Abstract The growth mechanism and properties of the oxide films on iron and AISI 304 stainless steel were studied in simulated acid rain (pH 4.5) by means of electrochemical techniques and atomic absorption spectrometry. The layer-pore resistance model was applied to explain a potentiodynamic formation of surface oxides. It was found that the growth of the oxide film on iron takes place by the low-field migration mechanism, while that on the stainless steel takes place by the high-field mechanism. Kinetic parameters were determined. Impedance measurements revealed that Fe surface film has no protective properties at the open circuit potential, while the resistance of stainless steel oxide film is very high. The concentration of the metallic ions released into solution and measured by atomic absorption spectroscopy was in accordance with the results obtained from the electrochemical techniques.

Abstract The growth mechanism and electrochemical properties of an oxide film on AISI 304 grade stainless steel were studied in 0.01 and 0.1 mol L−1 fluoride solutions with different pH values (4.5, 5.5, 6.5) by means of electrochemical techniques. The anodic growth and stability of the oxide film on the stainless steel were characterized using cyclic voltammetry. Potentiodynamic analysis suggests that the oxide film growth occurs according to the high-field mechanism. Electric field strength, high-field growth exponential law constants, ionic conductivity through the film and half jump distance were determined. The electrochemical properties of the oxide film, formed spontaneously at the open circuit potential, were studied using electrochemical impedance spectroscopy. The results showed that the fluoride concentration has more considerable influence on the dissolution rate and the resistance of the oxide film than the pH.

CoCrMo legure imaju vrlo siroku primjenu u medicini kao ortopedski implantati (nadomjestak kuku). Korozijska stabilnost tankog oksidnog filma spontano formiranog na povrsini kovinskih implantata osnovni je preduvjet biokompatibilnosti ovih materijala u kontaktu s realnim biookolisem ljudskog organizma. U ovom radu istraživan je utjecaj legirajucih elemenata kobalta, kroma i molibdena na svojstva pasivnih filmova formiranih na Co30Cr6Mo leguri u simuliranim fizioloskim otopinama (slina, pH 5.21 i Hankova otopina, pH 6.8) na temperaturi 37 C. Potenciodinamickim i potenciostatskim elektrokemijskim tehnikama i impedancijskom spektroskopijom istraživani su procesi na sucelju faza pasivni flm/elektrolit, elektricka i dielektricka svojstva spontano i anodno formiranih pasivnih filmova. Kemijska analiza pasivnih filmova provedena je X-ray fotoelektronskom spektroskopijom (XPS).

Abstract The effect of mimosa tannin on the electrochemical behavior of carbon steel (CS) in borate buffer solution (pH 8.4) was studied using potentiodynamic and electrochemical impedance spectroscopy techniques. Mimosa tannin was found to increase the dissolution rate of CS in the active range by forming a soluble iron(II) tannin complex. In this way, tannin suppresses electrochemical oxidation of Fe2+ ions and formation of a deposited porous outer layer with a composition similar to iron(III) oxyhydroxide (FeOOH). The results of both techniques showed that mimosa tannin contributes to CS passivation by forming an insoluble chelating complex that precipitates onto the electrode surface, resulting in a decrease in the passive current density.

Kovinski biokompatibilni materijali (titanijeve slitine, Co-Cr slitine i visokolegirani celici) upotrebljavaju se u medicini i stomatologiji za izradu razlicitih implatata. Biokompatibilnost implatata definira se kao stanje koegzistencije kovine (slitine) i organizma tako da uzajamno ne djeluju stetno jedno na drugo. Osnovna znacajka biokompatibilnosti kovinskih implatata je njihova kemijska (korozijska) otpornost u realnom biookolisu ljudskog organizma. Tjelesne tekucine su medij s jakim korozivnim djelovanjem, stoga je spontano nastajanje zastitnog pasivnog filma na povrsini kovinskog implatata od presudnog znacenja za njegovu primjenu. U ovom radu istraživani su korozija i pasivitet Co30Cr6Mo slitine u in vitro uvjetima simulirane fizioloske, Hankove, otopine pH 7, 8. Primjenom elektrokemijskih tehnika i impedancijske spektroskopije nađeno je da pasivni filmovi na Co30Cr6Mo slitini, spontano nastali na potencijalu otvorenog kruga ili formirani anodnom polarizacijom u Hankovoj otopini, pokazuju izvanredna dielektricna svojstva i korozijsku stabilnost. Pasivno podrucje slitine ja za oko 500 mV sire od onog na pojedinacnim komponentama slitine. Kobalt je podložan lokalnoj pitting koroziji, a molibden se transpasivno otapa uz izlucivanje kisika. XPS i Ramanova spektroskopija daju uvid u kemijski sastav pasivnog filma. Prijelaz iz aktivnog u pasivno stanje slitine povezan je s nastajanjem hidratiziranih nižih oksida kobalta i kroma (CoO / Co(OH)2 i Cr2O3 / CrOOH). Na tim potencijalima molibden je prisutan kao Mo(IV) oksid. Na pozitivnijim anodnim potencijalima pasivni film je, uglavnom, izrađen od kromovih oksida. Mo(VI) ioni Ťugrađeniť u taj film imaju odlucujucu ulogu u otpornosti slitine prema pitting koroziji u fizioloskoj otopini koja sadrži visoku koncentraciju korozivno agresivnih Cl- iona (0, 15 g/L) kao i realni biookolis. Na temelju rezultata ciklicke voltametrije i impedancijske spektroskopije objasnjen je mehanizam djelovanja Mo(VI) iona na smanjenje koncentracije vakancija u pasivnom filmu i povecanje otpornosti slitine prema lokalnoj pitting koroziji.

Immune thrombocytopenic purpura (ITP) associated with pregnancy often involves considerable risk both for mother and child, and usually worsens in the third trimester of gestation. Pregnancy and delivery are especially difficult in patients with severe ITP (platelet count below 20 x 10(9)/L), who are resistant to prednisone and high dose intravenous immunoglobulin (IVIgG). In those cases we applied cesarean section (CS), to prevent intracranial haemorrhage due to fetal/neonatal ITP, and splenectomy at the same time as an effective therapeutic strategy for ITP. We present 5 patients (4 with chronic ITP and 1 with ITP associated with HIV infection), aged 21-35 years, with severe ITP (platelet count 2-10 x 109/L), resistant to prednisone (1-2 mg/kg), and 2/3 were resistant to IVIgG (0.4 g/kg x 5 d). Four patients with severe resistant ITP were supported with 1-2 doses of platelets from cell separator before CS and 1-3 dose during splenectomy. One patient increased platelet count to 55 x 109/L after treatment with IVIgG and splenectomy following CS were done without platelet transfusion. Splenectomy was performed immediately after CS in all patients, and two of them were hysterectomised (one with HIV infection). After splenectomy, platelet count was normalised in all patients, and they had no haemorrhage, wound haematoma formation or any adverse events. But ITP relapsed in 2/5 patients after 1-2 months. Two newborns had severe thrombocytopenia, which solved spontaneously after 3 days in one or after treatment with IVIgG in other. We propose that splenectomy following cesarean section should be considered as approach for delivery and treatment option for mothers with severe resistant ITP.

Aluminium alloys with magnesium are of special importance for technical applications. They are used as an important construction material in shipbuilding and in conditions which require high corrosion resistance, especially in sea water and near the sea. These alloys are also important in manufacture of equipment for the chemical and food-processing industry. The presence of aggressive ions, like chloride, leads to a strong local attack due to adsorption of these ions to those areas of the surface where the oxide film is weaker. Application of organic inhibitors in highly corrosive media is a widely spread method of minimising corrosion damages in a number of technologies. However, most commercial inhibitors used for this purpose are toxic and their replacement with other non-toxic ones in the future is unavoidable. The aim of the present study was to find less toxic inhibitor compounds for aluminium alloy corrosion. To that purpose the extract of rosemary leaves was tested for efficiency as a corrosion inhibitor for the Al-2.5Mg alloy. Rosmarinus officinalis L. is an aromatic plant of Mediterranean origin with outstanding antioxidant and antimicrobial properties. Extract examined is an effective inhibitor of the localized attack. The inhibitory action decreases with the decreasing concentration of additive.

The authors studied all cases of triplets who were born at the Department of Gynaecology and Obstetrics of University Clinical Centre in Belgrade, over a twenty-year period (1970-1989). Thirty sets of triplets were born in this period. This means that one set of triplets was born per 5845 births. Preterm deliveries occurred in 19 cases. Liveborn children had lower Apgar score. Common birthweight was slightly below 1800 grams. In more than one half of the foetuses malpresentation was found. More than one fourth of sets were delivered by Cesarean section. Total foetal loss reached 23.33% and purified perinatal mortality rate reached 11.11%. The triplet diagnosis on time is important because of the necessary prevention measures and appropriate therapy.

The total 3492 complete measurements were performed in order to make asymptomatic curves of intrauterine foetal development. Of this number 1756 measurements concerned the biparietal diameter (BPD) and 1736 the abdominal diameter (ABD). Measurements of the biparietal diameter were done from the 13th to the 41st week of gestation. The mathematical processing of all serial groups was done according to defined algorithm. On the basis of statistical analysis of distribution frequency and dispersion parameters the necessary findings were obtained. Thanks to these findings asymptomatic curves of intrauterine foetal development were made.

In recent years the interest for the evidence of ovulation and its follow-up has increased. This increase is especially evident in the field of out-body insemination. The ultrasound follow-up of ovulations is performed in the case of the growth of the follicle; determination of the ovulation ring; and observation of the Douglas free liquid. The authors present values of the follicular diameter on the 14th day of gestation in 34 patients with spontaneous, stimulated and induced cycles. In their opinion this procedure is a very useful method which, in addition to other parameters, enables a good inspection into the functioning of the ovary.