Organske reakcije u vodi Dajana Gašo-Sokač; Valentina Bušić; Dora Zobundžija ...
Kemija u industriji; časopis kemičara i tehnologa Jugoslavije,
09/2023, Volume:
72, Issue:
9-10
Journal Article
Peer reviewed
Open access
Velik je izazov provoditi organske reakcije u vodi. U posljednjem desetljeću broj znanstvenih istraživanja koja se bave proučavanjem vode kao zelenog otapala nastavio je eksponencijalno rasti. Osim ...što je jeftina, voda nije štetna za okoliš, a ponekad daje potpuno neočekivanu reaktivnost u kemijskim reakcijama. Postoji širok raspon organskih reakcija koje se mogu odvijati u vodi: od uobičajenih oksidoredukcijskih reakcija, reakcija koje uključuju karbokatione, pericikličkih reakcija, reakcija prijelaznih metala itd. Organske reakcije u vodenom mediju primjenjuju se u kemiji ugljikohidrata i kemijskoj modifikaciji biomolekula. U novije vrijeme voda se upotrebljava kao medij u mikrovalnoj sintezi. Ovaj pregledni rad daje uvid u važnost ovog područja budući da se organske reakcije u vodi kao otapalu odvijaju po principima zelene kemije.
This paper presents research results of a Roman road on Mountain Konjuh (Bosnia and Herzegovina). It documents the remnants of road communications in modern settlements in Konjuh municipality. We ...documented the length of the discovered road sections (completely or partially preserved), their width, slope angle, embankment height, and stone type on the cleaned parts. According to the found remains, we concluded that this Roman road went from the direction of Olovo, and that it passed the Stara Karaula pass and over the slopes of Konjuh and then arrived at Kladanj. One leg of this road led from Kladanj through the settlements of Plahovići and Pauč to Pekara locality (today known as Muška voda), in the river valley of Drinjača River. We performed its georeferencing according to the found marks of the Roman road, recording them and studying the Austro-Hungarian maps.
Čedo Antolić, uvaženi kantautor duhovnih pjesama, rođen 1951. u Zagrebu, gdje je i umro 2019., kreće se unutar katoličkog religioznog vokabulara, ali ima osebujnu metaforiku. U njoj se ističe često ...spominjanje vode, i to u raznolikim vidovima – kao potok, rijeku, more, kišu, kap – i to unutar svoje tipične teme obraćanja Bogu, i u tom obraćanju razmatranja pitanja od egzistencijalne važnosti. Imaginarij Čede Antolića povezan s vodom veoma je bogat, a ovdje su analizirani neki njegovi vidovi, primjerice analogija između vode i svjetla, kao Božjeg atributa. Veoma je važno iskustvo vode kao medija očišćenja, koja to može biti bilo kao kiša što pada, bilo kao potok/rijeka u koju se ulazi, bilo kao more kojim se putuje. Voda se tako otvara u svojoj konotaciji u raznim smjerovima, pa je tako plodna metafora rijeke kao životnog puta i/ili protoka vremena, koja se može identificirati s cestom/ulicom. Niz metafora doseže na taj način alegorizaciju pa tako život (kao i rijeka ili cesta) ima početak čijoj se čistoći možemo pokušati vratiti, a ima i također i svoj kraj, kao ušće/smrt, odnosno susret s Bogom na kraju putovanja. Bog je istovremeno i prisutan i odsutan, on je i cilj i pratilac, dodir nadnaravnog u postojanju koje se nastoji transcendirati. Budući da je vjera istinita negdje drugdje, a u sadašnjem životu još nije ostvarena, putovanje se može shvatiti i kao lutanje, a voda ima negativne konotacije nečega što troši čovjeka ili ga pak odmiče od zajedništva s Bogom. Ulica, koja je zapravo rijeka, otkriva se dvostrukom ključu – ona je istovremeno mjesto lutanja za one koji ne poznaju Boga, kao i mjesto molitve za onoga koji ga poznaje; ona je i noć i dan – svijetla za one koji su u toj ulici kao u rijeci što ima siguran put, mračna za one koji taj put ne poznaju. Ta je ulica i mjesto u kojem pjesnik pjeva, pa se tako teme vode, života, vjere i umjetnosti povezuju.
Čedo Antolić, a respected singer-songwriter, born in 1951 in Zagreb, where he died in 2019, moves within the Catholic religious vocabulary, but has a distinctive metaphoric system. He emphasizes the frequent mention of water in various forms - such as a stream, river, sea, rain, drop - and within its typical theme of addressing God, and in that discusses issues of existential importance.
The imagery of Čedo Antolić related to water is very rich, and some of its aspects are analyzed here, for example the analogy between water and light, as an attribute of God. The experience of water as a medium of purification is very important, which can be presented either as rain that falls, or as a stream or river that is entered, or as the sea through which one travels. Fruitful metaphor of the river develops as a way of life or the flow of time, which can be identified with a road or street. A number of metaphors thus reach allegory, so that life - like a river or a road - has a beginning, which purity we can try to return to, and it also has its end, as estuary or death, when the poet is meeting God at the end of his journey.
God is both present and absent, he is both the goal and the companion; God is the touch of the supernatural in the existence, but existence also seeks to transcend life. Since faith is true elsewhere, and not yet realized in the present life, travel can also be understood as wandering, and water has negative connotations of something that consumes man or moves him away from communion with God. The street, which is actually a river, is at the same time a place of wandering for those who do not know God, as well as a place of prayer for one who knows him; it is both night and day - bright for those who are in that street, dark for those who do not know that path. The street - the river - is also the place where the poet sings, so the themes of water, life, religion and art are intertwined.
Applying geochemical proxies as measure for the weathering intensity of paleosols and sediments such as loess, the Quaternary scientist is confronted with various element ratios that have been ...proposed in literature. This paper gives an overview on the principle of geochemical weathering indices. Different types of indices are evaluated with respect to the suitability for loess–paleosol sequences, regarding the special characteristics of this type of sediments and paleosols. Case examples in this study are key sections in Southeastern and Eastern Europe: the loess–paleosol sequences Batajnica/Stari Slankamen (Serbia), Mircea Voda (Romania) and Stary Kaydaky (Ukraine), which represent archives of the Late and Mid-Pleistocene climate change of the region. Considering element behavior during weathering or diagenesis, the Chemical Proxy of Alteration (CPA) – i.e. the molar ratio Al
2O
3/(Al
2O
3 + Na
2O) × 100 – is proposed as the most appropriate index for silicate weathering. The CPA was evaluated against commonly used weathering indices including the “Chemical Index of Alteration” (CIA), the “Chemical Index of Weathering“ (CIW), the “Plagioclase Index of Alteration“ (PIA), the Index B of Kronberg and Nesbitt, and the Ba/Sr and Rb/Sr ratio. Depth profiles of “Sr-type indices” (e.g. Ba/Sr, Rb/Sr) are likely to be influenced by the dynamics of secondary carbonate. On the other hand, common “Na-type indices” (e.g. CIA, PIA, CIW) may suffer from uncertainties in separating carbonate–Ca from silicate–Ca or from biases due to K-fixation (illitization). The CPA is insensitive against such effects. Additionally, using the CPA (as with other Na-type indices) provides the possibility to evaluate the homogeneity of the parent material regarding the relevant host minerals via the A–CN–K diagram.
Seismically active fault zones receive a great deal of attention due to their potential for quantification of seismic hazards. Zones with low slip rates pose a challenge, however, since their poor ...topographic expression is related to difficulties in the quantification of fault movement. This study focuses on the Dobrá Voda Depression, an area with the highest level of seismic activity in the Western Carpathians. The Quaternary tectono-sedimentary evolution of the small intramontane basin was investigated with the use of facies analysis of cores, dated with the use of cosmogenic nuclide depth profiles (10Be, 26Al and 36Cl), together with 26Al/10Be burial dating and radiocarbon dating. A set of archived boreholes and geoelectric survey data was used for the correlation of results with those from new boreholes across the depression. Four facies associations were distinguished: (FA1) Colluvial deposits that comprise subaerial debris flows and mudflows; (FA2) Fluvial deposits with high sediment supply: accommodation ratio, composed mostly of sandy-gravelly channel fill facies; (FA3) Fluvial deposits with low sediment supply: accommodation ratio, consisting mostly of floodplain muds, overbank heterolithic facies and minor sandy-gravelly channel fills; and (FA4) Swamp deposits, which are mostly made up of peat. Geochronological results suggest that the studied part of FA3 was deposited before 1.0 Ma due to a rise in the base level following a major incision event. Overbank-dominated deposits of FA3 covered an incision surface, resulted in a difference of ca. 65 m of elevation of these strata, which represents the minimal thickness of FA3. The second phase of incision was related to reactivation of Miocene normal faults resulting in further topographic differentiation. The initiation of fault activity is recorded by the deposition of colluvial FA1 before ca. 250 ka. FA2 accumulated between ca. 160 and 100 ka, mostly at the toes of slopes bounding the fault scarps on the basin margins. The last documented phase of evolution represents an increase of accommodation, which was connected to the deposition of Holocene peat in swamps as well as floodplain muds of FA4 above FA2. The observed settings imply that variation between incision and accumulation in a scale of hundreds of thousands of years is characteristic for low relief tectonically active zones. The presented research demonstrates the significance of sedimentological analysis for reconstruction of tectonic evolution in areas with low slip rate activity.
•Depth profile exposure dating of 10Be, 26Al and 36Cl applied together with 14C dating.•Accumulation in the area was interrupted by two phases of incision at >1 Ma and 250–100 ka.•Reactivation of normal faults and topographic differentiation during 250–100 ka.•Overbank/channel fill ratio and alluvial/colluvial deposition changes driven by base level shifts.•Accumulation-incision alteration characteristic for moderate relief tectonically active zones.
Uporaba mikroorganizama u obliku biofilma sve je češći način biološke obrade jer reaktori s biofilmom na nosačima daju zadovoljavajuće rezultate obrade otpadnih voda različitog podrijetla te se ...intenzivno istražuju i unaprjeđuju. Dizajn uređaja za obradu otpadnih voda, unaprjeđenje postojećih reaktora i njihove učinkovitosti te rješavanje problematičnih točaka pri obradi otpadnih voda olakšano je matematičkim modeliranjem pomoću dostupnih modela, ovisno o njegovoj svrsi. Modeliranje u praksi zahtijeva promišljanje i prilagodbu modelu i njegovim pretpostavkama te postaje nezamjenjiv dio modernih istraživanja i izgradnje sustava za obradu otpadne vode.
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