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Nasl. z nasl. zaslona. Opis vira z dne 21. 6. 2023. Bibliografija: str. 11-12. Abstract.

Non-destructive, fast, and accurate methods of dating are highly desirable for many heritage objects. Here, we present and critically evaluate the use of near-infrared (NIR) spectroscopic data combined with three supervised machine learning methods to predict the publication year of paper books dated between 1851 and 2000. These methods provide different accuracies however, we demonstrate that the underlying processes refer to common spectral features. Regardless of the machine learning method used, the most informative wavelength ranges can be associated with C−H and O−H stretching first overtone, typical of the cellulose structure, and N−H stretching first overtone from amide/protein structures. We find that the expected influence of degradation on the accuracy of prediction is not meaningful. The variance-bias decomposition of the reducible error reveals some differences among the three machine learning methods. Our results show that two out of the three methods allow predictions of publication dates in the period 1851−2000 from NIR spectroscopic data with an unprecedented accuracy of up to 2 years, better than any other non-destructive method applied to a real heritage collection.

Pri eksperimentalnem delu magistrske naloge smo preučevali reakcijski sistem, ki ga predstavljajo cinkov(II) sulfat(VI) heptahidrat, pikolinska kislina, piperidin, acetonitril in metanol. Produkt, ki nastane po 24-urnem segrevanju pri 105 °C v avtoklavu, je [Zn(NH3)4]SO4·2H2O. Zanimal nas je vpliv reagentov na naravo produkta. V ta namen smo acetonitril zamenjali s propionitrilom, piperidin z morfolinom, pikolinsko kislino pa s pirazinojsko kislino ali kinaldinsko kislino. Iz spremenjenih reakcijskih sistemov smo pridobili [Zn(quin)2(NH3)], [Zn(quin)2(pipeam)]·CH3CN, (morphH)(NH4)SO4 in (pipeH)(propioamH)SO4. V drugem delu je predstavljen eksperiment Infrardeči spektri spojin s tetraamincinkovim(II) ionom. Pri mnogih v eksperimentalnem delu izvedenih reakcijah kot produkt nastane [Zn(NH3)4]SO4·2H2O. Slednja spojina ima enostaven, vendar zanimiv infrardeči spekter. Poznanih je kar nekaj spojin z ionom [Zn(NH3)4]2+ in tudi njihovi infrardeči spektri so dobro razloženi. Z izbranimi [Zn(NH3)4]2+ spojinami smo oblikovali eksperiment, ki bi ga lahko izvajali študentje prvostopenjskega programa Kemija v okviru vaj pri predmetu Spektroskopija. Zadnji del magistrske naloge je umestitev v učni načrt kemije za gimnazije. Predstavljeni sta pripravi na dve učni uri. Prva je na temo računanja izkoristka pri kemijski reakciji, druga na temo koordinacijskih spojin z amonijakom. In the experimental part of the masters thesis, a reaction system consisting of zinc(II) sulphate(VI) heptahydrate, picolinic acid, piperidine, acetonitrile and methanol was studied. A product that forms upon a 24-hour long heating in autoclave at 105 °C is [Zn(NH3)4]SO4·2H2O. We were interested in the influence of the reagents over the nature of the product. Therefore acetonitrile was replaced with propionitrile, piperidine with morpholine and picolinic acid with pyrazinoic acid or quinaldinic acid. Thus modified reaction systems afforded several other products: [Zn(quin)2(NH3)], [Zn(quin)2(pipeam)]·CH3CN, (morphH)(NH4)SO4 and/or (pipeH)(propioamH)SO4. The second part of the thesis presents a laboratory experiment titled Infrared spectra of the [Zn(NH3)4]2+ compounds. Several of the above mentioned reactions resulted in [Zn(NH3)4]SO4·2H2O. The latter compound has a simple, yet interesting spectrum. Several other compounds containing the [Zn(NH3)4]2+ ion are known. Their infrared spectra have already been interpreted. Selected [Zn(NH3)4]2+ compounds form part of a laboratory experiment which could be performed within Spectroscopy, a course that is attended by students of a first-cycle study program Chemistry. The last part of the masters thesis is its placement in the chemistry curriculum for high schools. There are instructions for the preparation of two lessons. The first one is about the yield of a chemical reaction and second about coordination compounds with ammonia.

Herein, we report a computational algorithm that follows a spectroscopist-driven elucidation process of the structure of an organic molecule based on IR, $^1$H and $^{13}$C NMR, and MS tabular data. The algorithm is independent from database searching and is based on a bottom-up approach, building the molecular structure from small structural fragments visible in spectra. It employs an analytical combinatorial approach with a graph search technique to determine the connectivity of structural fragments that is based on the analysis of the NMR spectra, to connect the identified structural fragments into a molecular structure. After the process is completed, the interface lists the compound candidates, which are visualized by the WolframAlpha computational knowledge engine within the interface. The candidates are ranked according to the predefined rules for analyzing the spectral data. The developed elucidator has a user-friendly web interface and is publicly available (http://schmarnica. si).

Infrardeča spektroskopija je uveljavljena analitska metoda z veliko možnostmi uporabe, ki segajo tudi izven področja kemije. Gre za vibracijsko spektroskopijo, s katero na podlagi absorpcije svetlobe določenih valovnih dolžin identificiramo prisotne funkcionalne skupine v molekuli. V sintezni organski kemiji se uporablja v kombinaciji z ostalimi metodami za določanje strukture organskih spojin. Z razumevanjem teoretičnih osnov za absorpcijo infrardeče svetlobe lahko identificiramo vplive na položaj absorpcijskih trakov v spektru neke spojine. V okviru diplomskega dela sem posnela infrardeče spektre izbranih organskih spojin ter v teh spektrih prepoznala karakteristične absorpcije funkcionalnih skupin. Infrared spectroscopy is an established analytical method with a wide range of applications beyond the scope of chemistry. It is categorized as vibrational spectroscopy. Based on absorption of light with specific wavelengths, it is used in organic chemistry to identify functional groups present in a compound. In synthetic organic chemistry, it is used in combination with other methods for structure determination of organic compounds. With insight in theoretical backgrounds of infrared absorption we gain understanding of factors which influence position of absorption bands in the spectra. I have recorded infrared spectra of selected organic compounds and identified in their spectra the characteristic absorption peaks of functional groups.

The effects of thermal modification of wood have been well established, particularly in terms of reductions in mechanical performance. In recent years, there has been an increase in studies related to the Maillard reaction. More commonly associated with food chemistry, it involves the reaction of amines and reducing sugars during cooking procedures. This study has attempted to combine the use of amines and thermal modification, with subsequent properties investigated for the treatment of spruce (Picea abies (L.) H. Karst) and beech (Fagus sylvatica L.). In this initial study, the combined effects of chemical treatments by tricine and bicine were investigated with thermal modification. Along with some preliminary data on mechanical properties, the modifications which appeared in the wood structure were evaluated by infrared spectroscopy and biological studies according to EN113 and EN117 methodologies. The hierarchal study interpretation of FTIR suggested interactions between the bicine or tricine and the wood, which was partly supported by the analysis of volatile organic compounds (VOC), though other tests were not as conclusive. The potential of the method warrants further consideration, which will be described. Validerad;2022;Nivå 2;2022-05-30 (hanlid);Funder: COST Action FP1407;Part of special issue: Performance and Modification of Wood and Wood-Based Materials

Diplomsko delo temelji na sintezi in karakterizaciji koordinacijskih spojin nekaterih purinskih baz in fluoridooksidovanadatnih(V) anionov. Kot purinske baze smo uporabili ksantin, hipoksantin, teobromin in kofein. Izvedene so bile štiri sintezne reakcije v fluorovodikovi kislini med vanadijevim(V) oksidom in ustrezno purinsko bazo v razmerju 1:2. Karakterizacija vseh sintetiziranih spojin je potekala z infrardečo spektroskopijo. V primeru teobrominijevega fluoridooksidovanadata(V) in kofeinijevega fluoridooksidovanadata(V) pa je bila uporabljena tudi rentgenska strukturna analiza. The Graduation Thesis is based on synthesis and characterization of coordination compounds of some purine bases and fluroridooxidovanadate(V) anions. Xanthine, hypoxanthine, theobromine and caffeine were used as purine bases. Several reactions between vanadium(V) oxide and corresponding purine base in hydrofluoric acid and in a stoichiometric ratio of 1:2 were carried out. All synthesized compounds were characterized by infrared spectroscopy. Theobromine fluoridooxidovanadate(V) and caffeine fluoridooksidovanadate(V) were further characterized by X-ray structural analysis.

Analiza materialov predmetov kulturne dediščine predstavlja prvi korak pri načrtovanju kakršnega koli konservatorskega-restavratorskega posega. V okviru magistrskega dela sem v realnih vzorcih odvzetih z umetniških slik iz 20. stoletja z uporabo infrardeče spektroskopije in plinske kromatografije sklopljene z masno spektrometrijo identificiral uporabljena veziva. Najprej sem si z izbiro ustreznih modelnih vzorcev pripravil knjižnico IR spektrov, MS spektrov in kromatogramov, s pomočjo katerih sem nato interpretiral rezultate analiz realnih vzorcev odvzetih iz umetniških slik. Poleg identifikacije veziv v realnih vzorcih sem s pomočjo infrardeče spektroskopije identificiral tudi nekatere anorganske primesi (pigmente in polnila). Na modelnih vzorcih damar smole, čebeljega voska in njunih mešanic sem z infrardečo spektroskopijo preučeval tudi vpliv povišane temperature za različna časovna obdobja. Analysis of the materials of cultural heritage objects is the first step toward any kind of a conservation-restoration procedure. In this work I have characterized binder materials in samples taken from 20th century paintings using infrared spectroscopy and gas chromatography coupled with a mass spectrometry. With appropriate selection of model samples the library of infrared spectra, MS spectra and chromatograms was prepared for further interpretation of the results of the real samples from paintings. Together with the identification of the binder materials in the samples also some inorganic compounds (pigments and fillers) were identified using infrared spectroscopy. I have also employed infrared spectroscopy to study the effects of increased temperature on model samples of dammar resin, beeswax and their mixtures.

Preučevali smo agregacijo konkanavalina A z uporabo infrardeče spektroskopije. Konkanavalin A je protein s pretežno sekundarno strukturo beta, ki ima zelo zanimivo vrsto agregacije. V kislem mediju se z nespremenjeno strukturo agregira v amorfne agregate, medtem ko v bazičnem okolju tvori amiloidne fibrile. Zato smo ga uporabili za testiranje zaviranja tvorbe amiloidov, ki so glavni povzročitelji tako imenovanih konformacijskih bolezni, kot sta npr. Parkinsonova in Alzheimerjeva bolezen. Tvorbo agregatov in amiloidov smo pospešili z dvigovanjem temperature. Za zaviranje smo uporabili dva znana zaviralca urejenih proteinskih agregatov, homotavrin in resveratrol. Izračunali smo sigmoidne krivulje ter določili in spremljali temperature prehoda iz raztopine v agregate, z in brez inhibitorja. Z metodo diferenčne spektroskopije smo spremljali majhne strukturne spremembe, ki nastanejo kot posledica zunanjih sprememb. Analizni spekter je izračunan kot razlika med dvema posnetima spektroma ob na primer različnih temperaturah. Zato nam ponuja metoda vpogled le v vrhove, ki niso skupni obema izhodnima spektroma. Temperatura prehoda ni naraščala, tako kot smo to pričakovali z naraščanjem koncentracije inhibitorja. Kjer se izkaže, da se je dvigovala, to ovržemo z negotovostjo meritev. Možnih razlogov za to je več, kriva je lahko napačna izbira koncentracijskih razmerij, nasičena raztopina, ali pa moja napaka pri mešanju raztopin. Največ težav pri raztapljanju smo imeli pri resveratrolu, zato mogoče ni bil najboljša izbira za izbrana koncentracijska razmerja. We investigated the aggregation of Concanavalin A using infrared spectroscopy. Concanavalin A is a protein with a predominantly $beta$-structure and has a very interesting way of aggregation. In acidic medium it aggregates in amorphous aggregates, whereas in alkaline medium it forms amyloid fibrils. Therefore, we have used it for testing retarding amyloids, which are the main cause of conformation diseases, such as Parkinson and Alzheimer disease. The growth of aggregates and amyloids was accelerated with the increase in temperature. We used two well-known inhibitors to slow down settled protein aggregates, which are homotavrine and resveratrol. We calculate sigmoid curves from structural changes taken from the analysis of amide I band and monitored the temperature of the transition from solution to aggregates, with and without inhibitors. Using the method of differential spectroscopy, we were able to accompany small structural changes, which are caused by temperature changes. The analysis spectrum is calculated as the difference between two spectra recorded at different temperatures. For this reason, this method allows us to look into spectral bands that are not the same for both spectra. The temperature of the transition did not rise, as we had expected, with the increase in inhibitor concentration. Where it shows the increase, it correlates with the measurement error. There can be many reasons for this, it could be a wrong choice of concentration ratio, a saturated solution or my error with the solutions. Most of the problems with solving occurred with resveratrol, maybe it was not the best choice for the chosen concentration ratios.

Zdravila za parenteralno rabo se vnesejo v človeško telo z injiciranjem in infundiranjem. Zaradi različnih lastnosti učinkovin parenteralni izdelki obstajajo v različnih oblikah: v praškasti obliki ali v raztopini. Vsi farmacevtski izdelki morajo ustrezati določenim standardom kakovosti, ki jih predpisujejo zdravstvene organizacije. Parenteralni izdelki morajo izpolnjevati še zahtevo po sterilnosti, saj so po definiciji namenjeni direktnemu vnosu v človeško telo mimo prebavnega sistema. Poleg zahteve po sterilnosti morajo parenteralni izdelki zadoščati še farmakopejskim zahtevam po odsotnosti vidnih delcev. Kontrola kakovosti parenteralnih izdelkov je rigorozna: vsak vsebnik je pred pakiranjem 100 %-no vizualno pregledan. Vsebniki z delci se med 100 %-no kontrolo izločijo. Z namenom sledenja pojavnosti delcev je potrebno vidne delce v izločenih vsebnikih tudi identificirati. Večinoma gre za delce, ki so tekom proizvodnega procesa v neposrednem stiku z izdelkom: npr. primarna embalaža, čepi, polnilne igle... Identifikacija poteka na več nivojih, končna stopnja pa je identifikacija na osnovi različnih spektroskopskih tehnik, med katerimi se najpogosteje uporabljajo: Ramanska spektroskopija, FTIR spektroskopija in LIBS spektroskopija. Identifikacija najpogosteje poteka preko primerjave spektrov delcev neznanih materialov s spektri referenčnih materialov, katerih vir je poznan. Za uspešno identifikacijo delcev na osnovi primerjav spektrov z referenčnimi spektri je ključnega pomena kvalitetna spektralna knjižnica. Magistrsko delo zajema postavitev spektralne knjižnice za namene identifikacije delcev z IR spektroskopijo v programskem okolju Spectrum 10 (Perkin Elmer). Vsaka knjižnica zahteva ustrezno ogrodje znotraj specifičnega programskega paketa, ki sem ga prilagodil potrebam Laboratorija za analizo delcev v družbi Lek d.d.. Najpomembnejši del je spektralna baza, ki vključuje spektre referenčnih materialov. Referenčni materiali so bili pridobljeni iz proizvodne enote, njihove infrardeče spektre pa sem posnel z različnimi tehnikami. Najpogosteje sem uporabil način snemanja spektra v ATR načinu z diamantnim kristalom. Materiale, ki so bili tanjši in bolj transparentni, sem posnel tudi v načinu transmisije. Na tak način sem metodi medsebojno primerjal, predvsem razlike v posnetih spektrih in ustreznost metode za določen material. Ugotovil sem, da način transmisije za debelejše vzorce odpove, zato sem se večinoma osredotočil na metodo ATR. Spektre sem knjižnici dodajal in testiral ustreznost njenega delovanja. Knjižnico je možno z novimi vnosi v prihodnosti nadgrajevati in predstavlja pomemben doprinos k identifikaciji delcev v Laboratoriju za analizo delcev družbe Lek. Parenteral pharmaceutical products are delivered into the human body by injection and infusion. Due to the different properties of the active pharmaceutical ingredients, parenteral products exist in different forms: either as a powder or a solution. All pharmaceutical products must meet certain quality standards prescribed by healthcare organizations. Parenteral products must also meet the requirement for sterility, as they are by definition intended for direct application into the human body past the digestive system. In addition to the requirement for sterility, parenteral products must meet the pharmacopoeial requirements for the absence of visible particles. Quality control of parenteral products is rigorous: each container is 100% visually inspected before packaging. Containers with particles are rejected during 100% control. In order to track the incidence of particles, visible particles found in the rejected containers need to be identified. These are mostly particles that are in direct contact with the product during the production process: e.g. primary packaging, stoppers, filling needles, etc. Identification is performed on several levels, and the final stage is identification based on various spectroscopic techniques, the most commonly used of which are Raman spectroscopy, FTIR spectroscopy and LIBS spectroscopy. Identification is usually performed by comparing the spectra of particles of unknown materials with those of the reference materials whose source is known. A successful spectral library is crucial for successful identification of particles based on spectra comparisons with reference spectra. The master's thesis covers the construction of a spectral library for the purpose of particle identification by IR spectroscopy in the software environment Spectrum 10 (Perkin Elmer). Each library requires an appropriate framework within a specific software package, which I have adapted to the needs of the Laboratory for Particle Analysis in the Lek company. Reference materials were obtained from the production unit and I recorded their infrared spectra using various techniques. Most often, I used the ATR mode with diamond crystal. The materials that were thinner and more transparent were also recorded in transmission mode. In this way, I compared the methods with each other, especially the differences in the recorded spectra and the appropriateness of the method to a particular material. I found that the transmission mode fails for thicker specimens, so I mostly focused on the ATR method. I added the spectra to the library and tested its suitability. The library can be upgraded with new entries in the future and represents an important contribution to the identification of particles in the Laboratory for Particle Analysis in Lek company.

V komunalni odpadni vodi je vedno večja prisotnost mikroplastike. Ta se med čiščenjem koncentrira na čistilni napravi, kar nalaga komunalnim čistilnim napravam veliko odgovornost koliko mikroplastike se izpusti nazaj v okolje in koliko se je zadrži ter kar se z zdržano mikroplastiko zgodi. V diplomskem delu smo s pomočjo postopkov filtracije, kemijske oksidacije, usedanja in dekantiranja izolirali mikroplastiko iz vodnih vzorcev ter vzorcev blata. Delce mikroplastike smo preučili pod optičnim mikroskopom ter jih karakterizirali z infrardečo spektroskopijo. S pomočjo infrardeče spektroskopije smo določili prisotnost značilnih funkcionalnih skupin v vzorcu mikroplastike, posnete spektre smo primerjali z referenčnimi spektri različnih polimernih materialov z znano strukturo. Določili smo tudi mase trdnih snovi po dveh filtracijah vzorcev vode in blata, ter določili uspešnost kemijske oksidacije organskih snovi. There is a growing presence of microplastics in municipal wastewater. During the cleaning process, it concentrates at the sewage treatment plant, which imposes a great responsibility on municipal sewage treatment plants on how much microplastics is released back into the environment and how much is retained and what happens with the lasting microplastics. In the Bachelor's degree, we islated microplastics from aqueous and sludge samples by filtration, chemical oxidation, deposition and decantation processes. Microplastics particles were examined under an optical microscope then we recorded infrared spectres, which were the basis for chemical identification. The presence of typical functional groups in the microplastic samples were determined by infrared spectroscopy. Recorded spectra were compared with the reference spectra of various polymeric materials with known structure. We also determined the masses of solids after two filtrations of water and sludge samples, and determined the success of chemical oxidation of organic matter.

This work presents a paradigm for high temperature stabilization of bulk amorphous aluminium oxide. The thermodynamic stabilization is achieved by preparing a nanocomposite, where polymethylsilane dendritic molecules are dispersed in an aluminium hydroxide gel. Upon heat-treatment the gel transforms to the amorphous aluminium oxide that is stable up to 900°C. The dispersion of the macromolecules and their covalent bonding to the alumina matrix induce homogeneously distributed strain fields that keep the alumina amorphous. The first part of the thesis focuses on the synthesis, characterization and solubility properties of the dendritic polymethylsilane. The polymethylsilane is synthetized by electrochemical polymerization from trichloromethylsilane monomer. The polymerization mechanism, involving a single polymerization pathway, is identified. The polymer growth proceeds through reduction of the monomers to the silyl anions and their addition to the growing polymer. The solubility of three chemically related but topologically different polysilanes (linear, dendritic and network) were studied by dynamic light scattering. At room temperature the agglomerates in a range from 500 to 1300 nm are present. They undergo de-agglomeration at slightly elevated temperatures of around 40°C. The de-agglomeration results in formation of stable solutions, where a hydrodynamic diameter of the individual polymer molecules was measured to be in a range from 20 to 40 nm. The obtained diameters of two dendritic polymethylsilane macromolecules, synthesized under different electrolysis conditions, are much larger than the theoretical size estimated for an ideal dendrimer. We determined by 29Si NMR that the reason for this is in a large number of branching irregularities (defects) contained in the molecular structure. Combining the experimental values obtained by DLS and density measurements with a structural model that considers the branching irregularities, it is shown that the inclusion of the defects allows the dendritic polymer to exceed the sterical limitations and form the hyperbranched dendritic structure. The final size depends on a relative amount of the branching defects. In the second part, the synthetized polymethylsilane molecules were successfully used for the nanocomposite formation. The aluminium hydroxide gel with the dispersed polymethylsilane molecules was prepared as a precursor. Upon heat-treatment it gives the amorphous aluminium oxide stable up to 900°C. The dispersed macromolecules induce homogeneously distributed strain fields that keep the aluminium oxide amorphous during the thermal treatment the dispersed macromolecules covalently bind to the matrix, inducing the interface strain. The amorphous state was confirmed by the presence of penta-coordinated aluminium detected by 27Al NMR and a low bandgap measured by UV-vis absorption spectroscopy. V doktorski disertaciji je predstavljen nov princip visokotemperaturne stabilizacije amorfnega aluminijevega oksida. Stabilizacijo dosežemo z disperzijo dendritičnih molekul polimetilsilana v gel aluminijevega hidroksida. Gel služi kot prekurzor, ki se pri termični obdelavi pretvori v amorfni aluminijev oksid, ki je stabilen do 900°C. Dispergirane makromolekule vnašajo v strukturo aluminijevega oksida napetosti, ki termodinamsko stabilizirajo amorfno fazo. V prvem delu je predstavljena sinteza, karakterizacija in topnost dendritičnega polimetilsilana. Polimerizacija je bila izvedena z elektrolizo trifunkcionalnega monomera, triklorometilsilana. Raziskan mehanizem polimerizacije predvideva le eno reakcijo na elektrodi, to je redukcija Si–Cl vezi na monomeru in nastanek silil aniona. Rast polimera poteka z adicijo aniona, na sosednji monomer, oligomer oziroma druge polimerne zvrsti. Za študij topnosti so bili uporabljeni trije kemijsko sorodni vendar različni polisilani: linearni polidimetilsilan, dendritični polimetilsilan in zamreženi polikarbosilan. Topnost in de-aglomeracijo smo zasledovali z dinamičnim sipanjem svetlobe in termično analizo. Pri sobni temperaturi so polimerne molekule aglomerirane. Velikost aglomeratov je v območju od 500 do 1300 nm. Pri temperaturah nad 40°C poteče de-aglomeracija. Nastanejo stabilne raztopine polimerov, v katerih je mogoče izmeriti velikost molekul. Hidrodinamski diameter posameznih molekul je v območju od 20 do 40 nm. Izmerjene velikosti dveh dendritičnih polimetilsilanov, sintetiziranih pod različnimi elektrolitskimi pogoji, so večje, kot lahko pričakujemo za strukturo idealnega dendrimera, ki bi se moral na vsakem monomeru vejati v tri smeri. Strukturna karakterizacija z 29Si NMR je pokazala, da je poleg atomov Si, ki se vejejo v tri smeri, prisoten tudi določen delež linearnih segmentov, ki predstavljajo defekte v vejanju. Rezultat prisotnosti teh defektov je rast polimera preko meje za idealen dendrimer. Dobljena struktura tako ni dendrimer ampak hiper-razvejani dendrit. Pokazali smo, da je dosežena velikost odvisna od deleža linearnih defektov. Večji kot je delež defektov, večji je lahko polimer. Posledično so polimeri z več defekti manj gosti. Sintetizirani polimetilsilan smo uspešno uporabili za pripravo nanokompozita. Kot prekurzor za nanokompozit smo uporabili s hidratacijo pripravljen gel aluminijevega hidroksida, ki je vseboval dispergirane molekule polimetilsilana. S termično obdelavo prekurzorja nastane amorfni aluminijev oksid, ki je stabilen do 900°C. Med termično obdelavo z aluminijevim oksidom se vzpostavitvijo kovalentne vezi. S tem homogeno preko celotnega nanokompozita ustvarjajo napetosti, ki ohranjajo matrico aluminijevega oksida amorfno. Amorfna struktura je bila potrjena z X-žarkovno in elektronsko difrakcijo, dodatno pa še z 27Al NMR, ki je pokazal prisotnostjo penta-koordiniranega aluminija in z UV-Vis refleksijsko spektroskopijo, ki je razkrila nizko vrednost prepovedanega pasu v primerjavi s kristaliničnimi polimorfi.

The electroanalytical and surface characterization of copper immersed in 3 wt.% NaCl solution containing 1 mM of 2-phenylimidazole (2PhI) is presented. It was proven that 2PhI can be employed as corrosion inhibitor for copper using various electrochemical analyses, such as cyclic voltammetry, chronopotentiometry, electrochemical impedance spectroscopy, and potentiodynamic curve measurements. The adsorption of 2PhI on copper was further analyzed by 3D-profilometry, attenuated total reflectance Fourier transform infrared spectroscopy, contact angle measurements, and scanning electron microscopy equipped with an energy dispersive X-ray spectrometer. This system was therefore comprehensively described by various analytical approaches.

Raziskali smo strukturne in kemijske spremembe v jedrovini lesa hrasta (Quercus sp.) povezane s staranjem. Vzorčili smo konstrukcijski les različne starosti iz več objektov v Sloveniji. Starost lesa smo določili dendrokronološko, strukturne in anatomske lastnosti pa s svetlobno mikroskopijo (svetlo polje, polarizirana svetloba, epi-fluorescenca) ter z infrardečo spektroskopijo s Fourierjevo transformacijo (FT-IR spektroskopijo). Potrjena splošna vizualno temnejša barva starejše hrastove jedrovine je bila med drugim odvisna od variabilne anatomske lesne zgradbe, z značilnim vplivom deležev kompleksov traheid, trahej, libriformskih vlaken in trakov. S FT-IR določena deleža hemiceluloz in lignina sta se primerjalno z osnovnimi lesnimi komponentami v procesu staranja hrastovine zmanjšala. Zmanjšanje deleža hemiceluloz je bilo statistično značilno, zmanjšanje deleža lignina pa neznačilno. Z uporabo polarizirane svetlobe smo v procesu staranja hrastovine zaznali tudi degradiranje celuloze. Pri vzorcu subfosilnega lesa, starem več kot 600 let, ki se je ohranil v z vodo napojenem stanju, pa smo z uporabo vseh tehnik zaznali povečan delež lignina ter zmanjšan delež celuloze in hemiceluloz. Raziskava je pokazala, da so spremembe v nekaterih podobno starih vzorcih v procesu staranja različni, kar pripisujemo variabilnim (in delno nepoznanim) pogojem izpostavitve lesa tekom uporabe. We examined structural and chemical changes in heartwood of oak (Quercus sp.), related to wood ageing. The research was made on samples of construction wood of various ages from different objects in Slovenia. The age of wood was determined dendrochronologically. Structural and anatomical properties were determined with help of light microscopy (techniques: bright field, polarized light, epi-flourescence) and Fourier Transform Infra Red (FT-IR) spectroscopy. It has been visually confirmed that the heartwood becomes visually darker due to ageing. Its colour proved to depend on variable wood anatomy, with different proportions of vessels, traheids, libriform fibres and rays. FT-IR spectroscopy showed that the percentage of hemicellulose and lignin decreased in comparison with basic wood components during the process of ageing. The decrease of hemicellulose proportion was statistically significant, whereas the decrease of lignin was not. Degradation of cellulose during the ageing was also shown by using polarized light. In the case of more than 600 years old sample of subfossil wood, which was preserved underwater, all techniques confirmed an increased proportion of lignin and decreased proportion of cellulose and hemicellulose. Different degree of changes in similarly old samples could be ascribed to variable (and partly unknown) conditions of wood exposure during its service life.

Vzorce smreke in jelke smo modificirali v vakuumu pri temeperaturah od 170 do 215 °C. Modificiranim vzorcem smo določili izgubo mase, ki je posledica termične obdelave. Posneli smo infrardeče spektre termično modificiranih in kontrolnih vzorcev v transmisijski tehniki. V dobljenih spektrih smo izmerili površine posameznih trakov ter jih primerjali z referenčnima trakovoma pri 2900 in 1510 cm(na-1), tako da smo dobili relativne površine posameznih trakov, ki smo jih primerjali z izgubo mase pri termični modifikaciji. Ugotovili smo, da obstaja linearna povezava pri trakovih: 1636, 1605, 1035 in 897 cm(na-1). Termično analizo smo izvajali na kontrolnih vzorcih in vzorcih smreke, modificiranih pri temperaturah 190 in 210 °C. Izgubo mase, ki smo jo zabeležili pri termični analizi, smo primerjali s tisto pri termični modifikaciji in ugotovili, da sta v linearni odvisnosti. Z naraščanjem izgube mase vzorcev, kot posledico termične modifikacije, se zmanjšuje izguba mase pri termični analizi. Spruce and fir samples were thermally modified in vacuum at temperatures from 170 to 215 °C. The mass losses caused by heat treatment were evaluated for modified samples. FTIR spectra of the heat treated and control samples were recorded in the transmision technique. In these spectra, the areas of single bands were measured and compared to the reference bands at 2900 and 1510 cm-1 to get the relative areas of single bands. Relative areas were then compared to the mass loss caused by thermal modification, and a linear relationship was observed for bands at 1636, 1605, 1035 and 897 cm-1. TG was also used for analysis of control spruce samples and samples modified at 190 and 210 °C. Mass losses observed by thermal analysis between 100 and 800 °C are linearly proportional with the mass losses caused by a heat treatment. Increasing the mass loss caused by a heat treatment the mass loss detected by the thermal analysis decreases.