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Diagnostic ultrasound in monitoring patients with rheumatoid arthritis compared to standard clinical disease activity indices
No full textUnatoč ACR/EULAR preporukama o korištenju dijagnostičkog UZV u RA, UZV pregled za sada nije dio standardnih indeksa kojima se prati aktivnosti bolesti, niti je uključen u kriterije remisije. Cilj ovog istraživanja je bio procijeniti vrijednost dijagnostičkog UZV u praćenju bolesnika s RA u odnosu na standardne metode praćenja. Ispitati odnos UZV nalaza s kliničkim, laboratorijskim, radiološkim pokazateljima aktivnosti bolesti, kliničkim indeksima aktivnosti bolesti, funkcionalnim upitnicima te ACR/EULAR kriterijima kliničke remisije. Predložiti model hrvatskog zglobnog bodovnog sustava te novi kompozitni bodovni sustav. Od uključenih 117 RA bolesnika koji su praćeni tokom 3 mjeseca, ukupno ih je 88 završilo istraživanje. UZV pregled je učinjen na predefiniranom setu zglobova i tetiva, a UZV promjene su bodovane prema posljednjim publiciranim konsenzusima stručnih društava. Broj otečenih zglobova, procjena aktivnosti bolesti na VAS skali od strane liječnika, CRP, radiološki verificirane erozivne promjene, CDAI i SDAI indeks su bili najsnažnije značajno povezani s objektiviziranjem upale pomoću UZV. UZV aktivnost je utvrđena kod do 75% (Boolean) odn. 57,1% (SDAI) ispitanika koji su bili u remisiji prema ACR/EULAR kliničkim kriterijima. Kreiran je i validiran CroUS koji obuhvaća RC, MCP2, MCP3, PIP3, koljena, MTP5 zglobove i tetive ECRL/ECRB, EDC, ECU,
tibialis posterior, PB/PL bilateralno. Rezultat kreiranog kompozitnog SonoFIA indeksa (CroUS, HAQ, DAS 28 SE) >8, uz osjetljivost od 83,33% i specifičnost od 61,54% upućuje na visoko aktivnu bolest. Potvrdili smo nužnost implementiranja UZV pregleda u redovni klinički pregled i njegovu dodatnu vrijednost i superiornost u objektiviziranju aktivnosti bolesti i remisije. Smatramo kako bi UZV praćenje aktivnosti RA, temeljem reduciranih bodovnih sustava i kompozitnih bodovnih sustava baziranih na UZV, svoju glavnu primjenu u praksi trebalo naći u dvojbenim kliničkim slučajevima, posebice kod bolesnika u stabilnoj remisiji kod kojih se razmatra redukcija terapije.Although ACR/EULAR recommends using diagnostic US in RA, it is still not incorporated into disease activity indices or remission criteria. The aim was to determine the value of diagnostic US in monitoring RA regarding standard methods
of monitoring. To examine the relationship of US finding with clinical, laboratory, radiological disease activity indicators, clinical disease acitivity indices, functional questionnaires, ACR/EULAR remission criteria. To propose a model of a Croatian
joint scoring system and a novel composite scoring system. 117 RA patients were included and 88 finished the study during the 3 month follow up. US examination was conducted on a predefined joint and tendon set and scored according to the
latest published consensus. SJC, evaluator GDA, CRP, X-ray erosive changes, CDAI and SDAI had the strongest correlation with US findings. US activity was found in up to 75% (Boolean) and 57,1% (SDAI) patients in remission. CroUS (RC, MCP2, MCP3, PIP3, knee, MTP5, ECRL/ECRB, EDC, ECU, tibialis posterior, PB/PL bilateraly) was developed and validated. Composite SonoFIA index (CroUS, HAQ, DAS28 SE) > 8 indicates high disease activity with 83,33% sensitivity and 61,54% specificity. We confirmed the necessity of US implementation into RA monitoring and it's added value and superiority in objectifying disease activity and remission. US monitoring using reduced joint counts and US based composite scoring systems should take place in questionable clinical cases and patients in sustained remission with perspecitve of drug tapering
Priprava i karakterizacija vezikularnog fosfolipidnog gela s timolom
No full textCilj istraživanja
Cilj ovog istraživanja bila je priprava i evaluacija vezikularnog fosfolipidnog gela (VFG) s
timolom, namijenjenog dermalnoj primjeni. Optimizirani su uvjeti priprave VFG-a, te je ispitan
utjecaj sastava VFG-a na fizikalna svojstava vezikula (liposoma) unutar VFG-a, oslobađanje
timola i reološke karakteristike formulacija.
Materijali i metode
Eksperimentalni dio rada obuhvaćao je izradu VFG-ova s timolom različitog (fosfo)lipidnog
sastava metodom visokotlačne homogenizacije. Provedeno je određivanje fizikalno-kemijskih
svojstava VFG-ova s timolom (srednji promjer, indeks polidisperznosti, zeta potencijal
liposoma unutar VFG-ova) te ispitivanje topljivosti timola u različitim otapalima kako bi se
odredio prikladan medij za provođenje ispitivanja in vitro oslobađanja. Ispitivanja in vitro
oslobađanja timola iz odabranih formulacija VFG-ova i kontrole (otopina timola) provedena
su metodom dijalize, a oslobođeni timol je određen spektrofometrijski. Reološka
karakterizacija formulacija uključivala je rotacijska (profil viskoznosti) i oscilatorna (test
promjene amplitude) mjerenja.
Rezultati
Visokotlačnom homogenizacijom uz primjenjeni tlak od 500 bara pripravljena su dva različita
tipa VFG-a srednjih promjera liposoma od 140 do 200 nm i blago negativnog zeta potencijala
(-5 do -8 mV). Postignuto je produljeno oslobađanje timola iz oba tipa VFG-a u odnosu na
kontrolu, pri čemu je (fosfo)lipidni sastav značajno utjecao na udio oslobođenog timola.
Prisustvo kolesterola u formulaciji je rezultiralo polaganijim oslobađanjem timola u odnosu na
formulaciju pripravljenu isključivo iz sojinog fosfadilkolina. (Fosfo)lipidni sastav VFG-a
utjecao je i na reološka svojstva formulacija. VFG pripravljen bez kolesterola bio je neznatno
viskozniji u odnosu na VFG s kolesterolom, dok temperatura na kojoj su provedena mjerenja
nije utjecala na viskoznost formulacija. Oba tipa VFG-a su pokazala viskoelastična svojstva
prikladna za dermalnu primjenu (G' > G“ u linearnom viskoelastičnom području).
Zaključak
Rezultati provedenih ispitivanja u sklopu ovog rada ukazuju na mogućnosti primjene VFG-a
kao inovativne polučvrste podloge za dermalnu dostavu timola. Reološkom karakterizacijom
potvrđena su pseudoplastična svojstva pripravaka, kojima se omogućuje produljeno
oslobađanje timola. Daljnjim ispitivanjima (permeabilnost kroz kožu, antimikrobni učinak,
biokomaptibilnost) procijenila bi se prikladnost formulacija VFG-ova s timolom za primjenu
na kožu.Objective
The aim of this research was to prepare and evaluate a vesicular phospholipid gel (VPG) for
dermal delivery of thymol. The preparation conditions of VPGs were optimized, and the impact
of the (phospho)lipid composition of the VPG on the release of thymol, physico-chemical
properties of the liposomes within the VPGs, and the rheological characteristics of the
formulations, was examined.
Material and Methods
Thymol-loaded VPGs of different (phospho)lipid composition were prepared using the highpressure homogenization method at applied pressure of 500 bar. The physicochemical
properties of liposomes within the thymol-loaded VPGs were determined (mean diameters,
polydispersity indexes, zeta potentials) and the solubility of thymol in different solvents was
tested in order to determine a suitable medium for conducting in vitro release studies. In vitro
release of thymol from the selected VPGs and the control (thymol solution) were performed
using the dialysis method, while the released thymol was determined spectrophotometrically.
Rheological characterization of the formulations included rotational (viscosity profile) and
oscillatory (amplitude test) measurements.
Results
Two different types of VPGs, with liposomes exhibiting mean diameters of 140 - 200 nm and
a slightly negative zeta potentials (-5 to -8 mV), were prepared by high-pressure
homogenization method. Prolonged release of thymol from the both types of VPGs was
achieved compared to the control, whereby the (phospho)lipid composition had a significant
effect on the release of thymol. The presence of cholesterol in the VPG resulted in a slower
release of thymol compared to the VPG prepared exclusively from soy phosphadylcholine. The
(phospho)lipid composition of VPGs also affected the rheological properties of the
formulations. VPG prepared without cholesterol was slightly more viscous compared to VPG
with cholesterol, while the temperature at which the measurements were carried out did not
affect the viscosity of the formulations. Both types of VPGs showed viscoelastic properties
suitable for dermal application (G' > G“, in linear viscoelastic region).
Conclusion
The results of all conducted studies indicate the suitability of VPG as an innovative semisolid
vehicle for dermal delivery of thymol. The rheological characterization confirmed the
pseudoplastic properties of VPGs, which enabled the prolonged release of thymol. However,
further investigations are required, such as skin permeability studies, antimicrobial testing, and
biocompatibility assessment, to evaluate the suitability of thymol-loaded VPGs for skin
application
Strukturna analiza detalja rešetkaste palubne konstrukcije poluuronjive plutajuće proizvodne jedinice
No full textSemi-submersible oil platforms are used in areas with harsher meteorological conditions and at depths greater than 520 meters, where the use of fixed structures is no longer practical. These Floating Production Units (FPU) are column-stabilized floating units with usually four or six major columns. They are also anchored (moored) to the seabed, which allows the translation and rotation of the structure. The columns are connected to the watertight pontoons that are submerged under the sea level. These pontoons secure enough buoyancy of the structure which keeps it afloat even in the heavy seas. Since the waterline of these structures is located along the position of the column, the small waterplane area is the first advantage of such structures due to lower wave load. Pontoons are filled with water once the unit is placed in the desired drilling location, providing enough stability. The deck of the FPU is supported on the very top of the columns by a truss structure[1]. Clearance of the deck truss allows the crew and the equipment to work and operate at the minimum wave load conditions. The deck truss consists of upper (main) deck and lower (production) deck. These decks consist of different I-profiles (bar elements), and they are connected using tubular bars. Consequently, multiple elements will cross into one specific point, creating very complicated joints in the process. These joints require specific approach of analysis where plate elements will be used to model very detailed and complicated joints, which will be shown in this thesis. Yielding analysis of two specific critical deck truss structure joints will be performed until they satisfy yielding strength criterion as described in ABS Rules
Application of TXRF-Mo and EDXRF techniques for elemental analysis of whey proteins
No full textProteini sirutke su praškasti oblik proteina dobivenih iz sirutke. Pokazuju brojne korisne učinke na ljudsko zdravlje: antikancerogeni, antioksidativni i antidijabetički učinak, kardioprotektivno i hipotenzivno djelovanje, pozitivno utječu na probavno zdravlje. Na tržištu su dostupni u obliku hidrolizata proteina sirutke, koncentrata proteina sirutke i izolata proteina sirutke. Danas su u širokoj upotrebi pogotovo u fitnes industriji te je zbog toga nužna kontrola elementarnog sastava kako bi se spriječio potencijalno negativan utjecaj na ljudsko zdravlje. Glavni cilj ovog istraživanja je odrediti sadržaj metala u različitim uzorcima proteina sirutke pomoću dvije analitičke tehnike (TXRF-Mo i EDXRF) kao i usporediti učinkovitost primijenjenih tehnika za određivanje sadržaja metala te njihova primjenjivost u kontroli kvalitete proizvoda. Uzorci su pripremljeni mikrovalnom digestijom za potrebe mjerenja TXRF-Mo dok su kod EDXRF tehnike uzorci izravno mjereni bez prethodne pripreme te je određen sadržaj sljedećih elemenata: željezo, bakar, cink, brom, rubidij i stroncij. Dobiveni rezultati pokazali su kako su obje tehnike prikladne za multielementarno određivanje metala te imaju potencijal za određivanje sadržaja broma u uzorcima. Uslijed primijenjenog načina pripreme uzoraka u ovom ispitivanju, EDXRF tehnika je ekološki prihvatljivija i više u skladu s načelima „zelene kemije“ dok je TXRF-Mo osjetljivija tehnika.Whey proteins are a powdered form of protein obtained from whey. They have numerous positive effects on human health: anti-cancer, antioxidant and anti-diabetic effects, cardioprotective and blood pressure lowering effects, positive effects on digestive health. They are available on the market in the form of whey protein hydrolysates, whey protein concentrates and whey protein isolates. Nowadays, they are widely used, especially in the fitness industry, which makes it necessary to control their elemental composition to avoid their potentially negative effects on human health. The main objective of this study is to determine the metal content in different whey protein samples using two analytical techniques (TXRF-Mo and EDXRF) and to compare the effectiveness of the techniques used to determine the metal content and their usefulness in controlling product quality. The samples for the TXRF-Mo measurements were prepared by microwave digestion, while the samples for the EDXRF technique were measured directly without prior preparation. The following elements were determined: iron, copper, zinc, bromine, rubidium and strontium. The results obtained showed that both techniques are suitable for the multi-element determination of metals and have the potential to determine the bromine content in samples. Due to the method of sample preparation used in this test, the EDXRF method proved to be more environmentally friendly and more in line with "green chemistry" principles," while TXRF-Mo is a more sensitive method
The possibility of torque reduction in drilling of horizontal wells placing protection ring on the drill pipes joint : doctoral dissertation
No full textTijekom izrade horizontalne bušotine mogu se pojaviti različiti tehnološki problemi, a najčešće su oni posljedica povećanih vrijednosti momenta torzije i sile natega. Kontakt između niz bušaćih alatki i zaštitnih cijevi/stijenki kanala bušotine uzrokuje povećanje sile trenja, što rezultira povećanom silom natega i momentom torzije tijekom izrade kanala bušotine osobito tijekom izrade zakrivljenih i horizontalnih dionica kanala bušotina. Osim spomenutog trenja također dolazi i do intenzivnog trošenja spojnica bušaćih šipki, s obzirom da je spojnica najširi dio niza bušaćih alatki pa samim tim i u neprestanom kontaktu sa stijenkama kanala bušotine. Najbolji je način za smanjenje momenta torzije i sile natega tijekom bušenja korištenje isplaka na bazi ulja ili sintetičkih isplaka umjesto isplake na bazi vode. Međutim, smanjenje momenta torzije i sile natega može se efikasno postići i na način da se u isplaku na bazi vode, koja je ekološki prihvatljivija dodaju komercijalni podmazivači koji imaju zadatak smanjenje koeficijenta trenja. Budući da se tijekom izrade horizontalnih bušotina velikog dosega najveći dio bušenja odvija kroz ležište, za ovo ispitivanje odabrana je polimerna isplaka (engl. drill-in fluid) odnosno fluid na bazi vode posebno namijenjen za bušenje kroz ležišta. Jedno od mogućih rješenja ovog problema je upotreba zaštitnih kliznih prstenova koji bi bili postavljeni na spojnicu bušaćih šipki u kombinaciji sa aditivima (podmazivačima) u polimernoj isplaci u cilju smanjenja momenta torzije i sile natega. Stoga su za ova istraživanja odabrana tri materijala odnosno poliamid 6 (PA6), politetrafluoretilen (PTFE – u nastavku teksta - Teflon) i polioksimetilen (POM), koji bi se potencijalno mogla koristili kao materijali za izradu zaštitnih kliznih prstenova i koji bi se postavili na spojnicu bušaćih šipki. Također, tijekom ispitivanja korištena su tri komercijalna podmazivača Z, X i Y od dva različita proizvođača, kako bi se ocijenio kumulativni utjecaj podmazivača i zaštitnih kliznih prstenova na smanjenje momenta torzije i sile natega tijekom bušenja. U okviru ovog doktorskog rada laboratorijska ispitivanja su provedena u dvije faze. Prva je faza ispitivanja provedena u Laboratoriju za bušotinske fluide na Rudarsko-geološko-naftnom fakultetu, Sveučilišta u Zagrebu gdje su ispitana osnovna fizikalna svojstva polimerne isplake te je provedeno ispitivanje na uređaju za određivanje podmazivosti isplake. Prva faza ispitivanja podijeljena je na tri dijela gdje su u prvom dijelu ispitana svojstva polimerne isplake u koju je dodan podmazivač Z, u drugom dijelu korišten je podmazivač X, dok je u trećem dijelu provedeno ispitivanje na polimernoj isplaci s podmazivačem Y. Na temelju dobivenih rezultata o podmazivosti polimerne isplake u koju je dodan jedan od tri podmazivača Z, X i Y II u različitim koncentracijama odlučeno je koristiti teflon za nastavak ispitivanja u drugoj fazi s obzirom da su kod njega izmjerene najmanje vrijednosti sile trenja. U drugoj fazi ispitivanja ispitano je trošenje ispitnog bloka izrađenog od teflona na uređaju za mjerenje trošenje strojnih elemenata koji su u kontaktu (Timken) na Fakultetu strojarstva i brodogradnje, Sveučilišta u Zagrebu. Ispitano je trošenje ispitnog bloka izrađenog od teflona u polimernoj isplaci sa i bez oteživača u koju je dodan jedan od tri podmazivača u koncentraciji 2% i 4%, pri sobnoj i povišenoj temperaturi. Nakon analiziranja svih podataka dobivenih na uređaju za mjerenje trošenja strojnih elemenata koji su u neposrednom kontaktu može se zaključiti da je trošenje ispitnog bloka izrađenog od teflona minimalno, odnosno u rasponu od 0,08 do 2,79%, te uglavnom posljedica konstrukcije samog laboratorijskog uređaja na kojem je provedeno laboratorijsko istraživanje kao i postupka ispitivanja. Temeljem provedenih sveobuhvatnih laboratorijskih ispitivanja ostvarena su oba postavljena cilja te su potvrđene postavljene hipoteze, odnosno postavljene dobre osnove za daljnja ispitivanja koja bi trebala voditi ka komercijalizaciji ovog tehničkog rješenja za konkretni problem iz prakse.During the drilling of a horizontal well, various technological problems may occur, and most often they are the result of increased values of torsion moment and drag force. The contact between the drill string and the casing/wellbore causes an increase in the frictional force, which results in an increased drag force and torsional moment while drilling the borehole especially during the drilling of curved and horizontal sections of the borehole. In addition to the mentioned friction, there is also wear and tear of the tool joint of drill pipe, considering that the tool joint is the widest part of a drill string and therefore in constant contact with the borehole of the well. The best way to reduce torsional moment and drag force during drilling is to use oil-based or synthetic muds instead of water-based muds. However, the reduction of the torsional moment and drag force can also be effectively achieved by adding commercial lubricants to the water-based mud, which have the task of reducing the friction coefficient. Since during the drilling of extended reach wells, most of the drilling takes place through the reservoir section, a polymer mud was chosen for this test. One of the possible solutions to this problem is the use of protective sliding rings that would be placed on the tool joint of the drill pipe in combination with additives (lubricants) in the polymer mud to reduce the torsional moment and drag force. Therefore, three materials were selected such as polyamide 6 (PA6), polytetrafluorethylene (PTFE – in the following text - Teflon) and polyoxymethylene (POM), from which it was intended to create a protective sliding ring that would be placed on the drill joint of a drill pipe. Also, three commercial lubricants Z, X and Y from two different manufacturers were used, which have the role of reducing the friction factor and thus the torsional moment and drag force. As part of this doctoral thesis, laboratory tests were carried out in two phases. The first phase of testing was carried out in the Laboratory for Drilling Fluids at the Faculty of Mining, Geology and Petroleum Engineering, University of Zagreb, where the basic physical properties of the polymer mud were tested, and a test was carried out on a device for determining the lubricity of the mud. The first phase is divided into 3 parts where in the first part the properties of the polymer mud to which lubricant Z has been added are tested, in the second part lubricant X, while in the third part lubricant Y is tested. In the first part basic physical properties testing was conducted on polymer mud with weighing agents in which lubricant Z was added in different concentrations from 1% to 6% and the lubricity of the mud using metal block and blocks made from Teflon, PA6 and POM. After analysing the data, it was concluded that increasing the concentration of lubricants to 5% and 6% it did not provide additional decrease IV in friction force, so it was decided to continue with concentrations from 1 to 4%. By this conclusion, same tests were conducted using polymer mud without weighing agents in which lubricant Z was added in different concentrations from 1% to 4%. From the obtained data, it has been decided for the second and third part of testing to use polymer mud with and without weighing agents in which lubricant X or Y was added in a concentration of 0,5% as a minimum value, 2% as a mean value and 4% as a maximum value. In the second and third part of testing same tests were conducted as in the first part. In the second part polymer mud with and without weighing agents in which lubricant X was added in concentrations of 0,5%, 2% and 4%. In the third part of first phase polymer mud with and without weighing agents in which lubricant Y was added in concentrations of 0,5%, 2% and 4%. After analysing all the obtained data on the friction force and mud lubricity, it was observed that the value of the friction force created by using test blocks made of Teflon is the lowest compared to all other test materials such as metal, POM and PA6. Based on this, it was decided to continue the laboratory tests in second phase using test blocks made of Teflon and polymer mud with and without weighing agents in which one of three lubricants Z, X and Y was added in concentrations of 2% and 4%. Second phase of testing is divided in two parts, and it was conducted at the Faculty of Mechanical Engineering and Naval Architecture, University of Zagreb, on a machine that measures mechanical wear of mechanical elements that are in direct contact (Timken) and provide the value of friction factor. The first part was testing mechanical wear of blocks made from Teflon in a polymer mud without weighing agents in which one of three lubricants Z, X and Y was added in concentration of 2% and 4%. To simulate real parameters, the test was conducted at room temperature and at higher temperature (50 °C). The second part was testing mechanical wear of blocks made from Teflon in a polymer mud with weighing agents in which one of three lubricants Z, X and Y was added in concentration of 2% and 4%. After completing all the tests as part of this doctoral thesis, it can be concluded that the use of a test block made of Teflon significantly reduces the friction factor compared to a metal block. Also, after analysing all the data obtained on the device for measuring the mechanical wear of mechanical elements that are in direct contact, it can be concluded that the mechanical wear of the test block made of Teflon is minimal (0.08-2.79%) and considering the imagined idea of placing sliding protective rings on the tool joint of drill pipe should reduce their mechanical wear, i.e. in this specific case, the protective sliding ring will wear out and not the tool join of the drill pipe
Influence of the type of the reactants and reaction parameters on the synthesis of biodiesel fuels from higher alcohols
No full textIstraživanje i razvoj naprednih biogoriva motiviran je smanjenjem negativnog utjecaja na okoliš uzrokovanog višestoljetnom primjenom fosilnih goriva, a potaknut i od strane zakonskih regulativa Europske Unije koje potiču energetsku diverzifikaciju, dekarbonizaciju prometnog sektora te načela kružnog gospodarstva. Jedno od takvih biogoriva je i biodizel, koji se proizvodi transesterifikacijom triglicerida alkoholom, u prisutnosti katalizatora. Nakon pročišćavanja, moguće ga je namiješati s fosilnim gorivom te, ukoliko zadovolji norme za dizelsko (HRN EN 590) i biodizelsko (HRN EN 14214) gorivo, koristiti kao obnovljivi izvor energije u dizel motorima. U Republici Hrvatskoj dopušteno je namiješavanje biodizelskog s dizelskim gorivom do volumnog udjela od 7 % da bi se njihova mješavina i dalje deklarirala dizelskim gorivom. Biodizel je moguće s dizelskim gorivom namiješati i u višim volumnih udjelima, no u tom se slučaju radi o mješavinama dizelskog i biodizelskog goriva. S obzirom da se komercijalni biodizel u Europi najčešće proizvodi iz djelomično obnovljivog metanola, cilj ovog doktorskog rada bio je ispitati utjecaj vrste reaktanata i reakcijskih uvjeta na proces sinteze biodizela iz izomera različitih viših alkohola (od propanola do oktanola), koje je moguće kao bioalkohole fermentacijom u potpunosti proizvesti iz biomase. U prvom dijelu ovog doktorskog rada praćen je utjecaj reakcijskih uvjeta (temperature, vremena reakcije, molarnog omjera reaktanata te masenog udjela katalizatora) na iskorištenje reakcije transesterifikacije. Primjenom Box-Behnkenovog dizajna eksperimenta i metodologije odzivnih površina, analizirani su i optimirani sustavi u kojima je biodizel sintetiziran iz suncokretovog ulja i alkohola 1-propanola ili 1-oktanola, odnosno otpadnog ulja i sekundarnog alkohola 2-propanola, 2-butanola, 2-pentanola ili 2-oktanola, u prisutnosti kalijeva hidroksida (KOH), kao katalizatora. Dodatno, praćena je i ovisnost iskorištenja sinteze biodizela o spomenutim reakcijskim uvjetima, kemijskoj strukturi te molekulskoj masi reaktanata, u prisutnosti KOH, pri čemu su različite biosirovine bile suncokretovo, repičino, kokosovo, otpadno ulje te životinjska (svinjska) mast, koje su reagirane s 1-propanolom,
1-butanolom, izobutanolom, 1-pentanolom, izopentanolom, 1-heksanolom ili 2-heksanolom.
U drugom dijelu rada, veće šarže biodizela (metilnih, propilnih, butilnih, izobutilnih, pentilnih, heksilnih i oktilnih estera masnih kiselina) sintetizirane su iz otpadnog ulja u prisutnosti KOH, pri uvjetima najviših eksperimentalnih iskorištenja; pročišćene te namiješane u dvokomponentne i trokomponentne mješavine s neaditiviranim mineralnim dizelom i/ili odgovarajućim alkoholom. Provedena je analiza primjenskih svojstava priređenih uzoraka prema odgovarajućim normiranim metodama (gustoće, kinematičke viskoznosti, maglišta, točke filtrabilnosti, tecišta, mazivosti, simulirane destilacije), čije su vrijednosti uspoređene s onima propisanima normom za dizelsko gorivo HRN EN 590. Dodatno su uzorci analizirani metodama: diferencijalna pretražna kalorimetrija, mjerenje napetosti površine goniometrom i mjerenje koeficijenta trenja. Glavni rezultati su pokazali da su za iskorištenje ovih reakcijskih sustava značajni reakcijski uvjeti molarni omjer reaktanata i maseni udio katalizatora KOH, odnosno da se u promatranim sustavima, generalno najviša iskorištenja dobivaju korištenjem kokosovog ulja, a najniža korištenjem životinjske masti, kao biosirovine. Iskorištenja biodizela sintetiziranih iz ravnolančanih alkohola generalno su bila viša od onih sintetiziranih iz granatih, a porast molekulske mase granatih alkohola dovodi do daljnjeg sniženja iskorištenja. Karakterizacijom uzoraka utvrđeno je da dodatak biodizelskih goriva do 20 vol.% u mješavine s dizelom i/ili pripadajućim alkoholom rezultira porastom njihove gustoće, kinematičke viskoznosti i površinske napetosti, dok dodatak viših alkohola do 15 vol.% u odgovarajuće mješavine s dizelom i biodizelom rezultira smanjenjem njihove gustoće, kinematičke viskoznosti i površinske napetosti. Vrijednosti gustoća i kinematičkih viskoznosti za sve dvokomponentne mješavine dizel-biodizel (s do 20 vol.% biodizela) te trokomponentne mješavine dizel-biodizel-pripadajući alkohol (s do 15 vol.% biodizela) nalaze se unutar granica propisanih normom za dizelsko gorivo HRN EN 590. Nadalje, namiješavanjem biodizelskih goriva i/ili odgovarajućih alkohola s mineralnim dizelom nije došlo do narušavanja njegovih nisko-temperaturnih svojstava (maglišta, točke filtrabilnosti, tecišta). Reološkim mjerenjima utvrđeno je da dodatak heksilnih estera masnih kiselina neaditiviranom mineralnog dizelu u količini od 2,5 vol.% značajno poboljšava njegovu mazivost, dok promjena udjela ili vrste biodizela namiješanog s mineralnim dizelom nema značajnog utjecaja na svojstva podmazivanja dizelskog goriva. Naposljetku, uočeno je da su za destilaciju istog postotka predestiliranog, dodatkom pentilnih estera masnih kiselina od
20 vol.% mineralnom dizelu, potrebne više temperature nego u slučaju dodatka istog biodizela u udjelu od 10 vol.%. Diferencijalna pretražna kalorimetrija pokazala je da dvokomponentne i trokomponentne mješavine svih biodizela s mineralnim dizelom i/ili pripadajućim alkoholom imaju temperature početke i kraja kristalizacije slične vrijednostima onih neaditiviranog mineralnog dizela. Navedeno može poslužiti kako dodatni pokazatelj izostanka njihova negativnog djelovanja na niskotemperaturna svojstva dizelskog goriva.The research and development of advanced biofuels is motivated by the reduction of negative environmental impact caused with the use of fossil fuels throughout the centuries, and encouraged with the legal regulations of European Union, that promote energy diversification, decarbonization of the traffic sector, as well as the principles of circular economy. One of such biofuels is biodiesel, that is produced via alcohol transesterification of a certain feedstock, in the presence of a catalyst. Post purification, it is possible to blend it with fossil fuel, if it fulfills the requirements set by the diesel (HRN EN 590) and biodiesel (HRN EN 14214) standard, and use as a renewable source of energy in diesel engines.
In the Republic of Croatia it is allowed to blend up to 7 vol% of biodiesel with diesel fuel for their blend to still be declared as diesel fuel. It is possible to blend higher volume fractions of biodiesel fuel with diesel fuel, as well, however these are referred to as the diesel-biodiesel blends. Since the commercial European biodiesel is most commonly produced from partly renewable methanol, the goal of this doctoral thesis was to investigate the influence of the reactant type and the reaction conditions on the biodiesel synthesis from isomers of selected higher alcohols (from propanol to octanol), which can, as bioalcohols, be completely produced via fermentation from biomass. In the first part of this doctoral thesis, the influence of reaction conditions (temperature, reaction time, molar ratio of the reactants, and mass fraction of the catalyst) on the reaction conversion of the biodiesel systems, was studied. With the use of Design of Experiments by Box-Behnken and Response Surface Methodology, the biodiesel synthesis from either sunflower oil and alcohols 1-propanol or 1-octanol, or waste cooking oil and 2-propanol, 2-butanol, 2-pentanol, or 2-octanol, was analyzed and optimized, in the presence of a catalyst potassium hydroxide. Additionally, the dependence of the reaction conversion on the mentioned reaction conditions, the chemical structure, and the molar mass of the reactants, in the presence of potassium hydroxide, was studied, with the selected feedstock being sunflower oil, rapeseed oil, coconut oil, waste cooking oil, or animal fat, that reacted with 1-propanol, 1-butanol, isobutanol, 1-pentanol, isopentanol,
1-hexanol, or 2-hexanol. In the second part of the thesis, larger amounts of biodiesels (fatty acid methyl, propyl, butyl, isobutyl, pentyl, hexyl, and octyl esters) were synthesized from waste cooking oil, in the presence of KOH, at the conditions of the highest experimental conversions; purified, and blended into the binary and trinary blends with non-additivated mineral diesel and/or corresponding alcohol. The prepared samples underwent the application property analysis via corresponding standardized methods (density, kinematic viscosity, cloud point, cold filter plugging point, pour point, lubricity, simulated distillation),
the results of which were compared with the ones prescribed by the standard for diesel fuel HRN EN 590. Additionallly, samples were analyzed via instrumental analytical methods: differential scanning calorimetry, surface tension measurements via goniometer, and friction coefficient measurements. The main results showed that the most significant reaction conditions in the given systems were the molar ratio of the reactants, and the mass fraction of the catalyst KOH, and that in the selected systems experimentally the highest conversions were obtained using coconut oil, while the lowest using animal fat, as a feedstock.
The reaction conversions in the synthesis using straight-chain alcohols were generally higher than those with branched alcohols, and the increase in the molecular weight of branched alcohols further led to a decrease in the conversion. Sample characterization determined the addition of selected biodiesel fuels up to 20 vol% into the blends with mineral diesel and/or corresponding alcohol led to the increase in their density, kinematic viscosity, and surface tension, while the addition of the selected higher alcohol up to 15 vol% in the blends with diesel and biodiesel resulted in the reduction of their density, kinematic viscosity, and surface tension. Density and kinematic viscosity values of all the binary diesel-biodiesel (with up to 20 vol% of biodiesel), and trinary diesel-biodiesel-corresponding alcohol blends (with up to 15 vol% of biodiesel) were within the limits required by the standard for diesel fuel HRN EN 590. Furthermore, blending of selected biodiesels and/or corresponding alcohols with mineral diesel did not aggravate its analyzed low-temperature properties (cloud point, cold filter plugging point, pour point). Rheological measurements determined that the addition of fatty acid hexyl esters to non-additivated mineral diesel of just 2.5 vol% significantly improved its lubricity, whereas the change in the volume fraction or the type of biodiesel blended with mineral diesel did not have a significant influence on the diesel’s lubricating properties. Finally, it was observed that for the distillation of the same percentage of the sample, the higher temperatures were required with the addition of fatty acid pentyl esters of 20 vol% to mineral diesel, than with the addition of the same biodiesel in the volume fraction of 10 vol%. On the other hand, differential scanning calorimetry showed that the binary and trinary blends of all biodiesels with mineral diesel and/or corresponding alcohol had onset and peak crystallization temperature values close to the ones of non-additivated mineral diesel. This could serve as an additional indicator for the lack of their negative impact on the diesel’s low-temperature properties
Experiences and Working Methods of Speech and Language Pathologists in the Field of Dysphagia
No full textCilj ovog istraživanja je stjecanje uvida u iskustva i praksu logopeda koji rade s osobama s disfagijama, poremećajima gutanja. Istraživanje se fokusira na dva ključna problema: 1) razumijevanje načina dijagnostičkog i terapijskog rada logopeda u Hrvatskoj s pacijentima s disfagijama, uključujući njihov osobni osvrt na postojeću praksu; i 2) istraživanje iskustava logopeda u radu s pacijentima, njihovim obiteljima te drugim stručnjacima. Kvalitativni pristup istraživanja proveden je putem polustrukturiranih intervjua s osam logopetkinja koje su stručnjakinje u području disfagija. Uzorak je prikupljen metodom "snježne grude". Rezultati istraživanja ukazuju na nekoliko ključnih područja koja zahtijevaju unapređenje i razvoj u logopedskoj praksi u Hrvatskoj. U dijagnostičkom pristupu, identificiran je nedostatak ujednačenosti u korištenju testova i upitnika te potreba za razvojem specifičnih smjernica i unapređenjem instrumentalne dijagnostike poput VFSS-a i FEES-a. Ulaganje u poslijediplomske edukacije moglo bi značajno doprinijeti tome da veći broj logopeda počne provoditi instrumentalnu dijagnostiku. U terapijskom radu, varijabilnost u korištenju opreme i metoda često je rezultat ograničenih resursa u zdravstvenom sustavu. Dok neki logopedi koriste specijaliziranu opremu, mnogi se oslanjaju na svakodnevne predmete, što je korisno zbog dostupnosti. Suradnja s pacijentima, obiteljima i drugim stručnjacima ističe se kao ključna komponenta uspješnog tretmana. Potrebno je posvetiti pažnju razradi smjernica za pacijente s različitim etiologijama disfagija i specifičnostima, poput pacijenata s tumorima glave i vrata i pacijenata s narušenim kognitivnim sposobnostima te integrirati psihološku podršku u terapijski proces. Razvoj protokola za rad s pacijentima bez obiteljske podrške i suradnja sa socijalnim radnicima također su preporučeni. Logopedi igraju ključnu ulogu u dijagnostici, terapiji i cjelokupnoj skrbi za pacijente s disfagijom, značajno utječući na poboljšanje njihove kvalitete života. Iako postoje izazovi u radu s disfagijama, dodatna edukacija može pomoći u prevladavanju tih izazova. Ovo istraživanje pruža uvid za daljnji razvoj i unapređenje logopedske prakse u ovom području.The aim of this research is to gain insights into the experiences and practices of speech and language pathologists working with individuals with dysphagia, a swallowing disorder. The study focuses on two key issues: 1) understanding the diagnostic and therapeutic practices of SLPs in Croatia with patients suffering from dysphagia, including their personal reflections on existing practices; and 2) exploring the experiences of SLPs in working with patients, their families, and other professionals. A qualitative approach was used for the research, conducted through semi-structured interviews with eight SLPs who are experts in the field of dysphagia. The sample was collected using the "snowball" method. The research findings highlight several key areas that require improvement and development in the practice of speech and language pathology in Croatia. In the diagnostic approach, a lack of consistency in the use of tests and questionnaires was identified, indicating a need for the development of specific guidelines and improvements in instrumental diagnostics such as VFSS and FEES. Investing in postgraduate education could significantly contribute to more speech therapists conducting FEES. In therapeutic work, variability in the use of equipment and methods is often a result of limited resources within the healthcare system. While some SLPs use specialized equipment, many rely on everyday items due to their availability. Collaboration with patients, families, and other professionals is highlighted as a crucial component of successful treatment. It is necessary to focus on developing guidelines for patients with different etiologies of dysphagia and different characteristics, such as patients with head and neck tumors and those with impaired cognitive abilities, and to integrate psychological support into the therapeutic process. The development of protocols for working with patients without family support and collaboration with social workers are also recommended. SLPs play a key role in the diagnosis, therapy, and overall care of patients with dysphagia, significantly impacting their quality of life. Despite the challenges in working with dysphagia, additional education can help overcome these challenges. This research provides insight for the further development and improvement of speech and language practices in this field
Nasopharyngeal and subcutaneous emphysema as a complication of third molar alveolectomy
No full textEmfizem je rijetka komplikacija stomatoloških zahvata. Najviša incidencija emfizema nakon stomatoloških zahvata je povezana s korištenjem zračne turbine. Ova komplikacija može imati ozbiljne posljedice ukoliko se ne dijagnosticira na vrijeme i pravilno ne liječi. Prikazujemo slučaj zdravog muškarca u dobi od 43 godine kod kojeg se pojavio emfizem lica, farinksa s promjenom boje glasa, potkožja vrata i prsnog koša nakon ispuhivanja nosa neposredno nakon alveotomije donjeg desnog umnjaka. Nakon pojave emfizema, pacijent je bio hospitaliziran i liječen intravenskom antibiotskom terapijom. Vrlo je bitno prepoznati i adekvatno liječiti emfizem te nakon alveolotomije umnjaka upozoriti pacijente da ne ispuhuju nos kako bismo prevenirali ovu rijetku, ali potencijalno ozbiljnu komplikaciju. Prema našem saznanju, ovo je prvi slučaj u kojem je opisan emfizem farinksa te posljedična promjena glasa nakon alveolotomije zuba. Pored prikaza slučaja, u ovom radu će se prikazati i opisati komplikacije koje se mogu javiti tijekom ili nakon vađenja ili alveolotomije zuba.Emphysema is a rare complication of dental procedures. The highest incidence has been associated with the use of air turbine handpieces. If not recognized and treated promptly, this complication can lead to serious outcomes. We present the case of a healthy 43-year-old man who developed pharyngeal and subcutaneous emphysema of the face, neck and chest along with the specific voice change due to nose blowing shortly after alveolectomy of the lower right third molar. The patient was hospitalized and treated with intravenous antibiotic therapy. It is essential to recognize and adequately manage emphysema, and to inform patients postoperatively not to blow their nose after third molar alveolectomy in order to prevent this rare but potentially serious complication. To our knowledge, this is the first reported case of pharyngeal emphysema with resultant voice alteration following third molar alveolectomy. Along with the case report, this paper will describe all the complications that can occur during and after tooth extraction or alveolotomy
The connection between knowledge sharing, innovative work behavior and hidden employee
No full textOvaj diplomski rad istražuje povezanost dijeljenja znanja, inovativnog radnog ponašanja i
skrivenog inoviranja zaposlenika, polazeći od pretpostavke da su ovi procesi međusobno
povezani i ključni za organizacijsku uspješnost u suvremenom, dinamičnom poslovnom
okruženju. Teorijski dio rada temelji se na relevantnoj znanstvenoj literaturi iz područja
upravljanja znanjem, organizacijskog ponašanja i inovacijskog menadžmenta. Naglasak je
stavljen na ulogu tacitnog znanja, koje se prenosi neformalno i često nesvjesno, a pokazuje se
posebno važnim u generiranju kreativnih rješenja i inovativnih ideja. Inovativno radno
ponašanje definira se kao niz aktivnosti zaposlenika koje uključuju generiranje, promociju i
implementaciju novih ideja, dok se skriveno inoviranje odnosi na neformalnu, često
neautoriziranu praksu razvoja inovacija izvan službenih okvira organizacije. Empirijski dio
rada temelji se na kvantitativnoj analizi prikupljenih podataka putem anketnog upitnika
provedenog među zaposlenicima iz različitih organizacija. Rezultati istraživanja provedenog
na uzorku od 108 zaposlenika iz različitih poduzeća pokazuju statistički značajnu povezanost
između dijeljenja znanja i inovativnog radnog ponašanja, kao i između inovativnog ponašanja
i sklonosti skrivenom inoviranju. Također je potvrđeno da inovativno ponašanje zaposlenika
djelomično posreduje odnos između dijeljenja znanja i skrivenog inoviranja. Ovi nalazi
upućuju na to da se sustavno poticanje dijeljenja znanja može pozitivno odraziti na spremnost
zaposlenika da aktivno sudjeluju u inovacijskim procesima, bilo formalno, bilo kroz skriveno
inoviranje. Rad daje teorijski doprinos razumijevanju odnosa između znanja i inovacija, a
istovremeno nudi i praktične implikacije za organizacije koje žele potaknuti kulturu dijeljenja,
kreativnosti i neformalne inovativnosti..This thesis explores the connection between knowledge sharing, innovative work behavior and
employee latent innovation, starting from the assumption that these processes are
interconnected and crucial for organizational success in a modern, dynamic business
environment. The theoretical part of the paper is based on relevant scientific literature in the
field of knowledge management, organizational behavior and innovation management.
Emphasis is placed on the role of tacit knowledge, which is transmitted informally and often
unconsciously, and has proven to be particularly important in generating creative solutions and
innovative ideas. Innovative work behavior is defined as a series of employee activities that
include the generation, promotion and implementation of new ideas, while latent innovation
refers to the informal, often unauthorized practice of developing innovations outside the official
framework of the organization. The empirical part of the paper is based on a quantitative
analysis of data collected through a questionnaire conducted among employees from different
organizations. The results of the research on 108 employees from different companies show a
statistically significant connection between knowledge sharing and innovative work behavior,
as well as between innovative behavior and a tendency to latent innovation. It was also
confirmed that innovative behavior partially mediates the relationship between knowledge
sharing and latent innovation. These findings suggest that systematically encouraging
knowledge sharing can positively affect employees' willingness to actively participate in
innovation processes, either formally or through latent innovation. The paper makes a
theoretical contribution to the understanding of the relationship between knowledge and
innovation, while also offering practical implications for organizations that want to foster a
culture of sharing, creativity, and informal innovation
Inhibitory effects of antibiotics and the deletion of morfogenetic genes on pseudomurein synthesis in Methanothermobacter thermautotrophicus
No full textMethanogenic archaea have recently gained attention thanks to their environmental significance and role in human microbiota. Some of them build their cell walls with pseudomurein, structural analog of bacterial murein, but the mechanisms behind its biosynthesis and regulation remain understudied. This thesis explores archaeal peptidoglycan through two complementary approaches. I tested the sensitivity of Methanothermobacter thermautotrophicus, an archaea with peptidoglycan, to cell-wall targeting antibiotics (bacitracin, gardymicin, enduracidin and nisin). I also utilized the first genetic manipulation tool developed for this organism, based on interdomain conjugation with bacteria Escherichia coli, to delete the genes (mreB, mbaP, rodA) potentially involved in morphogenesis. M. thermautotrophicus was sensitive to all tested antibiotics, with minimal inhibitory concentration similar to those observed in bacteria. Nisin, gardymicin and enduracidin induced cell deformations at their half maximal inhibitory concentration. Although mutations of morphogenetic genes mreB, mbaP and rodA were not confirmed in this research, significant phenotypic differences in comparison to wild type, such as altered cell dimensions, suggest the involvement of these genes in cell elongation. This research optimizes and establishes methods for peptidoglycan biology studies on M. thermautotrophicus, providing a foundation for further investigation of this unique cell wall structure of methanogens.Metanogene arheje u posljednje vrijeme privlače pažnju zbog svoje ekološke važnosti i uloge u sastavu ljudske mikrobiote. Neke od njih svoje stanične stijenke izgrađuju od pseudomureina, strukturnog analoga bakterijskog mureina, no mehanizmi njegove biosinteze i regulacije kod arheja još uvijek su nedovoljno istraženi. Ovaj rad istražuje arhealni peptidoglikan kroz dva komplementarna pristupa. Testirala sam osjetljivost Methanothermobacter thermautotrophicus, arheje koja sadrži peptidoglikan, na antibiotike koji cilјaju staničnu stijenku (bacitracin, gardimicin, enduracidin i nisin). Također, koristila sam prvi alat za genetsku manipulaciju razvijen za ovu vrstu, temeljen na interdomenskoj konjugaciji s bakterijom Escherichia coli, kako bih uništila gene (mreB, mbaP, rodA) potencijalno uključene u morfogenezu. Methanothermobacter thermautotrophicus je bio osjetljiv na sve testirane antibiotike, s minimalnom inhibitornom koncentracijom sličnom onoj kod bakterija. Nisin, gardimicin i enduracidin inducirali su deformacije oblika stanica pri polovini maksimalne inhibitorne koncentracije. Iako mutacije morfogenetskih gena mreB, mbaP, rodA treba još potvrditi, značajne fenotipske razlike u odnosu na divlji tip, poput promjena staničnih dimenzija, upućuju na sudjelovanje tih gena u dinamici stanične elongacije. Provedeno istraživanje optimizira i uspostavlja metode za istraživanje biologije peptidoglikana na arheji M. thermautotrophicus, pružajući temelj za daljnje istraživanje ove jedinstvene stanične stijenke metanogena