Razkrivanje delovanja vadozne cone alpskih kraških vodonosnikov: nova spoznanja iz sledilnega poskusa v jamskem sistemu Migovec (Julijske alpe, SZ Slovenija)

The aquifers of alpine karst and high karst plateaus are abundant water resources. They are difficult to characterise due to their complex, partly glaciokarstic, evolution in active tectonic environments, and an unsaturated zone up to two kilometres thick. We present and discuss the results of a tracing test in the alpine karst of the Julian Alps (Slovenia), more precisely in the Migovec System, the longest cave system in Slovenia (length = 43 km, depth = 972 m). The cave extends below a mountain ridge that separates the Soča and Sava Valleys, thus forming a topographic divide between the Adriatic and Black Sea basins, which gives the test greater regional significance. In early September 2019, three kilograms of uranine were injected into a perched lake in a remote part of the system, approximately 900 metres below the plateau and 100 metres above the low water table. All known springs in the valleys on either side of the mountain were monitored by manual or instrumental sampling and a field fluorometer. Due to the unexpectedly dry season, no tracer was detected at any site for two months until a heavy rainfall event in early November. Subsequently, about 60-65 % of the tracer mass appeared within 60 hours in the Tolminka River. No tracer was detected at other sites, either becauseit was not present or because it was highly diluted. The study suggests that the lake containing the tracer is bypassed by the vadose flow and that the tracer was only mobilised during large events when the lake became part of the epihreatic flow. The linear peak flow velocity from the injection site to the Tolminka Spring was only about 1.7 m/h. However, assuming that the tracer was only mobilised by the large rain event, the velocity would be 70 m/h. The study highlights the challenges and pitfalls of water tracing in alpine karst systems and suggests ways to avoid them.Vodonosniki visokega in alpskega krasa so pomembni viri pitne vode. Dinamika toka skozi te vodonosnike je izjemno kompleksna, saj je njihova struktura posledica večfaznega, deloma glaciokraškega razvoja v tektonsko aktivnem območju. Debelina vadozne cone visokogorskih kraških vodonosnikov lahko presega dva kilometra. V članku predstavljamo in obravnavamo rezultate sledilnega poskusa v alpskem krasu Julijskih Alp (Slovenija), natančneje v Sistemu Migovec, najdaljšem jamskem sistemu v Sloveniji (dolžina = 43 km, globina = 972 m). Jama se razteza pod gorskim grebenom, ki ločuje dolini Soče in Save ter tako tvori topografsko ločnico med jadranskim in črnomorskim bazenom. V začetku septembra 2019 smo injicirali tri kilograme uranina v jezero Colarado, približno 900 metrov pod planoto in 100 metrov nad nizkovodnim nivojem podzemne vode. Znane izvire v dolinah na obeh straneh razvodnice smo spremljali z ročnim ali samodejnim vzorčenjem in terenskim fluorometrom. Do izjemnega padavinskega dogodka v začetka novembra sledila nismo zaznali na nobenem od opazovanih mest. Ob dogodku se je sledilo zanesljivo pojavilo le na vzorčevalnem mestu v zgornjem toku Tolminke, kjer je po grobi oceni v 60 urah prešlo 60-65 % mase sledila. Na drugih mestih je bil dvig koncentracije, zaradi odsotnosti sledila ali prevelikega razredčenja, premajhen, da bi lahko potrdili pojav sledila. Rezultati kažejo, da vadozni tokovi ob manjših dogodkih niso sprožili zaznavnega prenosa sledila, pač pa je do tega prišlo šele, ko je epifreatični tok ob izjemnem dogodku dosegel nivo vodnih teles s sledilom. Če upoštevamo celoten čas od injiciranja do zaznave sledila, je navidezna hitrost potovanja 1,7 m/h, ob predpostavki, da je sledilo mobiliziral novembrski padavinski dogodek, pa je navidezna hitrost 70 m/h. Študija opozarja na izzive in pasti pri sledenju vode v alpskih kraških sistemih ter predlaga načine, kako se jim izogniti

Use of palladium immobilized on polyHIPE polymer as a catalyst for Suzuki reaction

V magistrskem delu smo raziskali vezavo paladija na polipiridinski trdni nosilec in njegovo uporabo kot obnovljivega katalizatorja za reakcije pripajanja. Pripravili smo heterogeni paladijev katalizator, tako da smo na polyHIPE kopolimer 4-vinilpiridina in divinilbenzena vezali paladij v obliki Pd(OAc)2. Na polimer se je vezalo 6,1% Pd oziroma 0,57 mmol Pd/g nosilca, analiza s SEM je pokazala, da se morfologija ohrani. Tak katalizator smo nato testirali na primeru Suzuki reakcije C-C pripajanja. Kot modelno reakcijo smo izbrali reakcijo med jodobenzenom in fenilborovo kislino. Testirali smo uspešnost Suzuki reakcije s tem katalizatorjem v različnih topilih, kjer se je najbolje obnesel etilen glikol monometil eter (EGME), kot bazo pa smo uporabili kalijev karbonat. Preverili smo vpliv količine katalizatorja na reakcijo s tremi različnimi molskimi deleži paladija (2,52 mol%, 1,26 mol% in 0,63 mol%) in primerjali rezultate s paladijevim acetatom. Po pričakovanjih je reaktivnost reakcije padala z nižanjem količine katalizatorja, paladijev acetat pa je bil ob enakem deležu paladija bolj aktiven od heterogenega katalizatorja. Raziskali smo tudi učinkovitost te metode na različnih substratih. Uporabili smo različno substituirane jodobenzene z elektron-donorskimi in elektron-akceptorskimi skupinami, med drugim tudi s karboksilno in aminsko skupino, in ugotovili, da reakcija bolje poteka z elektron-akceptorskimi substituenti na jodobenzenih, razen v primeru karboksilne kisline, kjer je reakcija kljub elektron-akceptorskemu značaju skupine potekala počasneje. Uporabili smo tudi nekaj različnih fenilborovih kislin, kjer je reakcija bolje potekala z elektron-donorskimi substituenti na feniliborovih kislinah, kljub temu pa se je najbolje obnesla nesubstituirana fenilborova kislina. Izkoristki produktov so bili od 66% do 93%, kjer je bila pretvorba popolna in niso potrebovali čiščenja s kolonsko kromatografijo ter med 55% in 66% pri produktih, ki jih je bilo zaradi nepopolne pretvorbe potrebno prečistiti. Naš katalizator smo poskusili tudi reciklirati in ga ponovno uporabiti v zaporednih reakcijah. Po koncu reakcije smo z razklopom polimera in sledečo atomsko absorpcijsko spektrometrijo ugotovili, da se med reakcijo paladij iz polimera spira, vendar največ v prvem koraku. Ko smo polimer uporabili za nadaljnje reakcije, je bilo spiranje manjše. Postopek smo izboljšali z vmesno regeneracijo oziroma z dodatkom diklorometana po reakciji. V prvem primeru smo nadomestili izgubljeni paladij, tako da smo polimer ponovno mešali v raztopini Pd(OAc)2, v drugem primeru pa smo z dodatkom manj polarnega topila po koncu reakcije ponovno vezali paladij, ki se je tekom reakcije raztopil. Poleg določitve količine paladija na polimeru smo posneli tudi SEM slike katalizatorja pred in po reakciji, da smo preverili strukturo polimera. Z izboljšano metodo smo zmanjšali izgubo paladija in ohranili reaktivnost heterogenega katalizatorja. Na koncu smo izvedli še sintezo bifenila direktno iz fenilborove kisline v enem koraku, tako, da smo raztopini fenilborove kisline dodali jod, kalijev karbonat in paladijev katalizator ter 24 h mešali pri 50 ºC.In this master thesis we studied the immobilization of palladium on a polypyridine solid support and its use as a renewable catalyst for coupling reactions. We prepared the heterogeneous palladium catalyst, by immobilizing palladium in the form of Pd(OAc)2 onto a polyHIPE copolymer of 4-vinylpyridine and divinylbenzene. The amount of Pd immobilized on the polymer was 6,1% or 0,57 mmol Pd/g, while SEM analysis showed, that the morphology of the material remained unchanged. We then tested this catalyst for the Suzuki C-C coupling reaction. As a model reaction we selected the reaction between iodobenzene and phenylboronic acid. We tested the reactivity of the Suzuki reaction using our catalyst in different solvents, where the best solvent for the reaction turned out to be ethylene glycol monomethyl ether (EGME) and as base we used potassium carbonate. We checked the effect of the amount of catalyst on the reaction using three different mol% of palladium (2,52 mol%, 1,26 mol% and 0,63 mol%) and compared that to palladium acetate. As expected the reactivity of the reaction was lower while using less catalyst and palladium acetate showed a higher activity than the heterogeneous catalyst with the same used amount. We also studied the efficiency of this method for different substrates. We used differently substituted iodobenzenes with electron-donating and electron-withdrawing groups, as among them carboxyl and amine groups, and we found that the reaction proceeds better with electron-accepting substituents on iodobenzenes, except in the case of carboxylic acid, where the reaction proceeded slower despite the electron-accepting nature of the group. We also used a few different phenylboronic acids, where the reaction proceeded better with electron-donating groups on phenylboronic acids, even though the unsubstituted phenylboronic acid turned out the best. The yields of products were 66-93% in the case where the conversion was quantitative and no purifying by column chromatography was required and 55-66% for products that had to be purified because of incomplete conversion. We also tried to recycle our catalyst and reuse it in subsequent reactions. At the end of the reaction we used digestion of the polymer and subsequent atomic absorption spectroscopy to find out that the palladium was leeching off of the polymer during the reaction, but mostly during the first use. With subsequent uses the leeching was much lower. We improved the procedure by regenerating the catalyst between reactions or by adding dichloromethane after the reaction. In the first case, we replaced the lost palladium by mixing the catalyst in a solution of Pd(OAc)2 again and in the second case we used a less polar solvent at the end of the reaction to rebind the palladium that dissolved during the reaction. Besides determining the amount of palladium on the polymer, we also took SEM pictures of the catalyst before and after the reaction to check the structure of the polymer. In the end we performed the synthesis of biphenyl directly from phenylboronic acid in one step, by adding iodine, potassium carbonate and palladium catalyst to a solution of phenylboronic acid and mixing for 24 h at 50 ºC

Controlled growth of ZnO nanoparticles using ethanolic root extract of Japanese knotweed

Synthesis of zinc oxide (ZnO) nanoparticles (NPs) was mediated by plant extracts to assist in the reduction of zinc atoms during the synthesis and act as a capping agent during annealing.The preparation used ethanolic extracts from the roots of Japanese knotweed (Fallopia japonica). Two major outcomes could be made. (i)A synergistic effect of multiple polyphenolic components in the extract is needed to achieve the capping effect of crystallite growth during thermal annealing at 450 °C characterized by an exponential growth factor (n) of 4.4 compared to n = 3 for bare ZnO. (ii) Synergism between the ZnO NPs and plant extracts resulted in superior antimicrobial activity against both Gram-positive bacteria, e.g., Staphylococcus aureus, and Gram-negative bacteria, e.g., Escherichia coli and Campylobacter jejuni. The materials were also tested for their antimicrobial activity against S. aureus under ultraviolet (UV) illumination. Also here, the photocatalyst prepared with plant extracts was found to be superior. The residues of the plant extract molecules on the surface of the catalyst were identified as the main cause of the observed differences, as proved by thermal gravimetry. Such a preparation using ethanolic extract of Fallopia japonica could serve as a more controlled synthesis of ZnO and potentially other metal oxides, with low environmental impact and high abundance in nature

Nickel-decorated ZnO nanoparticles for effective solar reduction of hexavalent chromium and removal of selected pharmaceuticals

The efficient visible light driven photocatalytic reduction of hexavalent chromium, Cr(VI) was demonstrated using ZnO nanoparticles (NPs) decorated with oxo-clusters of transition metals. The ZnO NPs were synthesized by a facile one-pot solvothermal synthesis followed by a fast microwave-assisted (MW) grafting of transition metals on the surface of NPs. Nickel was found to be the most active transition metal for photocatalytic activity as demonstrated by reduction of Cr(VI) to Cr(III). The optimally grafted samples contained 0.5 wt% Ni and increased photocatalytic activity by almost one-fold. The oxo-clusters did not enter the lattice of ZnO but rather resided on the surface and their efficient bonding to the ZnO surface was proved by Raman, TEM and X-Ray absorption techniques. Influence of MW power was studied and shown that excessive power load leads to formation of elongated structures of ZnO which decreases the photocatalytic activity. It was demonstrated by measuring fluorescent radical products that electrons, efficiently transferred via oxygen, were the main active species in combination with the unchanged oxidation power of holes and • OH in the grafted samples. The applicability of the materials was tested in immobilized plug flow photoreactor system degrading five pharmaceuticals simultaneously where their long-term use was shown

Reusable Pd-PolyHIPE for Suzuki–Miyaura Coupling

Palladium was immobilized on a highly porous copolymer of 4-vinylpyridine and divinylbenzene (polyHIPE─poly(high internal phase emulsion)) using palladium(II) acetate to obtain PolyPy-Pd with 6.1 wt % or 0.57 mmol Pd/g. The immobilized catalyst was able to catalyze the coupling of iodobenzene and phenylboronic acid in ethylene glycol monomethyl ether/water (3:1) within 4 h at rt and complete conversion was observed when 2.5 mol % of Pd per PhI was used. The reaction tolerated a wide range of substituents on the aromatic ring. Iodobenzene derivatives with electron-withdrawing substituents showed higher reactivity, while the opposite was true for the phenylboronic acid series. The polyHIPE-supported Pd catalyst was also used for the direct conversion of phenylboronic acid to biphenyl through an iodination/coupling reaction sequence. The recyclability of the heterogeneous catalyst was also optimized, and by finding a suitable combination of solvents for the loading of Pd, the reaction, and the isolation of the product, the solid-supported catalyst was completely regenerated and used in the next reaction with the same activity

Nickel-decorated ZnO nanoparticles for effective solar reduction of hexavalent chromium and removal of selected pharmaceuticals

The efficient visible light driven photocatalytic reduction of hexavalent chromium, Cr(VI) was demonstrated using ZnO nanoparticles (NPs) decorated with oxo-clusters of transition metals. The ZnO NPs were synthesized by a facile one-pot solvothermal synthesis followed by a fast microwave-assisted (MW) grafting of transition metals on the surface of NPs. Nickel was found to be the most active transition metal for photocatalytic activity as demonstrated by reduction of Cr(VI) to Cr(III). The optimally grafted samples contained 0.5 wt% Ni and increased photocatalytic activity by almost one-fold. The oxo-clusters did not enter the lattice of ZnO but rather resided on the surface and their efficient bonding to the ZnO surface was proved by Raman, TEM and X-Ray absorption techniques. Influence of MW power was studied and shown that excessive power load leads to formation of elongated structures of ZnO which decreases the photocatalytic activity. It was demonstrated by measuring fluorescent radical products that electrons, efficiently transferred via oxygen, were the main active species in combination with the unchanged oxidation power of holes and $^•$OH in the grafted samples. The applicability of the materials was tested in immobilized plug flow photoreactor system degrading five pharmaceuticals simultaneously where their long-term use was shown

Geographical Terminological Dictionary

The Geographical Terminological Dictionary contains 8,922 geographical terms and covers a total of nineteen geographical disciplines. It provides detailed definitions of terms, which are divided into individual disciplines, in particular: general geography, mathematical geography, cartography, geomorphology, climate geography, hydrogeography, soil geography, biogeography, population geography, rural geography, industrial geography, traffic geography, tourism and recreation geography, karst geography, settlement geography, landscape ecology, and environmental protection. Information on part-of-speech, declension, pronunciation, variants, synonyms, conceptually related terms, and English equivalents is also provided. This dictionary was published as a printed book: Bufon, Milan; Černe, Andrej; Gams, Ivan; Humar, Marjeta; Jeršič, Matjaž; Jurinčič, Igor; Kladnik, Drago; Kokole, Vladimir; Komac, Blaž; Košmrlj-Levačič, Borislava; Krevs, Marko; Kunaver, Jurij; Lovrenčak, Franc; Natek, Milan; Ogorelec, Breda; Orožen Adamič, Milan; Pavšek, Miha; Perko, Drago; Plut, Dušan; Radinja, Darko; Ravbar, Marjan; Smrekar, Aleš; Špes, Metka; Zorn, Matija. Geografski terminološki slovar. Ljubljana: Založba ZRC, ZRC SAZU, 2005. ISBN 961-6500-92-9