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V svojem diplomskem delu sem se osredotoc&#780 il na stare ljudi iz glavnega mesta Ljubljana, saj me zanima, kaks&#780 en je njihov interes za ohranjanje stikov z okolico in spletanje socialne mrez&#780 e. Zanimalo me je tudi, ali so osamljeni in kje dobijo informacije o aktivnostih, v katere se lahko vkljuc&#780 ujejo. O kakovosti z&#780 ivljenja starih ljudi je sicer napisanega z&#780 e veliko, kljub temu pa premalo predlogov in res&#780 itev, ki bi spodbujale starostnike k ohranjanju stika z okolico in posledic&#780 no vplivale na izboljs&#780 anje kvalitete z&#780 ivljenja. Starostniki so posebna, ranljiva skupina ljudi, ki so v danas&#780 njem c&#780 asu z&#780 al s&#780 e vedno prevec&#780 krat stigmatizirani s strani druz&#780 be in posledic&#780 no odrinjeni na rob. Na kvaliteto z&#780 ivljenja v tretjem z&#780 ivljenjskem obdobju pripomore dvig ozaves&#780 c&#780 enosti o pomenu zdravega z&#780 ivljenja in njihova socialna interakcija z okoljem. Zaradi podaljs&#780 evanja z&#780 ivljenjske dobe prihaja do novih izzivov, kot so osamljenost, obc&#780 utki nepripadnosti ... C&#780 edalje vec&#780 starih ljudi se zapre vase in jim zato tudi ni vec&#780 toliko do druz&#780 enja z ostalimi, ker mislijo, da so naenkrat prestari za vse. In my graduation thesis I focused on the old people from the capital city Ljubljana, because I am interested in their interest in maintaining contact with their surroundings and the social networking. I also wondered whether they are lonely and where they get information about their activities they can engage in. There is already a lot about the quality of life of the elderly, but there are insufficient suggestions and solutions that would encourage the elderly to maintain contact with the environment and consequently influence the quality of life. Elderly people are a special, vulnerable group of people who, unfortunately, are still too stigmatized by society today and, consequently, marginalized. The quality of life in the third life period helps to raise awareness about the importance of a healthy life and their social interaction with the environment. Due to the prolonging of life, there are new challenges, such as loneliness, feelings of inactivity ... An increasing number of old people are closing in and they are no longer so much to socializing with others because they think that they are suddenly too old for everyone.

Following the assumption that the crucial processes governing the formation, properties, and evolution of the core (amorphous silica)@shell (organocations) nanoparticles (NPs) take place during short-time, room-temperature (rt) stirring/aging of the homogeneous reaction mixtures (HmRMs) formed by hydrolysis of tetraethyl orthosilicate (TEOS) in solutions of Org(OH)n, we investigated these processes by various experimental methods (pH, ionic conductivity, 29Si NMR, dynamic light scattering, and atomic force microscopy). The analysis of the data obtained by detailed and careful investigation of the “model” HmRMs having the starting chemical composition, xTEOS/0.25TPAOH/20H2O (TPAOH = tetrapropylammonium hydroxide ; x = 0.05−1), offer some new elements for the understanding of the mechanisms of the formation and rt evolution of the core@shell silica NPs: (1) There is a resolute evidence of the formation of the stable, about 1.2 nm-sized core (amorphous SiO2)@shell (TPA+ ions) NPs below the critical aggregation concentration. (2) Because of the intensive particulate processes (growth, aggregation, disaggregation, and dissolution) which take place during the rt aging of the investigated HmRMs, the equilibrated core@shell silica NPs do not exist as individual primary ones but as the aggregates (about 2 to about 20 nm), composed of 1−2 nm-sized “primary” NPs. (3) In spite of the most frequent meaning that the NP shell is composed of the “free” TPA+ ions adsorbed on the surface of the NP core, the results of this study show that the NP shell can be formed mainly by the attachment of the polysilicate anions (silicate oligomers), associated with TPA+ ions, on the surfaces of the NP cores.

Reakcija tla najvažniji je čimbenik koji regulira primanje biogenih elemenata, a time i pojavu deficijencija. U alkalnim, karbonatnim tlima, deficijencije cinka i mangana su česte upravo zahvaljujući činjenici da se formiraju teško topivi spojevi koji značajno smanjuju njihovu dostupnost biljkama. Upotreba zeolita kao gnojiva temelji se na činjenici da su zamjenjivi kationi u zeolitu sporo otpuštajući izvor hraniva koji bi trebao osigurati stabilnu i konstantnu opskrbu biljkama kroz nekoliko vegetacijskih godina, unatoč negativnim kemijskim osobinama tla. Cilj ovog istraživanja bio je stoga utvrditi utjecaj gnojidbe modificiranim sintetskim zeolitima, putem tla, na mineralni sastav nadzemnog dijela lupine Lupinus albus L. U tu svrhu provedeno je u vegetacijskoj komori, tijekom 52 dana, istraživanje na alkalnom tlu (pH KCl = 7.4). Gnojidba Zn i Mn obavljena je u obliku sintetskog Zeolita A, u kojem su ionskom zamjenom Na ioni zamjenjeni kationima Zn, Mn. Istraživanje je provedeno po slučajnom bloknom rasporedu s 4 gnojidbena tretmana (Kontrola, NPK, Zeoliti mix, NPK + Zeoliti mix). Temeljem rezultata istraživanja vidljivo je da je pri tretmanu Zeoliti mix utvrđena statistički značajno veća količina Mn u nadzemnim dijelovima lupine u odnosu na sve ostale gnojidbene tretmane dok se količina Zn nije statistički razlikovala neovisno o gnojidbenim tretmanima.

Na području Dalmacije prevladavaju alkalna tla, pH vrijednosti u KCl-u >7.2, pa su deficijencije Zn, Mn, Fe i Mg učestala pojava. Razlog tomu je pored visokog pH i visoka koncentracije aktivnog vapna u tlu koje blokira primanje navedenih hraniva. Cilj preliminarnog istraživanja bio je stoga utvrditi utjecaj gnojidbe sintetskim zeolitima na mineralni sastav lišća a time i na nutritivnu vrijednost radiča Cichorium intybus var. foliosum L. kultivar Leonardo. U tu svrhu provedeno je istraživanje na alkalnom tlu (pH KCl = 7.4) u trajanju od 62 dana. Gnojidba Zn, Mn, Fe i Mg obavljena je u obliku sintetskog Zeolita A, u kojem su ionskom zamjenom Na ioni zamjenjeni kationima Zn, Mn, Fe i Mg. Prednost zeolita u odnosu na klasična gnojiva je ta što se iz njih hraniva sporo otpuštaju i ne ispiru iz tla, pa je i djelovanje na biljku dugoročnije te ekonomski i ekološki isplativije. Temeljem rezultata istraživanja vidljivo je da je pri tretmanu zeolitima utvrđena statistički značajno veća količina Zn u listu radiča te relativno veća količina Mn u odnosu na kontrolnu varijantu bez zeolita. Količine Fe i Mg u listu radiča nisu pokazale signifikantnu razliku između navedenih tretmana. Sve utvrđene vrijednosti minerala u radiču neovisno o tretmanu (P, K, Ca, Mg, Mn, Fe) u skladu su s ostalim literaturnim navodima, dok su značajno više vrijednosti Zn utvrđene pri primjeni zeolita što je značajno s nutritivnog ali i s agroekološkog aspekta

Na alkalnim, karbonatnim tlima, zbog formiranja teško topivih spojeva, smanjena je dostupnost cinka (Zn), mangana (Mn), i željeza (Fe). Razlog tomu je pored visokog pH i visoka koncentracija aktivnog vapna u tlu koje blokira primanje navedenih hraniva. Cilj ovog istraživanja bio je utvrditi utjecaj gnojidbe sintetskim zeolitima na mineralni sastav lišća masline Olea europaea L. sorte Leccino uzgajane na alkalnom, karbonatnom tlu. U tu svrhu provedeno je istraživanje, u vegetacijskoj komori, u trajanju od 200 dana. Gnojidba Zn, Mn i Fe obavljena je u obliku sintetskog zeolita A (ZA), u kojem su ionskom zamjenom Na ioni zamijenjeni kationima Zn2+, Mn2+ i Fe2+ (Fe3+). Temeljem rezultata istraživanja vidljivo je da je pri tretmanu zeolitima utvrđena statistički značajno veća koncentracija Mn u listu masline dok koncentracije Fe i Zn u listu masline nisu pokazale signifikantnu razliku između tretmana sa ili bez primjene zeolita.

The influence of the initial mass of the solid phase and concentration of NaOH on the kinetics of dissolution of an amorphous aluminosilicate precursor having an Si : Al molar ratio of 1.178:1 has been studied by measuring the change in the aluminium and silicon concentrations in the liquid phase during dissolution at 80°C. Analysis of the results obtained indicated that only the outside surface and not the internal surface (pore system) is relevant in the dissolution process. The process of dissolution is controlled by two reactions: a forward one, whose rate is proportional to the outer surface area, S, of the solid phase exposed to the action of OH- ions from the liquid phase, and a backward one, whose rate is proportional to the surface area, S, and to the concentration of reactive silicate and aluminate species from the liquid phase.

The seed-induced crystallization system has been adopted for the synthesis of sub-micrometer sized zeolite ZSM-5 in the absence of organic structure directing agent (SDA). The structural (phase purity), particulate (sizes and morphology) and chemical compositions (framework Si/Al ratios) of the crystalline end products could be well controlled via the batch alkalinity, excess of sodium ions, and aging of the reaction mixtures. More importantly, the crystallization mechanism has also been revealed as a typical linear, size-independent growth process on the surface of silicalite-1 seed nanocrystals embedded in the gel matrix without the formation of new nuclei either on the surface of growing seed crystals or in the gel matrix. The critical processes happened during crystallization have also been characterized by different methods and evaluated by population balance modeling approach.

Crystallization of sub-micrometer zeolite ZSM-5 from TPA-free reaction mixture1.0Al2O3/100SiO2/28Na2O/4000H2O, seeded with silicalite-1 seed crystals of different size (90 - 690 nm) was analyzed by population balance methodology. From this reason, mesured changes of crystal size distributions and fractions of newly formed crystalline phase (ZSM-5) were compared with the calculated (simulated) data. A small disagreement between measured and simulated crystal size distributions of the crystalline end products for D >= 0.5 micrometers (D is the spherical equivalent diameter measured by laser-light scattering method) is explained by formation of small proportion of crystal aggregates during crystallization. However, almost perfect correlation between measured and simulated kinetics of crystallization shows that the formation of aggregates do not considerably influences the growth rate of zeolite ZSM-5 on silicalite-1 seed crystals. Thus, population balance analysis of the crystallization process and particulate properties of the crystalline end products show that crystallization takes place by a linear, size-independent growth of silicalite-1 seed crystals embedded in the gel matrix and that there is not formation of new nuclei during crystallization. The obtained results also show that the developed population balance model enables control and prediction of the particulate properties of the crystalline end products.

Citric acid is often used as complexing agent as well as additive in various crystallization systems. It can have significant influence on the product's type and properties. Zeolite catalysts with transition metal ions can be applied in many important industrial processes. Zeolites with metal ions incorporated in the framework are even more convenient materials because of the reduced metal leaching. Here, we report the preparation of an analcime framework type material in the presence of copper (II) ions and citric acid: molar oxide composition of the starting reaction system was: 70Na2OxAl2O3x65SiO2x3CuOx1900H2Ox12CA (CA stands the citric acid). After its hydrothermal treatment at 120 oC, two different components were obtained. According to XRD results, the pale blue solid component consists of analcime and smaller, but detectable amount of gismondine material. DSC curve also showed peaks characteristic for analcime. Elemental analysis, made by atomic absorption spectroscopy, revealed that crystals contain substantial quantity of copper. So far, it remain unclear what form of copper is present in the system as well as how it is related to the zeolite's framework.

Zeolites’ particulate properties (crystal size distribution and crystals’ morphology) often have a very important role in use of zeolites in many applications: the mode and efficiency of their use as catalysts, adsorbents, cation exchangers, and molecular sieves. The influence of physico-chemical parameters (reaction mixture starting chemical composition of liquid and solid phase, system alkalinity, reaction temperature, stirring conditions, way of components adding, template presence, etc.), which have an impact on particulate properties of synthesized zeolites, is discussed. Special attention is given to the most important basic processes in zeolite crystallization - nucleation and crystal growth. The collected knowledge about mentioned synthesis processes and crystallization parameters, helps us in their modeling as well as in the designing of the products (crystals) having desired phase and particulate properties, needed for specific applications.

The possibility to control particulate properties (particularly morphology) of the synthesized crystals can be implemented through several physico-chemical parameters. In this paper, we have studied the influence of the alkalinity of the system on the size and morphology of zeolite A crystals. Prepared hydrogels were heated at 80°C in reactors made of HDPE, under static conditions. Starting compositions were: 3.2/12.0 Na2O × 2 SiO2 × 1.1 Al2O3 × 300.0 H2O. The characterization of the samples was performed using several analytical methods such as: X-ray diffraction (XRD), laser light scattering (LLS), optical microscopy (OM) and scanning electron microscopy (SEM). The analysis of the results show that the increase of alkalinity of explored system had two major effects: increase of the number of nuclei (crystals) in system and formation of crystals with more irregular shape.

The structural and particulate properties of the solid phases, separated from the reaction mixture (12.5Na2O-8TPABr-Al2O3-60SiO2-4000H2O) at various stages of crystallization of zeolite ZSM-5, were characterized by X-ray diffraction (XRD), scanning-electron microscopy (SEM) and transmission-electron microscopy (TEM). The change of the concentration of Si in the liquid phase during crystallization was measured by atomic absorption spectroscopy (AAS). On the basis of the analysis of experimental results as well as the previously published experiences, possible mechanism of crystallization is proposed.

Kinetics of isothermal crystallization of tetragonal modification of leucite and hexagonal modification of kalsilite from differently prepared precipitated amorphous aluminosilicate precursors were investigated at three different temperatures. Kinetic analysis of the transformation processes have shown that the crystallization of leucite occurs in the same way as the crystallization of kalsilite and follows a pseudo-zero-rate kinetic equation. The apparent activation energies calculated by the Arrhenius equation were 373 kJ/mol for the crystallization of kalsilite and 403 kJ/mol for the crystallization of leucite, which is explained by different microstructure of the prepared precursors.

Zeolites are materials with different applications. Every field of usage has special demands regarding zeolite particulate properties. Understanding the mechanisms of crystal formation enables control of these properties. After ageing at 25°C for ta = 0-209 h hydrogels of composition 3, 2 Na2O × 2 SiO2 × 1, 05 Al2O3 × 250 H2O were heated in reactor at 80°C under dynamic conditions. Optical microscopy and SEM images as well as particle size measurement provided data on crystal size and specific surface area of final products. Specific number of zeolite A crystals was calculated from particle size distributions. Observed effects were discussed on the grounds of the autocatalytic nucleation theory.

Atomic force microscopy (AFM) in combination with other well established techniques such as transmission electron microscopy (TEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Differential thermal gravimetry (DTG), electron diffraction (ED), scanning electrom microscopy (SEM), were used to investigate the very early stages of nucleation and crystallization on the surface of gel precursor in the synthesis of zeolite A and silicalite-1. Analysis of the precipitated sodium aluminosilicate /silicate precursor (gel) has shown that predominantly true amorphous phase of the gel contains small proportions of partially crystalline (“quasi-crystalline”) or even fully crystalline phase. In the case of the gel precursor for the synthesis of zeolite A is also found that the freshly prepared gel is mainly composed of disc-shaped primary particles, but also partially or even fully crystalline entities were observed by AFM analysis. AFM analysis of the solids separated from the hydrogel at various stages of its hydrothermal treatment (heating at 80o C) indicates that the particles of the partially and/or fully crystalline phase are nuclei for further crystallization of zeolite [1]. In this study is also monitored the behavior of the silicate species in relation with the structure directing agent TPABr during the formation of nuclei for the crystallization of silicalite 1. It is found that TPA+ cations linked together with silicate species by Vand der Waals forces and form short range ordered units having size below 10 nm that correspod to primary building units. The units agglomerate and form particles having size about 10 nm that was confirmed by AFM and TEM. These entities acts as the nucleation centers for the crystallization of silicalite-1 [2]. [1] Kosanović, C., Bosnar, S., Subotić, B., Svetličić, V., Mišić, T., Drazić, G. Havancsak, K., Microporous and Mesoporous Materials, 110 (2008)177-185. [2] De Moor, P-P. E. A., Beleen, TPM, Komanschek, B. U. , Beck, L. W., Wagner, P, Davis, M. E., Van Santen, R. A., Chem Eur. 1999, 5, 2083-2088.

Large influence of ageing process on kinetic of zeolite A synthesis was discussed from viewpoint of the most important factor - the distribution of nuclei within hydrogel matrix. The number of nuclei generated at surface-subsurface region increase with time of gel ageing.

Sinteza zeolita A iz hidrogela odvija se posredstvom tekuće faze, tj. istovremeno se odvija proces otapanja gela i rasta kristala zeolita. Otapanjem gela nastaju reaktivne aluminatne, silikatne i alumosilikatne čestice, koje se ugrađuju u kristale zeolita reakcijom na površini kristala. Većina nukleusa se također nalazi u česticama gela, a mogu rasti samo kada se u kontaktu s tekućom fazom. Budući da nukleusi u puni kontakt s tekućom fazom dolaze otapanjem gela, jasno je da kinetika nukleacije ovisi o brzini otapanja gela i o raspodjeli nukleusa unutar čestica gela. Struktura i sastav gela (time i raspodjela nukleusa unutar gela) ovise o kemijskom sastavu silikatne i aluminatne komponente i načinu taloženja gela (hidrodinamički uvjeti, temperarura, redoslijed dodavanja komponenti, naknadni tretman hidrogela, itd.). Dobiveni su pravilni djelom urasli kristali (kocke „isječenih“ bridova) prikazani na mikrografiji snimljenoj pomoću pretražnog elektronskog mikroskopa. Široka raspodjela veličina kristala upućuje na relativno homogenu raspodjelu nukleusa unutar matrice gela.

Solid phase (gel) separated from freshly prepared hydrogel having the batch molar composition: 2.5Na2O-8TPABr-60SiO2-800H2O as well as the solids drawn off the reaction mixture, during its hydrothermal treatment at 443 K and solid phase (gel) separated from freshly prepared hydrogel having the batch molar composition: 0.468Na2O×Al2O3×3.382SiO2×55.44H2O as well as the solids drawn off the reaction mixture, during its hydrothermal treatment at 353 K were analyzed by different methods such as powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning-electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED) and atomic force microscopy (AFM). It has been found that the first mentioned freshly prepared gel represents a “hierarchical structure” in which the largest individual gel aggregates (having the size 200 nm – 1000 nm, or more) are composed of smaller particles having the size in the range 40 nm – 80 nm, which represent aggregates of ≤ 10 nm particles. The second gel is mainly composed of disc-shaped primary particles as well of partially or even fully crystalline entities. Heating of the hydrogels causes structural changes in the gel matrix. 36T units of MFI structure present in the freshly prepared gel gradually transforms into fully crystalline nuclei of silicalite-1 and the “pyramidal-shaped” particles that have crystal structure closer to faujasite than zeolite A transform to zeolite A. The nuclei formed inside both the gel particles and/or small nanocrystals formed by a limited grow of nuclei in the gel matrix, can grow only after their release from the gel dissolved during the crystallization, i.e. when they are in full contact with the liquid phase.

After hydrothermal treatment, hydrogel is transformed into crystalline zeolite A via three steps: nucleation, gel dissolution and crystal growth. Most of the nuclei are formed within gel matrix, and released to the solution during the gel dissolution where they become growing crystals. Transformation ends when the concentration of reactive species drops to the value of ZA solubility. Hydrogels of the same chemical composition were aged for 10 and 158 hours. Products gained during and after hydrothemal treatment were characterized by XRD, optical and scanning electron microscopy while the concentrations of Si- and Al- reactive species in the liqud phase were monitored by atomic absoprtion spectrometry.

[SiO2/Al2O3] ratio has a influence on morphological properties of zeolite A. The decrease of ratio (y ≤ 2) at relatively high alkalinity (e.g., x > 0.005) decreases the crystal growth rate in and directions, and thus development of {; ; 110}; ; and {; ; 111}; ; crystal faces. Further increase of alkalinity and simultaneous decrease of y causes surface nucleation and “rounding” of crystal edges and apexes.