Karakterizacija i korozione karakteristike elektrohemijski taložene legure Ni-W

Ni-W alloys electrodeposited from citrate solution consist of three different phases, which are all present in high W-content alloys: a solid solution of W in a Ni matrix; an intermetallic compound Ni4W, as well as another solid solution of W in Ni with a W content higher than 20 mol. %. XPS analysis revealed that the alloys were covered with a surface layer of complex structure containing the pure metals Ni and W, Ni(OH)2 andWO3, on the very surface as well as some partially reduced oxideWO2.72 (most probably a solid solution ofWO2.72 in Ni) and tungsten carbide in the layer underneath. It is highly likely that some of the oxide species in the layer act as intermediates in the cathodic deposition process. Identifying these species should be the clue to a more detailed understanding of the mechanism of induced deposition of W than has been achieved so far. Corrosion of Ni-W alloys in sulfuric acid solution at OCP, occurs by the preferential dissolution of nickel from the surface layer. The longer the corrosion process lasts, the more the surface behaves like pure W. The lowest initial corrosion rates were recorded with alloys rich in W, but after aging at OCP the lowest corrosion c.d. was found for the Ni-W alloy with the most homogenous phase structure, consisting of the solid solution only.Elektrohemijski taložene legure Ni-W iz citratnog rastvora sadrže tri različite faze, koje su prisutne pri visokom sadržaju W u leguri: čvrst rastvor W u Ni; intermetalno jedinjenje Ni4Wi čvrst rastvor Wu Ni sa sadržajem W većim od 20 mol %. XPS analizom je pokazano da su legure pokrivene slojem složene strukture. Ovaj sloj sadrži čiste metale Ni i W, Ni(OH)2 i WO3, na samoj površini. U sloju ispod same površine nađeni su i delimično redukovan oksid WO2,72 (najverovatnije čvrst rastvor WO2,72 u Ni) i volfram-karbid. Vrlo je verovatno da neka od oksidnih vrsta u sloju učestvuje kao intermedijer u procesu katodnog taloženja. Identifikacija te vrste mogla bi doprineti boljem razumevanju mehanizma indukovanog taloženja volframa. Na potencijalu otvorenog kola u sumpornoj kiselini korozioni proces se odigrava tako što se preferencijalno rastvara Ni iz površinskog sloja legure. Ukoliko korozioni proces traje duže utoliko korozione karakteristike postaju sve sličnije onima za čist W. Niže početne brzine korozije dobijene su za legure sa većim sadržajem W. Međutim, nakon stajanja na potencijalu otvorenog kola niže korozione struje su dobijene za Ni-W leguru homogene fazne strukture koja sadrži samo čvrst rastvor

Primary hypothyroidism quality of life assessment by application of different questionnaires and its different processing

Primarni hipotireoidizam negativno utiče na kvalitet života obolelih. Poboljšanje kvaliteta života očekuje se uspostavljanjem eutireoidnog stanja primenom levotiroksina. Kvalitet života se može "proceniti" primenom različitih upitnika, poput upitnika opšteg zdravlja (GHQ12; engl. General Health Questionnaire) i tireoidno specifičnog upitnika (TSQ; engl. Thyroid Symptom Questionnaire). Ciljevi ovog rada su: sumiranje standardno i modifikovano rangiranih odgovora oba upitnika u skorove; ispitivanje postojanja razlika u apsolutnim vrednostima skorova među grupama ispitanika; svrstavanje dobijenih skorova u različite klastere (bez poremećaja, manji poremećaj, veliki poremećaj), i ispitivanje postojanja razlika u distribuciji frekvencija ispitanika među njima. Studija preseka je sprovedena u KBC Zemun i obuhvatila je 90 ispitanica, koje su bile podeljene u tri jednake grupe (30 po grupi): hipotireoidnu bez terapije, eutiroidnu sa levotiroksinom i kontrolnu, eutireoidnu grupu bez terapije. Ispitanice su zaokruživale svoj odgovor na postavljena pitanja upitnika, koji je potom rangovno transformisan pomoću dva modelastandardnog i modifikovanog, a potom zbirno sumiran. Za statističku analizu korišćen je softver SPSS for Windows 18.0. Prosečan nivo tireostimulišućeg hormona (TSH) u ispitivanoj populaciji je iznosio 1,3±0,3 (1,1-2,2) mU/L. Prosečni TSQm, TSQs, GHQm and GHQs skorovi su bili 14±7, 13±6, 11±7, i 11±6 i razlikovali su se među grupama. Najniži skorovi su registrovani u grupi levotiroksinom-tretiranih, nezavisno od modela rangiranja, pri čemu je nivo TSH ukazivao na adekvatnu supstituciju levotiroksinom. Prosečni TSQs/TSQm i GHQs/GHQm skorovi pokazuju međusobnu statističku korelaciju. Skorovi i skorom-definisani klasteri oba primenjena upitnika odgovaraju kliničkoj prezentaciji prikazanoj kroz grupe ispitivane populacije. S obzirom da se prosečni skorovi upitnika međusobno razlikuju, a da oba modela rangovne transformacije istog upitnika daju sličan skor, zaključujemo da je dovoljno koristiti po jedan upitnik iz obe kategorije instrumenata za ispitivanje kvaliteta života. Jednostavnost primene ovih upitnika, nezavisno od modela transformacije dobijenih odgovora u rangove, omogućava njihovu primenu pri započinjanju supstitucije levotiroksinom, ali takođe i proceni efikasnosti primenjene terapije.Primary hypothyroidism negatively affects patients' quality of life. Improving the quality of life is expected by establishing eutyreoid state using levothyroxine therapy. The quality of life can be "assessed" by applying various questionnaires, such as the general health questionnaire (GHQ12) and thyroid symptom questionnaire (TSQ). The aims of present study were to: sum standard and modified-ranked answers of both questionnaires, rank the scores, test differences in the absolute values of the scores between the groups, classify obtained scores in different clusters (no distress, a minor, and major distress), and test differences in the distribution of frequencies of the respondents among them. Cross-sectional study was conducted in Zemun Clinical Hospital and it included 90 subjects. The subjects were divided into three equal groups (30 subjects per group): hypothyroid without treatment, euthyroid with levothyroxine, and control, euthyroid group without treatment. The subjects answered the questions in the questionnaire, and the answers were then transformed into the ranking of two modelsstandard and modified, and then summarized. Statistical analysis was performed using the SPSS for Windows 18.0. The average level of thyroid stimulating hormone (TSH) in the study population was 1.3 ± 0.3 (1.1-2.2) mU/L. Average TSQm, TSQs, GHQm and GHQs scores were 14±7, 13±6, 11±7 and 11±6 and differed between groups. The lowest scores were registered in the group of levothyroxine-treated, regardless of the ranking models, with the level of TSH that indicates an adequate substitution levothyroxine. Average TSQs/TSQm and GHQs/GHQm scores show a statistical correlation with each other. Scores and scores-defined clusters of both questionnaires are appropriate for clinical presentation shown by specific groups of the population. Considering that the average scores of the questionnaire differ from each other, and that both models rank-transformation of the same questionnaire give a similar score, it is sufficient to use one questionnaire from both categories of instruments for testing the quality of life. The ease of applying these questionnaires, independent of the transformation obtained in response ranges and their application when starting levothyroxine substitution, were used to assess the effectiveness of the therapy

Lipid Peroxidative Damage on Cisplatin Exposure and Alterations in Antioxidant Defense System in Rat Kidneys: A Possible Protective Effect of Selenium

Cisplatin (Cis-diamminedichloroplatinum II, CP) is an important chemotherapeutic agent, useful in the treatment of several cancers, but with several side effects such as nephrotoxicity. The present study investigated the possible protective effect of selenium (Se) against CP-induced oxidative stress in the rat kidneys. Male Wistar albino rats were injected with a single dose of cisplatin (7 mg CP/kg b.m., i.p.) and selenium (6 mg Se/kg b.m, as Na2SeO3, i.p.), alone or in combination. The obtained results showed that CP increased lipid peroxidation (LPO) and decreased reduced glutathione (GSH) concentrations, suggesting the CP-induced oxidative stress, while Se treatment reversed this change to control values. Acute intoxication of rats with CP was followed by statistically significant decreased activity of antioxidant defense enzymes: superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px), glutathione reductase (GR) and glutathione-S-transferase (GST). Treatment with Se reversed CP-induced alterations of antioxidant defense enzyme activities and significantly prevented the CP-induced kidney damage

Hydrogen evolution at Zn-Ni alloys

Zn-Ni alloys were electrodeposited from a berate-citrate and TEPA bath in potentiostatic and galvanostatic regimes. Potential of electrodeposition or current density were varied and chemical composition and phase structure were determined. It was found that both chemical composition and phase structure of alloys electrodeposited at the same potential or current density but in the two electrolytes were different. Differences were found even when one and the same chemical composition was achieved. Hydrogen evolution kinetics at the Zn-Ni alloys deposited from the two baths was investigated in alkaline solution (1 M NaOH). Substantial differences in the reaction rates at the alloys with the same chemical but different phase composition were found

A contribution to the knowledge of electrochemical deposition of W induced by Ni

It was found that codeposition of Ni and W from an ammonia and citrate-containing electrolyte, is very sensitive to changes in operating conditions. The Ni-W alloy deposit exhibited sensitivity of chemical composition and phase structure on the composition of the electrolyte, pH in particular, as well as on the c.d., hydrodynamic conditions and quantity (thickness) of the deposit. Thus, small changes in pH, which arise during the process of bath utilization, are found to change the relationships between peaks in anodic dissolution voltammograms reflecting existence of different phases. The anodic linear sweep voltammograms (ALSV) of the alloys deposited at medium c.d.'s, pH lower than 8.4 and a high rate of rotation of the RDE contained two peaks. The first one could be ascribed to some tungsten oxide species while the appearance of the second one basically reflects the presence of solid solution of W in Ni, but also points to some other phases. The increase in pH, increase in c.d., and the decrease in the rate of rotation of the RDE all lead to ALSV with a single peak with a peak potential shifted in the negative direction i.e. towards the dissolution peak of pure Ni. Analysis confirmed a decrease of W content in that shift. Still a somewhat more noble behavior than that of Ni points out that some W still remains in Ni

Influence of substrate temperature and annealing on structural and optical properties of TiO2 films deposited by reactive e-beam evaporation

The influence of deposition and post-deposition annealing parameters on the structure and optical properties of TiO2 thin films synthesized by reactive e-beam evaporation is reported. Pure Ti (99.9%) was evaporated in oxygen atmosphere to form thin films on Si (100) and glass substrates. Depositions were conducted on substrates held at room temperature and at 200-400 degrees C heated substrates. Post-deposition annealing was done for 3 h at 500 degrees C in air. Compositional and structural studies were performed by Rutherford backscattering spectrometry, X-ray diffraction, and X-ray photoelectron spectroscopy, and optical properties were studied by ultraviolet-visible spectroscopy and analytically by pointwise unconstrained minimization approach method. It was found that both the structure and optical properties of the films are strongly influenced by the deposition and processing parameters. All deposited samples showed good stoichiometry of Ti:O similar to 1:2. Depending on the substrate temperature and oxygen pressure in the chamber during the deposition, anatase-rutile mixed films were obtained, and in some cases TiO and Ti2O3 phases were observed. Substrate deposition temperature appears to play the major role on the final structure of the films, while post-deposition annealing adds up for the lack of oxygen in some cases and invokes crystal grain growth of already initiated phases. The results can be interesting towards the development of TiO2 thin films with defined structure and optical properties. (C) 2015 Elsevier B.V. All rights reserved.16th International Conference on Thin Films (ICTF), Oct 13-16, 2014, Dubrovnik, Croati

Bioreactor validation and biocompatibility of Ag/poly(N-vinyl-2-pyrrolidone) hydrogel nanocomposites

Silver/poly(N-vinyl-2-pyrrolidone) (Ag/PVP) nanocomposites containing Ag nanoparticles at different concentrations were synthesized using gamma-irradiation. Cytotoxicity of the obtained nanocomposites was determined by MU assay in monolayer cultures of normal human immunocompetent peripheral blood mononuclear cells (PBMC) that were either non-stimulated or stimulated to proliferate by mitogen phytohemagglutinin (PHA), as well as in human cervix adenocarcinoma cell (HeLa) cultures. Silver release kinetics and mechanical properties of nanocomposites were investigated under bioreactor conditions in the simulated body fluid (SBF) at 37 degrees C. The release of silver was monitored under static conditions, and in two types of bioreactors: perfusion bioreactors and a bioreactor with dynamic compression coupled with SBF perfusion simulating in vivo conditions in articular cartilage. Ag/PVP nanocomposites exhibited slight cytotoxic effects against PBMC at the estimated concentration of 0.4 mu mol dm(-3), with negligible variations observed amongst different cell cultures investigated. Studies of the silver release kinetics indicated internal diffusion as the rate limiting step, determined by statistically comparable results obtained at all investigated conditions. However, silver release rate was slightly higher in the bioreactor with dynamic compression coupled with SBF perfusion as compared to the other two systems indicating the influence of dynamic compression. Modelling of silver release kinetics revealed potentials for optimization of Ag/PVP nanocomposites for particular applications as wound dressings or soft tissue implants

Disease intensity of some tomato viroses in Serbia

In this paper rye present the data on the disease intensity of the tomato plants grown in glass and plastic-houses, and in the open field. The infection was caused by the following viruses: Tomato mosaic virus (ToMV), Tobacco mosaic virus (TMV), Tomato spotted wilt virus (TSWV), Alfalfa mosaic virus (AMV), Potato virus X (PVX), Potato virus Y (PVY), Tomato black ring virus (TBRV), Tomato ringspot virus (ToRSV), Tomato aspermy virus (TAV), and Cucumber mosaic virus (CMV). These viruses represented most frequent tomato pathogens in Serbia. According to the obtained results, it could be concluded that 92.94 % of the rested tomato plants grown in glass and plastic-houses, and 89.82 % grown in the open field were infected by one of the above viruses. Most of the plant samples were infected by two or more viruses. The most frequent viruses - tomato pathogens in Serbia were ToMV, PVY and TMV

Frequencies of EGFR single nucleotide polymorphisms in non-small cell lung cancer patients and healthy individuals in the Republic of Serbia: a preliminary study

The purpose of this study was to determine the frequencies of EGFR -216G gt T, -191C gt A, and 181946C gt T in Serbian non-small cell lung cancer (NSCLC) patients, as well as to compare it with healthy individuals, in order to assess their potential importance for lung cancer in Serbia. The study involved 56 NSCLC patients and 53 unrelated healthy volunteers, and genotyping was performed on DNA samples obtained from formalin-fixed paraffin-embedded lung tumor tissue and blood, respectively. This was the first time to show genotype frequencies of those single nucleotide polymorphisms for this study group from the territory of the Republic of Serbia. There was very strong evidence of association between age and death due to lung cancer (Pearson chi-square = 43.439, df = 2, p lt 0,001), as well as between ever smoking and death due to lung cancer (Pearson chi-square = 31.727, df = 1, p lt 0.001). When dominant genetic model (GG vs. GT+TT) was used for -216G gt T, we have found significant association (p = 0.012) between -216GG genotype and NSCLC patients within smokers' subgroup. So, carriers of -216GG genotype had higher risk (OR = 4.33, 95 % CI = 1.324-14.179) than noncarriers (GT and TT) for developing non-small cell lung cancer in our patients