In this research, a cryogenically cooled, near-dry, wire-cut, electrical discharge machining (CNDWEDM) investigation was performed using air, oxygen, and helium gases mixed with the minimum quantity ...of dielectric water as the working medium to cut Inconel-718 alloy with a molybdenum wire tool. All the experiments have been performed using the –150 °C temperature of the liquid-nitrogen-cooled wire electrode. The comparative analysis of the wire wear ratio (WWR), and the material removal rate (MRR) have been performed using an L27 orthogonal array. The air/gas pressure, mixing water-flow rate, spark current, and pulse duration are considered as influencing parameters on the cutting characteristics. It was observed from a comparative analysis that the WWR of oxygen-mist and helium-mist CNDWEDM processes are 30.39 % and 27.91 % higher than air-mist CNDWEDM, respectively. The MRR of the oxygen-mist and helium-mist CNDWEDM processes are 7.09 % and 3.60 % higher than the air-mist CNDWEDM, respectively. The contributions of the process parameters on the MRR and WWR for all three dielectric media have also been illustrated. It was observed from scanning electron microscope (SEM) images that the crater size in the wire tool of the oxygen-mist CNDWEDM is higher than the crater-size of the wire in the air-mist and helium-mist CNDWEDM.
Kutjevo wine-hills are located on southern slopes of Papuk and Krndija mountains. The area is the most famous by production of Graševina grapes, but increasing share of other varieties cannot be ...ignored. Chardonnay is the most widespread variety all over the world, and in Požeško-slavonska county is represented by 5 % of total vineyards area. The aim of this research was to determine the influence of cluster thinning in Kutjevo wine-hills on maturation and must quality of Chardonnay grapes. Research was conducted in 2020 in Podgorje location (Kutjevo wine-hills). Experiment was established by a randomized block schedule in two treatments with three repetitions. Five vines in a row makes one repetition. The following parameters have been determined: sugar content and total acidity in grapes in period of one month before harvest, number of clusters per vine, cluster mass, mass of 100 berries, density, total acidity, volatile acidity, tartaric acid, malic acid, lactic acid, pH, reducing sugars, extract, glucose, fructose, glycerol, alfa amino nitrogen, ammonia nitrogen and potassium. Results have showed that cluster thinning had a significant influence on cluster mass and number of clusters per vine, but majority of chemical parameters were not significantly different between two treatments. Statistically significant difference was only in case of pH, lactic acid and ammonium nitrogen
Vinogorje Kutjevo smješteno na južnim obroncima Papuka i Krndije najpoznatije je po uzgoju grožđa Graševina, međutim ne smije se zanemariti i sve veća zastupljenost ostalih sorti. Chardonnay je najraširenija vinska sorta u svijetu, a u Požeško-slavonskoj županiji zauzima oko 5 % površine vinogradarskih nasada. Cilj ovog rada bio je odrediti utjecaj prorjeđivanja grozdova u vinogorju Kutjevo na kinetiku dozrijevanja grozdova, te kakvoću mošta kultivara Chardonnay. Istraživanje je provedeno tijekom 2020. godine na lokalitetu Podgorje (vinogorje Kutjevo), a pokus je postavljen po slučajnom bloknom rasporedu u dva tretiranja po tri repeticije. Repeticiju čini pet trsova u nizu. Ispitivani su sljedeći parametri: udio šećera i ukupna kiselost u grožđu u periodu mjesec dana prije berbe, broj grozdova po trsu, prosječna masa grozdova, te masa 100 bobica. U moštu su određeni sljedeći parametri: gustoća, ukupna kiselost, hlapiva kiselost, vinska, jabučna i mliječna kiselina, pH, reducirajući šećeri, ekstrakt, glukoza, fruktoza, glicerol, alfa amino dušik, amonijačni dušik, te kalij. Prorjeđivanje grozdova je statistički značajno utjecalo na broj grozdova, masu grozdova, pH vrijednost, mliječnu kiselinu i amonijačni dušik, dok kod drugih analiziranih parametara nije bilo statistički značajne razlike između pokusnih varijanata
Visokogorsko područje dinarskog krša obilježeno je raznolikošću reljefnih formi, koje su u kombinaciji s humidnom klimom i različitim odnosima dolomita i vapnenaca, posebice u pogledu brzine i načina ...trošenja, dodatni izvor varijabilnosti fiziografije tla. U Nacionalnom parku Risnjak dimenzijama se ističu dvije ponikve (Viljska ponikva - VIP i Velika ponikva - VP) gdje smo testirali hipotezu o postojanju značajnih razlika u fiziografiji površinskog dijela tla. Cilj je bio istražiti u kojoj se mjeri uzduž osojne i prisojne padine ponikve mijenjaju kemijske značajke površinskog dijela tla i očituje li se pri tomu i razlika između dviju ponikvi, s obzirom na postojanje razlike u njihovoj litološkoj građi i poziciji unutar gorskog masiva. Istraživanja su provedena tako da je u svakoj ponikvi postavljen transekt u pravcu ~sjever-jug preko dna ponikve, na komu je obavljeno uzorkovanje tla do dubine od 15 cm (ili do stijene, ako je tlo pliće). Pokazalo se da je u VIP izraženija diferencijacija prirode humusa u organičnom horizontu i da ona dobro korespondira s diferencijacijom vegetacije. U VP se fizička trošivost stijena (dolomitični supstrat) odražava na fiziografiji tla u obliku karbonatnosti i više pH-vrijednosti, koja u VIP raste od dna prema rubu ponikve, dok se u VP pH-vrijednost značajno ne mijenja uzduž padina. Na osojnoj ekspoziciji u VIP je udio organskog ugljika u tlu značajno veći (377 g kg–1) od udjela na prisojnoj ekspoziciji (97 g kg–1), pri čemu na osojnoj ekspoziciji udio organskog ugljika opada od dna prema rubu ponikve, a na prisojnoj ekspoziciji se očituje blagi rast. Za razliku od navedonoga, u VP udjel organskog ugljika ima obrnuti trend. Slične odnose i trendove pokazuje i udjel ukupnog dušika, osim pri dnu osojne padine u VIP, gdje je Ntot relativno nizak, a Corg relativno visok.
Zaključno, fiziografija tla dubokih gorskih ponikvi krša pod snažnim je utjecajem prirode stijena u pogledu dolomitičnosti. Tlo povrh dolomita i dolomitičnih vapnenaca obilježeno je karbonatnošću. U ponikvama u masivima čvrstih vapnenaca može se očekivati na njihovim osojnim padinama karakteristične trendove pH-vrijednosti tla te udjela organskog ugljika i ukupnog dušika zbog vrlo izraženog hidrotermičkog, odnosno bioklimatskog trenda. Na prisojnim ekspozicijama takvih ponikvi analogni trendovi s karakterističnim gradijentima izostaju, što korespondira i s izostankom prepoznatljivog vegetacijskog slijeda.
The high mountain area of the Dinaric karst is characterized by a variety of relief forms, which in combination with humid climate and different relationships of dolomite and limestone, especially in terms of rate and nature of weathering, are an additional source of variability of soil physiography. In the Risnjak National Park, two sinkholes stand out in terms of dimensions (Viljska ponikva - VIP and Velika ponikva - VP), where we tested the hypothesis of the existence of significant differences in the physiography of the surface part of the soil. The aim was to investigate the extent to which the chemical characteristics of the surface part of the soil change along the shady and sunny slopes of the sinkhole and whether the difference between the two sinkholes is evident, given the difference in their lithological structure (VIP is sinkhole in limestone and VP is sinkhole in dolomitic limestones and calcite dolomites) and positions within the mountain massif. The research was carried out in such a way that in each sinkhole a transect was placed in the direction north-south over the bottom of the sinkhole, on which soil sampling was performed to a depth of 15 cm (or to the rock, if the soil is shallower). Sampling was performed on rows of profiles in 5 replicates, which were placed perpendicular to the transect with a height difference of 10 m (Fig. 1). In each sinkhole, 22 rows of profiles were set up, on which 110 soil samples were collected, and the pH value, carbonate content, organic carbon content and total nitrogen content were measured on them. The research showed that on the shady slope in VIP, in addition to vertical vegetation differentiation, there is also a differentiation of the nature of humus in the organic horizon (hemimor, modermor, sphagnomor). This differentiation is much less pronounced in the VP, and on the sunny slope in both sinkholes it is almost absent. In VP, the physical weathering of rocks (dolomitic substrate) is reflected in the physiography of the soil in the form of free carbonate and higher pH values (Figs. 9 and 10). In VIP the pH rises from the bottom towards the edge of the sinkhole, both on the shady and sunny slope, while in VP the pH value does not change significantly, both along the shady and along the sunny slope. A recognizable factor in the spatial variability of carbonate content and pH value of this soil is phytopedoturbation in the form of tree felling and ejection of carbonate particles on the surface of the sinkhole slope, where they are exposed to gravitational and water erosion and further redistribution down the slope.
At the shady slope in VIP, the share of organic carbon in the soil is significantly higher (377 g kg – 1) than the share at sunny slope (97 g kg – 1). At the shady slope the share of organic carbon decreases from the bottom to the edge of the sinkhole (Fig. 11), and a slight increase is evident on the sunny slope. In VP, the mean values on the slopes and the trends of these shares on the slopes in relation to VIP have the opposite relationship (Fig. 12). Similar relatios and trends are shown by the share of total nitrogen (Fig. 13), except at the bottom of the shady slope in VIP. Here, the share of Ntot is relatively low, and the share of Corg is relatively high, so only in this part within both transects does C/N differ significantly from the remaining parts of the transects (Fig. 14).
In conclusion, the soil physiography of deep karst sinkholes is strongly influenced by the nature of the rocks in terms of dolomiticity. The soil above the dolomite and dolomitic limestones is marked by carbonates. In deep sinkholes in solid limestone massifs, characteristic trends of soil pH and the content of organic carbon and total nitrogen can be expected on their shady slopes due to a very pronounced hydrothermal and bioclimatic trend. Analogous trends with characteristic gradients are absent on the sunny slopes of such sinkholes, which corresponds to the absence of a recognizable vegetation sequence.
Cilj ovoga rada bio je utvrditi učinak gnojidbe dušikom (N) od 30 odnosno od 45 kg/ha, kao i trima komercijalnim dušičnim gnojivima, CaNO3 (15% N), KAN (27% N) i YaraMilaTM Cropcare (8:11:23), na ...agronomska svojstva: prinos, cijenu i vrijednost suhoga lista, kao i na šest morfoloških svojstava duhana tipa virdžinija. U poljski pokus, proveden u četiri okoline, bila su uključena tri hrvatska kultivara duhana. Gnojidba dušikom imala je signifikantan učinak samo na komponente prinosa: duljinu, širinu i površinu 9. lista, čije su vrijednosti kod gnojidbe s 45 kg N/ha bile za 2,2; 3,5 odnosno 5,8% veće u odnosu na gnojidbu s 30 kg N/ha. Tip korištenoga dušičnog gnojiva nije imao signifikantan učinak niti na jedno ispitivano svojstvo. Uzorak korelacija između morfoloških i gospodarskih svojstava bio je pod utjecajem okoline, kao i razine gnojidbe. Iako nije utvrđen učinak gnojidbe na gospodarska svojstva, signifikantno povećanje komponenata prinosa kod gnojidbe s 45 kg N/ha, u usporedbi s 30 kg N/ha, upućuje na višu razinu gnojidbe kao jamstvo osiguranja visokih i stabilnih prinosa te kvalitete osušenoga lista.
The aim of this study was to determine the effect of nitrogen (N) fertilization rate of 30 and 45 N kg/ha, as well as three commercial N fertilizers, CaNO3 (15% N), KAN (27% N) and YaraMilaTM Cropcare (8:11:23) on the agronomic traits: yield, price, and value, as well as six morphological traits of flue-cured tobacco. The field experiments, which included three Croatian tobacco cultivars, were conducted in four environments. Nitrogen fertilization had a significant effect only on yield components: length, width and area of the 9th leaf, whose values for fertilization with 45 kg N/ha were 2.2%, 3.5%, and 5.8% higher, respectively, compared to fertilization with 30 kg N/ha. The type of N fertilizer did not have a significant effect on any of the traits. The pattern of correlations between morphological and economic traits was influenced by the environment, as well as by the level of fertilization. Although no effect of fertilization level on economic traits was found, the significant increase in yield components at 45 kg N/ha compared to 30 kg N/ha suggests a higher level of fertilization as a guarantee of ensuring high and stable yields and quality of the cured leaf.
U ovom radu o osjetljivosti tla na propuštanje onečišćivača i ranjivosti podzemne vode na onečišćenje s površine tla, korišten je dio rezultata petogodišnjih istraživanja nizinskog područja ...Međimurske županije, Vidaček i sur. 2008. U donjem dijelu Međimurja ima najviše obradivih površina. S agroekološkog gledišta, to su površine potencijalno visokog stupnja onečišćenja agrokemikalijama. Kvartarne sedimente pokrivaju automorfna i hidromorfna tla različite teksture, strukture i propusnosti za vodu. Vodonosni horizont nizinskog područja županije se sastoji od dobro granuliranog šljunka s različitim postotkom pijeska. Od ukupno 42.893,5 hektara poljoprivrednog zemljišta, nalazimo sljedeće klase osjetljivosti tla na potencijalno propuštanje onečišćivača u podzemnu vodu: tla II. klase slabe osjetljivosti 1.496,5 ha, tla III. klase umjerene osjetljivosti 6.157,6 ha i tla IV. klase jake osjetljivosti 20.311,9 hektara. Vidi kartu u prilogu na kraju teksta. Najplići otvoreni vodonosni horizont je u nizinskom području županije jako ranjiv na onečišćenje s površine tla. Godišnje izmjerene količine procijeđene vode iz lizimetara, sa ili bez onečišćivača u pet godišnjem razdoblju, variraju od 75,8-281,5 mm. Količine ispranog mineralnog dušika su najveće u natapanju nasada jabuka 13,5 do 47,7 kg N/ha. Pri uzgoju ratarskih kultura, dominantno kukuruza, te vrijednosti variraju u vrlo širokom rasponu od 7,2 kg N/ha do 30,5 kg N/ha.
Cilj istraživanja bio je utvrditi utjecaj količine dušika i sumpora primijenjenih u dvije prihrane na prinos i sastavnice prinosa uljane repice u agroekološkim uvjetima Podravine. Istraživanje je ...provedeno na lesiviranom tlu tipičnom na pijesku na lokaciji Dinjevac tijekom 2015./2016. godine. U istraživanje su bile uključene tri varijante prihrane: 1) Kontrola - 70 kg/ha N (KAN), 2) PETROKEMIJas - 66 kg/ha N i 84 kg/ha S i 3) Prihrana prema rezultatima analize tla - 105 kg/ha N (KAN). Primjenom 105 kg/ha N u obliku KAN-a u prihrani signifikantno je povećan prinos sjemena za 0,68 t/ha i prinos ulja za 0,21 t/ha u odnosu na prihranu sa 70 kg/ha N (KAN). Istraživana količina sumpora (84 kg/ha) uz 66 kg/ha dušika (PETROKEMIJas) nije značajno utjecala na prinos sjemena i ulja. Primjenom 105 kg/ha N (KAN) te 66 kg/ha N uz 84 kg/ha S (PETROKEMIJas) značajno je povećana visina biljke, broj plodnih grana po biljci i broj komuški po biljci u odnosu na kontrolu (70 kg/ha N). Istraživane količine dušika i sumpora u prihrani nisu imale statistički značajan utjecaj na udio ulja, dužinu komuške, broj sjemenki u komuški i masu 1000 sjemenki.
U ovom se radu istražuju učinci različitih intenziteta turističke djelatnosti na aktivnost ugljika, dušika i enzima u tlu u suptropskom urbanom parku u Kini. Udjel organskog ugljika tla (SOC), ...ukupnog ili totalnog ugljika (TN), otopljenog organskog ugljika (DOC), otopljenog organskog ugljika (DON), nitratni oblik dušika (NO3-–N) i amonijski oblik dušika (NH4+–N). SOC, TN, DOC, NO3-–N i NH4+–N u tlu značajno je reduciran kao posljedica turističkih djelatnosti. Aktivnost pojedinih enzima, uključujući sukrazu, katalazu, ureazu i hitinazu, također je reducirana. S iznimkom NH4+-N, svi indikatori ugljika-dušika u tlu pokazali su pozitivnu korelaciju s aktivnosti četiri enzima u tlu. Rezultati ukazuju da turistička djelatnost dovodi do degradacije tla u suptropskom urbanom parku te da je tlo u oštećenim područjima potrebno često preokretati i dodavati više organskih gnojiva.
This study investigated the effects of different tourism disturbance intensities on carbon, nitrogen, and enzyme activities of soil in a subtropical urban park, China. The contents of the soil organic carbon (SOC), total nitrogen (TN), dissolved organic carbon (DOC), dissolved organic nitrogen (DON), nitrate nitrogen (NO3-–N), and ammonium nitrogen (NH4+–N) in the soil were significantly reduced by tourism disturbance. The activities of some soil enzymes, including sucrase, catalase, urease, and chitinase, were also reduced. Except for NH4+–N, the soil carbon–nitrogen indicators all exhibited significant positive correlations with the four soil enzyme activities. The results indicated that tourism disturbance caused soil degradation in the subtropical urban park. Therefore, the soil in damaged areas should be frequently turned up, and more organic fertilizers should be added.
Tretman kontinuiranim protokom plinovitog dušika (N2) produžuje trajnost sirovog mlijeka tijekom hladnog skladištenja. Utjecaj tretmana dušikom na ukupni antioksidativni kapacitet (TAC) i sadržaj ...askorbinske kiseline (AA) u sirovom mlijeku određivan je tijekom hladnog skladištenja. TAC sirovog ili deproteiniziranog mlijeka određivan je pomoću ABTS i DPPH metode, dok je sadržaj L (+) - AA u sirovom mlijeku određen kromatografski i to nakon 0., 4. i 7. dana skladištenja na 6±1 °C. TAC utvrđen pomoću ABTS metode snizio se tijekom hladnog skladištenja s 472,33±16,70 na 369,47±62,06 μM TEAC, dok je TEAC izmjeren pomoću DPPH metode pao s 13,30±0,84 na 8,20±0,66 μM. TAC sirovog mlijeka određen ABTS metodom smanjio se nakon 4-dnevnog skladištenja, međutim, ostale izmjerene vrijednosti bile su statistički jednake za N2-tretirane uzorke tijekom 7-dnevnog skladištenja. Sadržaj askorbinske kiseline (AA) sirovog mlijeka kretao se u rasponu od 14,06 do 10,76 mg/L tijekom skladištenja, te N2 tretman nije značajno utjecao na sadržaj AA. Deproteiniziranjem je značajno smanjena TAC vrijednost uzoraka mlijeka, te u slučaju mjerenja pomoću ABTS metode iznosilo je oko 47,50 % za kontrolne uzorke hladno skladištenih tijekom četiri dana, a 11,67 % za deproteinizirano sirovo mlijeko tretirano N2. Zaključno, tretman protočnim N2 kroz gornji dio posude u kojoj se skladišti mlijeko također je pokazao značajan zaštitni učinak na antioksidativne sastojke sirovog mlijeka tijekom hladnog skladištenja.
The aim of this experiment was to find out dynamics of the nitrogen (N) content in aboveground phytomass on the turf after fertilization of different forms of fertilizers under non–irrigated ...conditions. The experiment was carried out in warm and dry conditions in the area of Nitra (Slovak Republic). There were included 7 treatments: 1. Without fertilization, 2. Saltpetre with dolomite, Superphosphate, Potassium salt, 3. Turf fertilizer 15–3–8 (+ 3MgO + 0.8Fe + 18S), 4. Slow release fertilizer SRF NPK 14–5–14 (+ 4CaO + 4MgO + 7S), 5. Controlled release fertilizer Duslocote NPK (S) 13-9-18 (+ 6S), 6. Organic fertilizer Condit (5-1-1) and 7. Organic fertilizer Veget (3-2-1). In the begging of the seasons fertilizing by controlled release fertilizer Duslocote NPK (S) 13-9-18 (+ 6S) had a slow onset of action. The opposite trend had use of organic fertilizer Condit (5-1-1) on nitrogen content in aboveground turf phytomass. The nitrogen concentration was statistically higher in variants fertilized with inorganic fertilizer and organic fertilizer Condit (5-1-1) (33,727 mg*kg-1 – 36,737 mg*kg-1) as a non-fertilized turf (28,446 mg*kg-1). Higher nitrogen content in aboveground phytomass was after application of organic fertilizer Condit (5-1-1) into the turf in comparison with fertilization inorganic fertilizers.
Examines the risks associated with the release of excessive nitrogen into the environment (climate change, depletion of the ozone layer, air pollution, water pollution, loss of biodiversity, ...deterioration of soil quality). The report also examines the uncertainty associated with the ability of nitrogen to move from one ecosystem to another and cause 'cascading effects'. In addition to better management of nitrogen risks at the local level, there is a need to consider the global risks associated with the continued increase in nitrous oxide concentrations and to prevent excess nitrogen in all its forms by developing cost-effective strategies for all its sources.
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