19 research outputs found
Effect of radial impeller size in the presence and absence of baffles on the copper exchange on zeolite NaX
Effect of hydrodynamics on ion exchange in a batch reactor is still not appropriately studied even though proper mixing parameters may considerably affect the process of solid suspension and its costs. In this work, hydrodynamic conditions generated by straight blade turbine (SBT) impellers on suspension in the batch reactor with and without baffles were investigated. The aim of this work was to analyze influence of impeller diameter and zeolite mass on just suspended impeller speed, (NJS) power consumption, maximum amount of copper exchanged onto zeolite NaX and copper exchange kinetics as well. All experiments were conducted at the same temperature, initial concentration of the copper solution and zeolite particle size. The obtained results showed that just suspended impeller speed decreases as impeller diameter increases in the reactor with and without baffles but this trend is considerably more pronounced in the reactor with baffles. The increase in zeolite mass causes a slight increase of NJS in the both reactor. In the reactor with the baffles this increment became noticeably higher as impeller diameter decrease. Power consumption, at the state of complete zeolite suspension, decreases as impeller diameter increases and its values in the reactor without baffles are considerably lower as well. Kinetics results indicated that the amount of copper ion increases significantly in the initial stage and then gradually until the equilibrium is reached for all hydrodynamics conditions and mass of zeolite examined
Konkurentno uklanjanje teŔkih metala iz binarne otopine
The removal of copper and cobalt ions from binary metal solutions on zeolite NaX by ion exchange process was investigated. Experiments were conducted in unbaffled glass reactor with a Rushton turbine as a stirrer. The dependence of ion exchange kinetics and the amount exchanged were tested using different initial concentrations of metal ions in mixtures. The results obtained indicate that the removal efficiency depends on the initial heavy metal concentrations in binary solutions. Experimental kinetics data were analysed using Ritchie and Weber-Morris models. According to AARD values, the rate in this study was reaction-controlled.
This work is licensed under a Creative Commons Attribution 4.0 International License.Ispitano je uklanjanje iona bakra i kobalta iz binarnih otopina metala ionskom izmjenom na zeolitu NaX. Eksperimenti su provedeni u staklenom kotlastom reaktoru bez razbijala virova. Kao mijeÅ”alo upotrijebljena je Rushtonova turbina. Ovisnost kinetike izmjene iona i izmijenjene koliÄine iona metala ispitana je pri razliÄitim poÄetnim koncentracijama iona metala u smjesama. Prema dobivenim rezultatima, uÄinkovitost uklanjanja iona metala iz otopina ovisi o poÄetnim koncentracijama metala u binarnim otopinama. KinetiÄki podatci dobiveni eksperimentom analizirani su Ritchievim i Weber-Morrisovim modelom. Prema vrijednostima AARD-a, ukupna brzina procesa u ovoj studiji kontrolirana je reakcijom.
Ovo djelo je dano na koriÅ”tenje pod licencom Creative Commons Imenovanje 4.0 meÄunarodna
UPDATE ON GUIDELINES FOR PHARMACOLOGICAL TREATMENT OF MULTIPLE SCLEROSIS BY THE CROATIAN SOCIETY FOR NEUROVASCULAR DISORDERS OF THE CROATIAN MEDICAL ASSOCIATION AND CROATIAN SOCIETY OF NEUROIMMUNOLOGY AND NEUROGENETICS
Multipla skleroza (MS) je bolest srediÅ”njeg živÄanog sustava koja se prezentira brojnim simptomima iz razliÄitih funkcijskih cjelina toga sustava. Kako se posljednjih godina poveÄao broj dostupnih lijekova, ukazuje se potreba trajne provjere saznanja o dijagnostici i lijeÄenju ove bolesti putem medicine temeljene na dokazima. Time se nameÄe i potreba kontinuiranog obnavljanja nacionalnih i meÄunarodnih smjernica, u naÅ”em sluÄaju, na razini regionalnih smjernica Europskog odbora za lijeÄenje i istraživanje multiple skleroze (engl. ECTRIMS, European Committee of Treatment and Research in Multiple Sclerosis) i Europske neuroloÅ”ke akademije (engl. EAN, European Academy of Neurology) s ciljem omoguÄavanja najbolje medicinske terapije za svakog bolesnika, koja je temeljena na individualiziranom pristupu. Temelji novih smjernica su nedavno ažurirane EAN-ove preporuke za razvoj smjernica, koje su rezultat iscrpnog istraživanja literature do prosinca 2016. godine. S obzirom na rizik od sistemske pogreÅ”ke, kvaliteta dokaza za svaki ishod bila je stupnjevana u Äetiri kategorije kako slijedi: vrlo visoka, visoka, niska i vrlo niska. S obzirom na kvalitetu dokaza te omjera rizika i dobrobiti preporukama je pridružena snažna i slaba jaÄina. Pozornost istraživanja bila je usmjerena na nekoliko najvažnijih pitanja, koja su obuhvaÄala uspjeÅ”nost lijeÄenja, odgovor na primijenjenu terapiju, strategiju za prepoznavanje odgovarajuÄeg odgovora i sigurnost, te terapijsku strategiju lijeÄenja multiple skleroze u trudnoÄi. Smjernicama su obuhvaÄeni svi lijekovi koji modifi ciraju tijek bolesti, a koji su odobreni od strane Europske agencije za lijekove (engl. EMA, European Medicine Agency). U posebne skupine rasporeÄeni su bolesnici s kliniÄki izoliranim sindromom koji ne ispunjavaju dijagnostiÄke kriterije za kliniÄki defi nitivnu MS, dok su bolesnici s dokazanom MS podijeljeni s obzirom na razliÄite kliniÄke podtipove MS-a sukladno važeÄim dijagnostiÄkim smjernicama.Multiple sclerosis (MS) affects the central nervous system (CNS) and presents by numerous symptoms from different CNS functional systems. As the number of available treatments has increased in recent years, the need has emerged for continuous evaluation on MS diagnosis and treatment based on evidence-based medicine. This implies the need for continuous renewal of national and international guidelines, in our case, based on the regional guidelines of the European Committee for Treatment and Research in Multiple Sclerosis and European Academy of Neurology (EAN) with the aim of providing the best medical therapy for each patient, based on an individualized approach. These new guidelines are based on the recently updated EAN recommendations that have been derived as the result of exhaustive literature research as of December 2016. Given the risk of system error, the quality of evidence for each outcome has been subdivided into four categories, as follows: very high, high, low and very low. Given the quality of evidence and the risk and benefit ratio, the recommendations are accompanied by strong and weak strength. The research was focused on several key issues, including treatment effectiveness, response to therapy applied, strategy for recognizing appropriate response and safety, and therapeutic strategy for MS treatment during pregnancy. The guidelines cover all medicines that modify the course of the disease and are approved by the European Medicines Agency. Patients with clinically isolated syndrome that do not meet diagnostic criteria for clinically definitive MS have been assigned to special groups while patients with proven MS are divided into different clinical subtypes of MS in accordance with valid diagnostic guidelines
UPDATE ON GUIDELINES FOR PHARMACOLOGICAL TREATMENT OF MULTIPLE SCLEROSIS BY THE CROATIAN SOCIETY FOR NEUROVASCULAR DISORDERS OF THE CROATIAN MEDICAL ASSOCIATION AND CROATIAN SOCIETY OF NEUROIMMUNOLOGY AND NEUROGENETICS
Multipla skleroza (MS) je bolest srediÅ”njeg živÄanog sustava koja se prezentira brojnim simptomima iz razliÄitih funkcijskih cjelina toga sustava. Kako se posljednjih godina poveÄao broj dostupnih lijekova, ukazuje se potreba trajne provjere saznanja o dijagnostici i lijeÄenju ove bolesti putem medicine temeljene na dokazima. Time se nameÄe i potreba kontinuiranog obnavljanja nacionalnih i meÄunarodnih smjernica, u naÅ”em sluÄaju, na razini regionalnih smjernica Europskog odbora za lijeÄenje i istraživanje multiple skleroze (engl. ECTRIMS, European Committee of Treatment and Research in Multiple Sclerosis) i Europske neuroloÅ”ke akademije (engl. EAN, European Academy of Neurology) s ciljem omoguÄavanja najbolje medicinske terapije za svakog bolesnika, koja je temeljena na individualiziranom pristupu. Temelji novih smjernica su nedavno ažurirane EAN-ove preporuke za razvoj smjernica, koje su rezultat iscrpnog istraživanja literature do prosinca 2016. godine. S obzirom na rizik od sistemske pogreÅ”ke, kvaliteta dokaza za svaki ishod bila je stupnjevana u Äetiri kategorije kako slijedi: vrlo visoka, visoka, niska i vrlo niska. S obzirom na kvalitetu dokaza te omjera rizika i dobrobiti preporukama je pridružena snažna i slaba jaÄina. Pozornost istraživanja bila je usmjerena na nekoliko najvažnijih pitanja, koja su obuhvaÄala uspjeÅ”nost lijeÄenja, odgovor na primijenjenu terapiju, strategiju za prepoznavanje odgovarajuÄeg odgovora i sigurnost, te terapijsku strategiju lijeÄenja multiple skleroze u trudnoÄi. Smjernicama su obuhvaÄeni svi lijekovi koji modifi ciraju tijek bolesti, a koji su odobreni od strane Europske agencije za lijekove (engl. EMA, European Medicine Agency). U posebne skupine rasporeÄeni su bolesnici s kliniÄki izoliranim sindromom koji ne ispunjavaju dijagnostiÄke kriterije za kliniÄki defi nitivnu MS, dok su bolesnici s dokazanom MS podijeljeni s obzirom na razliÄite kliniÄke podtipove MS-a sukladno važeÄim dijagnostiÄkim smjernicama.Multiple sclerosis (MS) affects the central nervous system (CNS) and presents by numerous symptoms from different CNS functional systems. As the number of available treatments has increased in recent years, the need has emerged for continuous evaluation on MS diagnosis and treatment based on evidence-based medicine. This implies the need for continuous renewal of national and international guidelines, in our case, based on the regional guidelines of the European Committee for Treatment and Research in Multiple Sclerosis and European Academy of Neurology (EAN) with the aim of providing the best medical therapy for each patient, based on an individualized approach. These new guidelines are based on the recently updated EAN recommendations that have been derived as the result of exhaustive literature research as of December 2016. Given the risk of system error, the quality of evidence for each outcome has been subdivided into four categories, as follows: very high, high, low and very low. Given the quality of evidence and the risk and benefit ratio, the recommendations are accompanied by strong and weak strength. The research was focused on several key issues, including treatment effectiveness, response to therapy applied, strategy for recognizing appropriate response and safety, and therapeutic strategy for MS treatment during pregnancy. The guidelines cover all medicines that modify the course of the disease and are approved by the European Medicines Agency. Patients with clinically isolated syndrome that do not meet diagnostic criteria for clinically definitive MS have been assigned to special groups while patients with proven MS are divided into different clinical subtypes of MS in accordance with valid diagnostic guidelines
Kroz prostor i vrijeme: Zbornik u Äast Miri Menac-MihaliÄ
Zbornik Kroz prostor i vrijeme posveÄen je prof. dr. sc. Miri Menac-MihaliÄ, dugogodiÅ”njoj profesorici Filozofskog fakulteta SveuÄiliÅ”ta u Zagreba te Älanici suradnici Hrvatske akademije znanosti i umjetnosti. Prof. dr. sc. Mira Menac-MihaliÄ iznimno je plodna znanstvenica koja se, uz veliki broj radova iz dijalektologije, smatra i zaÄetnicom hrvatske dijalektne frazeologije. U zborniku posveÄenom njezinu radu i djelovanju objavljeni su prilozi koji su grupirani u dvije glavne tematske cjeline (dijalektologija/povijest jezika "O govorima kroz vrijeme" i frazeologija "Živost frazema"). Radovi predstavljaju izniman znanstveni doprinos hrvatskoj filologiji. Velikim su dijelom rezultat terenskih istraživanja kojima se prikupljala graÄa za obradu. Donose precizne rezultate o fonoloÅ”kim/morfoloÅ”kim/leksiÄkim znaÄajkama hrvatskih mjesnih govora, a istražuju se i frazemi potvrÄeni u hrvatskoj nacionalnoj ili dijalektnoj frazeologiji. Dio graÄe koji se opisuje ekscerpiran je iz postojeÄe literature te pomno i iscrpno analiziran
Kroz prostor i vrijeme: Zbornik u Äast Miri Menac-MihaliÄ
Zbornik Kroz prostor i vrijeme posveÄen je prof. dr. sc. Miri Menac-MihaliÄ, dugogodiÅ”njoj profesorici Filozofskog fakulteta SveuÄiliÅ”ta u Zagreba te Älanici suradnici Hrvatske akademije znanosti i umjetnosti. Prof. dr. sc. Mira Menac-MihaliÄ iznimno je plodna znanstvenica koja se, uz veliki broj radova iz dijalektologije, smatra i zaÄetnicom hrvatske dijalektne frazeologije. U zborniku posveÄenom njezinu radu i djelovanju objavljeni su prilozi koji su grupirani u dvije glavne tematske cjeline (dijalektologija/povijest jezika "O govorima kroz vrijeme" i frazeologija "Živost frazema"). Radovi predstavljaju izniman znanstveni doprinos hrvatskoj filologiji. Velikim su dijelom rezultat terenskih istraživanja kojima se prikupljala graÄa za obradu. Donose precizne rezultate o fonoloÅ”kim/morfoloÅ”kim/leksiÄkim znaÄajkama hrvatskih mjesnih govora, a istražuju se i frazemi potvrÄeni u hrvatskoj nacionalnoj ili dijalektnoj frazeologiji. Dio graÄe koji se opisuje ekscerpiran je iz postojeÄe literature te pomno i iscrpno analiziran
Immunosuppressive therapy after organ transplantation - drug monitoring of cyclosporine after heart transplantation
Transplantacija je standardna terapijska opcija kod bolesnika sa teÅ”kim zatajenjem srca ukoliko su iscrpljene sve druge moguÄnosti lijeÄenja ukljuÄujuÄi farmakoterapiju i razliÄite kirurÅ”ke metode. UnatoÄ detaljnoj predobradi i selekciji koju prolaze bolesnici prije samog zahvata, imunosni odgovor na presaÄeni organ je neizbježan. Stoga je za uspjeÅ”no prihvaÄanje transplantata nužno uvoÄenje imunosupresiva u doživotnu terapiju. Ciklosporin A (CsA) se nametnuo kao prvi izbor i temeljni lijek u razliÄitim kombinacijama za sprjeÄavanje odbacivanja. Tijekom godina doÅ”lo je do znaÄajnog napretka u razvoju formulacija i poboljÅ”anja farmakokinetiÄkih parametara, posebno apsorpcije koja je postala konzistentnija i brža s posljediÄno poveÄanom bioraspoloživoÅ”Äu. No unatoÄ ovim poboljÅ”anjima, zbog uskog terapijskog indeksa, ozbiljnih nuspojava i razlika u izloženosti meÄu pojedincima nakon primjene oralne doze potreba za terapijskim praÄenjem koncentracija u krvi (TDM) i dalje je postojala. Nužan preduvjet koji mora biti zadovoljen da bi se provodio TDM je postojanje korelacije izmeÄu terapijskog uÄinka i koncentracije lijeka u krvi. Mjerenje koncentracija u krvi i razmatranje korekcije doze na temelju izmjerenih vrijednosti pružilo je moguÄnost individualnog pristupa svakom pojedinom bolesniku i optimizaciji terapije s ciljem poboljÅ”anja ishoda lijeÄenja. UnatoÄ odreÄenim nedostatcima, najÄeÅ”Äe koriÅ”tene metode za kvantitativno odreÄivanje lijekova u krvi su imunokemijske, dok se zlatnim standardom smatra tekuÄinska kromatografija spregnuta s dvojnom spektrometrijom masa. Iako visoko selektivna, nije implementirana u rutinski rad zbog visoke cijene analizatora i složene predobrade uzorka. Osim izbora prikladne metode, važno je i pravilno uzimanje te priprema uzorka za analizu, Äuvanje na prikladnoj temperaturi i optimalan izbor vremena uzorkovanja. Standardni naÄin praÄenja koncentracije ciklosporina u krvi je preko najniže (trough,C0) koncentracije koji je tijekom godina ostao ustaljen u kliniÄkoj praksi. Na osnovu farmakokinetiÄkih karakteristika CsA (najviÅ”a koncentracija u krvi dostiže se 2h nakon administracije, maksimalan stupanj inter- i intraindividualnih razlika pojavljuje se oko apsorpcijske faze tijekom prva 4h nakon uzimanja doze) istraživali su se i drugi parametri kao Å”to je vrijednost AUC (0-4) te koncentracija u toÄki C2 (2h nakon primjene oralnog oblika). Vrijednosti C2 dobro reflektiraju stupanj imunosupresije i toksiÄnosti lijeka, ali unatoÄ tome, zbog sliÄnosti dobivenih rezultata za praÄenje CsA se koristi toÄka C0 koja se pokazala kao pouzdan alat za karakterizaciju profila apsorpcije lijeka i individualizaciju terapije.Transplantation is the standard therapeutic option for patients with severe heart failure if all other treatment options, including pharmacotherapy and various surgical methods, have been exhausted. Despite the detailed pretreatment and selection that patients undergo before the procedure itself, an immune response to the transplanted organ is inevitable. Therefore, the introduction of immunosuppressants into a lifelong therapy is necessary for successful graft survival. Cyclosporine A (CsA) has emerged as the first choice and core drug in various combinations to prevent rejection. Over the years, significant progress has been made in the development of formulations and improvements in pharmacokinetic parameters, especially absorption, which has become more consistent and faster with consequently increased bioavailability. However, despite these improvements, due to the narrow therapeutic index, serious side effects, and differences in exposure among individuals after oral administration, the need for therapeutic monitoring of blood concentrations (TDM) still existed. A necessary prerequisite that must be met in order to perform TDM is the existence of a correlation between the therapeutic effect and the drug concentration in the blood. The measurement of blood concentrations and dose adjustment based on measured values provided the possibility of an individual approach to each patient and optimization of therapy with the aim of improving treatment outcomes. Despite certain shortcomings, the most commonly used techniques for quantitative determination of drugs in the blood are immunoassays, while liquid chromatography coupled with tandem mass spectrometry is considered the gold standard. Although highly selective, it is not implemented in the routine practice due to the high cost of the analyser and the complex sample pretreatment. Apart from choosing the appropriate method, it is also important to properly take and prepare sample for analysis, storage at the appropriate temperature and choice of the right sampling time. The standard way to monitor cyclosporin blood levels is over the lowest (trough, C0) concentration and it has remained stable in clinical practice over the years. Taking into account pharmacokinetic characteristics of CsA (peak blood concentration is reached 2 h after administration, the maximum degree of inter- and intraindividual differences occur around the absorption phase during the first 4 h after dosing) other parameters such as AUC and concentration at point C2 (2h after oral administration) were studied. C2 values well reflect the degree of immunosuppression and drug toxicity, but despite this, due to the similarity of the results obtained, point C0 is used to monitor CsA and it has proven to be a reliable tool for characterizing drug absorption profiles and individualizing therapy
Zeolite NaX Mass and Propeller Agitator Speed Impact on Copper Ions Sorption
Sorption is often carried out in stirred batch reactors without any consideration of how much mixing is sufficient to avoid the effect of diffusion without compromising yield and cost due to overmixing. Therefore, the focus of this work was to study how the maximum sorption capacity, removal efficiency, kinetics and power consumption (P) of the studied process are affected by different mixing speeds, i.e., impeller speed/minimum impeller speed for complete suspension (N/NJS) ratio values and zeolite suspension mass concentrations. Experiments were conducted in a baffled reactor with the propeller at a standard off-bottom clearance. In addition to the experimental studies, numerical modelling approaches were carried out to investigate the sorption process using a transient multiphase computational fluid dynamics model and fitting selected kinetic models. The results show that an increase in zeolite mass leads to a slight increase in the NJS and consequently PJS. The impeller speed affects the velocities, power consumption, kinetics, final amount and removal efficiency of copper sorbed. The experimentally determined kinetic data fit Ritchie’s kinetic model well. However, for two experiments, performed at N/NJS ratios of 0.8 and 0.6, Mixed kinetic model fits better, suggesting that the second-order reaction is suppressed by diffusion. Due to the influence of diffusion, the experimentally determined sorption efficiency decreased from 59.377% to 54.486% and 46.372% for N/NJS ratios of 0.8 and 0.6, respectively
Immunosuppressive therapy after organ transplantation - drug monitoring of cyclosporine after heart transplantation
Transplantacija je standardna terapijska opcija kod bolesnika sa teÅ”kim zatajenjem srca ukoliko su iscrpljene sve druge moguÄnosti lijeÄenja ukljuÄujuÄi farmakoterapiju i razliÄite kirurÅ”ke metode. UnatoÄ detaljnoj predobradi i selekciji koju prolaze bolesnici prije samog zahvata, imunosni odgovor na presaÄeni organ je neizbježan. Stoga je za uspjeÅ”no prihvaÄanje transplantata nužno uvoÄenje imunosupresiva u doživotnu terapiju. Ciklosporin A (CsA) se nametnuo kao prvi izbor i temeljni lijek u razliÄitim kombinacijama za sprjeÄavanje odbacivanja. Tijekom godina doÅ”lo je do znaÄajnog napretka u razvoju formulacija i poboljÅ”anja farmakokinetiÄkih parametara, posebno apsorpcije koja je postala konzistentnija i brža s posljediÄno poveÄanom bioraspoloživoÅ”Äu. No unatoÄ ovim poboljÅ”anjima, zbog uskog terapijskog indeksa, ozbiljnih nuspojava i razlika u izloženosti meÄu pojedincima nakon primjene oralne doze potreba za terapijskim praÄenjem koncentracija u krvi (TDM) i dalje je postojala. Nužan preduvjet koji mora biti zadovoljen da bi se provodio TDM je postojanje korelacije izmeÄu terapijskog uÄinka i koncentracije lijeka u krvi. Mjerenje koncentracija u krvi i razmatranje korekcije doze na temelju izmjerenih vrijednosti pružilo je moguÄnost individualnog pristupa svakom pojedinom bolesniku i optimizaciji terapije s ciljem poboljÅ”anja ishoda lijeÄenja. UnatoÄ odreÄenim nedostatcima, najÄeÅ”Äe koriÅ”tene metode za kvantitativno odreÄivanje lijekova u krvi su imunokemijske, dok se zlatnim standardom smatra tekuÄinska kromatografija spregnuta s dvojnom spektrometrijom masa. Iako visoko selektivna, nije implementirana u rutinski rad zbog visoke cijene analizatora i složene predobrade uzorka. Osim izbora prikladne metode, važno je i pravilno uzimanje te priprema uzorka za analizu, Äuvanje na prikladnoj temperaturi i optimalan izbor vremena uzorkovanja. Standardni naÄin praÄenja koncentracije ciklosporina u krvi je preko najniže (trough,C0) koncentracije koji je tijekom godina ostao ustaljen u kliniÄkoj praksi. Na osnovu farmakokinetiÄkih karakteristika CsA (najviÅ”a koncentracija u krvi dostiže se 2h nakon administracije, maksimalan stupanj inter- i intraindividualnih razlika pojavljuje se oko apsorpcijske faze tijekom prva 4h nakon uzimanja doze) istraživali su se i drugi parametri kao Å”to je vrijednost AUC (0-4) te koncentracija u toÄki C2 (2h nakon primjene oralnog oblika). Vrijednosti C2 dobro reflektiraju stupanj imunosupresije i toksiÄnosti lijeka, ali unatoÄ tome, zbog sliÄnosti dobivenih rezultata za praÄenje CsA se koristi toÄka C0 koja se pokazala kao pouzdan alat za karakterizaciju profila apsorpcije lijeka i individualizaciju terapije.Transplantation is the standard therapeutic option for patients with severe heart failure if all other treatment options, including pharmacotherapy and various surgical methods, have been exhausted. Despite the detailed pretreatment and selection that patients undergo before the procedure itself, an immune response to the transplanted organ is inevitable. Therefore, the introduction of immunosuppressants into a lifelong therapy is necessary for successful graft survival. Cyclosporine A (CsA) has emerged as the first choice and core drug in various combinations to prevent rejection. Over the years, significant progress has been made in the development of formulations and improvements in pharmacokinetic parameters, especially absorption, which has become more consistent and faster with consequently increased bioavailability. However, despite these improvements, due to the narrow therapeutic index, serious side effects, and differences in exposure among individuals after oral administration, the need for therapeutic monitoring of blood concentrations (TDM) still existed. A necessary prerequisite that must be met in order to perform TDM is the existence of a correlation between the therapeutic effect and the drug concentration in the blood. The measurement of blood concentrations and dose adjustment based on measured values provided the possibility of an individual approach to each patient and optimization of therapy with the aim of improving treatment outcomes. Despite certain shortcomings, the most commonly used techniques for quantitative determination of drugs in the blood are immunoassays, while liquid chromatography coupled with tandem mass spectrometry is considered the gold standard. Although highly selective, it is not implemented in the routine practice due to the high cost of the analyser and the complex sample pretreatment. Apart from choosing the appropriate method, it is also important to properly take and prepare sample for analysis, storage at the appropriate temperature and choice of the right sampling time. The standard way to monitor cyclosporin blood levels is over the lowest (trough, C0) concentration and it has remained stable in clinical practice over the years. Taking into account pharmacokinetic characteristics of CsA (peak blood concentration is reached 2 h after administration, the maximum degree of inter- and intraindividual differences occur around the absorption phase during the first 4 h after dosing) other parameters such as AUC and concentration at point C2 (2h after oral administration) were studied. C2 values well reflect the degree of immunosuppression and drug toxicity, but despite this, due to the similarity of the results obtained, point C0 is used to monitor CsA and it has proven to be a reliable tool for characterizing drug absorption profiles and individualizing therapy
Kinetic analyisis of copper ions sorption on zeolite NaX in a batch reactor under different hydrodynamic conditions : doctoral thesis
Sažetak Zeoliti su mikroporozni kristalni alumosilikati koji su svojom primjenom kao katalizatori i sorbensi promijenili petrokemijsku i kemijsku industriju. KatalitiÄka svojstva zeolita mogu se prilagoditi āumetanjemā iona teÅ”kih metala u zeolit, a jedna od metoda koja se može koristiti za pripremu katalizatora je sorpcija. Sorpcija na zeolitima koristi se i za uklanjanje metala iz kontaminiranih voda. Ako se proces sorpcije vodi u kotlastom (Å”aržnom) reaktoru njegova uÄinkovitost ovisi o razliÄitim procesnim parametrima, ukljuÄujuÄi i parametre mijeÅ”anja, a Äiji utjecaj na samu sorpciju joÅ” uvijek nije dovoljno istražen. HidrodinamiÄki uvjeti u odreÄenom sustavu posljedica su geometrijskih karakteristika reaktora i koriÅ”tenog mijeÅ”ala te brzine vrtnje mijeÅ”ala. Stoga je u ovom radu ispitan utjecaj hidrodinamiÄkih uvjeta u reaktoru na uÄinkovitost i kinetiku sorpcije bakrovih iona na sintetskom zeolitu NaX u otvorenom Å”aržnom reaktoru s razbijalima virova. MijeÅ”anje se provodilo upotrebom triju razliÄitih tipova mijeÅ”ala: aksijalnog propelerskog mijeÅ”ala, radijalno-aksijalnog turbinskog mijeÅ”ala s ravnim lopaticama nagnutim pod kutom (PBT) i radijalnog turbinskog mijeÅ”ala s ravnim lopaticama (SBT). Za sve tipove mijeÅ”ala sagledan je utjecaj tipa mijeÅ”ala te masene koncentracije zeolita NaX u otopini na kritiÄnu brzinu vrtnje mijeÅ”ala za postizanje stanja potpune suspenzije, N JS , kao i na kinetiku i na uÄinkovitost sorpcije bakrovih iona na zeolitu NaX. Pri najnižoj ispitivanoj masenoj koncentraciji suspenzije zeolita NaX u otopini, za sve tipove mijeÅ”ala, ispitan je utjecaj brzine vrtnje mijeÅ”ala, N/N JS , na provedbu ispitivanog procesa. Za PBT tip mijeÅ”ala je ispitan i utjecaj pozicije i promjera mijeÅ”ala na kinetiku i na uÄinkovitost ispitivanog procesa pri najnižoj ispitivanoj masenoj koncentraciji zeolita NaX u otopini. Procjena kinetiÄkih parametara provedena je nelinearnom i linearnom regresijskom analizom za tri kinetiÄka modela: Ritchiejev model, MijeÅ”ani kinetiÄki model adsorpcije kontrolirane povrÅ”inskom reakcijom i difuzijom (MijeÅ”ani model) te Weber-Morrisov model. KinetiÄkom analizom dobivenih eksperimentalnih podataka odabranim kinetiÄkim modelima utvrÄeno je koji kinetiÄki model najprikladnije opisuje kinetiku sorpcije bakrovih iona na zeolitu NaX te su izraÄunati kinetiÄki parametri. BuduÄi da je sorpcija heterogeni proces odreÄen je i najsporiji korak procesa za ispitivane uvjete. Analizom eksperimentalnih kinetiÄkih podataka utvrÄeno je da sorpciju bakrovih iona na zeolitu NaX najpotpunije opisuje Ritchiejev model. MeÄutim, pri brzinama vrtnje propelerskog i SBT mijeÅ”ala N/N JS od 0,60 i 0,80, MijeÅ”ani model se bolje slaže s eksperimentalnim kinetiÄkim podatcima, sugerirajuÄi da je reakcija drugog reda ograniÄena difuzijom. Da bi se dobio potpuniji uvid u hidrodinamiÄka zbivanja u ispitivanom sustavu, uporabom programskog paketa ANSYS Fluent v17.2 simulirani su tokovi fluida. S obzirom na kinetiku i koliÄinu sorbiranih bakrovih iona predložena je najpovoljnija geometrija reaktora.Abstract Zeolites are microporous crystalline aluminosilicates that have transformed the petrochemical and chemical industries through their use as catalysts and sorbents. The catalytic properties of zeolites can be altered by introducing heavy metal ions into the zeolite, and one of the methods used to prepare catalysts is sorption. Sorption on zeolites can also be used to remove metals from contaminated water. If the sorption process is carried out in a batch reactor, its efficiency depends on various process parameters, including the mixing parameters, the influence of which on sorption itself has not been sufficiently studied. The hydrodynamic conditions in a given system result from the geometrical characteristics of the reactor and the impeller used, as well as from the impeller rotation speed. For this reason, the influence of hydrodynamic conditions on the efficiency and kinetics of copper ions sorption on synthetic zeolite NaX in an uncovered batch reactor with baffles was studied in this work. Mixing was performed using three different impeller types: an axial propeller impeller, a radial-axial pitched blade turbine impeller (PBT), and a radial straight blade turbine impeller (SBT). For all impeller types, the effect of impeller type and zeolite NaX mass concentration in a solution on the critical impeller speed required to achieve a state of complete suspension, N JS , was investigated. The effect of impeller type on the kinetics of copper ions sorption on zeolite NaX and removal efficiency was studied. At the lowest mass concentration of NaX zeolite in the solution investigated, the effect of the impeller rotation speed, N/N JS , on the performance of the studied process was also investigated for all impeller types. For the PBT impeller, the effect of the impellers' position and its diameter on the kinetics of the copper ion sorption process on zeolite NaX and the removal efficiency at the lowest mass concentration of NaX zeolite in the solution investigated, were studied too. Kinetic parameter estimation was performed using nonlinear and linear regression analysis for three kinetic models: Ritchieās model, Mixed kinetic model of adsorption controlled by surface reaction and diffusion (Mixed model), and Weber-Morris model. By kinetic analysis of the obtained experimental data using the selected kinetic models, a kinetic model that describes the kinetics of sorption of copper ions onto zeolite NaX, and the kinetic parameters were calculated. Since sorption is a heterogeneous process, the slowest step of the process was defined for the conditions studied. By analysing the experimental kinetic data, it was found that the sorption of copper ions onto zeolite NaX is well described by the Ritchieās model. However, at impeller speeds of N/N JS 0.60 and 0.80, the Mixed model agrees better with the experimental kinetic data, suggesting that the second order reaction is suppressed by diffusion. To obtain a more complete insight into the hydrodynamic processes in the studied system, the fluid flows were simulated using the ANSYS Fluent v17.2 software package. Taking into account the obtained results, i.e. the kinetics and the amount of sorbed copper ions, the most favourable reactor geometry was proposed