Hidrofilically modified silicones as dispersants in aqueous solutions

Cilj i svrha ovog diplomskog rada jest ispitati na koji način i u kojim uvjetima hidrofilno modificirani silikoni malih molarnih masa djeluju na svojstva suspenzija nanočestica $TiO_2$ i ZnO u vodenim otopinama. Korišteni su hidrofilno modificirani silikoni različitih proizvođača, Elkay® Silicones, Xiameter® Dow Corning. Silikoni su karakterizirani mjerenjem viskoznosti pri različitim koncentracijama i pH vrijednostima. Akustičkom spektroskopijom ispitano je kako silikoni utječu na stabilnost suspenzija nanočestica, a moguća adsorpcija na površini nanočestica testirana je metodom TGA/DSC (termogravimetrijska analiza/razlikovna pretražna kalorimetrija). Rezultati su pokazali da silikoni djeluju kao dispergatori na suspenzije nanočestica, odnosno pospješuju raspršenost suspenzije nanočestica. Metodički dio rada sadrži pripremu za nastavnu jedinicu pod naslovom „Silicij i silikati“. Nastavni sat zamišljen je kao kombinacija frontalnog i grupnog rada uz izvođenje pokusa.The aim and purpose of this work is to examine how and under which conditions hydrophilically modified silicones of small molecular weight affect the nanoparticle suspension ($TiO_2$ and ZnO) properties in aqueous solutions. The silicones of two different manufacturers, Elkay® Silicones, Dow Corning® Performance Products were used. They were characterized by viscosity measurements in broad concentration and pH ranges. Acoustic spectroscopy was used to explore on how the silicones affect the nanoparticle suspension stability and a possible adsorption on the surface of nano particles was tested using the TGA / DSC (thermogravimetry / differential scanning calorimetry). Results showed that silicones act as dispersants for the aqueous nanoparticle suspension. Methodical part of the work includes preparation for teaching unit entitled "Silicon and silicates". Lesson is designed as a combination of teacher`s frontal talk and group student`s work with experimentation

Shift of the scientific worldview in the context of General System Theory

Opća teorija o sistemima pojavila se u samome središtu znanosti 20. stoljeća, šireći se spontano i postupo na gotovo sve razine i perspektive ljudskoga znanja o prirodnom i društvenom svijetu. U ovome radu razmatraju se i opisuju osnovni pojmovi opće teorije o sistemima, uvjeti i kontekst njena nastanka te njeni začetnici. S time u vidu, izložit će se razvoj znanosti (posebice fizike i biologije) i kako je on postupno doveo do opće teorije o sistemima, odnosno do cjelovite slike svijeta i života. Osnovni pojmovi vezani uz opću teoriju sistema jesu otvoreni sistemi, dinamička ravnoteža i samoorganizacija. Navedena razmatranja se u posljednjem dijelu ovoga rada smještaju u kontekst etike, odnosno onoga što jedan od teoretičara opće teorije o sistemima naziva operativna etika.General System Theory has emerged within the very heart of 20th century science, spreading itself spontaneously and slowly on almost all levels and perspectives of human knowledge about the natural and the social world. This paper explores the main notions of General System Theory, describes the conditions and the context of its emergence and introduces its originators. With this in view, the development of science (especially physics and biology) will be outlined, followed by an explanation of how it gradually gave rise to General System Theory on the one hand and to a holistic view of the world and life on the other. The main notions connected to General System Theory are open systems, steady state, and self-organization. In the last part of this paper the above mentioned reflections are placed in the context of ethics in general, and operational ethics in particular (as it is called by one of the theoreticians of GST)

Priprava srebrovih soli s hidroksi karboksilnim i masnim kiselinama

Tema, a ujedno i cilj ovoga rada jest sinteza srebrovih soli s hidroksikarboksilnim i masnim kiselinama. U radu će se raspravljati kako o sintezi tako i o analizi spomenutih spojeva. Za sintezu srebrovih soli korištene su limunska, salicilna, oleinska i stearinska kiselina. Glavni prekursor u svim sintezama bila je jedna od najpoznatijih srebrovih soli, srebrov nitrat. Kako bi se pobliže otkrila molekulska struktura i graĎa ovih spojeva korištene su metode infracrvene spektroskopije (FTIR) i termogravimetrijske analize (TGA).The topic and a goal of this paper is a synthesis of silver salts with hydroxycarboxylic and fatty acids. Their synthesis and analysis will be described and discussed. Acids used in synthesis were citric acid, salicylic acid, oleic acid, and stearic acid. Main precursor in the synthesis was silver nitrate. TGA and FTIR were used for determination of molecular structure

Usporedba protutumorske aktivnosti liganada iz skupine benzo/hidrokispirona i bakrova(II) kompleksa s maltolom na 2D staničnim modelima in vitro

Heterocyclic structures are the basic building blocks of many naturally occurring organic compounds that are important for the development of essential biological processes in plants and animals, including carbohydrates and vitamins. They are also widely used as raw material sources to produce pharmaceuticals. In this study, three ligands from the groups of benzopyrones (chromone-2-carboxylic acid) and hydroxypyrones (maltol and coumalic acid), and a newly prepared complex of copper(II) nitrate with maltol as a ligand were investigated for their ability to inhibit cell proliferation. For research purposes, a series of solutions of the tested materials were prepared at different final concentrations (10–5 mol dm–3, 10–6 mol dm–3, and 10–7 mol dm–3), and then applied to a total of 7 selected cell lines, including one healthy cell line, while the others were tumour cell lines. The results of MTT cytotoxicity assay on the selected 2D cell models showed that none of the selected ligands exhibited antiproliferative activity at any concentration on any of the tested cell lines. The complex of copper(II) nitrate and maltol, in contrast to the tested ligands at the 10–5 mol dm–3 concentration, exhibited significant cytotoxicity as follows: KATO III > HT-29 > Hep G2 > NCI-H358 > MDA-MB-231 > Caco-2 > MRC-5. The healthy cell line (MRC-5) had a survival rate higher than 90.0 % at all tested concentrations, which led to the conclusion of the selectivity of the compound towards tumour cell lines.Heterocikličke strukture osnovne su gradivne jedinice mnogih prirodnih organskih spojeva ključnih za odvijanje životnih funkcija u biljnom i životinjskom svijetu kao što su ugljikohidrati i vitamini, a nije strana niti njihova uloga kao sirovina za proizvodnju lijekova. U ovom su radu ispitana antiproliferativna svojstva triju odabranih liganada iz skupine benzopirona (kromon-2-karboksilna kiselina) i hidroksipirona (maltol i kumalična kiselina) kao i novog kompleksnog spoja pripravljenog iz bakrova(II) nitrata s maltolom kao ligandom. Za potrebe istraživanja pripravljene su serije otopina ispitivanih tvari različitih finalnih koncentracija (10–5 mol dm–3, 10–6 mol dm–3 i 10–7 mol dm–3), koje su potom aplicirane na ukupno 7 odabranih humanih staničnih linija od kojih je jedna bila zdrava, a ostale tumorske stanične linije. Rezultati MTT testa citotoksičnosti na odabranim 2D staničnim modelima pokazali su da niti jedan od testiranih liganada ne pokazuje antiproliferativnu aktivnost ni pri jednoj koncentraciji niti na jednoj ispitanoj staničnoj liniji. Za razliku od liganada, kompleksni spoj pripravljen iz bakrova(II) nitrata i maltola pokazuje značajnu citotoksičnost pri koncentraciji 10–5 mol dm–3 na odabranim staničnim linijama kako slijedi: KATO III > HT-29 > Hep G2 > NCI-H358 > MDA-MB-231 > Caco-2 > MRC-5. Zdrava stanična linija (MRC-5) je pri svim ispitivanim koncentracijama imala stopu preživljenja višu od 90,0 %, što je uputilo na zaključak o selektivnosti spoja prema tumorskim staničnim linijama

Production of Forage Maize Yield under the Zinc Foliar Fertilization and Irrigation System

The objective of presented study was to evaluate the effects of zinc foliar fertilizer and drip irrigation system on some qualitative and quantitative parameters of forage maize. Soil water deficit, drought and unbalanced fertilization are the main reasons maize grain and forage yields decrease. In this trial, the basic NPK fertilization was applied on basis of soil analysis with additional foliar application of zinc at the fifth leaf stage. Trial was set up as complete randomized design in three replications. The zinc foliar treatment with or without irrigation system gave up to 18% higher yield compared to the control treatment. Other parameters such as hectoliter mass (1.12%), nitrogen yield content (6.25%), phosphorus (13.51%), potassium (5.38%) and zinc content (70%) had higher recorded values in treatment with included foliar zinc fertilization and irrigation system compared to the control. The foliar zinc applications had positive effect on measured parameters along with drip irrigations system. However, it is necessary to establish the economic justification for introducing an irrigation system in the production of forage maize

Synthesis, characterization and biological activity of platinum(II) and palladium(II) complexes with quinoline derivatives of thiosemicarbazones

The aim of this study was to elucidate the structure, geometry and biological activity of platinum(II) and palladium(II) complexes with different quinoline derivatives of thiosemicar-bazones. Four novel platinum(II) and palladium(II) complexes with 2-quinolinecarboxaldehyde thiosemikarbazone (H2QATSC) and 8-quinolinecarboxaldehyde thiosemikarbazone (H8QATSC) were synthesized. The complexes of platinum(II) and palladium(II) with H2QATSC ligand, [PtCl(2QATSC)] (1) and [PdCl(2QATSC)] (2), were synthesized by direct reaction and charac-terized by single crystal X-ray analysis. The complexes of platinum(II) and palladium(II) with H8QATSC ligand, [PtCl(8QATSC)] (3) and [PdCl(8QATSC)] (4), were characterized by NMR spectroscopy. In the complexes 1–4 ligands are coordinated tridentately via the quinoline and imine nitrogen atoms and thiosemicarbazone sulfur atom, forming two five-membered rings with metal ion. The geometry around metal ions is square-planar, where chloride ion occupies fourth coordination site. Antitumor activity of the complexes 1–4 was investigated and com-pared with the activity of cisplatin

Kompletni atrioventrikulski blok i asistolija tijekom epileptičkog napadaja: prikaz slučaja

Cardiac arrhythmias during or after epileptic seizures are one of the possible pathomechanisms of sudden unexpected death in epilepsy. These arrhythmogenic epilepsies are most commonly associated with sinus tachycardia, but atrioventricular block and asystole can also be seen. Although a rare occurrence, these arrhythmias can lead to significant morbidity and mortality, but also can be potentially preventable with pacemaker implantation. Here we describe a patient with recurrent epileptic seizures, diagnosed with ictal third-degree atrioventricular block and asystole during seizure, which required a permanent cardiac pacemaker.Srčane aritmije tijekom ili nakon epileptičkih napadaja jedan su od mogućih patomehanizama neočekivane smrti u bolesnika s epilepsijom. Ove aritmogene epilepsije najčešće su povezane sa sinus tahikardijom, ali se mogu uočiti i atrioventrikulski blok i asistolija. Iako se rijetko pojavljuju, ove aritmije mogu dovesti do značajnog pobola i smrtnosti, ali se također mogu prevenirati ugradnjom srčanog stimulatora. Ovdje opisujemo bolesnika s ponavljajućim epileptičkim napadajima i dijagnosticiranim atrioventrikulskim blokom trećeg stupnja i asistolijom tijekom napadaja kojemu je bilo potrebno ugraditi trajni srčani stimulator