79 research outputs found

    Insulin responses to acute glucose infusions in Buša and Holstein-Friesian cattle breed during the peripartum period: Comparative study

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    The aim of this study was to compare insulin responsevness to acute glucose infusion in cows of Holstein Friesian (HF) and Buša breeds during the peripartal period. Eight cows per each group (HF and Buša), were chosen. At day 7 prior to calving (ante partum) and day 14 after calving (post partum) animals were subjected to a glucose tolerance test (GTT). Blood samples were taken immediately before infusion and 15, 30, 60, 120 and 180 min thereafter. Glucose and insulin concentrations were measured in each blood sample, while BHBA and NEFA were measured only in samples taken before the infusion. QUICKY an indicator of insulin resistance in cows was calculated. Basal glycemia did not significantly differ between the breeds. Basal insulinemia was significantly higher in Buša than in HF cows in both examined periods (p<0.001, respectively). Basal NEFA levels tended (p=0.06) to be higher in Buša cows compared with those of HF ante partum, and was significantly higher (p<0.001) post partum. Basal BHBA was significantly lower in Buša than HF cows in both examined periods (p<0.01; p<0.001). QUICKI was significantly lower in Buša compared to HF cows both ante partum and post partum periods (p<0.001, respectively). Glycemia determined during GTT were higher in Buša than HF cows, both ante partum and post partum, but significantly starting from minute 15 ante partum i.e. minute 30 post partum. Insulinemia determined during GTT was significantly lower at min 15, and significantly higher starting from min 90 in Buša than HF cows, both ante partum and post partum. Results obtained in this study indicate on difference in insulin responsevness to acute glucose infusion between the examined breeds, which is probably a consequence of the difference in the degree of negative energy balance rather than of selection on high milk production. Namely, decreased insulin tissues sensitivity and decreased insulin responsiveness in Buša compared to HF cows is probably the consequence of inadequate energy intake from alimentary sources which leads to enhanced usage of energy from body reserves. [Projekat Ministarstva nauke Republike Srbije, br. 46002

    Vibration control of resonant vibratory feeders with electromagnetic excitation

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    Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

    Vibration control of resonant vibratory feeders with electromagnetic excitation

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    Vibracioni dodavači sa elektromagnetnom pobudom, odnosno elektromagnetni vibracioni dodavači (EMVD) su najčešće korišćeni u procesnoj industriji za obezbeđenje gravimetrijskog protoka sitnozrnih i rasutih materijala. Ovi pogoni obezbeđuju laku i jednostavnu kontrolu masenog protoka transportujućih materijala. U poređenju sa ostalim pogonima (pneumatskim, inercionim, centrifugalnim, itd.), oni su jednostavnije i kompaktnije konstrukcije, robusni i pouzdani u radu. Odsustvo habajući mehaničkih delova kao što su reduktori, kišnici, ekscentri i sl., čine EMVD veoma ekonomičnom opremom. Standardni pretvarački izlazni stepeni namenjeni za kontrolu EMVD su bazirani na SCR elementima (tiristorima i trijacima). Njihovo korišćenje podrazumeva korišćenje kontrole faznog ugla (KFU) i stoga konstantnu učestanost vibracija. Na ovaj način kontrolno kolo mora biti sinhronizovano sa mrežnom učestanošću 50(60)Hz. Uz pomoć KFU je jedino moguće ostvariti podešavanje amplitude vibracija, ali ne i njihove učestanosti. Primena prekidačkih tranzistorskih (IGBT ili MOSFET) energetskih pretvarača, omogućava amplitudsku i (ili) frekventnu kontrolu EMVD. Njihovo korišćenje podrazumeva pobudu EMVD nezavisno od mrežne učestanosti. Dodatno, frekventna kontrola dozvoljava rad u oblasti mehaničke rezonance. Rad u ovoj oblasti je veoma efikasan, pošto je moguće obezbediti značajne izlazne pomeraje, veoma malom ulaznom snagom. Optimalan i efikasan rad zahteva praćenje rezonantne učestanosti. U ovom radu su predstavljeni jedno moguće rešenje vibracione kontrole EMVD, kao i odgovarajući simulacioni i eksperimentalni rezultati.The vibratory feeders with electromagnetic excitation called electromagnetic vibratory feeders (EMVF) are commonly used for performing gravimetric flow of granular and particulate materials in processing industry. This drives offer easy and simple control the mass flow of conveying materials. In comparison with other drives (pneumatics, inertial, centrifugal, etc...), these have a more simple construction and they are compact, robust and reliable in operation. The absence of wearing mechanical part, such as gears, cams belts, bearings, eccentrics, etc., makes EMVF, most economical equipment. Standard power electronic output stages intended for control of the EMVF using SCR devices (thyristors and triacs). This implies phase angle control (PAC) and constant frequency of vibration. In this way control circuit must be synchronized to the mains supply frequency 50(60) Hz. PAC can only accomplish tuning amplitude of vibration, but not vibratory frequency. Application of transistor (IGBT or MOSFET) switch mode power converters enables accomplishing the amplitude and (or) frequency control of EMVF. Their use implies the excitation of an EMVF independent of the mains supply frequency. In addition, the frequency control ensures operation in the region of mechanical resonance. This operation is highly efficient, because large output displacement is provided by small input power. An optimal and efficient operation requires tracking of resonant frequency. This paper presents possible solution of the amplitude frequency control of EMVF and corresponding simulation and experimental results

    Experimental Investigation of Pyrolysis Process of Agricultural Biomass Mixture

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    This paper describes an experimental investigation of pyrolysis process of agricultural biomass mixture, without the addition of inert gas. The mixture consists of corn stalk, wheat straw, soy straw and oat straw with equal mass fractions. During the experiment, the mass of biomass sample inside the reactor was 10 g with a particle diameter of 5-10 mm. The sample in the reactor was heated in the temperature range of 24-650ºC at average heating rates of 21, 30 and 54ºC/min. The sample mass before, during and after pyrolysis was determined using a METTLER P1000 digital scale. Experimental results of the sample mass change indicate that the highest yield of pyrolytic gas, achieved at 650ºC, was in the range from 74 to 81%, while char yield ranged from 19 to 26%. Heating rate of biomass mixture sample has significant influence on the pyrolytic gas and char yields. It was determined that higher heating rates in the reactor induce higher yields of pyrolytic gas, while the char mass reduces. Condensation of pyrolytic gas at the end of the pyrolysis process at 650ºC produced 1.3-1.8 g of liquid phase. The results obtained represent a starting basis for determining material and heat balance of pyrolysis process as well as agricultural biomass pyrolysis equipment

    Targeted alpha therapy in vivo: direct evidence for single cancer cell kill using 149Tb-rituximab

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    This study demonstrates high-efficiency sterilisation of single cancer cells in a SCID mouse model of leukaemia using rituximab, a monoclonal antibody that targets CD20, labelled with terbium-149, an alpha-emitting radionuclide. Radio-immunotherapy with 5.5MBq labelled antibody conjugate (1.11GBq/mg) 2 days after an intravenous graft of 5·106 Daudi cells resulted in tumour-free survival for >120 days in 89% of treated animals. In contrast, all control mice (no treatment or treated with 5 or 300µg unlabelled rituximab) developed lymphoma disease. At the end of the study period, 28.4%±4% of the long-lived daughter activity remained in the body, of which 91.1% was located in bone tissue and 6.3% in the liver. A relatively high daughter radioactivity concentration was found in the spleen (12%±2%/g), suggesting that the killed cancer cells are mainly eliminated through the spleen. This promising preliminary in vivo study suggests that targeted alpha therapy with 149Tb is worthy of consideration as a new-generation radio-immunotherapeutic approac

    The problem of heritology abduction through instrumental analysis of cultural heritage materials

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    Heritološki fenomeni u oblasti istraživanja kompozitnih umetničkih dela, u vezi sa raznovrsnošću pristupa u kvalitativnim i kvantitativnim kriterijumima za izbor materijala, postavljaju složene zadatke u primeni instrumentalnih metoda, koje prethode izradi protokola za konzervaciju-restauraciju predmeta kulturne baštine. U ovom radu u fokusu je problem heritološke abdukcije, u heurističkoj proceni broja neophodnih analiza, odnosno deficita podataka u fragmentarnim strukturama koje su izraz umetničkog spontaniteta, a sa akcentom na fenomen praemissa minor u traganju za metodološki čvrstom platformom za interpretaciju podataka.Taking into account the diversity of approaches in qualitative and quantitative criteria for material selection heritology phenomena in the field of research of composite art works set complex tasks in the application of instrumental methods, which precede the development of protocols for conservation and restoration of cultural heritage. The focus of this paper is on the problem of heritology abduction, particularly in the domain of heuristic assessment concerning the number of necessary analyses, i.e. the deficit of data in fragmentary structures, these being expressions of artistic spontaneity. At the same time, the paper also tackles the phenomenon of minor assumptions while pursuing a methodologically sound platform for interpreting data

    Contribution to the research of oscillatory loads of sprung and unsprung masses in order to create conditions for laboratory tests of heavy motor vehicles

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    Introduction/purpose: Motor vehicles are complex dynamic systems due to spatial displacements, changes in the characteristics of components during their lifetime, a large number of influences and disturbances, the appearance of backlash, friction, hysteresis, etc. The aforementioned dynamic phenomena, especially vibrations, cause driver and passenger fatigue, reduce the lifetime of the vehicle and its systems, etc. Methods: In general, the movement of vehicles is carried out on uneven roads and curvilinear paths in the road. Not only do oscillatory movements cause material fatigue of vehicle parts, but they also have a negative effect on people's health. That is why special attention must be paid to the coordination of the mutual movement of the subsystems, and in particular, the vehicle suspension system, even at the stage of the motor vehicle design. For these purposes, theoretical, experimental or combined methods can be used. Therefore, it is very useful to have the experimental results of the oscillations of the vehicle subsystem in operating conditions, so the aim of this work was to use the movement of the 4x4 drive FAP 1118 vehicle in operating conditions (due to higher speeds - in road conditions) to define the conditions for testing oscillatory loads in laboratory conditions. Results:This is made possible by registering and identifying statistical parameters of registered quantities. Conclusion: Based on the measured data, the research can be programmed on shakers in laboratory conditions, and, at the same time, the size to be reproduced can be chosen as well

    Modeling and simulation of hydraulic buffering valve for power-shift transmission

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    Introduction/purpose: The hydraulic buffering valve has the greatest influence on the dynamic characteristics of power-shift transmission. The hydraulic buffering valve is a transmission element that controls increase in pressure in friction assemblies during the gear shifting process. By choosing the optimal control of pressure increase during shifting, reduction of dynamic loads in gear transmissions and thermal loads in friction assemblies is achieved. Methods: The paper analyzes the principle of one of hydraulic buffering valve solutions as well as the influence of certain parameters on the control of pressure increase. After the analysis of the working principle of the hydraulic buffering valve, a simulation model was developed in the MATLAB/Simulink software package. Results: The results obtained using the simulation model were compared with the experimental results of the selected pressure modulator solution. The selected hydraulic buffering valve was developed as part of the development of a device for power-shift transmission. The simulation results showed a satisfactory match with the experimental results. Conclusion: The developed simulation model enables a relatively easy and quick change of the parameters of the hydraulic buffering valve as well as a possibility of a faster and better understanding of the influence of individual parameters on pressure increase during the gear shifting process

    Estimation of measurement uncertainty in measuring radiopharmaceutical activity in dose calibrator

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    Doze kalibrator je jedan od osnovnih uređaja u nuklearnoj medicini, koji se koristi za merenje aktivnosti (doza) radiofarmaceutika koji se daju pacijentima bilo u dijagnostičke ili u terapijske svrhe. Aktivnosti gama i beta emitera različitih energija moraju da budu izmerene što tačnije da bi izlaganja ljudi (pacijenata) jonizujućem zračenju bila svedena na najmanji mogući nivo, a da se dobiju klinički značajni rezultati. Početna tačnost kalibratora (nesigurnost 5% ili manje) može se vremenom menjati kao rezultat promene pritiska u jonizacionoj komori ili električnog drifta. Zbog toga kontrola kvaliteta doze kalibratora treba da se sprovodi rutinski kako bi se osigurala tačnost i sledljivost merenja.U radu su prikazani rezultati procene nesigurnostipri merenjima aktivnosti radiofarmaceutika u doze kalibratoru u Laboratoriji za radioizotope. Komponente nesigurnosti, koje su važne za ova merenja, identifikuju se i uzimaju u obzir prilikom procene merne nesigurnosti. Razumevanje izvora nesigurnosti i korišćenje odgovarajućih korekcionih faktora mogu minimizirati netačna merenja.A dose calibrator is an essential device in a nuclear medicine, utilized for measurement the activity of radiopharmaceuticals administered to patients both for diagnostic and therapeutic purposes. It has to measurethe radioactivity of gamma and beta with different energies precisely for high quality imaging and for applying the right amount of radiation to treat disease. Initial accuracy (uncertainty 5% or less) may change with time as a result of changing pressureof the chamber gas and slow electrical drift. The quality controls should be undertaken on a routine basis to ensure the accuracy and traceability of measurements of the activities of radiopharmaceuticals.The paper presents the results of estimation of uncertainty in the measurement of the activity in the dose calibrator in the Laboratory for radioisotopes. The uncertainty components, that are important for these measurements, are identified and taken into account while estimating the uncertainty of measurement. Understanding the source of uncertainty and using appropriate techniques can minimize inaccurate measurements.Proceedings: [http://vinar.vin.bg.ac.rs/handle/123456789/8681]XXX симпозијум ДЗЗСЦГ (Друштва за заштиту од зрачења Србије и Црне Горе), 2- 4. октобар 2019. године, Дивчибаре, Србиј

    Genetic Markers for Coronary Artery Disease

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    Coronary artery disease (CAD) and myocardial infarction (MI) are recognized as leading causes of mortality in developed countries. Although typically associated with behavioral risk factors, such as smoking, sedentary lifestyle, and poor dietary habits, such vascular phenotypes have also long been recognized as being related to genetic background. We review the currently available data concerning genetic markers for CAD in English and non-English articles with English abstracts published between 2003 and 2018. As genetic testing is increasingly available, it may be possible to identify adequate genetic markers representing the risk profile and to use them in a clinical setting. © 2018 by the authors. Licensee MDPI, Basel, Switzerland
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