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32. Increased augmentation index and central systolic arterial pressure are associated with lower school and motor performance in young adolescentsBernarda Vogrin, Marjan Rupnik, Dušanka Mičetić-Turk, 2017, izvirni znanstveni članek Opis: Objective: In adults, improper arterial function has been linked to cognitive impairment. The pulse wave velocity (PWV), augmentation index (AIx) and other vascular parameters are useful indicators of arterial health. In our study, we monitored arterial properties, body constitution, school success, and motor skills in young adolescents. We hypothesize that reduced cognitive and motor abilities have a vascular origin in children.
Methods: We analysed 81 healthy school children aged 11-16 years. Anthropometry central systolic arterial pressure, body mass index (BMI), standard deviation scores (SDS) BMI, general school performance grade, and eight motor tests were assessed. PWV, AIx, and central systolic arterial pressure (SBPao) were measured.
Results: AIx and SBPao correlated negatively with school performance grades. Extremely high AIx, PWVand SBPao values were observed in 5% of children and these children had average to low school performance. PWV correlated significantly with weight, height, and waist and hip circumference. AIx, PWV, school success, and BMI correlated strongly with certain motor functions.
Conclusions: Increased AIx and SBPao are associated with lower school and motor performance in children. PWV is influenced by the body's constitution.
Ključne besede: augmentation index, pulse wave velocity, school success, motor functions, young adolescents, central systolic arterial pressure, body mass index
Objavljeno v DKUM: 13.07.2017; Ogledov: 1285; Prenosov: 349
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33. Determining the speed of sound, density and bulk modulus of rapeseed oil, biodiesel and diesel fuelBoban Nikolić, Breda Kegl, Saša Marković, Melanija Mitrović, 2012, izvirni znanstveni članek Opis: Modern tendencies in the development of diesel engines include the operation of the system for injecting diesel fuel at pressures higher than 100 MPa. Knowing the characteristics of liquid fuels such as speed of sound, bulk modulus and density depending on pressure, is important for predicting the behavior of fuel injection systems for diesel engines and optimization of the same. The paper presents an original method and apparatus (device) for determining the speed of sound and density of fluids depending on the pressures. With this method, values of these characteristics for rapeseed oil, biodiesel and conventional diesel fuel at pressures up to 160 MPa are determined. The method is non-destructive, it can also be applied to higher pressures than 160 MPa, as well as other liquid fluids that are used at high pressure - hydraulic oil, for example.
Ključne besede: biodiesel, rapeseed oil, speed of sound, bulk modulus, density, high pressure
Objavljeno v DKUM: 07.07.2017; Ogledov: 1258; Prenosov: 363
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34. Partial pressure of end-tidal carbon dioxide successful predicts cardiopulmonary resuscitation in the field - a prospective observational studyMiran Kolar, Miljenko Križmarić, Petra Klemen, Štefek Grmec, 2008, izvirni znanstveni članek Opis: Introduction: The prognosis among patients who suffer out-of-hospital cardiac arrest is poor. Higher survival rates have been observed only in patients with ventricular fibrillation who were fortunate enough to have basic and advanced life support initiated early after cardiac arrest. The ability to predict outcomes of cardiac arrest would be useful for resuscitation. Changes in expired end-tidal carbon dioxide levels during cardiopulmonary resuscitation may be a useful non-invasive predictor of successful resuscitation and survival from cardiac arrest, and help in the termination of cardiopulmonary resuscitation in the field.
Methods: This is a prospective observational study of 737 cases of victims who suffered sudden out-of-hospital cardiac arrest. The patients were intubated and the measurements of end-tidal carbon dioxide were performed. Data according to the Utstein criteria, demographic information, medical data and partial pressure of end-tidal carbon dioxide (petCO2) values were collected for each patient in cardiac arrest, by the emergency physician. We presumed that an end-tidal carbon dioxide level of 1.9 kPa (14.3 mmHg) or more after 20 minutes of standard advanced cardiac life support would predict restoration of spontaneous circulation (ROSC).
Results: Partial pressure of end-tidal carbon dioxide after 20 minutes of advanced life support averaged 0.92+/- 0.29 kPa (6.9mmHg +/- 2.2 mmHg) in patients who did not have ROSC and 4.36 +/-1.11 kPa (32.8 mmHg +/- 9.1 mmHg) in those who did (p<0,001). End-tidal carbon dioxide values of 1.9 kPa (14.3 mmHg) or less discriminated between the 402 patients with ROSC and 335 patients without ROSC. When a 20-minute end-tidal carbon dioxide value of 1.9 kPa (14.3 mmHg) or less was used as a screening test to predict ROSC, the sensitivity, specificity, positive predictive value, and negative predictive value were all 100 percent.
Conclusions: Measurements of end-tidal carbon dioxide levels of more than 1.9 kPa (14.3 mmHg) after 20 minutes should be used to accurately predict ROSC. End-tidal carbon dioxide levels should be monitored during cardiopulmonary resuscitation and considered a useful prognostic value for determining the outcome of resuscitative efforts and termination of cardio-pulmonary resuscitation in the field.
Ključne besede: out-of-hospital cardiac arrest, cardiopulmonary resuscitation, CPR, partial pressure of end-tidal carbon dioxide, PetCO2
Objavljeno v DKUM: 29.06.2017; Ogledov: 1968; Prenosov: 171
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35. Process design for flavour encapsulation into carbohydrate melts using high pressure homogenizerUrban Feguš, 2016, doktorska disertacija Opis: The aim of the research project was to develop encapsulated flavourings suitable for the final food applications such as chewing gums, instant teas and confectionary products. For this purpose that water soluble particles with particle size distribution 400-1500 µm and flavour loading up to 30 wt. % should be developed.
In order to produce encapsulates with desired physical properties research work was divided into three project phases. The scope of Phase 1 was to select suitable carrier materials and to perform preliminary experiments using laboratory scale process set-up. Different carbohydrates (maltodextrin, simple sugars and sugar syrups) were tested and selected according to their physical characteristics and their process performance. Afterwards preliminary experiments were performed by using laboratory scale set-up. Observations were used for defining process parameters for the design and construction of the pilot plant.
Phase 2 covered design and development of the pilot plant for flavour encapsulation while In Phase 3 different process parameters were tested. In the first part influence of the process parameters (processing temperature, homogenizing pressure, mass flow, temperature of the cooling media, retention time in the cooling media and ratio between cooling media and product) on the encapsulation efficiency was investigated. Experiments were performed according to the Design of Experiments (DoE) analysed using analysis of covariance (ANCOVA). Process temperature, pressure at second homogenization step and residence time in cooling media had significant effect on the encapsulation efficiency while pressure at first homogenizing step, mass flow, temperature of the cooling media and ratio between product and cooling media were nonsignificant. Increase in the process temperature (T>130 °C) resulted in paste-like product with increased moisture content up to 13,3 wt.% which was not suitable for further processing. On the other hand samples processed at lower temperature (T<130 °C) resulted in crystalline-like structure with low moisture content. Low flavour retention (<4,5 %) was observed within all samples. Results obtained by ANCOVA were used for further optimization of the process parameters (e.g. homogenizing pressure and the retention time in the cooling media). Maximum flavour load of 3,5 % was observed regardless the homogenizing pressure. Low encapsulation efficiency (η<35 %) was related to poor emulsion stability. Additionally, effect of expansion pressure on the particle size distribution was investigated. It was observed that particle size distribution was little affected by varying expansion pressure (nozzle diameter). All formulation showed similar particle size distribution in-between 40-440 µm. In the last section effect of the emulsifier, flavouring properties and carrier were studied. Emulsifiers with different HLB values were tested in order to increase encapsulation efficiency. Flavourings were selected on the basis of their composition (polarity and volatility). For the encapsulation experiments mentha arvensis oil, orange oil and compounded pineapple flavouring were used. As an alternative carrier material erythritol was used. Addition of emulsifier improved flavour retention for samples containing mentha arvensis oil, while no affect was observed within samples containing orange oil and pineapple flavouring due to the volatility and diffusion of active compounds from matrix to surrounding environment.
Ključne besede: encapsulation, carbohydrate melts, flavouring, high pressure homogenizer
Objavljeno v DKUM: 25.07.2016; Ogledov: 2378; Prenosov: 155
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36. O kontaktni leči Sensor Triggerfish : dosedanje izkušnjeChristoph Faschinger, Eva Faschinger, Sarah Krainz, Georg Mossböck, 2012, pregledni znanstveni članek Opis: Namen prispevka je prikazati novo napravo, senzorsko kontaktno lečo Triggerfish, za stalno merjenje intraokularnega pritiska, dosedanje izkušnje in oceniti možnost njene uporabe. Prikazane so do sedaj objavljene raziskave na to temo. Naprava se dobro prenaša, je varna, preiskava se lahko ponovi. Do sedaj je še premalo podatkov, da bi jo lahko uporabljali že v vsakodnevni praksi pri zdravljenju glavkoma. Potrebne bodo še dodatne raziskave.
Ključne besede: intraocular pressure, sensor contact lens, safety, tolerability, reproducibility, validity
Objavljeno v DKUM: 30.12.2015; Ogledov: 1210; Prenosov: 57
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37. Analiza cevovodov v NEK d.o.o.Iztok Deržanič, 2015, magistrsko delo Opis: Magistrsko delo se nanaša na področje načrtovanja in analiziranja cevovodnih sistemov v podjetju Nuklearna elektrarna Krško (NEK), d. o. o. Prikazan je potek načrtovanja novega sistema odmuljevanja v zgradbi bistvene oskrbne vode (ESW), ki bi nadgradil obstoječi način odstranjevanja usedlin s pomočjo potapljača. Sistem bistvene oskrbe vode ima pomembno vlogo pri zagotavljanju varnosti, saj je njegov primarni namen odvajanje toplote iz sistema hlajenja komponent. Z vgradnjo novega sistema bi tako varnost delovanja elektrarne še povišali. Analiza cevovoda je izvedena s pomočjo računalniškega programa Bentley AutoPIPE, ki je certificirano orodje za izdelavo analiz v jedrski industriji. Za analizo je izdelan model, ki temelji na zahtevah standardov ASME B31.1 in ASME BPVC, sekcija III, ki se v NEK uporabljata za načrtovanje novih cevovodnih sistemov. Prikazani in primerjani so rezultati analiz po posameznem standardu. V splošnem pa predstavljeno delo zajema opis podjetja in nekaj splošnih informacij o njegovem delovanju, predstavljeni so standardi in pripadajoča zakonodaja, opisana in izvedena pa je tudi zgoraj omenjena analiza.
Ključne besede: Nuklearna elektrarna Krško, preračun cevovodov, ASME B31.1, ASME Boiler and Pressure Vessel Code
Objavljeno v DKUM: 28.10.2015; Ogledov: 1774; Prenosov: 257
Celotno besedilo (3,12 MB) |
38. Konstruiranje, gradnja in umerjanje SHPB preizkuševališčaLuka Adanič, 2015, diplomsko delo Opis: Split Hopkinson Pressure Bar test omogoča določanje mehanskih lastnosti materialov pri hitrostih specifične deformacije od 10^2 do 8 x 10^3 s-1. Pri tako visokih hitrostih specifičnih deformacij, kovine lahko prenesejo višje obremenitve, kot pri statičnem obremenjevanju, ki pa jih vzdržijo zgolj kratek čas. Namen diplomskega dela je konstruiranje in izdelava kompletne tehnične dokumentacije, sestava ter umerjanje novega Split Hopkinson Pressure Bar preizkuševališča na Fakulteti za strojništvo Univerze v Mariboru. Geometrija in sestavni elementi preizkuševališča so bili določeni na podlagi izkustvenih priporočil v literaturi. Vrednotenje rezultatov umerjanja udarnega telesa je temeljilo na primerjavi s teoretično izračunanimi podatki.
Ključne besede: Split Hopkinson Pressure Bar preizkuševališče, Dinamično preizkušanje materialov, Konstruiranje.
Objavljeno v DKUM: 27.10.2015; Ogledov: 2392; Prenosov: 289
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39. Determination of pressure losses in hydraulic pipeline systems by considering temperature and pressureVladimir Savić, Darko Knežević, Darko Lovrec, Mitar Jocanović, Velibor Karanović, 2009, izvirni znanstveni članek Opis: Generally accepted methods for calculating pressure losses within flat pipelines, as presented in literature and used in praxis, are based on the Reynolds number, which considers the viscosity and density of fluid, internal pipe friction coefficient, pipe geometry, and oil circulation velocity. Such an approach contains serious inconsequentiality. Namely, only nominal values for viscosity and density are considered in the calculation, which differs substantially from real conditions. It often leads to inaccurate calculations of pressure losses. A numerical model has been developed within the work prescribed in the paper, which takes into account actual changes in density and viscosity under the current oil pressure and temperature in order to overcome the above weaknesses of standard calculation procedures. Such an approach is novel and provides new capacity for an accurate pressure drop analysis of advanced hydraulic systems.
Ključne besede: tlačne izgube, ravne cevi, viskoznost, gostota, temperatura, pressure loss, float pipelines, viscosity, density, temeprature
Objavljeno v DKUM: 11.08.2015; Ogledov: 1478; Prenosov: 77
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40. Gonilni mehanizmi kavitacijskega vrtinca v vstopnem vodu radialne črpalkeAndrej Predin, Ignacijo Biluš, 2001, izvirni znanstveni članek Opis: V prispevku je podana analiza gonilnih mehanizmov in tlačnih utripanj povezanih s pojavom kavitacijskega vrtinca v vstopnem vodu radialne črpalke. Kavitacijski vrtinec je rezultat interakcije številnih zapletenih sekundarnih tokovnih pojavov, ki nastopijo kot posledica obratovanja s podoptimalnimi pretoki v kavitacijskem obratovalnem režimu. Izvedene in predstavljene so tudi meritve tlačnih utripanj v vstopnem vodu radialne črpalke na različnih razdaljah od rotorskega ustja na sklenjeni kavitacijski merilni progi. Meritve so izvedene pri različnih vrtilnih hitrostih in različnih tlakih nad spodnjo vodno gladino. Podani so tudi rezultat frekvenčne analize posnetih tlačnih utripanj.
Ključne besede: radial pumps, cavitation, swirl, operating regime, pressure pulsation measurements
Objavljeno v DKUM: 10.07.2015; Ogledov: 1400; Prenosov: 27
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