353 research outputs found

    Endangerment and conservation of tuatara (Sphenodon punctatus and Sphenodon guntheri)

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    Iako su tuatare rasprostranjene samo na otocima Novog Zelanda svijest o njihovom očuvanju mora doprijeti do znanstvenika diljem svijeta. Velika važnost premosnika leži u njihovom statusu živih fosila, i mislim da oni predstavljaju nevjerojatne izvore u prikupljanju podataka koji se mogu izvući iz njihovih životnih ciklusa, podataka koji su sigurno iznimno bitni za proučavanje ne samo evolucije i razvitka novozelandskih otoka, već i cijele Zemlje. Tuatare su jedne od rijetkih životinja preko kojih možemo proučavati život organizama od prije čak 200 milijuna godina i tako spoznavati istine o povijesti naÅ”eg planeta. Put ka očuvanju premosnika leži u rukama lokalnih znanstvenika, ali po mom miÅ”ljenju prije svega u svijesti tamoÅ”njih građana koji svojim postupcima mogu uvelike pridonijeti spasu ovih gmazova. Male stvari, poput redovitog hranjenja svog mačka, te pažljivog održavanja svog zeca, ali i pomoći u istrebljivanju opasnih Å”takora i miÅ”eva, prvi su, no i veliki koraci u očuvanju tuatara na otocima koje dijele s ljudima. Zabranjuje se i unoÅ”enje ljubimaca na nenaseljene otoke prilikom turističke ili bilo kakve druge posjete. Volonteri su uvijek dobrodoÅ”li, a DOC se može pohvaliti s mnoÅ”tvom mladih dobrovoljaca koji su spremni dati svoj udio u zaÅ”titi tuatara, no sve se viÅ”e i ljudi starije dobi uključuje u volonterske programe. U budućnosti mi je velika želja da otputujem na Novi Zeland i barem se nakratko uključim u bogate akcije spaÅ”avanja tuatara, ali i njihovog proučavanja, Å”to smatram svojevrsnom privilegijom u danaÅ”njem znanstvenom svijetu. Zbog svega navedenog, priča o tuatari trenutno ima sretne konotacije. Međutim, miÅ”ljenja sam da će ovi prastari gmazovi, ogledala proÅ”losti, naposljetku ipak izumrijeti. Naravno, to neće biti tako skoro, ali zbog prirode njihove evolucije i slabe genetičke varijabilnosti, one se neće moći nositi sa budućim naglim klimatskim promjenama. Premosnici su čak 220 milijuna godina preživljavali razne dramatične promjene u svijetu, i Å”teta je da se samo jedno tisućljeće kojeg su proveli s ljudima dokaže kao njihov krajnji poraz. Ali, ljudi u ovom slučaju nisu direktni krivci, naime većina ostalih vrsta i okoliÅ”a na planetu su žalosno zanemarivane i eksploatirane od strane čovjeka, ali kad zadnja tuatara ugine, mislim da ipak ne bi smjeli kriviti sami sebe.Although Tuataras are distributed only on the islands of New Zealand, awareness of their conservation must reach out to scientists around the world. Tuataraā€™s great importance lies in their status as living fossils, and I think theyā€™re incredible sources to collect data that can be drawn from their life cycles, data which is certainly very important for the study of not only the evolution and development of the New Zealand islands, but of the whole Earth. Tuataras are one of the few animals through which we can study living organisms from even before 200 million years, and so to realize the truth about the history of our planet. The way of preserving tuataras is in the hands of local scientists, but in my opinion, primarily in the minds of local citizens, and their actions which can greatly contribute into saving these reptiles. Little things, like regular feeding of your cat, and careful maintenance of your rabbit, but also help in the extermination of dangerous rats and mice are the first, but giant steps in preserving the tuatara islands that are shared with humans. Itā€™s prohibited to introduce pets on an uninhabited island during tourist or any other visits. Volunteers are always welcome, and DOC can boast with many young volunteers who are willing to do their part in protecting the tuatara, but more and more elderly people are involved in volunteer programs. In the future, I have a great desire to travel to New Zealand and at least briefly engage into rich tuatara rescue missions and study their behavior, which I think is kind of a privilege in today's scientific world. Consequently, the story of the tuatara currently has happy connotations. However, it is my opinion that these ancient reptiles, mirrors of the past, will ultimately perish. Of course, it will not be so soon, but due to the nature of their evolution and low genetic variability, they will not be able to cope with future abrupt climate changes. Sphenodons survived 220 million years of many dramatic world changes, and itā€™s a shame that only one millennium in which they coexist with people, prove to be their ultimate defeat. But humanity in this case is not the direct executioner. Other species of wildlife and other environments have been woefully neglected and actively mistreated by man, but when the last tuatara dies, I think we really should not blame ourselves

    Phenotypic, ITS phylogenetic and pathogenic analyses of Pyllosticta Multicorniculata associated with needle blight symptoms of balsam fir in Canada

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    Phyllosticta multicorniculata Bissett & Palm causes needle blight on Abies balsamea (L) Mill. in eastern Canada. The disease symptoms are similar to those provoked by Phyllosticta abietis Bissett & Palm on Abies grandis Lindl. in the U.S.A. Preliminary study based on rDNA ITS sequence data analysis, revealed that P. multicorniculata formed distinct but closely-related clade with other sister mitosporic Phyllosticta and teleomorphic Guignardia and Botryosphaeria taxa. However, the phylogenetic position of the fungus is still doubtful which demand further and more advanced molecular investigation. This is the first report of a microconidial stage in P. multicorniculata and, for the first time, description of the developing mucilaginous appendages in macroconidia. This study contributes in disease diagnostics and gives new information on distribution of the disease in Canada

    2-Hexadecynoic Acid

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    The hitherto undescribed 2-hexadecynoic acid (III) was prepared by the following route. Dodecylmagnesium bromide was reacted with 2,3-dibromopropene to give 2~:bromop e ntadecene (I) in 35 % yield. Refluxing the bromo compound I with freshly prepared sodium amide in xylene gave pentadecyne(II) in 49 .1 % yiel

    2-Hexadecynoic Acid

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    The hitherto undescribed 2-hexadecynoic acid (III) was prepared by the following route. Dodecylmagnesium bromide was reacted with 2,3-dibromopropene to give 2~:bromop e ntadecene (I) in 35 % yield. Refluxing the bromo compound I with freshly prepared sodium amide in xylene gave pentadecyne(II) in 49 .1 % yiel

    Improving the sustainability of cement production by using numerical simulation of limestone thermal degradation and pulverized coal combustion in a cement calciner

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    The cement industry sector is one of the largest carbon emitting industrial sectors, and due to the effect of global warming sustainable cement production is increasingly gaining on importance. Controlling the combustion of coal and the thermal degradation of limestone, the two main thermo-chemical processes that occur inside a cement calciner, is of significant importance, since these processes have a direct influence on the cement quality, pollutant formation and overall energy efficiency of the cement manufacturing process. One of the possibilities for the improvement and control of these thermo-chemical processes are Computational Fluid Dynamics- CFD simulations. The results gained from these simulations are being increasingly used to enhance the efficiency of cement production, since they improve the understanding of the flow characteristics and transport phenomena taking place inside the cement calciner. The purpose of this paper is to present that a more energy efficient and sustainable cement production can be achieved by deploying CFD simulations in the process of cement production. The numerical models of limestone thermal degradation, also known as the calcination process, and pulverized coal combustion were developed and implemented within the commercial computational fluid dynamics code FIRE, which was then used for the analysis. The developed models are based on the solution of Navier-Stokes equations for the gas phase, and on the Lagrangean dynamics for the discrete particles. A three dimensional complex geometry of a real industrial cement calciner was used for th

    The role of preventive maintenance of fleets powered by conventional and alternative fuels in road transport of dangerous goods

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    The paper surveys two companies that have homogeneous fleets for the transport of dangerous goods. The observed companies use fleets of various propulsion, conventional diesel fuel and compressed natural gas to carry out the transport process, and strive to ensure greater reliability and availability of vehicles at the lowest possible cost of preventive maintenance. In that sense, the role of preventive maintenance of fleets with different propulsion, diesel and compressed natural gas is analysed, and differences in terms of construction and operational characteristics of vehicles, procedures and costs of preventive maintenance are presented. Fleet managers must take into account environmental impacts, requirements and regulations defined in the European Agreement concerning the International Carriage of Dangerous Good by Road when managing the operation and maintenance of vehicle fleet in the road transport of dangerous goods. The conducted research shows that vehicles with compressed natural gas drive achieve certain advantages in terms of preventive maintenance in relation to conventional diesel vehicles and can be successfully used in road transport of dangerous goods
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