591 research outputs found
Sort by
Quaternization reaction under the influence of microwave radiation
No full textKvaterne amonijeve soli imaju široku primjenu. Predstavljaju potencijalne antidote kod trovanja bojnim otrovima i pesticidima. Nekoliko kvaternih amonijevih spojeva, uključujući i piridinijeve soli s različitim duljinama lanaca, posjeduju antibakterijsku aktivnost prema Gram-pozitivnim i Gram-negativnim bakterijama. U ovom su radu izvedene reakcije kvaternizacije primjenom nove ekološki prihvatljive metode. Kvaterne su soli derivata piridina sintetizirane pod utjecajem mikrovalnog zračenja u acetonu i apsolutnom etanolu kao otapalu. Kvaternizacije su izvedene na piridoksal-oksimu, nikotinamidu i izonikotinamidu pomoću različitih elektrofila: 2-brom-4'-bromacetofenona, 2-brom-acetofenona, benzoil klorida, 1,3-dijodpropana, dibrompropana i metil-jodida.Quaternaryammonium salts have wide use. They are antidotes for the poisons with nerve agents and pesticides. Some of quaternary ammonium compounds regarding their potential antimicrobial activity against Gram-positive and Gram-negative bacteria. In this thesis new eco-friendly method of quaternization was performed. A microwave induced quaternization in the presence of a solvent were examined. Reactions of quaternization were made under microwave heating of pyridoxal-oxime, nicotinamide and isonicotinamide with different electrophiles: 2-bromo-4'-bromoacetophenone, 2-bromoacetophenone, benzoyl chloride, 1,3- diiodopropane, dibromopropane and methyl iodide
Effect of smoking on biochemical markers in oxidation stress
No full textPušenje je navika opasna po zdravlje čovjeka. Cigaretni dim sadržava brojne opasne i karcinogene tvari koje utječu na zdravlje. Upravo zbog duhanskog dima dolazi do oslobađanja slobodnih radikala i reaktivnih kiskovih vrsta u tijelu. Oni su odgovorni za pojavu oksidacijskog stresa. Pušenje također uzrokuje brojne koronarne bolesti te aterosklerozu. Vrlo važnu ulogu u borbi protiv istog imaju atioksidansi koje bismo trebali unositi svakodnevno. U ovom radu opisat ćemo nastanak oksidacijskog stresa kao posljedice pušenja.Smoking is habit that is dangerous for human health. Tobacco smoke contains many dangerous and carcinogenic compunds. Because of the tobacco smoke, free radicals and reactive oxygen species are made in organism. They are responsible for oxidative stress. Smoking causes many coronary diseases and atherosclerosis. Very important is consuming antioxidants to fight oxidative stress. In this paper, we will describe how smoking affect oxidative stress
Influence of nonionic surfactants on determination of anionic surfactants using liquid membrane electrode modified by carbon particles
No full textTenzidi su kemijski spojevi koji imaju svojstvo snižavanja površinske napetosti. Dijelimo ih na anionske, kationske, amfolitske i neionske tenzide. Sastoje se od polarne (hidrofilne, lipofobne) glave i nepolarnog (hidrofobnog, lipofilnog) repa. Hidrofilna skupina čini tenzid topiv u polarnim otapalima, a hidrofobna skupina čini tenzid topiv u nepolarnim otapalima. Najzastupljenija vrsta tenzida su anionski tenzidi koji u vodenim otopinama disociraju i daju negativno nabijene površinski aktivne organske ione. Oni su ujedino visoko pjeneće površinski aktivne tvari koje se lako raspršuju i zbog toga se najviše koriste u praškastim detrgentima. Potenciometrijska titracija korištena je za određivanje anionskog tenzida natrijevog dodecilsulfata (NaDDS), c = 4x M, uz dodatak neionskih tenzida Genapol T080, Genapol T110 i Genapol T150, c = 1x M. Ispitan je utjecaj prirode (broja etoksi grupa) i koncentracije neionskih tenzida. Za određivanje je korišten novi senzor s tekućom membranom na bazi dimetildioktadecilamonjevog tetrafenilborata (DDA-TPB) koji je inofor, uz dodatak čestica ugljika.Surfactants are chemical substances with ability to lower surface tension. They can be classified as cationic, anionic, ampholytic and nonionic surfactants. They are composed of polar (hydrophilic, lipophobic) ''head'' and nonpolar (hydrophobic, lipophilic) ''tail''. The hydrophilic group makes tenside soluble in polar solvents, and hydrophobic in nonpolar. The most common type of tensides are anionic ones which dissociate in aqueous solution and give negatively charged organic ions. They are widely used as detergents or other cleaning products because of their ability to foam and disperse easily. Potentiometric titration was used to determine anionic surfactant sodium dodecyl sulfate (NaDDS), c = 4x M, with addition of nonionic surfactants Genapol T080, Genapol T110 and Genapol T150, c = 1x M. The influence od nature (number of ethoxy groups) and concentration of nonionic sufractants were tested. The new sensor with liquid membrane based on dimethyldioctadecylammonium-tetraphenylborate (DDA-TPB) as a sensing material with addition of carbon particles, was used
Comparison of dynamics and monotonic titrations as methods for determination of anionic surfactants in effluents
No full textTenzidi su organski spojevi koji na jednom kraju molekule imaju hidrofobnu ili lipofilnu grupu, a na drugom kraju molekule imaju hidrofilnu ili lipofobnu grupu. To su tvari koje snižavaju površinsku napetost, a pri određenim koncentracijama u otopini, kada se postigne kritična micelarna koncentracija (CMC) formiraju se u micele. Dijele se na kationske, neionske, anionske i amfolitske, a zbog njihove široke primjene u raznim područjima potrebno je vrlo brzo i točno odrediti njihovu koncentraciju u proizvodima i otpadnim vodama. Najčešće korištena metoda za određivanje njihove koncentracije je potenciometrijska titracija. U eksperimentalnom dijelu rada određene su koncentracije anionskih tenzida u standardnoj otopini anionskog tenzida te u tri različita uzorka otpadnih voda, koristeći dvije metode potenciometrijske titracije: dinamičku i monotonu titraciju. Rezultati su uspoređeni kako bi se ispitalo postoji li razlika u mjerenjima pri određivanju točke ekvivalencije te koja metoda je preciznija i zašto.Surfactants are organic compounds that have a hydrophobic or lipophobic group on one end of the molecule and a hydrophilic or lipophilic group at the other. They are substances that reduce surface tension and at certain concentration in the solution, when the critical micellar concentration (CMC) is achieved, they form micelles. They are divided into cationic, nonionic, anionic and ampholitic. Due to their wide application in different areas, it is necessary to determine their concentration in products and effluents fast and accurate. The most commonly used method for determining their concentration is potentiometric titration. In the experimental part, anionic surfactant concentrations were determined in the standard anionic surfactant solution and in three different wastewater samples using two potentiometric titration methods: dynamic and monotonic titration. The results were compared to see if there is a difference between the measurements in equivalence point determination and which method is more precise and why
Thalidomide and its teratogenicity
No full textTalidomid je sedativ koji se koristio pedesetih i šezdesetih godina 20. stoljeća. Uglavnom su ga koristile trudnice, a zapravo je imao vrlo štetan učinak na sam fetus. U ovom radu opisana je sama povijest talidomida, njegova sinteza i struktura, mehanizam njegova djelovanja, utjecaj na trudnoću te razne nuspojave i posljedice koje su nastale konzumiranjem ovog lijeka.Thalidomide is a sedative that was used in the fifties and sixties in the twentieth century. It was mostly used by pregnant women and actually had a very harmful effect on the fetus itself. This thesis describes the history of thalidomide, its synthesis and structure, its mechanism of action, its influence on pregnancy and the various consequences of consuming this drug
Quaternization reaction in choline cloride based eutectic solvents
No full textKonstantnim razvojem kemije javlja se i pitanje utjecaja na okoliš, zbog toga se razvila "zelena" kemija, grana kemije koja za cilj ima smanjiti uporabu štetnih otapala i sirovina kroz razvoj novih procesa koji nisu škodljivi za okoliš, koriste manje energije i manje štetna otapala. Eutektička otapala spadaju u 4. generaciju ionskih tekućina, smatraju se sigurnijom alternativom mnogim organskim otapalima, relativno su jeftina i ne zahtjevaju dodatno pročišćavanje nakon priprave. Prednost im je što se mogu reciklirati i ponovno koristiti. Cilj ovog rada bio je priprava eutektičkih otapala na bazi kolin-klorida te ispitivanje mogućnost njihove primjene u eakcijama kvaternizacije. Kvaternizacija je reakcija tercijarnih amina s primarnim alkil-halogenidima, slijedi mehanizam pri čemu nastaju kvaterne soli koje imaju široku primjenu u svakodnevnom životu.With constant advancement of chemistry the question of impact on environment causes a lot of reasons for concern, that is the reason for development of "green" chemistry, the part of chemistry which aims to reduce the use of harmful solvents by developing a new processes that aren't harmful to environment, use less energy and less harmful solvents, it is based on 12. principles. Eutectic solvents are the 4th generation of ionic liquids, they are considered a safer alternative to organic solvents, they are relatively cheap and they don't need to be purified after preparation. Another advantage is possibility to be recycled and re-used. This paper is based on preparation of eutectic solvents based on choline-chloride and attempt of quaternization reaction in said solvents. Quaternization reactions are substitution reaction, they follow mechanism and products are quaternium salts which are widely used everyday
The role of transgltaminase in celiac disease
No full textCelijakija je autoimuni poremećaj netolerancije glutena koji se javlja kod ljudi s nasljednom predispozicijom. Gluten je protein koji se nalazi u žitaricama kao što su pšenica, ječam, raž i zob. Celijakija se može pojaviti u bilo kojoj životnoj dobi, a jedini način liječenja je doživotna prehrana bez glutena. Peptidi glutena se sastoje od glijadina i glutenina te sadrže oko 30-40% glutaminskih ostataka što ih čini dobrim supstratom za tkivnu transglutaminazu (tTG). tTG je enzim ovisan o kalciju koji se prvenstveno nalazi u crijevima gdje katalizira posttranslacijsku modifikaciju proteina stvaranjem izopeptidnih veza. Gluten koji je unesen u probavni sustav teško se razgrađuje crijevnim enzimima pa takve neprobavljene frakcije glutena podliježu reakcijama deamidacije ili umreženog povezivanja koje katalizira tTG. Modificirani glijadin potom potiče upalne reakcije koje dovode do aktivacije urođenog i stečenog imunosnog odgovora. tTG predstavlja ciljni autoantigen u imunosnoj reakciji čime nastaju specifična protutijela.Celiac disease is autoimmune disorder characterized by gluten intolerance and occurring in genetically predisposed people. Gluten is a protein found in cereals such as wheat, barley, rye and oats. Celiac disease can develop at any age and the only way of treatment is a life-long nutrition without gluten. Gluten is composed of gliadin and glutenin and it contains about 30-40% of glutamine residues making it a good substrate for tissue transglutaminase (tTG). tTG is calcium dependent enzyme which catalyses posttranslational modification of proteins by forming isopeptide bonds. Gluten, introduced in digestive system, is partially resistant to degradation by gastrointestinal enzymes and such undigestive fractions of gluten are susceptible for the reaction of deamidation or cross-linking, catalysed by tTG. Modified gliadin induces inflammatory reactions leading to activation of the innate and adaptive immune response. tTG represents the target autoantigen in the immune response, resulting in specific antibodies
Methotrexate - application in a malignant diseases treatment
No full textMaligna oboljenja jedan su od glavnih uzroka smrti u svijetu. Karakteristika malignih stanica je nekontrolirana proliferacija te se stoga maligne stanice brzo razmnožavaju i prodiru u druga tkiva. Uzroci malignih oboljenja su brojni što dokazuju i razne studije i znastvena istraživanja. Danas postoji mnogo metoda liječenja malignih oboljenja, a koja metoda će se primijeniti određuje se ovisno o vrsta tumora i njegovoj uznapredovalost. Lijekovi koji se koriste u liječenju malignih oboljenja nazivaju se citostatici. Metotreksat je citostatik koji spada u skupinu antimetabolita, on je analog folne kiseline. Djelovanje metotreksata temelji se na inhibiciji dihidrofolat-reduktaze, enzima važnog u sintezi deoksitimidin monofosfata. Inhibicijom spomenutog enzima, metotreksat inhibira sintezu deoksitimidin monofosfata i tako onemogućava sintezu deoksiribonukleinske kiseline (eng.deoxyribonucleic acid-DNA). Metotreksat uz dihidrofolat-reduktazu inhibira i druge enzime važne u sintezi purina, serina i metionina. Budući da je polarna molekula za njegov prijenos potrebni su transporteri za prijelaz krvno-moždane barijere. Metotreksat se u stanici prevodi u metotreksat poliglutamate, 2,4-Diamino-N-10-metil-pteroičnu kiselinu i 7- hidroksi metotreksat. Metotreksat poliglutamat je aktiviran oblik metotreksata i može sadržavati do 6 glutamatskih ostataka. Primjenom metotreksata stanice razvijaju određenu otpornost prema lijeku zbog čega je prilikom liječenja potrebno povećavati dozu ili smanjivati vremenske intervale između primjene lijeka. Metotreksat se može primijeniti intratekalno, oralno, intravenozno ili intramuskularno. Prilikom korištenja metotreksata potrebna je stroga kontrola koncentracije metotreksata u krvi zbog jakog toksičnog djelovanja.Malignant diseases are one of the most common causes of death in the world. The characteristic of malignant cells is uncontrolled proliferation, hence the malignant cells rapidly multiply and penetrate into other tissues. The causes of malignant illnesses are numerous, as evidenced by various studies and scientific research. There are many methods available for treating malignant diseases, but which will be applied depends on cancer type and stage at diagnosis. Cytotoxic drugs or cytostatics are used fore cancer treatment. Methotrexate, a folic acid analog is a cytostatic from antimetabolite group. Methotrexate inhibits dihydrofolate reductase, an enzyme essential to the deoxythymidine monophosphate synthesis. By inhibition of dihidrofolate reductase methotrexate disables DNA synthesis. Methotrexate also inhibits other enzymes important in purine, serine and methionine synthesis. Because of methotrexate polarity, transproters are needed to make the drug pass through the blood-brain barrier.When methotrexate enters the cell it is converted into methotrexate polyglutamate, 7-hydroxy methotrexate and 2,4-Diamino-N-10- methylpteroic Acid. Methotrexate olyglutamate is activated form of methotrexate, this form can contain up to 6 glutamate residues. With common use of methotrexate cells can develop a certain resistance to the drug, which means that it is necessary to increase dose or reduce the time intervals between drug administration. Methotrexate can be administered intrathecally, orally, intravenously or intramuscalarly. Methotrexate must be safely administered, because it can cause significant toxicity
Extraction of metal ions from aqueous solutions
No full textMetali su kemijski elementi koji su zbog svoje rasprostranjenosti u cjelokupnom ekološkom sustavu predmet mnogih istraživanja. Nagli razvoj tehnologije uveliko je narušio kvalitetu životu zbog izlaganja toksičnih tvari u prirodu. U ovome radu opisana je metoda ekstrakcije metalnih iona iz vodenih otopina kao primjer jedne od učinkovitih metoda izoliranja metalnih iona. Za ekstrakciju se koriste makrociklički spojevi koji su građom velike cikličke molekule koje sadrže barem devet atoma unutar prstena od kojih minimalno tri moraju biti donori elektronskoga para. Makrocikli svojim donorskim atomom lako vežu metalne katione dajući kompleks iz kojega se izoliraju metalni kationi. Jedna od vrsta makrocikličkih spojeva su Schiffove baze nastale kondenzacijom amina s aldehidima ili ketonima. Zbog svoje kemijske stabilnosti i mogućnosti vezanja kationa prijelaznih metala, ova vrsta makrocikla ima važnu ulogu u ekstrakciji metalnih iona. U eksperimentalnom dijelu napravljena je ekstrakcija vodenih otopina soli različitih nitrata uz pomoć dva markociklička liganda te je mjerena apsorbancija metalnih kationa na UV-VIS spektrofotometru. Na osnovi dobivenih podataka izračunata je ekstraktibilnost u postotku za svaki metalni kation.Metals are chemical elements which, due to their prevalence in the entire ecological system, are subject of extensive research. Today's technology development affected the quality of life due to exposure of toxic substances in nature. This paper describes the methods of metal ion extraction from aqueous solutions. This method is an example of effective way for isolation of the metal ions. Extraction using macrocyclic compounds that are cyclic molecules containing at least nine ring atoms, of which at least three have to be an electron pair donor was studied. Donor atom of the macrocycle easily binds the metal cations, and in such way they make complex from which metal cations can be isolated. One type of macrocyclic compounds are Schiff bases, that are formed by the condensation of amines with aldehydes or ketones. Due to its chemical stability and the ability to bind metal cations, this type of macrocycle is important in the process of metal ion extraction. Experimental section desribes extraction of metal cations from aqueous solutions of different salts using two microcyclic ligands and the absorbance was measured using UV-VIS spectrophotometer. The percentage of extractability was calculated for each metal cation
Electrochemical characterization of rutin
No full textU ovom radu ispitivana su elektrokemijska svojstva rutina u različitim puferima (pH = 3,5 do 8,0) cikličkom voltametrijom i diferencijalnom pulsnom voltametrijom. Cilj rada bio je ispitati utjecaj pH vrijednosti na potencijal oksidacijskog strujnog vrha rutina, istražiti utjecaj koncentracije rutina i brzinu promjene polarizacije elektrode na oksido-redukcijska svojstva rutina, te istražiti moguću adsorpciju oksidacijskog produkta rutina na površinu elektrode od staklastog ugljika. Elektrokemijska mjerenja su provedena u elektrokemijskoj ćeliji s troelektrodnim sustavom, a kao radna elektroda korištena je elektroda od staklastog ugljika. Utvrđeno je da je proces oksidacije rutina reverzibilan, ovisan o pH i uključuje izmjenu dva protona i dva elektrona. Potencijal oksidacijskog strujnog vrha rutina linearno se smanjuje s povećanjem pH vrijednosti, dok se struja oksidacijskog strujnog vrha povećava do pH = 5,5 i nakon toga opada (optimalna pH vrijednost za oksidaciju je pH = 5,5). Također je ustanovljeno da povećanjem koncentracije rutina raste visina oksidacijskog i redukcijskog strujnog vrha, te da struja oksidacijskog i redukcijskog strujnog vrha raste s povećanjem brzine polarizacije elektrode. Rezultati su također pokazali da dolazi do adsorpcije rutina i oksidacijskih produkata rutina na površinu elektrode od staklastog ugljika, budući da visina oba oksidacijska strujna vrha rutina opada uzastopnim snimanjem voltamograma za sve pH vrijednosti. U metodičkom dijelu rada obrađena je nova nastavna jedinica "Reakcije oksidacije i redukcije", koja je predviđena za jedan školski sat. Nastavna jedinica uključuje obradu novog nastavnog sadržaja, pokus, brojne primjere i zadatke za ponavljanje.In this work electrochemical properties of rutin in different buffers (pH = 3,5 to 8,0) was studied by cyclic voltammetry and differential pulse voltammetry. The main goal of this thesis was to examine the influence of pH on the rutin oxidation peak potential, to investigate the effect of rutin concentration and scan rate on the oxido-reduction properties of rutin and the possible adsorption of the oxidation product of rutin on the surface of the glassy carbon electrode. Electrochemical measurements were carried out in an electrochemical cell with a three electrode system and as a working electrode was used a glassy carbon electrode. It was found that the oxidation process of rutin is reversible, pH dependent and involves the exchange of two protons and two electrons. The oxidation peak potential of the rutin decreases linearly by increasing the pH value, while the oxidation peak current increases to pH = 5,5 and then decreases (the optimum pH for oxidation is pH = 5,5). It has also been found that the increase of rutin concentration and scan rate increases the oxidation and reduction peak current. The results also showed that the adsorption of rutin and its oxidation products on the surface of the glassy carbon electrode occurs since the height of both oxidation peaks of rutin decreases with successive scans for all pH values. In the methodological part of the thesis, a new teaching unit "Oxidation and Reduction Reactions" is provided, which is foreseen for one class. The teaching unit includes the processing of new teaching content, experiment, numerous examples and repetition tasks