stages with crystallization peaks temperatures of the first stage at 690 K and of the second stage at 790 K. The effect of structural relaxation and crystallization of powder on magnetic properties was predicted by measurement of the relative magnetic permeability change in isothermal and nonisothermal conditions. On the basis of the time change of relative magnetic permeability at a defined temperature in the temperature range of the first and second crystallization peak on the thermogram, the kinetics of crystallization was defined. It was predicted, that in the initial time interval, in the range of the first crystallization peak, the rate of crystallization is determined by the rate of nucleation of the amorphous part of the powder. However, in the second time interval, the crystallization rate is determined by the rate of diffusion. In the range of the second peak, in the beginning the rate of crystal growth is determined by activation energy of the atom pass from smaller to bigger crystal grain. In second time interval, the rate of crystal grain growth is determined by the diffusion rate of atoms to the location of integration into bigger crystal grains. For all processes which determine the rate of crystallization in temperature ranges of both crystallization peaks, the Arrhenius temperature dependence of rate for those processes is obtained. The relative magnetic permeability of crystallized powder at 873 K, is smaller for about 30 % than the relative magnetic permeability of fresh powder at room temperature. However, structurally relaxed powder at 573 K has an about 22 % larger magnetic permeability than the same fresh powder at room temperature

Analysis of isothermal sintering of zinc-titanate doped with MgO

The aim of this work was analysis of isothermal sintering of zinc titanate ceramics doped with MgO obtained by mechanical activation. Mixtures of ZnO, TiO2 and MgO (0, 1.25 and 2.5%) were mechanically activated 15 minutes in a planetary ball mill. The powders obtained were pressed under different pressures and the results were fitted with a phenomenological compacting equation. Isothermal sintering was performed in air for 120 minutes at four different temperatures. Structural characterization of ZnO-TiO2-MgO system after milling was performed at room temperature using XRPD measurements. DTA measurements showed different activation energies for pure and doped ZnO-TiO2 systems. Thus addition of MgO stabilizes the crystal structure of zinc titanate

Analiza tehnologičnosti personalizovanih implantata metodama veštačke inteligencije

Customized implants are complex free geometrical forms. Requests for its precision, appropriate material selection and manufacturing time require that even at the designing phase right decisions are made. That is why customized implant manufacturability analysis and the use of artificial intelligence are very important. Customized implant knowledge model will be created and system for acquisition, systematization, and modeling of knowledge about customized implant designing and manufacturing will be developed. By creating knowledge basis we make a foundation for creating adaptable expert system for customized implant manufacturability analysis. It will be a part of a system for designing, manufacturing and monitoring workflow, based on web technologies