On the Aromatic Stability of Positional Isomers Consisting of Bicyclic Systems Composed Entirely of Five-Membered Heterocycles

Isomeric bicyclic conjugated systems consisting entirely of five-membered heterocycles were studied using a novel aromaticity index named topological resonance energy (TRE). TRE has correctly predicted the aromatic behaviour of all the groups of isomers studied. (These isomers called positional isomers because they formally differ only by the position of a-bivalent heteroatoms) may be classified into a particular group according their annelation mode, which closely parallels TRE predictions and experimental findings

Huckel Molecular Orbital Calculations of Aromatic Stabilization of Annulenes

Annulenes were studied using the concept of aromatic stabilization. A simple expression is presented for the calculation of aromatic stabilization of annulenes. The index of aromatic stabilization differentiates correctly between the [4n + 2] - and [4n] -annulenes. The analysis of the approach of Kruszewski and Krygowski shows that their KK index differs only by a constant from the value of aromatic stabilization of a particular annulene. Similarly, the relation between REPE values of Hess and Schaad and indices of aromatic stabilization is discussed

Graph Theory and Molecular Orbitals. XVIII. On Topological Resonance Energy

Mathematical relations necessary for the calculation of the previously introduced15 topological resonance energy, TRE, are derived. TRE, as defined in ref. 15, was rather inconvenient for numerical calculations. In the present work these computing difficulties are overcome. Acyclic characteristic polynomial pac and acyclic spectrum of a graph are defined and their close relationship to TRE is demonstrated. Hence, the evaluation of pac is the crucial .step in the computation of TRE\u27s. A graphical procedure is described and exemplified for the determination of P"c\u27s both for simple graphs and for graphs with loops and weighted edges

Uticaj paragenetskih faktora na reproduktivne osobine krava simentalske rase

The examination was made on the effect of systematic factors (parturition group, calving season, birth type, calf gender, and birth type-calf gender interaction) and age at first conception on the expression of reproductive traits (gestation length, service period, fertility intensity and calf birth weight) in 143 Simmental cows. The overall mean (μ) for gestation length, service period, intercalving period and calf birth weight was 284.14 days, 153.82 days, 416.92 days and 35.40 kg, respectively. The parturition group effect on all fertility traits was highly significant (P lt 0.01). The calving season statistically significantly (P lt 0.05) affected the intercalving period and calf birth weight. Birth type induced very significantly longer gestation (P lt 0.01) and higher calf birth weight in singles (P lt 0.01) and significantly longer service period in twins (P lt 0.05). Calf gender had a very significant effect (P lt 0.01) only on calf birth weight, and the interaction between birth type and calf gender significantly affected gestation duration only (P lt 0.05). The regression effect of age at first conception on all fertility traits was not significant (P>0.05).Na ispoljenost reproduktivnih osobina (dužina bremenitosti, servis period, intenzitet plodnosti i masa teladi pri rođenju) kod 143 krave simentalske rase, ispitivan je uticaj sistematskih faktora (grupe partusa, sezone telenja, tip rođenja, pol teladi i interakcija tipa rođenja i pola teladi) i uzrasta pri prvoj oplodnji. Opšti prosek (μ) za dužinu bremenitosti iznosio je 284.14 dana, servis period 153.82 dana, međutelidbeni interval 416.92 i masu teladi pri rođenju 35.40 kg. Uticaj grupe partusa na sve osobine plodnosti bio je visoko značajan (P lt 0.01). Sezona telenja statistički značajno (P lt 0.05) je uticala na međutelidbeni interval i masu teladi pri rođenju. Tip rođenja uslovio je vrlo značajno dužu bremenitost (P lt 0.01) i veću masu teladi pri rođenju kod jedinaca (P lt 0.01) i značajno duži servis period kod blizanaca (P lt 0.05). Pol teladi vrlo značajno je uticao (P lt 0.01) samo na masu teladi pri rođenju, dok je interakcija tipa rođenja i pola teladi značajno uticala samo na trajanje bremenitosti (P lt 0.05). Regresijski uticaj uzrasta pri prvoj oplodnji na sve osobine plodnosti nije bio signifikantan (P>0.05)

Uticaj sistematskih faktora na mlečnost krava Simentalske rase u celim laktacijama

The effect of systematic factors on production traits over complete lactations was investigated in 2,805 Simmental cows born in 1982 and onwards. The cows were housed at three farms in different areas: at the Zlatiborski Suvati dairy farm, Zlatibor, at the Dobricevo Agricultural Farm, Cuprija and at private farms in the region of Kotraze. The systematic factors (farm, calving season, lactation groups, group (year x season of birth), farm x calving season and farm x lactation group interactions) and age at first conception had statistically highly significant (P (lt) 0.001) effects on all complete lactation traits, with the exception of the effect of calving season on complete lactation duration (P (lt) 0.05) and milk-fat content (P>0.05). No statistically significant effect was produced by age at first conception on complete lactation duration and milk-fat content (P>0.05). Determination coefficients ranged from 0.100 in complete lactation duration to 0.361 in milk-fat content.Ispitivanje uticaja sistematskih faktora na ispoljenost proizvodnih osobina celih laktacija obavljeno je kod 2805 krava simentalske rase rođenih od 1982. godine pa na dalje. Krave su smeštene na tri farme, odnosno područja: farmi muznih krava 'Zlatiborski suvati' na Zlatiboru, Poljoprivrednom dobru Dobričevo u Ćupriji i području Kotraže na individualnim gazdinstvima. Sistematski faktori (farma, sezona telenja, grupe laktacija, grupa (godina x sezona rođenja), interakcije farma x sezona telenja i farma x grupe laktacija) i uzrast pri prvoj oplodnji statistički su vrlo visoko značajano (P (lt) 0.001) uticali na sve osobine punih laktacija, izuzimajući uticaj sezone telenja na trajanje punih laktacija (P (lt) 0.05) i sadržaj mlečne masti (P>0.05). Uzrast pri prvoj oplodnji nije statistički značajno uticao na trajanje celih laktacija i sadržaj mlečne masti u njima (P>0.05). Koeficijenti determinacije kretali su se od 0.100 kod trajanja celih laktacija do 0.361 kod sadržaja mlečne masti

Korelaciona analiza povezanosti proizvodnih osobina kroz tri generacije krava simentalske rase

The relationship between milk production traits over whole lactations was evaluated across three generations of Simmental cows, i.e. between daughters, dams and grand dams, by a phenotypic regression analysis with whole lactation traits in the daughter generation being used as the dependent variables (x1), and those in the dam and grand dam generations being used as the independent variables (x2 and x3). The results were obtained from a sample of 1170 daughters and as many dams and grand dams. The significance of the partial regression coefficients b2 and b3 was separately evaluated by a t-test. An analysis of variance was used to estimate the significance of the simultaneous effect of the production traits of dams and grand dams on the milk production achieved in the daughter generation. The calculated value of the partial regression coefficients for the whole lactation production traits across three generations (grand dams, dams and daughters) and their statistical significances determined by the t and F tests, as well as the regression equations used, suggested that the effect of the grand dam generation on the milk production traits in granddaughters was substantially lower than the effect of dams. The calculated partial regression coefficients (b2 and b3) were positive and statistically very significant (P lt 0.01), excepting the regression coefficients b3 for lactation length and b2 for milk fat content that were not statistically significant (P>0.05). A very significant change (P lt 0.01) was observed in all production traits in the daughter generation as simultaneously affected by the traits in the dam and grand dam generations.Povezanost osobina mlečnosti u punim laktacijama analizirana je između tri generacije krava simentalske rase, odnosno između kćerki, majki i baba, fenotipskom regresionom analizom u uslovima kada su osobine punih laktacija u generaciji kćerki posmatrane kao zavisno (x1), a osobine punih laktacija u generaciji majki i baba kao nezavisno promenljive (x2 i x3). Rezultati su dobijeni na uzorku od po 1170 kćerki, majki i baba. Pojedinačno ispitivanje značajnosti delimičnih regresionih koeficijenata b2 i b3 izvršeno je t-testom, a analizom značajnosti istovremenog uticaja proizvodnih osobina majki i baba na ostvarenu proizvodnju kod kćerki izvršena je metodom analize varijanse. Na osnovu izračunate vrednosti delimičnih regresionih koeficijenata za proizvodne osobine celih laktacija kroz tri generacije (babe, majke i kćerke) i njihove statističke značajnosti određene t i F testom, kao i jednačina regresije konstatovano je da je uticaj generacije baba na proizvodnju unuka znatno manji u odnosu na uticaj kojeg imaju majke. Svi izračunati delimični koeficijenti regresije (b2 i b3) bili su pozitivni i statistički vrlo značajni (P lt 0.01), izuzimajući koeficijent regresije b3 kod trajanja laktacije i b2 kod sadržaja mlečne masti koji nisu bili statistički značajni (P>0.05). Značajnost promena svih posmatranih proizvodnih osobina u generaciji kćerki pri istovremenom uticaju tih osobina iz generacije majki i baba bila je vrlo visoka (P lt 0.01)

Resonance Energy as a Criterion for Reactivities of Conjugated Hydrocarbons

A simple method based on a topological resonance energy index is proposed for predicting the reactivities of conjugated hydrocarbons. In comparison with other simple methods introduced (e.g., the Kekule structure count method\u27) it embraces both alternant and non-alternant hydrocarbons without additional adjustment of the theory

Auger-spektroskopija visoke resolucije u metalurgiji: moderna tehnika površinske analize

A brief review of the high spatial resolution Auger electron spectroscopy (HRAES) and its usage in metallurgy is presented. A combination of HRAES and X-ray photoelectron spectroscopy makes a powerful combination to resolve a large number of problems encountered in metallurgy. Several selected examples of such problems studied in the authors’ laboratory are presented: influence of surface active impurities on the surface properties and structure, chemical composition of nano-scaled inclusions, homogeneity of oxide layers formed by decarburization, chemical composition of inter- and intra-grain surfaces obtained by fracture in vacuum and interfacial study of 19Cr-13Ni austenitic stainless steel after treatment at elevated temperatures.Predočen je kratki pregled Auger-ove elektronske spektroskopije (HREAS) visoke spacijalne resolucije i njene primjene u metalurgiji. Kombinacija HREAS i röntgenske fotoelektronske spektroskopije učinkovita je pri rješavanju velikog broja problema koji se susreću u metalurgiji. Predočeno je nekoliko odabranih primjera takvih problema studiranih u laboratoriju autora: utjecaj površinski aktivnih nečistoća na svojstva i strukturu površine, kemijski sastav “nano-uključaka”, homogenost oksidnih slojeva nastalih odugljičenjem, kemijski sastav površina u zrnu i među zrnima nastalih lomljenjem u vakuumu te međufazna studija 19Cr-13Ni nehrđajućeg austenitnog čelika nakon obrade kod povišenih temperatura

Huckel Molecular Orbital Calculations of Aromatic Stabilization of Annulenes

Annulenes were studied using the concept of aromatic stabilization. A simple expression is presented for the calculation of aromatic stabilization of annulenes. The index of aromatic stabilization differentiates correctly between the [4n + 2] - and [4n] -annulenes. The analysis of the approach of Kruszewski and Krygowski shows that their KK index differs only by a constant from the value of aromatic stabilization of a particular annulene. Similarly, the relation between REPE values of Hess and Schaad and indices of aromatic stabilization is discussed

Efekat interakcije sistematskih faktora na mlečnost krava simentalske rase u standardnim laktacijama

The effect of interaction between the farm and calving season, as well as the farm and group of lactations on milk performance traits (milk yield, yield of milk fat, 4% fat corrected milk and milk fat content) was analyzed on sample of 2805 Simmental cows with total 9718 standard lactations, housed on dairy farm 'Zlatiborski suvati' on Zlatibor (578 cows and 1968 lactations), dairy farm of the Agricultural holding Dobričevo in Ćuprija (964 cows and 3237 lactations) and dairy animals housed on family farms/households in the region of Kotraža (1263 cows and 4513 lactations). The significance of the effect of interaction between the farm and calving season, as well as interaction between the farm and group of lactations on all milk performance traits was very high (P (lt) 0.001), which justified their inclusion into models for assessment of the breeding value of dairy cows. The share of variance of interactions in total variance of milk performance traits in standard lactations was low (below and around 4%), which clearly indicated even more systematic factors and their interactions which influence the total variability of observed traits of milk performance of cows in standard lactations.Uticaj interakcije farme i sezone telenja kao i farme i grupe laktacija na osobine mlečnosti (proizvodnja mleka, mlečne masti, 4% mast-korigovanog mleka i sadržaj mlečne masti) analizirano je kod 2805 krava simentalske rase sa ukupno 9718 standardnih laktacija koje su bile smeštene na farmi muznih krava 'Zlatiborski suvati' na Zlatiboru (578 krava i 1968 laktacija), farmi muznih krava na Poljoprivrednom dobru Dobričevo u Ćupriji (964 krava i 3237 laktacija) i području Kotraže na individualnim gazdinstvima (1263 krava i 4513 laktacija). Značajnost uticaja interakcija farme i sezone telenja, kao i interakcije farme i grupe laktacija na sve osobine mlečnosti standardnih laktacija bila je vrlo visoka (P (lt) 0.001), što opravdava njihovo uključivanje u modele za ocenu priplodne vrednosti muznih krava. Udeo varijanse interakcija u ukupnoj varijansi osobina mlečnosti standardnih laktacija bio je nizak (ispod i oko 4%), što jasno ukazuje na još veliki broj sistematskih faktora i njihovih interakcija koji utiču na ukupnu varijabilnost posmatranih osobina mlečnosti krava u standardnim laktacijama