Hybridization in Several Polycyclic Alkanes by the Method of Maximum Overlap

The hybridization · in spiropentane, nortricyclene, cu bane, tricyclo( l.1.0.02,4)butane, bicyclo(l.1.l)pentane, and tetracyclo(3,3.l 2, 8.04,6) nonane has been determined by the method of maximum overlap. For the atomic functions Clementi Orbitals (ref. 1) have been assumed. A comparison between these results and those, obtained previously, by assuming Slater orbitals indicates the improvements that can be achieved by using more exact wave functions. The overlaps for CC bonds fall into the groups: (1) S 0.64. They are characteristic of highly strained three-membered rings, (6 ~ 20°), of four membered rings, (b ~ 10°), and of normal or very slightly bent bonds, (6 < 5°), respectively

The Synthesis and Structure Determination of Tetrasubstituted 4,4\u27 -Biisoxazoles

Tetrasubstituted 4,4\u27-biisoxazoles were synthesized as a mixture of isomers by treatment of enolic tautomers of 3,4-diaroyl-2,5-hexanedione with hydroxylamine hydrochloride. A single isomer,· 3,3\u27- diphenyl-5,5\u27-dimethyl-4,4\u27-biisoxazole was isolated from the reaction product mixture. The structure of these compounds has been determined by spectrometric measurements (ir, 1H NMR and mass spectra). Mass spectra have been studied in detail. The determination of metastable transitions and accurate masses of important fragment ions led to the construction of fragmentation schemes

Investigation of the pressure distribution in a 2D rocket nozzle with a mechanical system for thrust vector control (TVC)

This paper introduces a new physical model of the gas flow through the 2D nozzle with the tilted obstacle in exit section. Experimental research on the 2D full span model in the supersonic indraft tunnel, which includes over three hundred tunnel runs, are presented. Variable geometric parameters were: nozzle shadow area, obstacle-nozzle wall angle, obstacle-nozzle gap and nozzle area ratio. In its conclusion, the paper discusses results and presents some suggestions for the future research

Investigation of the pressure distribution in a 2D rocket nozzle with a mechanical system for thrust vector control (TVC)

This paper introduces a new physical model of the gas flow through the 2D nozzle with the tilted obstacle in exit section. Experimental research on the 2D full span model in the supersonic indraft tunnel, which includes over three hundred tunnel runs, are presented. Variable geometric parameters were: nozzle shadow area, obstacle-nozzle wall angle, obstacle-nozzle gap and nozzle area ratio. In its conclusion, the paper discusses results and presents some suggestions for the future research

Variability of terpene composition and morphological characteristics of Taxus baccata L. needles from Serbia

U radu su ispitani sastav etarskog ulja i morfološke karakteristike četina Taxus baccata L. Uzorkovanje biljnog materijala (četina sa grančicama) je izvršeno u jesen 2012. i 2013. godine iz tri prirodne populacije tise u Srbiji sa sledećih lokaliteta: Požar (Nacionalni park „Tara“), rezervat prirode „Jelak“ (Nacionalni park „Kopaonik“) i spomenik prirode „Lazarev kanjon“ (planina Malinik). Sastav i sadržaj etarskog ulja ispitan je na ukupno 47 uzoraka iz sve tri populacije. Ekstrakcije su vršene hidrodestilacijom po Clevenger-u, a sastav izolovanog ulja rastvorenog u pentanu je utvrđen GC-FID i GC-MS analizama. Ukupno je detektovana 91 komponenta, od kojih je 87 identifikovano. U sastavu etarskog ulja preovlađuju alifatični alkoholi (43.31%), terpeni (19.34%), alifatični ugljovodonici (13.18%) i alifatični aldehidi (11.09%). Ketoni, masne kiseline, derivati karotenoida, estri i aromatična jedinjenja zastupljeni su u manjem procentu. Neidentifikovana jedinjenja čine 1.96% ulja. Najzastupljenija terpenska frakcija za sve tri populacije su oksigenovani monoterpeni (13.99%). U etarskom ulju najzastupljenija jedinjenja su 1- okten-3-ol (23.48%), (Z)-3-heksenol (11.46%) i mirtenol (11.38%). U radu je ispitana međupopulaciona varijabilnost sadržaja etarskog ulja pomoću jednofaktorske analize varijanse, analize glavnih komponenti, klaster analize i kanonijske diskriminacione analize. ANOVA je pokazala da se 8 jedinjenja (koja imaju normalnu raspodelu) statistički značajno razlikuje prema zastupljenosti među populacijama (p<0.05): n-oktanal, -linalol, -ciklocitral, (E)- -jonon, eikozanal, transferuginol, trikozanal i heksakozan. Analiza glavnih komponenti sa 22 najzastupljenije hemijske komponente etarskog ulja je pokazala razdvajanje jedinki iz populacija Kopaonik i Malinik, kao i jedinki iz populacija Tara i Malinik. Sa grafičkih prikaza analize mogu se uočiti jedinjenja kojima obiluju pojedine populacije. Jedinke sa Tare obiluju sadržajem heksahidrofarnezil acetona, pentakozana, geraniola i mirtenola, jedinke sa Kopaonika sadržajem 1-okten-3-ola, 1-okten-3-ona, 3-oktanona, n-nonanala, palmitinske kiseline i junicedranola, a jedinke sa Malinika sadržajem n.k. 1, (Z)-3- heksenola, fitola i heptadekana. Statistički značajne razlike (Mann-Whitney U test) utvrđene su u sadržaju: pentakozana, 1-okten-3-ola, 1-okten-3-ona, 3-oktanona, nnonanala, palmitinske kiseline, junicedranola, (Z)-3-heksenola i heptadekana...In this study, the composition of the essential oil and morphological characteristics of Taxus baccata L. needles were examined. Plant material (twigs with needles) was collected in the autumn of 2012 and 2013, from three natural yew populations in Serbia from the following locations: Požar (National Park “Tara”), nature reserve “Jelak” (National Park “Kopaonik”) and natural monument “Lazarev kanjon” (Mt. Malinik). The composition of the essential oil was investigated on a total of 47 samples from all studied populations. The isolation of oil was performed by hydrodistillation using Clevenger-type apparatus, and the composition was determined by GC-FID and GC-MS analyses. Of the 91 detected compounds, 87 were identified. The most abundant compound classes were aliphatic alcohols (43.31%), terpenes (19.34%), aliphatic hydrocarbons (13.18%) and aliphatic aldehydes (11.09%). Ketones, fatty acids, carotenoid derived compounds, esters and aromatic compounds were presented in smaller amounts. Unknown compounds had an average relative content of 1.96%. In the terpene fraction, oxygenated monoterpenes dominated (13.99%). The predominant constituents of the essential oil were 1-octen-3-ol (23.48%), (Z)-3-hexenol (11.46%) and myrtenol (11.38%). To assess variability of the essential oil content between studied populations analysis of variance, principal component analysis, cluster analysis and canonical discriminant analysis were performed. One-way ANOVA revealed that 8 (normally distributed compounds) exhibited statistically significant differences between populations (p<0.05): n-octanal, β-linalool, β-cyclocitral, (E)-β-ionone, eicosanal, trans-ferruginol, tricosanal and hexacosane. The principal component analysis of 22 selected compounds revealed differentiations of individuals from populations Kopaonik and Malinik, as well as individuals from populations Tara and Malinik. The graphical visualization of analysis showed that individuals from Tara were rich in hexahydrofarnesyl acetone, pentacosane, geraniol and myrtenol, individuals from Kopaonik contained high levels of 1-octen-3-ol, 1-octen-3-one, 3-octanone, n-nonanal, hexadecanoic acid and junicedranol and individuals from Malinik contained high levels of unknown compound 1, (Z)-3-hexenol, phytol and heptadecane..

Determination of contents of macroelements and microelements in samples of mushroom macrolepiota procera and soil substrates from Rasina region

Pečurke, u zavisnosti od vrste, imaju više ili manje razvijen efikasan mehanizam apsorpcije makroelemenata i mikroelemenata. Zemljište predstavlja glavni izvor velikog broja elemenata za njih. U zavisnosti od porekla, spoljašnjih uticaja i antropogenih aktivnosti, koncentracije elemenata u zemljištu mogu varirati u širokom opsegu. Od oblika i jačine veze elemenata sa supstratom zavisi njihova mobilnost i biodostupnost. U cilju ispitivanja sposobnosti akumulacije elemenata jestive divlje vrste pečurke Macrolepiota procera, određen je sadržaj 20 makroelemenata i mikroelemenata (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti, Zn, Ag, Se, As, Ca, Mg, Na i K) u njenim šeširima i stabljikama, sakupljenim na pet lokacija u Rasinskom okrugu, kao i u njihovim zemljišnim supstratima. Zemljišni supstrati su pripremani na dva načina: 1) prema modifikovanoj BCR sekvencijalnoj ekstrakcionoj proceduri sa četiri faze, radi podele na frakcije: kiselo-rastvorne/izmenjive, reducibilne, oksidabilne i rezidualne i 2) razaranjem u carskoj vodi, u cilju određivanja pseudototalne koncentracije elemenata. Za merenje sadržaja svih elemenata u pečurkama, osim Ca, Mg, Na i K, primenjena je indukovano spregnuta plazma sa masenom spektrometrijom (ICP-MS), dok su ovi makroelementi, kao i svi elementi u zemljištu određivani indukovano spregnutom plazmom sa optičko emisionom spektometrijom (ICP-OES). Koncentracije makroelemenata nalazile su se u opsegu uobičajenom za ovu vrstu pečurke. Rezultati sadržaja elemenata u zemljištu i pečurkama podvrgnuti su multivarijantnoj analizi podataka. Analiza glavnih komponenata (Principal Component Analysis, PCA) istakla je razliku u uzorcima pečuraka sa različitih geografskih područja i otkrila uticaj sastava zemljišta na sadržaj elemenata u pečurkama. Hijerarhijska klasterska analiza (HCA) potvrdila je da su prve tri faze BCR sekvencijalne ekstrakcije najvažnije za apsorpciju elemenata iz zemljišta od strane pečuraka. Rezultati linearne regresione korelacije pokazali su da postoje značajne korelacije između sadržaja Ag, Cd, Se, Pb i As u šeširima i stabljikama sa različitih lokacija. Izračunati su biokoncentracioni (BCF) i translokacioni faktori (TF) za svaki element. M. procera značajno akumulira Cd, Cu, Ag i K, u manjem obimu Zn, dok vrednosti BCF za Se i Na pokazuju različito ponašanje, u zavisnosti od lokacije. Dobijene vrednosti TF ukazuju na efikasnu translokaciju od stabljike do šešira metalnih jona Cd, Zn, Cu i u nešto manjem obimu, zavisno od lokacije, Pb i As. Što se tiče nutritivne vrednosti, rezultati pokazuju da M. procera može služiti kao dobar izvor esencijalnih elemenata, kao što su Cu, Zn, Mn, Fe, Mg, K i Se. Ipak, zbog povećane koncentracije kadmijuma, a na pojedinim lokacijama i olova, konzumacija ove vrste pečurke sa ispitivanih područja može predstavljati rizik po zdravlje konzumenata za vreme sezone njihovog branja.Mushrooms, depending on species, have more or less developed mechanism of absorption macroelements and microelements. Soil represents the main source of a large number of elements to them. Depending of the origin, external influences and antropogenic activities, concentrations of elements in soil may vary over a wide range. Mobility and bioavailability of elements depend of their forms and the bond strength with their soil substrate. In order to investigate the mobility and availability of elements from soil to mushrooms, the content of twenty elements (Al, Ba, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, Ti, Zn, Ag, Se, As, Ca, Mg, Na and K) in caps and stipes of wild-grown edible mushroom Macrolepiota procera and soil substrates, collected from five sites in Rasina region, was determined. Soil substrates were prepared in two different ways: 1) according to the modified sequential extraction procedure proposed by the Community Bureau of Reference in order to fractionate acid-soluble/exchangeable, reducible, oxidizable and residual fractions and 2) digestion with aqua regia in order to determine the pseudototal concentrations of elements. The content of all elements in mushroom, except Ca, Mg, Na and K was determined by inductively coupled plasma mass spectrometer (ICP-MS), while the content of these macroelements and all elements in soil substrates was determined by inductively coupled plasma optical emission spectrometer (ICP-OES). Concentrations of macroelements were in the range of usual concentrations for this mushroom specie. The results of the contents of elements in soils and mushrooms were subjected to multivariate data analysis. Principal Component Analysis (PCA) distinguished the mushrooms samples from different geographical area and revealed the influence of soil composition on metal content in fruiting bodies. Hierarchical cluster analyses (HCA) confirmed that the first three phases of extraction were the most important for metal uptake by mushrooms from soil. Results of the linear regression correlation test showed the existence of significant correlations between contents of Ag, Cd, Se, Pb and As in caps and stipes at different geographic sites separately. The bioconcentration factors and translocation factors for each metal were calculated. These results indicated that M. procera significantly accumulates cadmium, copper, silver and potassium, and to a lesser extent zinc, while the BCF values for selenium and sodium showed different behaviour, depending on the geographic sites. Obtained TF values showed efficient translocation of Cd, Zn and Cu ions, from stipe to cap, and to a lesser extent, depending on sites, lead and arsenic. As far as the nutritional value concern, the results showed that M. procera could serve as a good dietary source of essential elements, especially Cu, Zn, Mn, Fe, Mg, K and Se. However, because of high concentrations of cadmium, and at some sites, lead, the consumption of this mushroom specie from investigated areas, may pose a health risk for consumers during the “season of mushrooms.

Heating energy consumption optimization of multifamily residential building sector of the city using energy model

Razumevanje energetskog ponašanja zgrada na nivou grada je neophodno da bi se formirala gradska politika energetskog planiranja i donele strateške odluke o tome koje zgrade je potrebno termički poboljšati. Energetsko modeliranje građevinskog fonda zgrada je metodologija koja procenjuje potrošnju energije u zgradama i simulira efekte poboljšanja energetske efikasnosti u njima. U disertaciji je razvijena nova metodologija inženjerskog bottom-up modeliranja potrošnje energije za grejanje višeporodičnog stambenog fonda grada. Metodologija se sastoji od: određivanja kriterijuma na osnovu kojih se definišu tipovi zgrada, kreiranja geo-baze podataka o zgradama, izbora uzorka realnih zgrada, modeliranja zgrada uzorka, normalizacije stvarne potrošnje energije za grejanje zgrada uzorka, simulacije energetskog ponašanja modela zgrada uzorka, računanja potrošnje energije za grejanje višeporodičnog stambenog građevinskog fonda grada i unosa izračunatih podataka u geo- bazu. Ova metoda se od već postojećih metoda razlikuje po svojoj detaljnosti i novinama koje su primenjene u određivanju kriterijumima na osnovu kojih se definišu tipovi zgrada i proračunu potrošnje energije za grejanje. Pri određivanju pomenutih kriterijuma, arhitektonsko-urbanistički kriterijum je dopunjen i definisani su novi kriterijumi. Proračun potrošnje energije za grejanje višeporodičnog stambenog građevinskog fonda koristi originalne koncepte, kao što su koeficijenti modifikacije i orijentacije, uz korišćenje kalibracije ciljanom potrošnjom simuliranih modela zgrada uzorka. Inženjerskom bottom-up metodom, koja je predstavljena u ovoj disertaciji, modelirana je potrošnja energije za grejanje višeporodičnog stambenog građevinskog fonda grada Kragujevca, izgrađenog do 2012. godine. Optimizacija potrošnje energije za grejanje poboljšavanjem termičkih omotača višeporodičnih stambenih zgrada izvršena je na tri hijerarhijska nivoa u gradu Kragujevcu i obuhvatala je simulaciju ugradnje termičke izolacije na spoljašnje zidove, ugradnje termičke izolacije na horizontalne međuspratne konstrukcije ka negrejanom prostoru podruma i ugradnje novih prozora. Najveća ušteda potrošnje energije za grejanje višeporodičnih stambenih zgrada posle pojedinačnog poboljšanja iznosi 22,8%, dok kombinacija poboljšanja dovodi do maksimalne uštede od 31,56%. Ušteda potrošnje energije za grejanje od 37,52% bila bi ostvarena kod slobodno stojećih zgrada izgrađenih u periodu 1961-1970. godine posle ugradnje termičke izolacije na spoljašnje zidove. Ušteda potrošnje energije za grejanje od 37,61% bila bi ostvarena kod solitera izgrađenih u periodu 1971-1980. godine posle ugradnje novih prozora.Understanding of the buildings energy performance at the city level is necessary in order to form a city energy planning policy and make a strategic decision on which buildings should be thermally improved. Energy modeling of the building sector is а methodology that estimates energy consumption in buildings and simulates the effects of their energy efficiency improvements. In this thesis, engineering bottom-up method was developed for modeling the heating energy consumption of a multi-family residential building sector of the city. It consists of: determination of the criteria based on which building types were defined, creation of the buildings geo-database, selection of the real sample buildings, modeling of the sample buildings, normalization of the sample buildings actual heating energy consumption, simulation of the sample building models heating energy consumption, calculation of the heating energy consumption of multi-family residential building sector of the city and importation of the calculated data into geo-database. This method is distinguished from existing methods by details and novelties used in the determination of the criteria based on which building types were defined and calculation of the heating energy consumption. In the determination of the mentioned criteria, architectural - urban criterion was supplemented and the new criteria were defined. Calculation of energy consumption for heating multi-family residential building sector uses original concepts, such as modification amd orientation coefficients, using calibration with targeted heating energy consumption of the simulated sample building models. Engineering bottom-up method, presented in this thesis, models heating energy consumption in multifamily residential building sector of the city of Kragujevac, built before 2012. Heating energy consumption optimization by improving the thermal envelope of multifamily residential buildings was performed on three hierarchical levels in the city of Kragujevac and consisted of the simulation of installation of thermal insulation on the external walls, installation of thermal insulation on floor construction above the unheated basement area and installation of new windows.The biggest reduction of heating energy consumption of multifamily residential buildings after the individual improvement is 22.8%, while maximum reduction after the combination of improvements is 31.56%. The reduction in heating energy consumption of 37.52% would be achieved in the free-standing buildings, constructed between 1961 and 1970, after the installation of thermal insulation on the external walls. The reduction in heating energy consumption of 37.61% would be achieved in the high-rise buildings, constructed in the period 1971-1980, after the installation of new windows

Statističke karakteristike prvog i drugog reda signala u bežičnom telekomunikacionom sistemu sa selekcionim kombinovanjem

In doctoral dissertation, first and second order system performances of wireless communication system in the presence of fading and interference are considered. Theoretically, four cases are taken into consideration, and obtained numerical results are graphically presented and analyzed. Firstly, wireless mobile communication system with the receiver that contains automatic frequency control (AFC) loop operating over fading channel in the presence of single interference is considered. Performance measures, such as average switching rate (ASR) and mean time lose of lock (MTTL), are defined. In this doctoral dissertation, ASR and MTTL, for three different fading channels: Kg, α-μ and k-μ are obtained. In the next chapter, wireless relay communication system with two sections in the presence of multipath fading is considered. Signal envelope at the input of the receiver can be expressed as product of the first section signal envelope and the second section signal envelope. For such system model, average level crossing rate (LCR) for the case when radio relay system of the first section operates over Nakagami-m fading environment and second section operates over k-μ fading environment is obtained. Wireless relay system with two sections in the presence of non-linear α-μ fading channel is than taken into consideration. Moreover, radio relay system with two sections in the presence of multipath fading and interference is also considered. LCR of the ratio of the product of two k-μ random processes and k-μ random process is calculated. Finally, LCR of the ratio of Rician random process and product of two Rician random processes is obtained. Wireless communication system with two inputs SSC diversity receiver operating over correlated multipath η-μ fading in the presence of interference is than considered. Joint probability density function and joint distribution cumulative function of the ratios of signal to interference at inputs of SSC receivers are calculated. By using obtained expressions for probability density function (PDF), average bit error probability (ABER) for different coherent and non-coherent modulation schemes is obtained while by using derived cumulative distribution function (CDF), outage probability (OP) is obtained. At the end of doctoral dissertation, macrodiversity system with macrodiversity SSC receiver and two microdiversity SC receivers operating over Gamma shadowed multipath fading channel is proposed. In one case Nakagami-m multipath fading channel is considered while in the second case k-μ multipath fading is considered. System performances of the proposed system are derived and numerical results are graphically presented and discusse

Histiocytosis x: Recurrent isolated mandibular lesion (case report)

Histiocytosis X usually affects children and adolescents. In our case, a 54-year-old woman was admitted to hospital for evaluating and treatment of an isolated, painless swelling of the left side of the mandible. Orthopanthomogram showed a cystic formation located on the left side of the mandibular body. Radiographs of the scull and body showed no pathologic changes. Laboratory findings did not reveal any abnormality. Surgical enucleation of the mandibular cystic lesion was performed and histopathological analysis confirmed the presence of histiocytosis X. One year after the first operation a relapse formation was found and surgically removed. Resection of the left side of the mandibular body was performed immediately followed by reconstruction of the mandibular defect with free osseos graft taken from the iliac crest. All follow-ups in the period of three years after the second operation showed no sign of relapse

Thermal stress analysis of a fiber-epoxy composite material

Paper presents stress calculation in the stationary temperature domain for a hybrid structure with standard epoxy-carbon fiber composite and metallic part, showing different thermal behavior. The thermal stress analysis is based on the finite element method. A sample problem involving such a composite plate and metallic part of structure or mould at two different temperature levels, corresponding to curing process (co-curing) and operating temperatures, respectively, is calculated and discussed. The specific properties of composite are emphasized particularly for thermal coefficients, especially if the shear coefficient is different than zero, causing completely different behavior compared to isotropic materials