23 research outputs found
NITRATES AND NITRITES, METABOLISM AND TOXICITY
Nitrati i nitriti su kemijski spojevi koji se koriste kao gnojivo, rodenticidi ili konzervansi. Mogu se
naÄi u zraku, tlu, vodi ili hrani (posebice povrÄu) a mogu se i stvarati u ljudskom tijelu. Nitrati imaju
važnu ulogu u hranjenju i metabolizmu biljaka. Nastaju oksidacijom organskog otpada djelovanjem
duÅ”iÄnih bakterija. Ljudi mogu biti izloženi nitratima i nitritima preko konzumacije povrÄa i mesnih
preraÄevina, a manjim dijelom preko vode ili ostale hrane. Pijenje vode sa veÄom koncentracijom
nitrata može djelovati na ljudsko tijelo na dva naÄina: (i) akutno, Å”to se najÄeÅ”Äe manifestira
methemoglobinemijom (nitrati u probavnom sustavu se reduciraju u nitrite koji potom oksidiraju
željezo u hemoglobinu crvenih krvnih stanica stvarajuÄi methemoglobin koji nije sposoban prenositi
kisik po tijelu), a koja se manifestira pojavom plave boje kožw, i (ii) kroniÄno, Å”to se manifestira
pojavom karcinoma kao rezultata izloženosti nitrozaminima (koji nastaju tijekom reakcije nitrata sa
aminima u tijelu).Nitrates naturally occur in the environment and are involved in the nitrogen cycle. Nitrates and nitrites
are chemical compounds used in fertilizers, rodenticides and as food preservatives. They can be
found in the air, soil, water and food (especially in vegetables) and can be synthesized in the human
body. Nitrates play a significant role in the diet and metabolism of plants. Nitrates are formed by oxidation
of organic waste by the action of nitrogen-binding bacteria. Humans are exposed to nitrates
and nitrites via consumption of vegetables and processed meat products, and to a lesser extent via water
and other food. Consumption of drinking water with an increased concentration of nitrate may affect
the human body in two ways: (i) acutely, most often manifested as methemoglobinemia (where
nitrates in the digestive system are reduced to nitrites, which then oxidize iron in the hemoglobin of
the red blood cells forming methemoglobin unable to transmit oxygen in the body), resulting in blue
skin, and (ii) chronic, manifested by the occurrence of cancer as a result of organism exposure to nitrosamines
(formed during the reaction of nitrates with amines in the body)
Epidemiologija problema mentalnog zdravlja u mladih s podruÄja Osijeka, koriÅ”tenjem upitnika snaga i teÅ”koÄa (SDQ)
Introduction: Mental disorders begin at an early age. Screening is the first step in early intervention for the mental health problems of children and adolescents. The aim of this study was to analyse the prevalence of mental health problems among adolescents from Osijek, to early detect the risks of possible mental disorders, and to analyse gender differences. Materials and methods: The main screening instrument was The Strengths and Difficulties Questionnaire (SDQ), which assesses the emotional and behavioural difficulties of children and adolescents, as well as the prosocial skills. Over 5 school years (2012/13-2016/17), a total of 5787 students were examined. 5514 (95.3%) first-year students from 16 high schools and 273 (4.7%) seventh-grade students from 10 elementary schools were examined in the City of Osijek. Results: 10.4% of students had the borderline or abnormal score on the Total difficulties score. Girls had higher scores on the Total difficulties score (p<0.01), Emotional symptoms subscale (p<0.01), Prosocial behaviour subscale (p<0.01), and on the Hyperactivity/inattention subscale (p<0.01). On the Conduct problems subscale and the Peer relationships problem subscale, boys scored significantly higher than the girls (p<0.01). Conclusion: In the Osijek area, girls are more affected by mental problems than boys, scoring higher on the total scale, as well as on the emotional and hyperactivity scale. Whereas boys scored higher on the conduct and peer relationship scales. The data obtained through this screening allows for further planning of public health measures, preventive activities, treatment, and mental health promotion.Uvod: Mentalni poremeÄaji zapoÄinju u ranoj dobi. Probir je prvi korak u ranoj intervenciji mentalnih poremeÄaja djece i adolescenata. Ciljevi ove studije su bili istražiti prevalencije mentalnih poteÅ”koÄa adolescenata s podruÄja grada Osijeka, pravovremeno uoÄiti rizike moguÄih mentalnih poremeÄaja te istražiti razlike meÄu spolovima. Materijal i metode: Glavni instrument probira je bio Upitnik snaga i poteÅ”koÄa namijenjen procjeni emocionalnih i poteÅ”koÄa u ponaÅ”anju djece i adolescenata kao i procjeni prosocijalnih vjeÅ”tina. Tokom pet Å”kolskih godina (2012/13 - 2016/17), ispitano je ukupno 5787 uÄenika, od toga 5514 (95.3%)uÄenika prvih razreda 16 srednjih Å”kola te 273 (4.7%) uÄenika sedmih razreda osnovnih Å”kola grada Osijeka. Rezultati: 10.4% uÄenika je imalo graniÄan ili poviÅ”en rezultat na ljestvici ukupnih poteÅ”koÄa. DjevojÄice su imale viÅ”i rezultat na ljestvici ukupnih poteÅ”koÄa (p<0.01), na ljestvicama emocionalnih poteÅ”koÄa, prosocijalnog ponaÅ”anja i hiperaktivnosti (p<0.01). Na ljestvicama problema u ponaÅ”anju i problema s vrÅ”njacima su djeÄaci imali viÅ”i rezultat (p<0.01). ZakljuÄak: Na podruÄju grada Osijeka, djevojÄice su ÄeÅ”Äe pogoÄene mentalnim poteÅ”koÄama, emocionalnim poteÅ”koÄama i hiperaktivnoÅ”Äu. DjeÄaci su ÄeÅ”Äe pogoÄeni problemima u ponaÅ”anju i problemima u odnosu s vrÅ”njacima. Podaci dobiveni ovim probirom služe u planiranju javnozdravstvenih mjera, preventivnih aktivnosti, lijeÄenja i promocije mentalnog zdravlja
Biocatalytic reductions by plant tissue - Green alternative to alcohol production
The use of biocatalysts for the industrial synthesis of chemicals has been attracting much attention as an environmental friendly synthetic method. Various plants, such as apple (Malus pumila), carrot (Daucus carota), cucumber (Cucumis sativus), onion (Allium cepa), potato (Solanum tuberosum), radish (Raphanus sativus) and sweet potato (Ipomoea batatas) were used as biocatalysts. Enzymes that plants produce are able to perform reactions under mild conditions (pH and temperature), with remarkable chemo-, regio-, and stereoselectivity. Due to this feature the number of biocatalysts used in organic synthesis has rapidly increased during the last decades, especially for the production of chiral compounds. This review presents biotechnological processes for the production of chiral alcohols by reducing prochiral ketones with whole plant tissue. Chiral alcohols are important building blocks for the synthesis of pharmaceuticals, pesticides, pheromones, flavors, fragrances and advanced materials such as liquid crystals. Reductase-catalyzed reactions are dependent on cofactors, and therefore, one major task in process development is to provide an effective method for regeneration of the cofactors consumed. The need for expensive cofactors is eliminated by using the whole plant tissue since the plant automatically provides this requirement. Depending on the vegetable used, either enantiomer may be obtained in high yield and high enantiomeric excess (ee), which could be a critical factor for drug development/bioactivity evaluation perspective. In this paper, various processes carried out on laboratory scales are presented. Attention is turned to conversion, yield, enantiomeric excess (ee)
Nitrate removal from water by ion exchange
High concentrations of nitrate in water, both in surface and in groundwater, is a consequence of geological composition of soil or human activity. Increased concentrations of nitrate in drinking water is a serious hazard to human health, causing abnormalities such as cancerous growth in human digestion system, while excessive nitrate intake via drinking water can cause methemoglobinemia in infants. Furthermore, the presence of nitrate in aquifers can stimulate eutrophication, which compromise the growth of algae and depletion of dissolved oxygen. Natural and chemical fertilizers in crop production, detergent manufacturing, uncontrolled land discharge of municipal wastewater, and industrial wastes have been identified as the main sources of nitrate in water sources. Nitrate is a stable, highly soluble ion that is difficult to remove by conventional water treatment methods such as coagulation and flocculation. The ion exchange is the most widely used procedure for removing nitrate from water. In this research the possibility of removing nitrate from water was examined by using commercial ion exchangers: Duolite A7 and Relite A490, respectively. The influence of the initial concentration of nitrate (10, 50 and 100 mg/l), the contact time (15 - 1440 min) and the mass of the ion exchanger (0.1 to 0.6 g) was also examined
UTJECAJ MIJEÅ ANJA NA UÄINKOVITOST PROCESA KOAGULACIJE I FLOKULACIJE PRI KONDICIONIRANJU VODE VODOCRPILIÅ TA āJARÄEVACā
Najvažniji izvori vode za piÄe na podruÄju istoÄne Hrvatske su podzemne vode koje karakterizira visoka tvrdoÄa i poviÅ”ene koncentracije željeza, amonija, mangana, arsena i organskih tvari, Å”to negativno utjeÄe na organoleptiÄka svojstva i zdravstvenu ispravnost vode za piÄe. Jedan od procesa koji se Äesto primjenjuje pri kondicioniranju vode je koagulacija i flokulacija uz naknadnu filtraciju. Na uÄinkovitost navedenog procesa utjeÄu Äimbenici poput fizikalno-kemijskih karakteristika sirove vode, doza i vrsta koagulanta te brzina i vrijeme mijeÅ”anja u pojedinim fazama navedenog procesa. U ovom radu ispitan je utjecaj brzine i vremena mijeÅ”anja koagulanata i vode na uÄinkovitost koagulacije i flokulacije pri obradi aerirane podzemne vode vodocrpiliÅ”ta āJarÄevacā s dva željezova koagulanta ā željezov klorid i željezov(II) sufat te je praÄen utjecaj brzine i vremena mijeÅ”anja na uÄinak procesa kroz dva seta, uz poÄetnu pH vrijednost vode od 7.5 i poÄetnu koncentraciju ukupnog željeza od 4 mg/l. UÄinkovitost je praÄena mjerenjem polaznih i zavrÅ”nih vrijednosti koliÄine organskih tvari, ukupne tvrdoÄe, alkaliteta i koncentracije ukupnog željeza te pH vrijednosti i vodljivosti vode. S obzirom na dobivene rezultate moguÄe je zakljuÄiti da je uÄinkovitija obrada podzemne vode vodocrpiliÅ”ta āJarÄevacā postignuta pri doziranju željezova klorida
NITRATE REMOVAL FROM WATER USING SURFACE-MODIFIED ULTRAFILTRATION MEMBRANES
Elevated nitrate concentrations in natural water sources are a worldwide concern due to the extensive levels of soil N-fertilization. This study investigates three commercially available polyethersulfone (PES) ultrafiltration (UF) membranes with different molecular weight cut-offs (5, 10, and 30 kDa), which we modified with a cationic surfactant, cetylpyridinium chloride to improve their nitrate removal. The nitrate removal efficiency of these membranes was examinated as functions of initial nitrate concentration, pH, and permeate flux. The best nitrate removal efficiency was obtained with a 5 kDa surface-modified UF membrane
Važnost znanstveno utemeljenih Äinjenica u kriznom komuniciranju: Dokazi iz zagrebaÄkog i petrinjskog potresa
Earthquakes are natural phenomena that can strongly affect the human population,
infrastructure, and the environment. Croatia is part of a tectonically and seismically active
area so its habitants and relevant institutions should be aware of possible hazardous events,
which can be devastating. Therefore, crisis communication is extremely important, and in the
event of natural disasters such as earthquakes, it must be clear, timely and concise. Scientific
institutions dealing with earthquakes should also be involved in crisis communication. The information
on two strong earthquakes in 2020 that shocked the area of Zagreb and Petrinja and
the wide surrounding area, have shown how relevant institutions can deal with information
on earthquakes and their consequences and share them publicly. This paper adopts a mixedmethods
research design, combining both qualitative, and quantitative data on the Zagreb and Petrinja earthquakes from various sources of scientific and professional institutions in the field
of geology, geophysics, seismology and civil engineering in Croatia. Empirical data suggest that
interactive communication that strives to address local contextual concerns, explain actions,
and provide honest, timely, accurate and reliable information is most effective. In the future,
institutions have to find a way to react or share their information to help in the crisis.Potresi su prirodni fenomeni koji mogu snažno utjecati na zajednice, infrastrukturu i okoliŔ.
Hrvatska je dio tektonski i seizmiÄki aktivnog podruÄja, tako da bi njezini stanovnici i nadležne
institucije trebali biti svjesni moguÄih opasnih dogaÄaja, koji mogu biti razorni. Stoga je
krizna komunikacija izuzetno važna, a u sluÄaju prirodnih katastrofa poput potresa mora biti
jasna, pravodobna i sažeta. Znanstvene institucije koje se bave potresima takoÄer bi trebale biti
ukljuÄene u krizno komuniciranje. Podaci o dva snažna potresa 2020. godine koji su potresli
podruÄje Zagreba i Petrinje te Å”iru okolicu, pokazali su kako se relevantne institucije mogu
nositi s informacijama o potresima i njihovim posljedicama i javno ih dijeliti. Ovaj rad usvaja
mjeÅ”oviti dizajn istraživanja, kombinirajuÄi i kvalitativne i kvantitativne podatke o potresima
u Zagrebu i Petrinji iz razliÄitih izvora znanstvenih i struÄnih institucija iz podruÄja geologije,
geofizike, seizmologije i graÄevinarstva u Hrvatskoj. Empirijski podaci sugeriraju da je najuÄinkovitija
interaktivna komunikacija koja nastoji rijeŔiti lokalne kontekstualne probleme,
objasniti radnje i pružiti iskrene, pravodobne, toÄne i pouzdane informacije. UbuduÄe institucije
moraju pronaÄi naÄin da reagiraju ili podijeliti svoje informacije kako bi pomogle u krizi
Water preparation for industrial brewing
Voda je vrlo važna sirovina za proizvodnju piva jer pivo sadrži 85 ā 95 % vode. Prema Pravilniku o
temeljnim zahtjevima za pivo i pivu sliÄne proizvode (NN 6/98), tehnoloÅ”ka voda koja se koristi za
proizvodnju piva mora u fizikalnom, kemijskom i mikrobioloŔkom smislu odgovarati kvaliteti vode
za piÄe, Äije karakteristike su propisane Pravilnikom o parametrima sukladnosti i metodama analize
vode za ljudsku potroÅ”nju (NN 125/13). Kako bi pivovare bile neovisne o gradskim vodovodima Äesto
imaju svoje vlastite izvore - bunare. U prirodnim vodama uvijek postoje odreÄene koliÄine raznih
otopljenih tvari. Ovisno o otopljenim mineralnim tvarima, vode se dijele na meke, srednje tvrde i
tvrde. Tehnologija obrade voda u pivarstvu je vrlo važna jer kvaliteta, odnosno vrsta piva znaÄajno
ovisi o njoj, stoga u veÄini sluÄajeva pivovare provode obradu vode u svrhu dobivanja tehnoloÅ”ke
vode za proizvodnju piva odreÄenih karakteristika. Kada govorimo o obradi vode u pivovarama s
vlastitim izvorima vode koje sadržavaju veÄe koliÄine željeza, mangana i arsena, tada bi obrada vode
svakako ukljuÄivala uklanjanje manganovih odnosno feratnih bikarbonata putem pjeÅ”Äanih filtera i
aeracije; uniŔtavanje mikroorganizama doziranjem klora, uklanjanje slobodnog klora i ostalih
primjesa adsorpcijom na aktivnom ugljenu te proÄiÅ”Äavanje vode putem membranskih metoda
odnosno mikrofiltracije, nanofiltracije i reverzne osmoze. Navedenom obradom vode može se dobiti
voda s optimalnim vrijednostima koja je spremna za proizvodnju piva.Water quality for beer production is very important, because beer contains 85-95% of water. Water
for beer production due to physical, chemical and microbiological characteristics must comply with
the Regulations on the basic requirements for beer and beer like products (NN 6/98) and the
Regulations on the parameters of assessment and methods of analysis of water for human
consumption (NN 125/13). Breweries often use water from their own wells. In natural water certain
amount of dissolved matter are present. Depending on dissolved minerals, water can be divided into
soft, medium hard and hard water, respectively. Water treatment for beer production is very important
because the quality or type of beer depend on it. Water treatment for beer production with elevated
concentrations of iron, manganese and arsenic in water, certainly would include removal of
manganese and ferric bicarbonate by sand filter and aeration, removal of microorganisms with
chlorine, removal of free chlorine and other impurities by adsorption on activated carbon and water
treatment with membrane processes such as reverse osmosis. This technologies for water treatment
are promising for production of high quality beer products