1861. The role of relative humidity on crystallization of calcium carbonate from calcium acetoacetate precursorAndreja Pondelak, Francesca Rosi, Celeste Maurich, Costanza Miliani, Srečo D. Škapin, Andrijana Sever Škapin, 2019, original scientific article Abstract: Calcium acetoacetate, Ca(OAcAc)2, was exposed 7, 30 and 365 days to different values of relative humidity (33%, 48%, 75% and 96%) at 40 °C in order to study its transformation to CaCO3. The resulting Ca(OAcAc)2 decomposition and the time dependence of the phase transformations were monitored and critically evaluated by Fourier transform infrared spectroscopy, field emission scanning electron microscopy and X-ray powder diffraction. The impact of relative humidity on CaCO3 polymorph formation was thoroughly assessed. In all of the conditions used and for all ageing periods, the formed crystal structure is found to be vaterite. At the lowest relative humidity (33%), the amorphous CaCO3 remains more or less almost untransformed even after one year of exposure. It is proposed that the reason for the stability of amorphous CaCO3 is due to the limited amount of physisorbed water on the surfaces of the particles, which is considered the driving force for its transformation. However, the carbonation process is faster in the case of the highest humidity (96%). The findings are not only important for better solutions in the field of cultural heritage, but also shed new light on the fundamental mechanism of CaCO3 crystallization.
Keywords: calcium acetoacetate, relative humidity, carbonation, amorphous carbonate, vaterite, mechanism
Published in DiRROS: 22.11.2023; Views: 505; Downloads: 208
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1862. Epidemiologija raka dojk in presejanjeMaja Primic-Žakelj, Vera Pompe-Kirn, 1998, review article Abstract: Rak dojk je v Sloveniji najpogostejši rak pri ženskah. Leta 1995 je za njim zbolelo 784 žensk (76,7/100.000), pričakujemo pa , da se bo v prihodnjih desetih letih incidenca še večala. Delež rakov, odkritih v omejenem stadiju se povečuje; leta 1995 je bilo takih 44% vseh primerov. Čeprav se je preživetjolnic izboljšalo (67-odstotno 5-letno relativno preživetje bolnic z rakritim v letih 1988-92), ostaja rak dojk pri ženskah na prvem mestu med vzroki smrti zaradi raka. Med dikazane nevarnostne dejavnike sodijo poleg spola in starosti še poprejšnji rak dojk , nekatere benigne bolezni dojk, družinska obremenitev, ionizirajoče sevanje, nekateri reproduktivni dejavniki in debelost. V primarni preventivi zaenkrat ni posebnih priporočil, so le splošna: vzdrževanje normalne telesne teže, pravilna prehrana, telesna dejavnost in zmernost pri pitju alkoholnih pijač. Ocenjujejo, da presejanje, redno mamografsko pregledovannje žensk po 50. letu starosti z dodatnim kliničnim pregledom ali brez njega, zmanjša umrljivost za rakom dojk med pregledanimi za okrog 30%. Populacijsko presejanje priporočajo večinoma po 50.letu starosti. Problem raka dojk je mogoče reševati celostno, s primarno preventivo, zgodnjim odkrivanjem in dostopnostjo do užinkovitega zdravljenja, predvsem pa z vlaganjem sredstev tja, kjer je razmerje med stroški in koristjonajugodnejše.
Published in DiRROS: 21.11.2023; Views: 323; Downloads: 126
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1865. Stanje slovenskih gozdov : poročilo o rezultatih nacionalne gozdne inventure 2022Mitja Skudnik, Luka Krajnc, Gal Kušar, Anže Martin Pintar, 2023, treatise, preliminary study, study Keywords: monitoring, nacionalna gozdna inventura, odmrla lesna biomasa, temeljnica, površina gozda, lesna zaloga, vzorčne ploskve, poročila
Published in DiRROS: 21.11.2023; Views: 451; Downloads: 0 |
1866. Discretionary capitalization of development expendituresPrimož Petek, Mateja Jerman, Sandra Janković, 2023, original scientific article Abstract: The paper examines the discretionary nature of (non)capitalizing development expenditures in financial statements. A review of the literature shows that companies may have different motives and factors for (non)capitalizing development expenditures. This study analyzes a sample of 547 companies from the information and communications technology (ICT) sector listed on the Frankfurt Stock Exchange in the period 2009-2018. The ICT sector was selected because it represents an industry with high R&D (research and development) expenditures. The results of the probit regression analysis made on 3,718 observations show that the capitalization of development expenditures is significantly positively related to the size and return on assets of the firm and negatively related to the age of the firm. Larger and more profitable firms are more likely to capitalize development expenditures, while older firms are less likely to capitalize development expenditures. Our results contribute to the literature in the field of positive accounting theory providing additional insights into factors associated with decisions to (non)capitalize development expenditures.
Keywords: capitalization, development expenditures, discretion, incentives, intangible assets
Published in DiRROS: 21.11.2023; Views: 359; Downloads: 227
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1868. Efficiency of novel photocatalytic coating and consolidants for protection of valuable mineral substratesAndreja Pondelak, Sabina Dolenec, Jonjaua Ranogajec, Luka Škrlep, Snezana B. Vučetić, Vilma Ducman, Andrijana Sever Škapin, 2019, original scientific article Abstract: In the process of protection and consolidation of valuable materials, the efficiency is the crucial property that needs to be considered. TiO2/ZnAl layered double hydroxide (LDH) coating and silicate- and carbonate-based consolidants were synthesized and proposed to be used for protection and consolidation of four porous mineral substrates: brick, stone, render and mortar. The photocatalytic efficiency of TiO2/ZnAl LDH coating, as well as consolidation efficiency of two consolidants, both applied on model substrates, were studied. The photocatalytic coating showed significant activity and performed well after the durability tests involving rinsing and freezing/thawing procedures. After treatment with both consolidants, a serious enhancement of consolidation of the used substrates was found. On the other hand, the application of TiO2/ZnAl LDH, as well as consolidants, caused negligible changes in the water vapour permeability values and in appearance of the porous mineral substrates, indicating a high level of compatibility.
Keywords: photocatalytic coating, consolidant, protection, conservation, porous substrate, cultural heritage
Published in DiRROS: 21.11.2023; Views: 366; Downloads: 224
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1869. Activation and repassivation of stainless steels in artificial brines as a function of pHEmir Mujanović, Bojan Zajec, Tadeja Kosec, Andraž Legat, Stefan Hönig, Gerald Zehethofer, Gregor Mori, 2019, original scientific article Abstract: When planning oil wells with stainless steel components, two possible reasons for depassivation have to be considered-chemical depassivation caused by acidizing jobs and mechanical depassivation caused by various tools and hard particles. The study explores conditions causing chemical activation of investigated steels and circumstances under which repassivation occurs after activation. The main focus of the study is to determine, how quickly various steels can repassivate under different conditions and to find pH values where repassivation will occur after depassivation. The investigated steels were ferritic (martensitic or bainitic) in the cases of 13Cr, 13Cr6Ni2Mo, and 17Cr4Ni2Mo, austenitic in the case of 17Cr12Ni2Mo, and duplex (austenitic and ferritic) in the case of 22Cr5Ni3Mo. Potentiodynamic experiments were employed to obtain electrochemical properties of investigated steels, followed by immersion tests to find ultimate conditions, where the steels still retain their passivity. After obtaining this information, scratch tests were performed to study the repassivation kinetics. It was found that repassivation times are similar for nearly all investigated steels independent of their chemical composition and microstructure.
Keywords: stainless steels, activation, repassivation
Published in DiRROS: 21.11.2023; Views: 353; Downloads: 161
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1870. Explore the briefcase - learning about raw materials through non-conventional teaching toolsKim Mezga, Petra Vrhovnik, Dragana Šolaja, Lidia Gullon, Alenka Mauko Pranjić, Ainara Garcia Uriarte, 2019, original scientific article Abstract: We live in a material world where the markets are flooded with all kinds of products. At the same time, we are facing a population growth, as well as a product demand growth. But, are we aware of the raw materials needed for our favourite daily products? In which part of the world are they extracted? Do we recognize the value chains from the mine to the product? And, where do these products end up after we use them? Many school curriculums include this topic only briefly, thus there is a need to raise awareness among youngsters about mining and raw materials in general. EIT RawMaterials funded by the European Commission, is the largest community dealing with raw materials in Europe. One of its main objectives is to raise awareness among general public about the raw materials and their indispensability, about the consequences of their uses, about the mining and production systems as well as about the utilization and recycling. Innovative and attractive pathways are employed in the process. One of the projects bringing raw materials and mining closer to pupils is the BRIEFCASE project. Using non - conventional teaching methods, tools and guided workshops, the project provides pupils with a unique hands - on experience. It draws their attention to raw materials and their applications and helps pupils recognize minerals in products we use every day. Besides emphasizing the importance of minerals in our everyday life and addressing sensible issues like conflict minerals, the consequences of our purchase decisions, the sustainability of mining operations and their environmental implications are also presented.
Keywords: Project BRIEFCASE, minerals, raising awareness, non-conventional teaching tools, EIT RawMaterials, award
Published in DiRROS: 21.11.2023; Views: 929; Downloads: 191
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