Sorption of febantel onto natural soil and sediment

U novije doba otpadni farmaceutici predstavljaju sve veću opasnost za okoliš te za zdravlje ljudi i životinja. Proces kojim se može doći do informacija o sudbini, utjecaju i transportu otpadnih farmaceutika u okolišu te time doprinijeti uklanjanju istih naziva se sorpcija. U ovom radu ispitan je proces sorpcije farmaceutski aktivne tvari febantela na prirodna tla i sedimente s područja Republike Hrvatske. Febantel se koristi kao veterinarski lijek te ima široku upotrebu u svijetu. U radu su ispitani mehanizam i kinetika sorpcije, utjecaj ionske jakosti te utjecaj pH. S ciljem određivanja mehanizma sorpcije primjenjeni su linearni, Freundlichov te Dubinin-Radushkevichev model izotermi pri čemu su eksperimentalni podaci pokazali najbolje slaganje s linearnim modelom (R^2>0,99), dok je kinetičkim modelom pseudo-drugog reda najbolje opisana brzina sorpcije. Najviše vrijednosti koeficijenta sorpcije pokazuje uzorak tla Josipovac i uzorak sedimenta Glina, dok najniže vrijednosti pokazuju uzorak tla Gračac te uzorak sedimenta Birovača. Ispitivanjem utjecaja ionske jakosti i pH uočava se trend povećanja koeficijenta sorpcije (Kd) sa smanjenjem ionske jakosti otopine, kao i sa smanjenjem pH vrijednosti otopine.Recently, waste pharmaceuticals represent an increasing danger for the environment as well as for the human and animal health. The process by which you may get information about the fate, the impact and transport of waste pharmaceuticals in the environment and thus contribute to removing them is called sorption. In this study, the subject of examination was the process of sorption of the pharmaceutically active agent febantel on natural soils and sediments from the Croatian teritory. Febantel is used as a veterinary medicine worldwide. In this study, the mechanism and kinetics of sorption, the impact of ionic strenght and the influence of pH are examined. In order to determine the sorption mechanisms, linear, Freundlich and Dubinin- Radushkevich isotherm model are applied. Experimental data showed the best agreement with the linear model (R^2>0,99), while the rate of sorption is the best described with the kinetic model of pseudo-second-order. The highest values of the coefficient of sorption (Kd) shows a sample of soil Josipovac and sample of sediment Glina, while the lowest values indicate a soil Gračac and sediment Birovača. In the results obtained by examing the influence of ionic strength and pH, there is a noticable trend of increasing sorption coefficient with decreasing ionic strength and pH of the solution

Sorption of febantel onto natural soil and sediment

U novije doba otpadni farmaceutici predstavljaju sve veću opasnost za okoliš te za zdravlje ljudi i životinja. Proces kojim se može doći do informacija o sudbini, utjecaju i transportu otpadnih farmaceutika u okolišu te time doprinijeti uklanjanju istih naziva se sorpcija. U ovom radu ispitan je proces sorpcije farmaceutski aktivne tvari febantela na prirodna tla i sedimente s područja Republike Hrvatske. Febantel se koristi kao veterinarski lijek te ima široku upotrebu u svijetu. U radu su ispitani mehanizam i kinetika sorpcije, utjecaj ionske jakosti te utjecaj pH. S ciljem određivanja mehanizma sorpcije primjenjeni su linearni, Freundlichov te Dubinin-Radushkevichev model izotermi pri čemu su eksperimentalni podaci pokazali najbolje slaganje s linearnim modelom (R^2>0,99), dok je kinetičkim modelom pseudo-drugog reda najbolje opisana brzina sorpcije. Najviše vrijednosti koeficijenta sorpcije pokazuje uzorak tla Josipovac i uzorak sedimenta Glina, dok najniže vrijednosti pokazuju uzorak tla Gračac te uzorak sedimenta Birovača. Ispitivanjem utjecaja ionske jakosti i pH uočava se trend povećanja koeficijenta sorpcije (Kd) sa smanjenjem ionske jakosti otopine, kao i sa smanjenjem pH vrijednosti otopine.Recently, waste pharmaceuticals represent an increasing danger for the environment as well as for the human and animal health. The process by which you may get information about the fate, the impact and transport of waste pharmaceuticals in the environment and thus contribute to removing them is called sorption. In this study, the subject of examination was the process of sorption of the pharmaceutically active agent febantel on natural soils and sediments from the Croatian teritory. Febantel is used as a veterinary medicine worldwide. In this study, the mechanism and kinetics of sorption, the impact of ionic strenght and the influence of pH are examined. In order to determine the sorption mechanisms, linear, Freundlich and Dubinin- Radushkevich isotherm model are applied. Experimental data showed the best agreement with the linear model (R^2>0,99), while the rate of sorption is the best described with the kinetic model of pseudo-second-order. The highest values of the coefficient of sorption (Kd) shows a sample of soil Josipovac and sample of sediment Glina, while the lowest values indicate a soil Gračac and sediment Birovača. In the results obtained by examing the influence of ionic strength and pH, there is a noticable trend of increasing sorption coefficient with decreasing ionic strength and pH of the solution

Bone mineral density in adolescents with chronic kidney disease: a follow-up study

Cilj istraživanja jest odrediti promjenu koštane gustoće u bolesnika adolescentne dobi s kroničnim zatajenjem bubrega i odrediti utjecaj visine i težine, odnosno veličine skeleta na koštanu gustoću. U ispitivanju je sudjelovalo 30 bolesnika, prosječne dobi 13,5±3,5 godina. Svim ispitanicima denzitometrijski je određena mineralna gustoća kosti na kralježnici i cijelom skeletu metodom dvoenergetske apsorpciometrije X zraka (DXA). Laboratorijski su određeni kalcij, fosfor i PTH u serumu i izračunat je klirens kreatinina. Prosječno vrijeme između početnoga i kontrolnoga mjerenja bilo je 15,7 mjeseci. Utvrđenje značajan porast visine i težine u ispitanika, ali su u oba mjerenja antropometrijske varijable bile ispod referentnoga prosjeka (Z vrijednost za visinu i težinu < -1). Mineralna gustoća skeleta na kralježnici i cijelom skeletu je također značajno porasla između dva mjerenja, ali nakon korekcije prema visini i težini, taj porast više nije bio značajan. Zato je kod djece s kroničnim zatajenjem bubrega potrebno izvršiti korekciju koštane gustoće u odnosu na njihovu visinu i težinu, obzirom daje brzina njihovoga rasta usporena.The aim of this follow-up study was to analyze the change of bone mineral density in adolescents with chronic kidney disease and to determine the influence of height, weight and bone size on bone density The study included 30 patients, aged 13.513.5 years. Regular biochemistry included serum calcium, phosphorus and PTH. Bone mineral density (BMD) was measured by dual energy absorptiometry (DXA). The mean time between baseline and follow up measurements was 15.7 months. Despite the significant increase in weight and height in all participants, anthropometric variables were below one standard deviation from reference values in both measurements (Z value < -1, for height and weight). After correction for height and weight, the increase of BMAD between two measurements was not significant. It is necessary to correct the bone density for height and weight in children with chronic kidney disease, due to their retarded growth velocity

Bone mineral density in adolescents with chronic kidney disease: a follow-up study

Cilj istraživanja jest odrediti promjenu koštane gustoće u bolesnika adolescentne dobi s kroničnim zatajenjem bubrega i odrediti utjecaj visine i težine, odnosno veličine skeleta na koštanu gustoću. U ispitivanju je sudjelovalo 30 bolesnika, prosječne dobi 13,5±3,5 godina. Svim ispitanicima denzitometrijski je određena mineralna gustoća kosti na kralježnici i cijelom skeletu metodom dvoenergetske apsorpciometrije X zraka (DXA). Laboratorijski su određeni kalcij, fosfor i PTH u serumu i izračunat je klirens kreatinina. Prosječno vrijeme između početnoga i kontrolnoga mjerenja bilo je 15,7 mjeseci. Utvrđenje značajan porast visine i težine u ispitanika, ali su u oba mjerenja antropometrijske varijable bile ispod referentnoga prosjeka (Z vrijednost za visinu i težinu < -1). Mineralna gustoća skeleta na kralježnici i cijelom skeletu je također značajno porasla između dva mjerenja, ali nakon korekcije prema visini i težini, taj porast više nije bio značajan. Zato je kod djece s kroničnim zatajenjem bubrega potrebno izvršiti korekciju koštane gustoće u odnosu na njihovu visinu i težinu, obzirom daje brzina njihovoga rasta usporena.The aim of this follow-up study was to analyze the change of bone mineral density in adolescents with chronic kidney disease and to determine the influence of height, weight and bone size on bone density The study included 30 patients, aged 13.513.5 years. Regular biochemistry included serum calcium, phosphorus and PTH. Bone mineral density (BMD) was measured by dual energy absorptiometry (DXA). The mean time between baseline and follow up measurements was 15.7 months. Despite the significant increase in weight and height in all participants, anthropometric variables were below one standard deviation from reference values in both measurements (Z value < -1, for height and weight). After correction for height and weight, the increase of BMAD between two measurements was not significant. It is necessary to correct the bone density for height and weight in children with chronic kidney disease, due to their retarded growth velocity

Genotype-predicted tetrahydrobiopterin (BH4)-responsiveness and molecular genetics in Croatian patients with phenylalanine hydroxylase (PAH) deficiency

a b s t r a c t Specific mutations in the gene encoding phenylalanine hydroxylase (PAH), located on chromosome 12q22-24.1, are linked to tetrahydrobiopterin (BH 4 ; sapropterin)-responsive phenylketonuria (PKU). Diagnosis is usually done through the newborn screening for PKU, followed by a BH 4 loading test. So far, more than 60 mutant alleles, presenting with a substantial residual PAH activity (average $47%), were identified in more than 500 patients worldwide. We investigated the predictive value of BH 4 -responsive PAH mutations in Croatian population. From a group of 127 PKU patients, 62 were selected (based on the genotype) as potentially BH 4 -responsive and 39 loaded with BH 4 (20 mg/kg). The overall frequency of BH 4 -responsiveness (&gt;30% blood phenylalanine reduction within 24 h) was 36% (14 out of 39 patients with 23 different genotypes), significantly less than expected. The best responders were patients with mild hyperphenylalaninemia (4/4; 100%), followed by mild PKU (8/9; 89%), and classical PKU (2/26; 8%). The most common BH 4 -responsive genotypes were p.E390G/p.R408W and p.P281L/ p.E390G. These genotypes correspond for approximately &gt;30% residual PAH activity. The p.E390G mutation was 100% associated with BH 4 -responsiveness, regardless of the second allele (p.R408W, p.P281L, p.F55Lfs, p.L249P). With regard to the predicted relative PAH activity of recombinantly expressed mutant alleles, there was a significant (p &lt; 0.002) difference between BH 4 -responders and non-responders. In a general Croatian PKU population, disease-causing mutations were identified on 226 alleles (99%). There were 35 different mutations: 21 missense, 8 splice site, 3 nonsense, 2 single nucleotide deletions

Novije metode upravljanja sklopom za bušenje pomoću ultrazvuka

Uz mnoge metode mehaničkih obrada, metoda obrade ultrazvukom jako je zanimljiv proces koji se sve više upotrebljava. Ultrazvučna obrada je zamijenila neke od konvencijalnih metoda obrade svojom efikasnošću i preciznošću. Koristi se uglavnom u serijskoj izradi novih predmeta i to onda kada se obrada ne može obaviti klasičnim postupcima obrade. U okviru ovog rada opisat će se neka svojstva ultrazvuka, proces obrade materijala ultrazvukom, parametri procesa, stroj za ultrazvučnu obradu, te ukratko ultrazvučna tehnologija obrade keramike i titana, te titan legura

Determinants of achievement and satisfaction with grades in mathematics among electrical engineering and computer science students

Cilj je ovog istraživanja bio ispitati odnose vrste završene srednje škole, roda, upravljanja vremenom i uvjetima učenja, ispitne anksioznosti te vrijednosti zadatka i intrinzične ciljne orijentacije s uspjehom i zadovoljstvom ocjenom na kolegiju iz matematike na prvoj godini studija elektrotehnike i računarstva. U istraživanju je sudjelovalo 607 studenata prve godine Fakulteta elektrotehnike i računarstva Sveučilišta u Zagrebu, koji su odslušali kolegij Matematika 1. Sudionici su ispunjavali upitnik sastavljen od upitnika sociodemografskih podataka te četiri podskale upitnika MSQL; Intrinzična ciljna orijentacija, Vrijednost zadatka, Upravljanje vremenom i uvjetima učenja te Ispitna anksioznost. Podaci su analizirani hijerarhijskim regresijskim analizama te je korištenim prediktorima objašnjeno ukupno 24% varijance kriterija ocjene na ispitu iz Matematike 1. Pokazalo se da bolje upravljanje vremenom i uvjetima učenja, završena srednja škola s većim brojem sati matematike godišnje, viša intrinzična ciljna orijentacija te niža ispitna anksioznost predviđaju bolji uspjeh na kolegiju Matematika 1. Za kriterij zadovoljstvo dobivenom ocjenom objašnjeno je 38% varijance, pri čemu se boljom ocjenom na ispitu može objasniti najveći postotak varijance kriterija. Intrinzična ciljna orijentacija i vrijednost zadatka pokazali su se značajnim negativnim prediktorima, kao i ispitna anksioznost, gdje se nižim rezultatima na ovim skalama može predvidjeti više zadovoljstvo ocjenom na ispitu.The aim of this research was to examine the relationship between the type of finished high school, gender, time and study environment, test anxiety, task value and intrinsic goal orientation with achievement in mathematics exam and satisfaction with the grade in the mathematics course in the first year of electrical engineering and computer science studies. The participants were 607 first-year students of the Faculty of Electrical Engineering and Computer Science, University of Zagreb, who attended the course Mathematics 1. The participants filled out a questionnaire consisting of a sociodemographic data and four subscales of the MSQL questionnaire: intrinsic goal orientation, task value, time and study environment and test anxiety. The data were analyzed using hierarchical regression analysis, and the used predictors explained a total of 24% of the variance of the Mathematics 1 exam grade. Better time management and efficient study environment, finished secondary school with a greater number of hours of mathematics per year, higher intrinsic goal orientation, and lower test anxiety were positive predictors for the mathematics course success. 38% of the variance in the criterion of grade satisfaction was explained, and the highest percentage of the variance of the criterion can be explained by a higher grade on the exam. Intrinsic goal orientation and task values were significant negative predictors, as well as test anxiety, where lower scores on these scales predicted higher satisfaction with the exam grade

Utjecaj precipitiranih faza na krhkost dupleks čelika

Dupleks čelici predstavljaju relativno nove materijale u skupini korozijski postojanih čelika. Posebni su po tome što jedini u skupini imaju bifaznu strukturu sastavljenu od austenita i ferita u omjeru 50:50. Ovakva mikrostruktura osigurava specifična svojstva ovih čelika, prije svega izvanrednu kombinaciju mehaničkih i antikorozijskih svojstava. Ako se iz bilo kojeg razloga naruši izbalansirani odnos ferita i austenita, ili ako dođe do izlučivanja nekih drugih mikrostrukturnih faza, to će se negativno odraziti na svojstva. Nehrđajući čelici, pa tako i dupleks čelici, osjetljivi su na pojavu krhkosti za vrijeme toplinske obrade ili pri povišenoj temperaturi. Jedan od oblika krhkosti koji se može pojaviti nazvan je "krhkost 475°C". Krhkost 475°C javlja se pri zagrijavanju svih Fe-C-Cr legura s 15 - 70% Cr u temperaturnom intervalu između 400 i 540°C. Pojava je najjače izražena kod temperature od 475°C, a nešto više o cijeloj pojavi opisano je u ovom radu. Uzrok ovoj pojavi jest formiranje α' faze u obliku vrlo sitnih nakupina (precipitata). Izlučivanje nove faze u dupleks čeliku narušava dobra mehanička i antikorozijska svojstva