ERP spektroskopija suprahiperfinog međudjelovanja bakarnog paramagnetskog centra u kristalima citozin monohidrata

The planar complex of Cu(II) with two cytosine bases was formed by gamma irradiation of the cytosine monohydrate crystal, containing copper impurities. The paramagnetic complex was probably formed by trapping the radiation-induced migrating holes by Cu(I), that is originally present in the crystal lattice. The structure of the complex was analyzed from the superhyperfine pattern of its EPR spectra. The experimentally evaluated tensor elements of the three 14N couplings and the observation of an additional proton coupling unequivocally confirm the structure. The ab initio B3LYP density functional method calculations are in good agreement with the experiments. Both experiments and the calculations demonstrate large spin delocalization in the cytosine ring plane.Gama ozračivanjem kristala citozin monohidrata, koji je sadržavao bakarne nečistoće, pripremali smo planarni kompleks Cu(II) s dvije citozinske baze. Paramagnetski se kompleks vjerojatno stvarao vezanjem zračenjem proizvedenih šupljina i Cu(I) koji je prvotno bio u kristalnoj rešetci. Proučavali smo strukturu kompleksa analizirajući suprahiperfinu strukturu njegovog EPR spektra. Eksperimentalno određeni elementi tenzora triju vezanja 14N i opažanje dodatnog protonskog vezanja pouzdano potvrđuju strukturu. Ab initio B3LYP računi metodom funkcionala gustoće u dobrom su slaganju s mjerenjima. Eksperimenti i računi pokazuju jaku delokalizaciju spina u ravnini citozinskog prstena

ERP spektroskopija suprahiperfinog međudjelovanja bakarnog paramagnetskog centra u kristalima citozin monohidrata

The planar complex of Cu(II) with two cytosine bases was formed by gamma irradiation of the cytosine monohydrate crystal, containing copper impurities. The paramagnetic complex was probably formed by trapping the radiation-induced migrating holes by Cu(I), that is originally present in the crystal lattice. The structure of the complex was analyzed from the superhyperfine pattern of its EPR spectra. The experimentally evaluated tensor elements of the three 14N couplings and the observation of an additional proton coupling unequivocally confirm the structure. The ab initio B3LYP density functional method calculations are in good agreement with the experiments. Both experiments and the calculations demonstrate large spin delocalization in the cytosine ring plane.Gama ozračivanjem kristala citozin monohidrata, koji je sadržavao bakarne nečistoće, pripremali smo planarni kompleks Cu(II) s dvije citozinske baze. Paramagnetski se kompleks vjerojatno stvarao vezanjem zračenjem proizvedenih šupljina i Cu(I) koji je prvotno bio u kristalnoj rešetci. Proučavali smo strukturu kompleksa analizirajući suprahiperfinu strukturu njegovog EPR spektra. Eksperimentalno određeni elementi tenzora triju vezanja 14N i opažanje dodatnog protonskog vezanja pouzdano potvrđuju strukturu. Ab initio B3LYP računi metodom funkcionala gustoće u dobrom su slaganju s mjerenjima. Eksperimenti i računi pokazuju jaku delokalizaciju spina u ravnini citozinskog prstena

Fizikalni mehanizmi i metode u tumorskim terapijama i prijenosu lijekova do tumora

In addition to several well-known drug delivery strategies developed to facilitate effective chemotherapy with anticancer agents, some new approaches have been recently established, based on specific effects arising from the applications of ultrasound, magnetic and electric fields on drug delivery systems. This paper gives an overview of newly developed methods of drug delivery to tumors and of the related anticancer therapies based on the combined use of different physical methods and specific drug carriers. The conventional strategies and new approaches have been put into perspective to revisit the existing and to propose new directions to overcome the threatening problem of cancer diseases.Osim dobro poznatih metoda prijenosa lijekova u kemoterapijskom pristupu liječenja tumora, nedavno su otkriveni novi načini prijenosa koji se zasnivaju na specifičnim mehanizmima uzrokovanim upotrebom ultrazvuka, magnetskih i električnih polja. Članak sadrži prikaz fizikalnih mehanizama na kojima se temelje ove nove metode, kao i pregled novootkrivenih prijenosnika lijekova (Pluronske micele, magnetoliposomi, magnetski fluidi), novih terapija tumora (magnetska hipertermija, elektrokemoterapija) i najnovijih istraživanja temeljenih na fizikalnom pristupu ovoj problematici

Zadaci iz fizike : interna skripta za studente Farmaceutsko−biokemijskog fakulteta

Skripta je namijenjena studentima prve godine Farmaceutsko–biokemijskog fakulteta oba smjera (studij Farmacije i studij Medicinske biokemije), a sadržaj je prilagođen gradivu i seminarskoj nastavi predmeta Fizika. Zadaci u skripti nešto su složeniji od zadataka koji se standardno rješavaju u okviru srednjoškolske nastave iz fizike, no s druge su strane mnogo jednostavniji od zadataka iz zbirki pisanih za potrebe studija Prirodoslovno–matematičkog fakulteta i mnogih tehničkih fakulteta

Zadaci iz fizike : interna skripta za studente Farmaceutsko−biokemijskog fakulteta

Skripta je namijenjena studentima prve godine Farmaceutsko–biokemijskog fakulteta oba smjera (studij Farmacije i studij Medicinske biokemije), a sadržaj je prilagođen gradivu i seminarskoj nastavi predmeta Fizika. Zadaci u skripti nešto su složeniji od zadataka koji se standardno rješavaju u okviru srednjoškolske nastave iz fizike, no s druge su strane mnogo jednostavniji od zadataka iz zbirki pisanih za potrebe studija Prirodoslovno–matematičkog fakulteta i mnogih tehničkih fakulteta

Kinetics and Mechanism of Oxidation of Hydroxyurea with Hexacyanoferrate(III) Ions in Aqueous Solution

Hydroxyurea (HU) effectively reduces Fe(CN)63− to Fe(CN)6 4− species in neutral and basic aqueous solution via an electron transfer process that includes the formation and subsequent fading out of a free radical, U•(U• ≡ H2N−C(=O)N(H)O•). The EPR spectrum of U• in H2O solutions suggests that the unpaired electron is located predominantly on the hydroxamate hydroxyl-oxygen atom. Visible spectrophotometric data reveal HU as a two-electron donor. Stoichiometry of the studied reaction can be formulated as: 2Fe(CN)63− + NH2CONHOH + ½H2O → 2Fe(CN)64− + CO2 + NH3 + ½N2O + 2H+. Lack of evidence for the formation of NO probably is a consequence of fast dimerization of HNO in comparison with the rate of its oxidation, which is slow due to the low reduction potential of the Fe(CN)63−/ Fe(CN)64− couple.The kinetic of oxidation of HU by Fe(CN)63− was studied using stopped-flow technique, as a function of H+, HU, Fe(CN)63− and Fe(CN)64− concentrations, as well as a function of ionic strength and temperature. The kinetic results reveal that oxidation of HU by Fe(CN)63− proceed via an outer-sphere electron-transfer process. The effect of ionic strength on the reaction rate reveals that NaFe(CN)62− is the reacting species rather than Fe(CN)63− ion. The rate of the redox process was found to be first order with respect to both redox reactants while the H+ concentration dependence make clear that U− is about four orders of magnitude more reactive than HU. The formal reduction potentials for U•/U− and HU•/HU couples were estimated from the kinetic results as +0.47 V and +0.84 V, respectively.</p

Association between Nutritional Status, Lifestyle Habits, and Disease Activity in Dalmatian Patients with Rheumatoid Arthritis

The aim of this study was to evaluate body composition, handgrip strength, quality of life, disease duration and activity and lifestyle habits in patients with rheumatoid arthritis (RA) and to evaluate possible associations between all of the abovementioned factors. Seventy-five stable RA patients were included. Data on sociodemographic data, disease activity, quality of life, nutritional risk, body mass composition, anthropometric parameters, and clinical and laboratory parameters were collected for each study participant. The results showed that the mean score of the disease activity score (DAS28) was 5.4, the mean score of the health assessment questionnaire-disability index (HAQ-DI) was 1.19, and the mean disease duration in our population was 13.9 years. Our studied population had a long disease duration and high disease activity. Positive predictors of muscle mass in RA patients were daily caloric intake, fat-free mass, bone mass, basal metabolic rate, total body water, weight, body mass index (BMI), height, and muscle strength. There were no significant negative predictors. Positive predictors of muscle strength in RA patients were daily caloric intake, basal metabolic rate, predicted muscle mass, fat-free mass, bone mass, weight, total body water, metabolic age, hemoglobin, BMI, and number of exercises per week. In contrast, negative predictors of muscle strength were number of comorbidities, number of swollen joints, DAS, number of tender joints, erythrocyte sedimentation rate (ESR), and duration of RA. An association was also found between bone mineral density and both muscle mass and muscle strength. A structured nutritional approach in terms of multidisciplinary collaboration between rheumatologist, dietitian and physical medicine specialist is needed in the Dalmatian RA population

Kinetics and Mechanism of Oxidation of Hydroxyurea Derivatives with Hexacyanoferrate(III) in Aqueous Solution

Kinetics and mechanisms of the oxidation of methoxyurea and N-methylhydroxyurea were studied in neutral and basic aqueous solutions. The obtained pH dependences of the oxidation rates indicate that for both hydroxyureas the reactive species are the deprotonated ones. The second order rate constants, the activation enthalpies and the activation entropies for the reactions of methoxyurea (O-methylhydroxyurea) and N-methylhydroxyurea anions with Fe(CN)6 3− at 25 oC, I = 2 mol dm−3 (NaClO4) were determined as (5.06 ± 0.01) x 102 mol−1 dm3 s−1, (1.92 ± 0.02) x 104 mol−1 dm3 s−1, 27 ± 1 kJ mol−1, 16 ± 1 kJ mol−1, −101 ± 2 J mol−1 K−1, and −107 ± 4 J mol−1 K−1, respectively. The pKa value of methoxyurea at 25 oC and 2 mol dm−3 ionic strength was determined kinetically as 12.7 ± 0.1 and the thermodynamic parameters for the deprotonation reaction were determined as ΔaH = 43 ± 1 kJ mol−1, and ΔaS = −96 ± 4 J mol−1 K−1. When the kinetic results are compared with the data reported for hydroxyurea, an inverse dependence of the rate constants on the pKa of the hydroxyurea derivatives at 25 oC is observed. Such unexpected behaviour has been explained by the ab initio calculations and NBO analysis of HOMOs for all three hydroxyureates. (doi: 10.5562/cca1799