Herndon\u27 s Structure-Resonance Theory. On the Valence Structure Count for Conjugated Radical Cations

Enumeration of valence structures for conjugated radical cations is of interest in estimating the first ionization potentials of conjugated hydrocarbons. Alternative routes for enumeration are reviewed and a novel method, based on the properties of the acyclic polynomials of conjugated structures, is outlined. The method is illustrated for several molecules and results reported for a number of conjugated systems involving either 14 or less carbon atoms

Flora i vegetacija otoka Sveti Andrija, južna Hrvatska

The first record of as many as 160 vascular plant taxa, 134 genera and 61 families on Sveti Andrija Island (5.38 hectares), southern Adriatic, was established on the basis of floristic research in 2005. An analysis of the life-forms and floral elements was also carried out and comparisons were made with other Dubrovnik islands. Altogether, four associations were determined: Querco ilicis-Pinetum halepensis, Posidonietum oceanicae, Limonietum anfracti and Lavateretum arboreae.Na temelju istraživanja u 2005. godini, na otoku Sveti Andrija (5,38 ha) u južnom Jadranu zabilježeno je 160 svojti vaskularnih biljaka, svrstanih u 134 roda i 61 porodicu. Analizirani su životni oblici i florni elementi, te uspoređeni s ostalim dubrovačkim otocima. Na otoku su utvrđene četiri biljne zajednice: Querco ilicis-Pinetum halepensis, Posidonietum oceanicae, Limonietum anfracti i Lavateretum arboreae

Nicotiana glauca Graham (Solanaceae), a new invasive plant in Croatia

The South American species Nicotiana glauca Graham (Solanaceae) is invasive in the western Mediterranean and has been found for the first time at four localities in Croatia. The first locality was discovered in 1977 on the island of Lokrum, but has previously been neglected, the second in Komi`a on the island of Vis, the third in the city of Split and the fourth in the city of Dubrovnik. The newly discovered N. glauca is a woody perennial species, while two other Nicotiana species occurring in Croatian, N. tabacum L. and N. rustica L., are annual herbs. An identification key for these three species and their morphological comparison is presented. The further spreading of N. glauca in Croatian littoral can be expected, and should be prevented

Bond Energies of Nitrogen and Phosphorous Hydrides and Fluorides

Recent measurements of bond energies in the N-Hn and P-Hn systems by photoionization mass spectrometry are compared with modern ab initio calculations and a semi-empirical theory. Good agreement is noted, providing confirmation for the level of accuracy of the ab initio calculations, and for the essential correctness of the semi-empirical parametrization. However, the N-Fn and P-Fn systems, also measured, are currently beyond the capabilities of such high quality ab initio calculations, and the trend s observed in the bond energica indicate that other parametrizations are necessary in the semi-empirical approach

Herndon\u27 s Structure-Resonance Theory. On the Valence Structure Count for Conjugated Radical Cations

Enumeration of valence structures for conjugated radical cations is of interest in estimating the first ionization potentials of conjugated hydrocarbons. Alternative routes for enumeration are reviewed and a novel method, based on the properties of the acyclic polynomials of conjugated structures, is outlined. The method is illustrated for several molecules and results reported for a number of conjugated systems involving either 14 or less carbon atoms

Nicotiana glauca Graham (Solanaceae), a new invasive plant in Croatia

The South American species Nicotiana glauca Graham (Solanaceae) is invasive in the western Mediterranean and has been found for the first time at four localities in Croatia. The first locality was discovered in 1977 on the island of Lokrum, but has previously been neglected, the second in Komi`a on the island of Vis, the third in the city of Split and the fourth in the city of Dubrovnik. The newly discovered N. glauca is a woody perennial species, while two other Nicotiana species occurring in Croatian, N. tabacum L. and N. rustica L., are annual herbs. An identification key for these three species and their morphological comparison is presented. The further spreading of N. glauca in Croatian littoral can be expected, and should be prevented

New localities of the subendemic species Berberis croatica, Teucrium arduini and Micromeria croatica in the Dinaric Alps

New localities of three subendemic species (Berberis croatica, Teucrium arduini and Micromeria croatica) have been found in the Dinaric Alps. Berberis croatica was found at ten new locations, nine of them in Croatia and one in Bosnia and Herzegovina. Teucrium arduini was found on Mt Učka, Mt Velebit, Mt Biokovo and Mt Sniježnica, at nine new locations while Micromeria croatica was found at four new locations, only on Mt Velebit

Syntaxonomy of <i>Arundo</i> stands along the eastern Adriatic coast

<p>Based on the diagnostic morphological characters of the <i>Arundo</i> taxa, and after both field and herbarium observation, three species (<i>A</i>. <i>micrantha</i>, <i>A</i>. <i>plinii</i> and <i>A</i>. <i>donax</i>) were found along the eastern Adriatic coast. Altogether, 50 phytocoenological relevés from <i>Arundo</i> stands were collected in Croatia, Montenegro and Albania between 2010 and 2013. Three associations with a predominance of <i>Arundo</i> species were determined: <i>Arundinetum plinianae</i>, <i>Arundinetum micranthae</i> and <i>Arundini donacis–Convolvuletum sepium</i>. Among them, <i>Arundinetum micranthae</i> is described and proposed as a new association, belonging to the <i>Artemisietea vulgaris</i> class. It occurs frequently along the coastal belt between the cities of Split and Dubrovnik in South Croatia. The syntaxonomy of the associations is discussed and comparison with similar communities from Italy is made. The vegetation and floristic structure of the associations is discussed as a potential basis for biodiversity conservation programmes and for evaluating the state of these ecosystems in the future.</p