Quality monitoring at fusion welding of polyethylene high-density pipes

The paper presents the main parameters of fusion welding and their Off - line analysis of Polyethylene high-density (PE-HD) pipes. By direct measurements of voltage and current at the coupler, inductive and the resistant character changes in amplitude modulation waveforms of the measured signal are observed. In early measuring device analyzes the scanned parameters with certain types of fittings and compares them with the tested and measured parameters is done by welding machines. There can be seen the time delay or “dead time” when the system analyzes the parameters and dimensioned regulatory function of the system

Nadzor kvalitete elektrofuzijskog zavarivanja polietilenskih cijevi visoke gustoće

The paper presents the main parameters of fusion welding and their Off - line analysis of Polyethylene high-density (PE-HD) pipes. By direct measurements of voltage and current at the coupler, inductive and the resistant character changes in amplitude modulation waveforms of the measured signal are observed. In early measuring device analyzes the scanned parameters with certain types of fittings and compares them with the tested and measured parameters is done by welding machines. There can be seen the time delay or “dead time” when the system analyzes the parameters and dimensioned regulatory function of the system.U radu se prikazuju glavni parametri fuzijskog zavarivanja te njihova Off – line analiza PE-HD cijevi. Izravnim mjerenjem napona i struje na spojnici induktivnog i djelatnog karaktera uočene su promjene u amplitudnoj modulaciji valnih oblika mjerenih signala. Početkom mjerenja uređaj analizira skenirane parametre sa pojedine vrste spojnice i uspoređuje ih sa ispitanim i izmjerenim parametrima koje je odradio sam uređaj za zavarivanje. Upravo se tu vidi zadrška u vremenu tzv. „mrtvo vrijeme“ kada sustav analizira parametre i dimenzionira sustav regulatorske funkcije

Supplementary material for the article: Šoštarić, T. D.; Petrović, M. S.; Pastor, F. T.; Lončarević, D. R.; Petrović, J. T.; Milojković, J. V.; Stojanović, M. D. Study of Heavy Metals Biosorption on Native and Alkali-Treated Apricot Shells and Its Application in Wastewater Treatment. Journal of Molecular Liquids 2018, 259, 340–349. https://doi.org/10.1016/j.molliq.2018.03.055

Supplementary material for: [https://doi.org/10.1016/j.molliq.2018.03.055]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2152]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2970

Comparison of extraction agents for metal determination in sediments from artificial lakes and rivers in Serbia

The purpose of this paper was to investigate the effectiveness of three different extraction agents for the extraction of 25 elements from sediment samples collected from 4 artificial lakes and 12 rivers in Serbia (33 samples in total). The extraction efficiency of the agents was evaluated by its ability to extract the highest quantity of the elements. For that purpose, three acids (1M HCl, 2M HNO3 and 0.43M CH3COOH) have been used. Inductively coupled plasma atomic emission spectrometry (ICP-OES) was used for quantitative determination of following elements: Al, As, B, Ba, Be, Bi, Ca, Cd, Cr, Co, Cu, Fe, Hg, K, Li, Mg, Mn, Ni, Na, Pb, Sb, Se, Sr, V, and Zn. The extraction with 1M HCl has shown the best results for the majority of investigated elements (especially Sr, Mn and Ca). Antimony (Sb) was detected only after extraction with 0.43M CH3COOOH, while selenium (Se) could not be detected when 2M HNO3 was applied as extraction agents. The present study could be very useful for choosing a suitable method for specific elements and also can be helpful in the evaluation of the contaminants in freshwater sediments in Serbia. This might contribute to environmental risk assessment of the present elements

Food Waste (Beetroot and Apple Pomace) as Sorbent for Lead from Aqueous Solutions—Alternative to Landfill Disposal

This article presents studies, whose main goal was to minimize food waste. To achieve this goal, it is necessary to expand the scope of their application, for example, for the purification of polluted water from heavy metals. Millions of tons of waste from the fruit and vegetable industry, including pomace of apples and beetroots, are thrown into landfills, posing a danger to the environment. In order to solve the problems with the disposal of these wastes, the authors investigated their sorption potential for the removal of lead from wastewater. The sorbents, dried apple (AP), and beetroots (BR) pomaces were characterized by various methods (study of composition, zeta potential, FTIR-ATR, and SEM-EDX). Various models of sorption kinetics and sorption isotherms were analyzed. Kinetical studies under optimal conditions showed that the sorption process occurs through complexation and ion exchange and the determining stage limiting the rate of sorption is the diffusion of lead ions in the sorbent. The maximum sorption capacity was 31.7 and 79.8 mg/g for AP and BR, respectively. The thermodynamic data revealed the spontaneous sorption of lead ions by sorbents. The temperature rise contributes to the sorption increase by the AP sorbent, while for the BR sorbent, the opposite effect is observed. The obtained results showed that apple and beetroots pomaces can serve as effective renewable materials for the preparation of sorbents, contributing to the solution of complex environmental problems

Overview of carotenoids distribution among wild plant species of the Balkan Peninsula

The Balkan Peninsula is characterized by a great diversity of flora and vegetation. Moreover, it is native to a large number of wild plant species containing carotenoids, biologically active compounds, beneficial for human health. Carotenoid pigments exhibit a great antioxidant and anti-inflammatory effect, in addition to beneficial impact on eye health, heart, blood vessels, cognitive function and antiaging. Nevertheless, their role has been scientifically proven in prevention and treatment of cancer. The aim of the research was to form a database on carotenoid plants of Serbia and the Balkans that is set up electronically for easy access, management and updating. The research included the analysis and organization of information on collected plants, as well as literature data related to the traditional use and storage of plants and plant parts and products rich in carotenoids in fresh, dried or canned state. Sixty wild plants from more than ten plant families were registered to contain these antioxidant pigments. Among them three endemic species namely Lilium bosniacum (Beck) Fritsch (lily native to Bosnia and Herzegovina), Ramonda nathaliae Pančić & Petrović and R. serbica Pančić were inscribed, of which the last two are Tertiary relicts. The type and level of carotenoids varied depending on the plant species and organs including leaves, petals, immature and ripe fruits, pulp, seeds, etc. According to database, fruits were the richest source of these pigments. Reported carotenoid content, included both xanthophylls and carotenes, whereas lutein and β-carotene were predominantly major compounds in berries and flowers respectively. Total carotenoid content, determined by HPLC method, was the highest in fresh berries of Rubus fruticosus L. (440 μg/100g

Occurrence of enteric redmouth disease in rainbow trout (Oncorhynchus mykiss) on farms in Croatia

During the spring of 1996 and autumn of 1997 unusual mortality outbreaks among rainbow trout fry and yearlings occurred at two different trout farms, resulting in mortality of 20 and 10 per cent, respectively. Generally, the affected fish, swimming at the water surface, were reluctant to eat and were dark pigmented with visible haemorrhages around and within the oral cavity. Bacterial isolates from moribund fish from both cases were identified as Yersinia ruckeri by standard biochemical tests and API 20E. The isolated strains were found to be sensitive to tetracycline, chloramphenicol, co-trimoxazole, nalidixic acid, flumequine, enrofloxacin, carbenicillin and gentamicin. Microplate agglutination assay confirmed that both isolates belonged to serotype O1. The pathogenicity of the isolated bacteria was confirmed by challenge experiment. Titres of specific antibodies were determined in the sera of survivors. The titre was highest on the 21st day postchallenge and was detectable until the 81st day

ORGANIC-BIOLOGICAL AND CONVENTIONAL TOMATO GROWEN (Lycopersicon lycopersicum Mill) IN A GREENHOUSE

The aim of this research was to determine the possibility of tomato production in the organic-biological conditions and to compare it with the conventional tomato production. The research lasted for three years. Each type of organic manure and organic substrates used as the preparation of the organic-biological production underwent many agrochemical and microbiological analyses. There were no significant plant diseases or pests during the entire course of organic-biological tomato production. Duration of organic-biological production from the day of planting till picking time was shorter than for the conventional production. Moreover, the Monroe hybrid had heavier mean fruit weight, whereas both hybrids had approximately the same mean fruit number per plant. Regular monitoring and control of all technological parameters which are the most influential in greenhouse conditions for organic-biological tomato production provided satisfying qualitative and quantitative tomato yield for further market demands. Statistical data analysis was conducted through three way covariance analysis (ABC) with three repetitions for each trial. The trial revealed statistically justified difference for the studied hybrid types (P<0,05) throughout the three years' period (P<0,01). The differences between the crop production were not statistically significant (P<0,05), whereas interaction of hybrids and crop production was statistically very significant (P<0,01). Interaction of the studied factors has not been statistically justified (P<0,05)

INFLUENCE OF DIFFERENT SOURCES OF WATER FOR IRRIGATION ON PEPPER (Capsicum annuum L.) YIELD IN GLASSHOUSE CONDITIONS

The aim of this paper was to determine the influence of different sources of water used for irrigation on the yield of pepper hybrids Cecil F1 and Bianca F1 in the early glasshouse production for the period 1998 - 2000 in the controlled glasshouse conditions in «D.G. – PROMET», Magadenovac, Croatia. Lagoon water and well water were two main sources of water used for irrigation in this experiment. Drip irrigation system was applied for pepper production. In comparison to lagoon water, chemical analyses of well water have shown increased values of the following elements: EC, sodium, potassium, calcium, chlorine, magnesium, bicarbonate, sulphate, iron and boron. Temperature of well water was lower than the allowed minimum and therefore had direct influence on the yield decrease. Consequently, areas which have been irrigated by well water have had problems with accumulation of slime and blocking of sprinklers, disturbed soil structure, fruit deformation and decreased crop yield. Statistical data analysis was conducted by the method of covariation three factorial trial (ABC) with three repetitions for each treatment. The trial showed absolute difference regarding water efficiency of irrigation water from two sources, which has also been statistically determined (P<0,05). Furthermore, statistically justified difference in the average weight of the fruit of each investigated pepper hybrid (P<0,05) has been proven. Codependence of «water for irrigation» (A) and «pepper hybrid» (B), i.e. (AB) is statistically significant as well, and justified at the P<0,05 limit. This means that both pepper hybrids (Cecil F1 i Bianca F1) reacted differently to lagoon water and well water. Factor «year» (C) has not proven to be statistically justified, and therefore does not have any significant influence on the crop yield due to controlled conditions in the glasshouse