Analiza bronce voltametrijom mikrokristala i tankoslojnom kromatografijom

Corrosion potentials of five samples of bronzes having different compositions and the stripping peak potentials of their main components were determined by abrasive stripping voltammetry. Using thin-layer chromatography in combination with electrochemical dissolution of bronzes in the two electrode sampler, the ions of tin, copper, lead and nickel were detected as the products of electro-oxidation of bronzes. It is shown that the dissolution of tin is preferential at low potential differences between the electrodes in the sampler, while the electro-oxidation of copper is significant only at a potential difference higher than 8 V.Određeni su korozijski potencijali pet uzoraka bronci različitoga sastava i potencijali oksidacije njihovih glavnih sastojaka. Kromatografskom je analizom dokazano da su produkti elektrokemijske oksidacije bronce ioni kositra, bakra, olova i nikla. Pokazano je da se kod malog napona u dvoelektrodnoj elektrokemijskoj ćeliji pretežito oksidira kositar, dok se bakar znatnije oksidira tek kod napona većih od 8 V

Testing the Applicability of the Official Croatian DTM for Normalization of UAV-based DSMs and Plot-level Tree Height Estimations in Lowland Forests

The Airborne Laser Scanning (ALS) technology has been implemented in operational forest inventories in a number of countries. At the same time, as a cost-effective alternative to ALS, Digital Aerial Photogrammetry (PHM), based on aerial images, has been widely used for the past 10 years. Recently, PHM based on Unmanned Aerial Vehicle (UAV) has attracted great attention as well. Compared to ALS, PHM is unable to penetrate the forest canopy and, ultimately, to derive an accurate Digital Terrain Model (DTM), which is necessary to normalize point clouds or Digital Surface Models (DSMs). Many countries worldwide, including Croatia, still rely on PHM, as they do not have complete DTM coverage by ALS (DTMALS). The aim of this study is to investigate if the official Croatian DTM generated from PHM (DTMPHM) can be used for data normalization of UAV-based Digital Surface Model (DSMUAV) and estimating plot-level mean tree height (HL) in lowland pedunculate oak forests. For that purpose, HL estimated from DSMUAV normalized with DTMPHM and with DTMALS were generated and compared as well as validated against field measurements. Additionally, elevation errors in DTMPHM were detected and eliminated, and the improvement by using corrected DTMPHM (DTMPHMc) was evaluated. Small, almost negligible variations in the results of the leave-oneout cross-validation were observed between HL estimated using proposed methods. Compared to field data, the relative root mean square error (RMSE%) values of HL estimated from DSMUAV normalized with DTMALS, DTMPHM, and DTMPHMc were 5.10%, 5.14%, and 5.16%, respectively. The results revealed that in the absence of DTMALS, the existing official Croatian DTM could be readily used in remote sensing based forest inventory of lowland forest areas. It can be noted that DTMPHMc did not improve the accuracy of HL estimates because the gross errors mainly occurred outside of the study plots. However, since the existence of the gross errors in Croatian DTMPHM has been confirmed by several studies, it is recommended to detect and eliminate them prior to using the DTMPHM in forest inventory

EFFECT OF YEAR AND SEASON ON THE CHEMICAL COMPOSITION AND HYGIENIC QUALITY OF ORGANIC COWS MILK

Cilj istraživanja bio je utvrditi utjecaj godine i sezone na kemijski sastav i higijensku kvalitetu sirovog kravljeg mlijeka proizvedenog po ekološkim principima. U istraživanje je bilo uključeno 15 ekoloških gospodarstava koja se bave ekološkom proizvodnjom mlijeka na području Osječko-baranjske županije. U uzorcima sirovog mlijeka (n=1.769) od kemijskih parametra određen je: udio mliječne masti, bjelančevina, laktoze, bezmasne suhe tvari, a od higijenskih parametara: broj mikroorganizama i somatskih stanica. Utvrđen je značajan (p<0,05) utjecaj godine (2011., 2012., 2013.) na sve istraživane parametre osim na ukupan broj mikroorganizama. Sezona je značajno utjecala na kemijske parametre (p<0,05), istovremeno nije utvrđen značajan utjecaj na higijenske parametre. Najveći udjeli mliječne masti, bjelančevina i suhe tvari zabilježeni tijekom jesenskoga i zimskog razdoblja, a laktoze tijekom zimskog i proljetnog razdoblja. Rezultati istraživanja pokazali su da su godina i sezona značajno utjecale na većinu istraživanih parametara u ekološki proizvedenom mlijekuThe aim of this study was to determine the effect of year and season on the chemical composition and hygienic quality of raw organic cow\u27s milk. The study included 15 organic farms engaged in organic production of milk in the Osijek-Baranja County. In the raw milk samples (n = 1 769) following chemical parameters were determined: the proportion of fat, protein, lactose, non-fat solids, and hygiene parameters: number of microorganisms and somatic cells. It was determined a significant (p <0.05) effect of the year (2011, 2012, 2013) on all studied parameters except to the total number of microorganisms. Season had a significant effect on a chemical parameters (p <0.05), while hygiene parameters were not affected by season. The highest proportions of fat, protein and dry matter were recorded during the autumn and winter period, and lactose during the winter and spring period. The results showed that the year and season significantly affected the majority of the studied parameters in organically produced milk

Identification of Cobalt and Chromium in Prosthetic Restorations by thin Layer Chromatography

Zbog velike ponude dentalnoga tržišta danas postoji više od tisuću raznih sustava i vrsta slitina za protetske namjene. Svrha rada bila je identificirati osnovne sastavnice postojećih protetskih konstrukcija u pacijenata kojima je trebala daljnja protetska terapija. Uporabom minielektrode s grafitnim nastavkom, vodene otopine NaCl kao elektrolita i baterije od 4,5 V kao izvora struje, anodno se uzrokovalo osam protetskih radova nepoznata sastava. Uzorci su analizirani kvantitativnom tankoslojnom kromatografijom (QTLC). Kromatogrami uzoraka razvijeni su sustavom otapala: aceton i 2 M HCl. Vizualizacija kobalta dobivena je vodenom otopinom natrijdietilditiokarbonata, a kroma etanolnom otopinom dimetilglioksima. Postotni udio identificiranih elemenata određen je na analizatoru slike, koji je predhodno baždaren poznatim standardima.Owing to the ample dental market supply, more than a thousand different systems and alloys for prosthetic use are presently available. The aim of the study was to identify the basic components of the existent prosthetic constructions in patients requiring additional prosthetic therapy. Anodic sampling of eight prosthetic restorations of unknown composition was performed using a minielectrode with a graphite handpiece, aqueous NaCl solution as electrolyte, and a 4.5 V battery as a source of electric current. The samples were analyzed by quantitative thin-layer chromatography (QTLC). Sample chromatograms were developed by use of the acetone and 2 M HCl solvent system. Cobalt was visualized using aqueous solution of sodium-diethyldithiocarbonate, and chromium by ethanol solution of dimethylglyoxime. The percentage proportion of the elements identified was determined on an image analyzer, previously gauged according to the known standards

Testing the Applicability of the Official Croatian DTM for Normalization of UAV-based DSMs and Plot-level Tree Height Estimations in Lowland Forests

The Airborne Laser Scanning (ALS) technology has been implemented in operational forest inventories in a number of countries. At the same time, as a cost-effective alternative to ALS, Digital Aerial Photogrammetry (PHM), based on aerial images, has been widely used for the past 10 years. Recently, PHM based on Unmanned Aerial Vehicle (UAV) has attracted great attention as well. Compared to ALS, PHM is unable to penetrate the forest canopy and, ultimately, to derive an accurate Digital Terrain Model (DTM), which is necessary to normalize point clouds or Digital Surface Models (DSMs). Many countries worldwide, including Croatia, still rely on PHM, as they do not have complete DTM coverage by ALS (DTMALS). The aim of this study is to investigate if the official Croatian DTM generated from PHM (DTMPHM) can be used for data normalization of UAV-based Digital Surface Model (DSMUAV) and estimating plot-level mean tree height (HL) in lowland pedunculate oak forests. For that purpose, HL estimated from DSMUAV normalized with DTMPHM and with DTMALS were generated and compared as well as validated against field measurements. Additionally, elevation errors in DTMPHM were detected and eliminated, and the improvement by using corrected DTMPHM (DTMPHMc) was evaluated. Small, almost negligible variations in the results of the leave-oneout cross-validation were observed between HL estimated using proposed methods. Compared to field data, the relative root mean square error (RMSE%) values of HL estimated from DSMUAV normalized with DTMALS, DTMPHM, and DTMPHMc were 5.10%, 5.14%, and 5.16%, respectively. The results revealed that in the absence of DTMALS, the existing official Croatian DTM could be readily used in remote sensing based forest inventory of lowland forest areas. It can be noted that DTMPHMc did not improve the accuracy of HL estimates because the gross errors mainly occurred outside of the study plots. However, since the existence of the gross errors in Croatian DTMPHM has been confirmed by several studies, it is recommended to detect and eliminate them prior to using the DTMPHM in forest inventory

Sadržaj kadmijuma u Hypericum perforatum L. i Thymus serpyllum L. sa lokaliteta planina Rtnja i Ozrena

Background/Aim. The beneficial effects of medicinal plants are well-known from the ancient times. However, expansion of phytopharmacy and phytotherapy occured during the last decades. Medicinal plants can absorb environmental contaminants from the ground and consequently may cause harmful effects on human health. Quality control usually comprises standard methodology which includes macroscopic identification and examination of active ingredients. Additionaly, there is a permanent need to control the level of pollutants in herbs, with a particular attention to the level of toxic metals. In this study we estimated the level of contamination by determining the content of cadmium (Cd) in the herbs of Hypericum perforatum and Thymus serpyllum collected from the different localities of the mountains Rtanj and Ozren. Methods. Herbs of investigated plants were collected during July 2005 from various localities of Rtanj and Ozren mountains. After drying, homogenization and mineralization, Cd content was determined by atomic absorption spectrophotometry. Results. The obtained results show that Cd content varies significantly in Hypericum perforatum samples collected. The lowest Cd level was found in samples from the one of Rtanj localities (0.25 mg Cd/kg), while the highest was observed in Hypericum perforatum from Ozren locality (1.24 mg/kg). Levels of Cd in the three of four investigated localities were higher than pro posed by WHO (0.3 mg/kg dried herb material). In all investigated samples of Thymus serpyllum herbs Cd levels were below the limit of detection of analytical method (0.2 mg Cd/kg dried materials). Conclusion. This work contributes to the issue of Cd content in Hypericum perforatum and Thymus serpyllum grown in localities of Rtanj and Ozren, and implies the importance for systemic control of Cd content in Hypericum species in order to provide safety of their preparations. Furthermore, regarding Cd toxicity, maximal permissible level of Cd in plant material should be evaluated and established concerning national legislative frame.Uvod/Cilj. Lekovitost nekih biljnih vrsta bila je poznata čoveku još pre naše ere. Međutim, do ekspanzije fitofarmacije i fitoterapije dolazi tek poslednjih decenija. Lekovite biljke usled zagađenja životne sredine mogu da apsorbuju prisutne zagađivače. Kvalitet biljnih sirovina prati se standardnim metodama koje se prvenstveno odnose na identifikaciju biljne vrste i ispitivanja aktivnih principa. Ipak, i pored toga, uočena je potreba za kontrolisanjem i praćenjem nivoa zagađivača, među kojima značajno mesto zauzimaju toksični metali. U ovom radu ispitivan je sadržaj kadmijuma (Cd) u herbi dve biljne vrste, Hypericum perforatum L. i Thymus serpyllum L. koje su prikupljene sa različitih lokaliteta planina Rtanj i Ozren, sa ciljem procene nivoa kontaminacije. Metode. Herbe ispitivanih lekovitih biljaka sakupljene su tokom jula 2005. godine sa različitih lokaliteta planina Rtnja i Ozrena. Nakon sušenja, homogenizacije i mineralizacije, sadržaj Cd određivan je metodom atomske apsorpcione spektrofotometrije. Rezultati. Dobijeni rezultati ukazali su na značajne varijacije sadržaja Cd u sakupljenim uzorcima Hypericum perforatum. Najniži sadržaj Cd od 0,25 mg Cd/kg dobijen je u uzorku sa lokaliteta Rtnja, dok je najviši nivo Cd određen u uzorku Hypericum perforatum sa lokaliteta Ozrena (1,24 mg/kg). Dobijene vrednosti sadržaja Cd u herbi Hypericum perforatum sa tri od četiri ispitivana lokaliteta bile su iznad vrednosti koju preporučuje SZO (0,3 mg/kg osušene droge). U svim ispitivanim uzorcima Thymus serpyllum nivoi Cd bili su ispod nivoa detekcije primenjene analitičke tehnike (0,2 mg Cd/kg osušene herbe). Zaključak. Rezultati ovog rada doprineli su istraživanju sadržaja Cd u biljnim vrstama Hypericum perforatum i Thymus serpyllum koje rastu na lokalitetima Rtnja i Ozrena i ukazuju na potrebu uvođenja sistematske kontrole sadržaja Cd u Hypericum vrstama radi bezbedne upotrebe preparata izrađenih na bazi ovih biljnih vrsta. Imajući u vidu toksičnost Cd nameće se potreba da se nacionalnim zakonodavstvom odrede i ustanove maksimalno dozvoljene koncentracije sadržaja ovog metala u biljnim lekovitim sirovinama

Synthesis and Immunological Evaluation of Mannosylated Desmuramyl Dipeptides Modified by Lipophilic Triazole Substituents

Muramyl dipeptide (N-acetylmuramyl-L-alanyl-D-isoglutamine, MDP) is the smallest pep- tidoglycan fragment able to trigger an immune response by activating the NOD2 receptor. Structural modification of MDP can lead to analogues with improved immunostimulating properties. The aim of this work was to prepare mannosylated desmuramyl peptides (ManDMP) containing lipophilic triazole substituents to study their immunomodulating activities in vivo. The adjuvant activity of the prepared compounds was evaluated in the mouse model using ovalbumin as an antigen and compared to the MDP and referent adjuvant ManDMPTAd. The obtained results confirm that the α-position of D-isoGln is the best position for the attachment of lipophilic substituents, especially adamantylethyl triazole. Compound 6c exhibited the strongest adjuvant activity, comparable to the MDP and better than referent ManDMPTAd

SALINITY AND PHYSICOCHEMICAL WATER PARAMETERS OF THE LOWER FLOW OF NERETVA RIVER

The lower flow of the Neretva River (delta) covers approximately 20.000 hectares. This is a unique, humid Mediterranean area with a number of important and protected wetland habitats and is a ornithological, ichthyology, and botanical reserve. By measuring the physico-chemical parameters at 20 locations, the water quality was determined with special attention to the occurrence of salinity. Increasing salinity of the Neretva water was found, owing to inflow reduction groundwater of the river Trebišnjica and the uncontrolled deepening of the Neretva riverbed. During a one-year monitoring period, field tests were conducted of significant maritime impacts on water quality. The physical parameters were the measured temperature, conductivity, electrical resistance, salinity, chemical quantity of dissolved oxygen (expressed as a percentage, mg L-1), the oxygen pressure in water, and the pH value. The values of the above parameters were measured in the field with WTW multiparameter instruments