Научни радови / Scientific papers

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A comprehensive assessment of medical schools in Bosnia and Herzegovina
(Wiley, 2006) Šimunović, Vladimir J.; Sonntag, Hans-Gu¨nther; Hren, Darko; Dørup, Jens; Krivokuća, Zdenka; Bokonjić, Dejan; Verhaaren, Henry; Horsch, Axel; Mimica, Mladen; Vojniković, Benjamin; Selesković, Hajrija; Marz, Richard; Marušić, Ana; Marušić, Matko
OBJECTIVES To perform internal and external evaluations of all 5 medical schools in Bosnia and Herzegovina against international standards. METHODS We carried out a 2-stage survey study using the same 5-point Likert scale for internal and external evaluations of 5 medical schools in Bosnia and Herzegovina (Banja Luka, Foča ⁄East Sarajevo, Mostar, Sarajevo and Tuzla). Participants consisted of managerial staff, teaching staff and students of medical schools, and external expert assessors. Main outcome measures included scores on internal and external evaluation forms for 10 items concerning aspects of school curriculum and functioning: "School mission and objectives"; "Curriculum"; "Management"; "Staff"; "Students"; "Facilities and technology"; "Financial issues"; "International relationships"; "Internal quality assurance", and "Development plans". RESULTS During internal assessment, schools consistently either overrated their overall functioning (Foča ⁄ East Sarajevo, Mostar and Tuzla) or markedly overrated or underrated their performance on individual items on the survey (Banja Luka and Sarajevo). Scores for internal assessment differed from those for external assessment. These differences were not consistent, except for the sections "School mission and objectives", "Curriculum" and "Development plans", which were consistently overrated in the internal assessments. External assessments was more positive than internal assessments on "Students" and "Facilities and technology" in 3 of 5 schools. CONCLUSIONS This assessment exercise in 5 medical schools showed that constructive and structured evaluation of medical education is possible, even in complex and unfavourable conditions. Medical schools in Bosnia and Herzegovina have successfully formed a national consortium for formal collaboration in curriculum development and reform.
The Effect of Potassium Channel Opener Pinacidil on the Non-Pregnant Rat Uterus
(Wiley, 2007) Novakovic, Radmila; Milovanovic, Slobodan; Protic, Dragana; Djokic, Jelena; Heinle, Helmut; Gojkovic-Bukarica, Ljiljana
The effects of the K+ channel opener, pinacidil on the spontaneous rhythmic contractions and contractions provoked by electrical field stimulation (50 Hz) or by oxytocin were investigated in the isolated uterus of the non-pregnant rat in oestrus. Pinacidil produced more potent inhibition of oxytocin-elicited contractions than of spontaneous rhythmic contractions or electrical field stimulation-induced contractions. Glibenclamide, a selective blocker of adenosine triphosphate (ATP)-sensitive K+ (KATP) channels, antagonized the pinacidil-induced inhibition of contractions elicited by oxytocin in a competitive manner. However, the pinacidil-induced inhibition of electrical field stimulation-elicited contractions and spontaneous rhythmic contractions was antagonized non-competitively by glibenclamide. In the uterine strips precontracted with 80 mM K+, the pinacidil-induced maximal relaxation was not affected. The present data show that pinacidil exhibits potent relaxant properties in the rat non-pregnant uterus in oestrus and therefore should be taken into account as a possible agent for treatment of dysmenorrhoea. Based on glibenclamide affinity, it appears that the inhibitory response to pinacidil involves KATP channels. We need further investigations to explain why the interaction between glibenclamide and pinacidil in this experimental model depends on the nature of contractions. The ability of pinacidil to completely relax the rat non-pregnant uterus pre-contracted with K+ -rich solution suggests that K+ channel-independent mechanism(s) also play a part in its relaxant effect.
Morphology and growth of electrodeposited silver powder particles
(Elsevier, 2007) Maksimović, V. M.; Pavlović, Lj. J.; Tomić, M. V.; Jović, V. D.
The effect of overpotential pulsing and periodic current reversal on the morphology of silver powders was investigated using a scanning electron microscope (SEM). It is shown that the profile of pulses or current reversal determines the micromorphology of the electrodeposited silver particles. Generally, three forms of silver were detected: (1) dendrites, (2) equiaxial crystals (independent and/or agglomerates) and (3) rods. The shape of particle seems to be the result of an interplay between the surface energy and growth kinetics.
Registration and analysis of bioelectric activity of sensory-motor cortex during the electrical stimulation of nucleus caudate in rats
(Association of Basic Medical Sciences Federation of Bosnia and Herzegovina, 2007) Medenica-Milanović, Snežana; Ristić, Siniša; Turuntaš, Vladimir; Mirić, Mirjana; Kulić, Milan
Background and purpose: The caudate circuit takes part in cognitive control of motor activity. The purpose of the present work was registration and analysis of basic bioelectrical activity of ventral and dorsal sensory-motor cortex and nucleus caudate, study of the changes in EEG after nucleus caudate electrical stimulation and to identify of threshold level of electrical stimuli responsible for changes of electrical activity in registered brain area. Materials and methods: We used 28 albino Wistar rat of both genders. After the animal fixation on stereotaxic apparatus to dry bone, the places for electrode fixation were marked. Two days after the electrodes had been implanted an EEG was registered so that the animals would adjust to the conditions and so they would repair the tissue reactions. EEG was registered with bipolar electrodes with ten-channeled apparatus. For first half an hour spontaneous activity of the brain was registered, and after that the head of nucleus caudate was stimulated with altered impulses of various voltages, frequency and duration. Results and conclusions: Threshold values of electric stimulus intensity from 3 to 5 V, frequency from 3 to 5 Hz, duration from 3 to 5 ms, by stimulation the head of nucleus caudate of rat, lead to the change of basal bioelectric activity of cerebrum. Th e change of bioelectric activity is firstly recorded in equilateral cortex, and with the higher intensity of the stimulus the changes overtake the contra lateral cortex.
Prevalence of Antibodies to Rickettsiae in Different Regions of Serbia
(Mary Ann Liebert Inc., 2008) SAMARDZIC, SVETOMIR; MARINKOVIC, TATJANA; MARINKOVIC, DRAGAN; DJURICIC, BOSILJKA; RISTANOVIC, ELIZABETA; SIMOVIC, TATJANA; LAKO, BRANISLAV; VUKOV, BILJANA; BOZOVIC, BOZOVIC; GLIGIC, ANA
We assayed the presence of antibodies specific for Rickettsia typhi, R. akari, and R. conorii in sera of persons from several localities in Serbia with different geographic, climatic, and lifestyle characteristics. Sera from 140 patients with unclear clinical symptoms and 273 healthy persons were tested for the presence of rickettsiae-specific antibodies by indirect immunofluorescence assay. In this study, for the first time we detected the presence of rickettsiae from the spotted fever group in Serbia. We detected the presence of antibodies against R. conorii in the samples from all tested localities. The proportion of positive cases was low in the plain agricultural areas but reached up to 23% in the mountain areas. We also observed a significant number of cases positive for antibodies against R. akari. Antibodies specific for the antigens of R. typhi were detected in only 2 samples from the municipality of Pec (Kosovo region). These findings contribute to the prevalence of Rickettsia species in Southeast Europe. Our study also revealed a dramatic lack of awareness of rickettsioses among medical personnel and pointed to the need for urgent measures that would help improve the current situation in the region.
INFLUENCE OF PRESSURE AND TIME ON EXTRACTION PROCESS USING SUPERCRITICAL CO2
(Technical Faculty in Bor, Serbia, 2008) Mićić, V.; Lepojević, Ž.; Mandić, B.; Jotanović, M.; Tadić, G.; Tolić, A.
The supercritical fluid extraction (SFE) by carbon dioxide (CO2) of Salvia officinalis L. was investigated. SFE by CO2 was performed at different pressure (80, 100, 150, 200 and 300 bar) and constant temperature of 40ºC (all other extraction conditions, such are flow rate, particle diameter of Salvia officinalis, extraction time were kept constant. The GC – MS method was used for determination of qualitative and quantitative composition of obtained extracts and essential oils.
Lead and silver extraction from waste cake from hydrometallurgical zinc production
(Serbian Chemical Society, 2008) STANOJEVIĆ, DUŠAN, D.; RAJKOVIĆ, MILOŠ, B.; TOŠKOVIĆ, DRAGAN, V.; TOMIĆ, MILANA, A.
This paper presents the experimental results of the extraction of lead and silver from a lead-silver waste cake obtained in the process of hydrometallurgical zinc production. While controlling the pH value, the lead-silver cake was leached at a temperature close to boiling point in different concentrations of aqueous calcium chloride solutions. The experiments were performed applying different ratios between the mass of cake and the volume of the leaching agent under different durations of the process. It was concluded that at the optimal process parameters (pH 2.0-2.5; CaCl2 concentration, 3.6 mol dm-3; temperature, 95°C; solid/liquid ratio, 1:5), the leaching efficiency of lead and silver could reach the approximate value of 94 %. Applying the same optimal process parameters, the method was applied to the leaching of a lead-silver cake in a magnesium chloride solution, but with significantly lower efficiencies. The results show that leaching of lead and silver in a calcium chloride solution could be a prospective method for increasing the recovery of lead and silver during hydrometallurgical zinc production.
EFFECT OF PROTAMINE SULFATE ON THE ISOLATED MESENTERIC ARTERIES OF NORMOTENSIVE AND SPONTANEOUSLY HYPERTENSIVE RATS
(Institute for Biological Research, Serbia, 2008) OREŠČANIN-DUŠIĆ, ZORANA; MILOVANOVIĆ, S.; SPASIĆ, M.; RADOJIČIĆ, R.; BLAGOJEVIĆ, D.
We tested the relaxant effect of increased protamine sulfate (PS) amounts (10, 20, 50, 100 and 150 μg/ml) on the isolated mesenteric arteries of normotensive and spontaneously hypertensive (SH) rats, with or without endothelium. PS caused concentration-dependent relaxation of isolated mesenteric arteries in both types of rats. The relaxation effect of PS was lower in SH rats than in normotensive ones. Our results indicate that the vascular smooth muscles play a significant role in PS-mediated relaxation.
TMD chronic pain and masseter silent period in psychiatric patients on antidepressive therapy
(Wiley, 2008) IVKOVIC, N.; MLADENOVIC, I.; PETKOVIC, S.; STOJIC, D.
The aim of the study was to evaluate the long-term effects of antidepressive therapy on chronic pain and related disability, and masseter silent period in psychiatric depressive patients with temporomandibular disorders (TMD). The study included hospitalized psychiatric depressive patients on antidepressive therapy protocol (tetracyclic antidepressant-maprotiline and anxiolyticdiazepam) (n = 30) and non-psychiatric patients seeking prosthodontic treatment (control group, n = 38). TMD were diagnosed by Research Diagnostic Criteria for temporomandibular disorders proposed by Dworkin and LeResche. The surface electromyography was recorded from left and right masseter muscles and masseter inhibitory reflex (masseter silent period) was recorded after mechanical stimulation. The incidence of TMD appearance was very similar, of aproximately 40% in both group of patients. The results of the study also indicated a higher prevalence of joint related TMD, a lower prevalence of muscular subtype of TMD and a lower grade of chronic pain and related disability in the psychiatric group of patients on antidepressive therapy in comparison with findings in the control group. In the patients on antidepressive therapy with TMD masseter silent period was not prolonged, while in the control group of patients with TMD the prolongation of the silent period was observed. The study provided evidence that long-term, combined therapy (maprotiline and diazepam) in psychiatric depressive patients significantly modulated signs and symptoms of TMD in comparison with the control group.
IR Resonant Absorption in Molecular Nanofilms
(Polish Academy of Sciences, 2009) Pelemiš, S. S.; Šetrajcic, J. P.; Markoski, B.; Delic, N.V.; Vucenovic, S. M.; Mirjanic, D. Lj.
The paper presents a theoretical research of changes of optical properties of various nanofilm molecular crystals which are caused by the presence of two parallel and close borders. We used combined analytical-numerical calculation to find the allowed energy states of excitons and their spatial distribution (per layers) along the axis perpendicular to surface planes. We determined permittivity for the observed models of these ultrathin dielectric films and explored the influence of boundary parameters on the occurrence of discrete (per frequencies) and selective (per layers) absorption. The conditions for occurrence of smallest number of resonant absorption lines have been found and their localization has been defined.
ANALIZA KRISTALIZACIJE NATRIJUM HLORIDA IZ RASTVORA U VAKUUM KRISTALIZERU SA RECIRKULACIJOM SUSPENZIJE
(Association of the Chemical Engineers of Serbia, 2009) JOTANOVIĆ, MILOVAN B.; SULJKANOVIĆ, MIDHAT S.
U ovom radu je izvedena analiza kristalizacije NaCl iz vodenih rastvora u vakuum kristalizerima sa recirkulacijom suspenzije. Vakuum kristalizer kao objekat projektovanja prikazan je kao skup osnovnih aparativno-procesnih jedinica. Aparativno-procesna jedinica je krupni sastavni dio aparata u kojoj se odvija niz fizičko-hemijskih pojava koje zajedno čine jedinični proces kristalizacije. Analizom teorijskih postavki, literaturnih podataka i rezultata istraživanja opisana je svaka aparativno-procesna jedinica odgovarajućim sistemom matematičkih funkcija. Ovaj rad je doprinos stvaranju jedinstvene metodologije projektovanja vakuum kristalizera.
Simvastatin and Indomethacin Have Similar Anti-Inflammatory Activity in a Rat Model of Acute Local Inflammation
(Wiley, 2009) Nežić, Lana; Škrbić, Ranko; Dobrić, Silva; Stojiljković, Miloš P.; Jaćević, Vesna; Stoisavljević Šatara, Svjetlana; Milovanović, Zoran A.; Stojaković, Nataša
Statins, such as simvastatin, lower circulating cholesterol levels and are widely prescribed for the treatment of hypercholesterolaemia. Several studies have shown unexpected effects of statins on inflammation. We studied the anti-inflammatory effect of simvastatin using a standard model of an acute local inflammation, the carrageenan-induced footpad oedema. Experimental groups (n=6–8) were given simvastatin in a dose range 5–30 mg/kg, indomethacin 1–8 mg/kg and methylcellulose (control)per os. Footpad volume was measured with a plethysmograph and compared with the pre-injection volume of the same paw. Swelling (in microlitres) was then calculated, and in drug-treated animals, per cent inhibition was derived through comparison with the control group. Histopathological examination of the skin biopsies was performed to examine severity of paw skin lesions and to confirm the simvastatin-induced inhibition of acute inflammation. Both simvastatin and indomethacin administered orally, 1 hr before carrageenan injection, significantly reduced the extent of footpad oedema. Indomethacin dose-dependently blocked the swelling; the maximal effect was obtained with 8 mg/kg by 48.3% (P<0.05). Simvastatin produced a comparable anti-inflammatory activity at a dose of 5 mg/kg (32%), while 10 and 30 mg/kg caused a 47.6% and 51.7% reduction, respectively, with the maximal effect observed at 20 mg/kg by 57.2% (P<0.05). The comparison of the ED50 of these agents on molar basis showed equipotent anti-inflammatory activity. Histopathological examination of the footpad skin biopsies revealed that simvastatin, dose-dependently and comparablly to indomethacin, reduced polymorphonuclear leucocyte infiltration. These data support the hypothesis that simvastatin has an acute anti-inflammatory activity.
Hydrogen peroxide affects contractile activity and anti-oxidant enzymes in rat uterus
(Wiley, 2009) Appiah, I.; Milovanovic, S.; Radojicic, R.; Nikolic-Kokic, A.; Orescanin-Dusic, Z.; Slavic. M.; Trbojevic, S.; Skrbic, R.; Spasic, M. B.; Blagojevic, D.
Background and purpose: The effects of hydrogen peroxide (H2O2) on uterine smooth muscle are not well studied. We have investigated the effect and the mechanism of action of exogenous hydrogen peroxide on rat uteri contractile activity [spontaneous and calcium ion (Ca2+)-induced] and the effect of such treatment on anti-oxidative enzyme activities. Experimental approach: Uteri were isolated from virgin Wistar rats and suspended in an organ bath. Uteri were allowed to contract spontaneously or in the presence of Ca2+ (6 mM) and treated with H2O2 (2 mM–3 mM) over 2 h. Anti-oxidative enzyme activities (manganese superoxide dismutase-MnSOD, copper-zinc superoxide dismutase-CuZnSOD, catalase-CAT, glutathione peroxidase-GSHPx and glutathione reductase-GR) in H2O2-treated uteri were compared with those in uteri immediately frozen after isolation or undergoing spontaneous or Ca2+-induced contractions, without treatment with H2O2. The effect of inhibitors (propranolol, methylene blue, L-NAME, tetraethylamonium, glibenclamide and 4-aminopyridine) on H2O2-mediated relaxation was explored. Key results: H2O2 caused concentration-dependent relaxation of both spontaneous and Ca2+-induced uterine contractions. After H2O2 treatment, GSHPx and MnSOD activities were increased, while CuZnSOD and GR (In Ca2+-induced rat uteri) were decreased. Nw-nitro-L-arginine methyl ester antagonized the effect of H2O2 on Ca2+-induced contractions. H2O2-induced relaxation was not affected by propranolol, potentiated by methylene blue and antagonized by tetraethylamonium, 4-aminopyridine and glibenclamide, with the last compound being the least effective. Conclusions and implications: H2O2 induced dose-dependent relaxation of isolated rat uteri mainly via changes in voltagedependent potassium channels. Decreasing generation of reactive oxygen species by stimulation of anti-oxidative pathways may lead to new approaches to the management of dysfunctional uteri.
Effect of simvastatin on proinflammatory cytokines production during lipopolysaccharide-induced inflammation in rats
(Slovak Academy of Sciences, 2009) Nežić, Lana; Škrbić, Ranko; Dobrić, Silva; Stojiljković, Miloš P.; Šatara, Svjetlana S.; Milovanović, Zoran A.; Stojaković, Nataša
The effect of simvastatin applied in a short-term pretreatment on proinflammatory cytokines production in acute systemic inflammation induced by endotoxin – lipopolysaccharide (LPS) in rats was investigated. Both LPS and simvastatin doses were established in separate experiments in which increasing doses of both compounds were given to obtain the LD50 LPS and the maximally protective dose of simvastatin against LD50 LPS. To determine the anti-inflammatory effect, simvastatin was given orally for 5 days, followed by a single intraperitoneal non-lethal dose of LPS (0.25 LD50). Plasma concentrations of tumor necrosis factor alpha (TNF-α), interleukin (IL)-1β and IL-6 were measured by enzyme-linked immunosorbent assay. The acute i.p. LD50 LPS amounted to 22.15 mg/kg. Simvastatin of 20 mg/kg p.o. was maximally protective against LD50 LPS, and this dose was used for studying its effects on LPS-induced cytokines production. Cytokines concentrations were significantly increased upon challenge of non-lethal dose of LPS. The peak levels of TNF-α and IL-1β were significantly suppressed by simvastatin, compared to control rats only treated with dimethylsulfoxide before LPS. In contrast, simvastatin did not affect IL-6 levels at all timepoints. Simvastatin pretreatment given orally produced acute anti-inflammatory effects by inhibiting TNF-α and IL-1β, but no IL-6 production.
Effects of protamine sulphate on spontaneous and calcium-induced contractile activity in the rat uterus are potassium channels-mediated
(Slovak Academy of Sciences, 2009) Oreščanin-Dušić, Zorana; Milovanović, Slobodan; Radojičić, Ratko; Nikolić-Kokić, Aleksandra; Appiah, Isabella; Slavić, Marija; Čutura, Neđo; Trbojević, Stevan; Spasić, Mihajlo; Blagojević, Duško
Protamine sulphate (PS) effect on spontaneous and calcium-induced rhythmic contractions of isolated virgin rat uteri was studied. PS caused dose-dependent relaxation of both types of contractions (two-way ANOVA, significant dose effects). Pretreatment with NG-nitro-L-arginine methyl ester (L-NAME; 10–5 mol/l), methylene blue (MB; 0.9 × 10–6 mol/l) or propranolol (1.7 × 10–5 mol/l) enhanced PS-mediated uterine muscle relaxation of spontaneous contractions. Dosedependent relaxation of spontaneous active isolated rat uterus with PS was lower in uteri pretreated with single dose of tetraethylammonium (TEA; 6 × 10–3 mol/l), glibenclamide (2 × 10–6 mol/l) and 4-aminopyridine (4-AP; 10–3 mol/l). Calcium-induced activity of the isolated rat uterus pretreated with the same concentration of L-NAME, MB, or propranolol modified the kinetic of PS-induced relaxation without changes in EC50 values. Pre-treatment with glibenclamide, TEA and 4-AP significantly reduce PS relaxing effect of calcium-induced activity and according to EC50 values the order of magnitude was glibenclamide > TEA > 4-AP. PS is mixture of polyamines and may activate different signal-transduction pathways. Our results cleary demonstrate that in uterine smooth muscle PS act dominantly through potassium chanels and marginaly through β-adrenergic receptos or nitric oxide-dependent pathways.
Selective Absorption in Twolayered Optic Films
(American Scientific Publishers, 2009) Pelemiš, S. S.; Šetrajčić, J. P.; Markoski, B. S.; Delić, N. V.; Vučenović, S. M.
This paper summarizes theoretical investigations of changes in optical properties of smallest symmetrical nanofilm-molecular crystals due to the presence of boundaries and different boundary parameters. Using analytic and numerical calculations, the energy spectrum of excitons was found and relative permittivity of these ultrathin dielectric films was determined. The influence of boundary parameters on the occurrence of discrete (by parameters)and selective (by planes)absor ption of external electromagnetic radiation was also investigated. Because of the symmetric conditions on film boundaries, double resonant peaks appear.
Partial root drying: New approach for potato irrigation
(Cereal Research Non-Profit Company, Hungary, 2009) Broćić, Zoran; Jovanović, Zorica; Stikić, Radmila; Vucelić Radović, Biljana; Mojević, Mirjana
Drought is one of the most common environmental stresses that may limit agricultural production worldwide. To overcome the drought problems efficiently, an innovative sustainable irrigation technique called Partial Root Drying (PRD) was proposed. PRD is an irrigation technique where half of the root zone is irrigated while the other half is allowed to dry out. The treatment is then reversed, allowing the previously well-watered side of the root system to dry down while fully irrigating the previously dry side. The PRD benefit is in the terms of improved water-use efficiency (IWUE). The aim of presented work was to compare the effects of PRD with full irrigation (FI) on yield of field-grown potato, and to test for effects of PRD on IWUE, tuber yield and quality. The experiments were conducted during 2007 and 2008 seasons. In PRD treatment in 2007 season 70% of the irrigation water in FI was applied to one half of the root system, although in 2008 season PRD was applied dynamically (by replacing 70% PRD with 50% PRD in last two weeks). Irrigation scheduling was based on evapotranspiration and soil water data (measured by TDR). Experimental results for both seasons confirmed that with PRD irrigation it is possible to increase IWUE, save water for irrigation and increase quality of potato tuber (starch content).
Diethyldithiocarbamate potentiates the effects of protamine sulphate in the isolated rat uterus
(Taylor & Francis, 2009) Oreščanin-Dusić, Zorana; Milovanović, Slobodan; Blagojević, Duško; Nikolić-Kokić, Aleksandra; Radojičić, Ratko; Spasojević, Ivan; Spasić, Mihajlo
Protamine sulphate causes potassium ion channel-mediated relaxation of spontaneous and calcium ion-induced contractions of the isolated rat uterus. Diethyldithiocarbamate (DDC) potentiated the effect of protamine sulphate. A mechanism for DDC’s action was postulated on the basis of its interactions with divalent iron ions and Cu,Zn-SOD. DDC chelates divalent iron ions creating DDC-iron (Fe-DDC) complexes. Fe-DDC forms stable NO-Fe-DDC2 complexes by NO scavenging and de-nitrosylation processes, which in combination with DDC (5 mM) provoke inhibition of Cu,Zn-SOD resulting in specific oxidative conditions culminating in potassium ion channel opening, membrane hyperpolarisation, inhibition of calcium ion influx and subsequent muscle relaxation. As Fe-DDC and NO-Fe-DDC2 complexes exclude divalent iron ions from participating in the hydroxyl radical generating Fenton reaction, DDC can also prevent iron-related pathophysiological manifestations. Such permissive roles of DDC open the possibility for application of its pharmacological form (disulfiram) to a wider spectrum of pathophysiological conditions related to smooth muscles.
Adaption and application of the Green function method to research on molecular ultrathin film optical properties
(IOP Publishing, 2009) Setrajčić, Jovan P; Ilić, Dušan I.; Markoski, Branko; Setrajčić, Ana J.; Vučenović, Siniša M; Mirjanić, Dragoljub Lj.; Škipina, Blanka; Pelemiš, Svetlana
Interest in the study of the exciton subsystem in crystalline structures (in this case nanostructures, i.e. thin films) occurred because dielectric, optical, photoelectric and other properties of materials can be explained by means of it. The basic question to be solved concerning theoretical research into the spatially strongly bounded structures is the inability to apply the standard mathematical tools: differential equations and Fourier analysis. In this paper, it is shown how the Green function method can also be efficiently applied to crystalline samples so constrained that quantum size effects play a significant role on them. For the purpose of exemplification of this method’s application, we shall consider a molecular crystal of simple cubic structure: spatially unbounded (bulk) and strongly bounded alongside one direction (ultrathin film).
JEDAN MODEL ZA ANALIZU I PRORAČUN POUZDANOSTI PRIMENJEN NA PRIMERU IZ HEMIJSKE INDUSTRIJE
(Association of the Chemical Engineers of Serbia, 2010) PEJOVIĆ, BRANKO B.; TADIĆ, GORAN S.; JOTANOVIĆ, MILOVAN B.; TOMIĆ, MILORAD V.; MIĆIĆ, VLADAN M.
Predmet rada se odnosi na projektovanje pouzdanosti kod procesa polimerizacije koji se odvijaju u reaktorima jedne hemijske industrije. Kroz razvijeni model, određene su karakteristike i pokazatelji pouzdanosti, a time i utvrđeni osnovni faktora koji doprinose lošem odvijanju procesa. S obzirom na mogućnost njihove kontrole, mogu se smanjiti očekivani gubici, i na taj način postići kvalitetnija proizvodnja. Za analizu i proračun pouzdanosti, primenjena je deduktivna metoda zasnovana na konstruisanju šeme stabla otkaza sistema na bazi induktivnog zaključivanja. Pri ovome korišćeni su standardizovani logički simboli, odnosno pravila Bulove algebre i matematičke logike. Rezultati rada kroz kvantitativnu i kvalitativnu analizu pouzdanosti posmatranog procesa, omogućavaju dobijanje potpunih informacija o verovatnoći neželjenog događaja procesa i donošenje objektivnih odluka i alternativnih rešenja.

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