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Introduction and Hypothesis: The exact positioning of the dominant hand at the time of manual perineal protection is not clearly specified. The overarching aim of this work was to collect data on the bregma to posterior fourchette distance (BFD), as a surrogate measure for the degree of fetal head extension, and maternal perineal body length (PBL) at the time of manual perineal protection (MPP). Methods: This was a two-center study. Term cephalic singleton nulliparous women having spontaneous vaginal delivery were considered eligible for recruitment into the study. Once crowning was diagnosed and just prior the initiation of manual perineal protection (MPP) or cutting an episiotomy, the BFD and PBL were measured using a standardized measurement protocol.Results: A total of 100 women (50 women in each center) were recruited into the study. The overall mean BFD was 2.8 ± 0.5 cm. The overall mean PBL was 4.4 ± 0.8 cm. There were no statistically significant differences between the measurements taken in both units regarding BFD or PBL (p = 0.81 and 0.10 respectively). There was a weak correlation between both measurements.Conclusion: This is the first study to generate data on the bregma to fourchette distance and the perineal body length just prior to fetal head expulsion. This information will probably be useful to inform future biomechanical computational modeling studies to optimize hands and fingers placement during manual perineal protection.

Episiotomy should be cut at certain internationally set criteria to minimize risk of obstetric anal sphincter injuries (OASIS) and anal incontinence. The aim of this study was to assess the accuracy of cutting right mediolateral episiotomy (RMLE). An institution-based prospective cohort study was undertaken in a Palestinian maternity unit from February 1, to December 31, 2016. Women having vaginal birth at gestational weeks ≥24 or birthweight ≥1000 g and with intended RMLE were eligible (n=240). Transparent plastic films were used to trace sutured episiotomy in relation to the midline within 24-hour postpartum. These were used to measure incisions’ distance from midline, and suture angles were used to classify the incisions into RMLE, lateral, and midline episiotomy groups. Clinical characteristics and association with OASIS were compared between episiotomy groups. A subanalysis by profession (midwife or trainee doctor) was done. Less than 30% were RMLE of which 59% had a suture angle of

Background: There is variation in the reported incidence of levator avulsion (LA). Objective: Explore incidence of LA by mode of birth, imaging modality, timing of diagnosis and laterality of avulsion. Search strategy: We searched MEDLINE, EMBASE, CINAHL, AMED and MIDIRS with no language restriction from inception to April 2019. Study eligibility criteria: A study was included if LA was assessed by an imaging modality after the first vaginal birth or if only delivered by caesarean section. Case series and reports were not included. Data collection and analysis: RevMan v5.3 was used for the meta-analyses and SW SAS and STATISTICA packages for type and timing of imaging analyses. . Results: We included 37 primary non-randomized studies from 17 countries and involving 5594 women. Incidence of LA was 1%, 15%, 21%, 38.5% and 52% following caesarean, spontaneous, vacuum, spatula and forceps births respectively, with no differences by imaging modality. OR of LA following spontaneous birth vs. caesarean was 10.69. While the OR for LA following vacuum and forceps compared to the spontaneous birth were 1.66 and 6.32 respectively. LA was more likely to occur on the right side following spontaneous birth (p = 0.02) and unilaterally vs. bilaterally following spontaneous (P < .0001) and vacuum-assisted births (P = 0.0103) only. Incidence was higher if assessment was performed in the first 4 weeks postpartum. Conclusions: Forceps significantly increases incidence and severity of LA. Ultrasound and MRI are comparable diagnostic tools but early postpartum imaging may lead to over diagnosis of LA.

Objective To explore rates and review practices regarding induction of labor (IOL) among singleton pregnancies in Palestine. Design A prospective population-based cohort study. Setting Six secondary and tertiary governmental hospitals located in the two regions of Palestine: West Bank and Gaza. Participants Singleton pregnancies who had IOL in participating units during the study period were included (n=8290). Women having multiple gestations (1004), planned cesarean births (703), those admitted with cervical dilation >6cm (11228), and pregnancies with no record of cervical dilation and/or gestational age on admission (219) were excluded. Primary outcome measure Rates of IOL in participating units and regions. Results There were a total of 33,402 singleton births during the study period with an IOL rate of 24.8%. Rates of IOL significantly varied between units, ranging from 12.9% to 45.6% (P-value

Perineal pain and dyspareunia are experienced by women undergoing a vaginal birth that can have short and longer term physical and psychological morbidities. This review aimed to determine the incidence of perineal pain and dyspareunia following spontaneous vaginal birth (SVB) with intact perineum, first and second-degree perineal trauma or episiotomy. Searches of MEDLINE, EMBASE, CINAHL, AMED and MIDIRS (inception – December 2017) were undertaken with selection criteria of any study evaluating the effect of intact perineum, first- or second-degree perineal trauma on perineal pain or dyspareunia in women with SVB. Eighteen studies (8 RCTs and 10 NRSs) were included. Fourteen and 12 studies were undertaken to assess perineal pain and dyspareunia after SVB, respectively. Meta-analysis of 16 studies (3133 women) demonstrated that women at 2 days postpartum experienced nearly the same incidence of perineal pain whether perineal trauma existed or not. At 4–10 days postpartum there was a significant reduction in the incidence of perineal pain for both presence and absence of any perineal trauma. Episiotomy was associated with the highest rate of perineal pain. The incidence of dyspareunia was high at resumption of sexual intercourse following SVB with an intact perineum. At 12 months, women still experienced dyspareunia whether perineal trauma existed or not. Women experience perineal pain and dyspareunia regardless of the presence or absence of perineal trauma after SVB; nonetheless, the reported incidence is higher if perineal trauma occurred.

Poly 1-amino-9, 10-anthraquinone (PAAQ) films were prepared by the electropolymerization of 1-amino-9,10-anthraquinone (AAQ) on platinum substrate from aqueous media, where 5.0 × 10 −3 mol L −1 AAQ and 6.0 mol L −1 H 2 SO 4 were used. The kinetics of the electropolymerization process was investigated by determining the change of the charge consumed during the polymerization process with time at different concentrations of both monomer and electrolyte. The results have shown that the process follows first order kinetics with respect to the monomer concentration. The order of the reaction with respect to the aqueous solvent i.e. H 2 SO 4 was found to be negative. The polymer films were successfully used as sensors for the electroanalytical determination of many hazardous compounds, e.g. phenols, and biologically important materials like dopamine. The electroanalytical determination was based on the measurements of the oxidation current peak of the material in the cyclic voltammetric measurements. The cyclic voltammograms were recorded at a scan rate of 100 mV s −1 and different analyte concentrations. A calibration curve was constructed for each analyte, from which the determination of low concentrations of catechol and hydroquinone (HQ) as examples of hazardous compounds present in waste water and also for ascorbic acid and dopamine as examples of valuable biological materials can be achieved.

Electropolymerization of 2-aminobiphenyl was carried out on glassy carbon, gold, and platinum electrodes, in aqueous–organic solvent mixtures, using a potentiodynamic technique. The choice of organic solvent strongly influences the film formation. In a mixture of 60% acetonitrile and 40% 1.0M HClO4, stable films were obtained. The poly(2-aminobiphenyl) films were characterized with cyclic voltammetry, where the electrochemical activity of the formed polymer films was investigated in acidic and neutral aqueous solutions containing perchlorates or in potassium ferrocyanide. The prepared films posses a remarkable stability in acidic aqueous solutions and are also stable in some organic solvents. The stability of the polymer films depends on the pH of the solution, and the mechanism of the polymerization process involves deprotonation and head-to-tail coupling of oxidized monomers with its oligomeric radical cations. The kinetics of the electropolymerization process was investigated by determining the charge consumed during the electropolymerization as a function of time at different concentrations of the electrolyte components. The electropolymerization process follows first-order kinetics with respect to the monomer and negative order with respect to HClO4. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Corrosion behaviour of sputter-deposited Mg–Zr alloys was examined in a borate buffer solution of pH 8.7. XRD measurements showed that the alloys were supersaturated with Zr. The addition of 29 at.% Zr or more was very effective in increasing the corrosion resistance of Mg by more than four orders of magnitude. XPS analysis of spontaneously formed passive films revealed that the passive film consisted of double oxyhydroxide composed of enriched tetravalent Zr and divalent Mg cations. The enrichment of Zr cations in the passive film is responsible for the enhanced corrosion resistance of Mg–Zr alloys.

1-Amino-9,10-anthraquinone was electropolymerized on platinum substrates either from aqueous or nonaqueous electrolytes. The aqueous electrolyte was 6.0 mol L−1 H2SO4, and the nonaqueous solvent was acetonitrile containing lithium perchlorate, LiClO4, as a supporting electrolyte. The formed polyaminoanthraquinone was stable, and the polymerization process was reproducible. The kinetics of the electropolymerization process was investigated by determining the charge consumed during the electropolymerization as a function of time at different concentrations of the electrolyte components. The results of chronoamperometry have been used to determine the orders of reaction. In either aqueous or nonaqueous solution, the electropolymerization process follows first-order kinetics with respect to the monomer concentration. In nonaqueous solution, the very small concentrations of water did not affect the order of reaction. The order of reaction with respect to the traces of water and the supporting electrolyte concentration was found to be zero. In aqueous solution, the order of the electropolymerization reaction with respect to the concentration of H2SO4 was found to be negative (−0.66), which means that the aqueous electrolyte inhibits the polymerization reaction. © 2011 Wiley Periodicals, Inc. Int J Chem Kinet 43: 141–146, 2011

The electrochemical behavior of Cu–Ni alloys with different Ni contents (5–65 mass%) in acidic sulfate solutions was investigated. The effects of working conditions e.g. concentration of sulfate ions, immersion time and temperature were studied and discussed. In this respect, open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. Potentiodynamic measurements revealed that the increase in the Ni content improves the stability of the Cu–Ni alloys. The polarization measurements were confirmed by EIS experiments. The stability of the alloys with higher Ni contents is due to the increased amount of Ni in the surface film. The corrosion process of the cupronickels in the acidic sulfate solution was found to be diffusion controlled. The experimental impedance data were fitted to theoretical data according to an equivalent circuit model representing the electrode/electrolyte interface.

The efficiency of cysteine as a non-toxic corrosion inhibitor for copper metal in 0.6 M NaCl and 1.0 M HCl has been investigated by electrochemical studies. Potentiodynamic polarization measurements and electrochemical impedance spectroscopy “EIS” were used to study the effect of cysteine on the corrosion inhibition of copper. Inhibition efficiency of about 84% could be achieved in chloride solutions. The presence of Cu 2+ ions increases the inhibition efficiency to 90%. Potentiodynamic polarization measurements showed that the presence of cysteine in acidic and neutral chloride solutions affects mainly the cathodic process and decreases the corrosion current to a great extent and shifts the corrosion potential towards more negative values. The experimental impedance data were analyzed according to a proposed equivalent circuit model for the electrode/electrolyte interface. Results obtained from potentiodynamic polarization and impedance measurements are in good agreement. Adsorption of cysteine on the surface of Cu, in neutral and acidic chloride solutions, follows the Langmuir adsorption isotherm. The adsorption free energy of cysteine on Cu (∼−25 kJ mol −1 ) reveals a strong physical adsorption of the inhibitor on the metal surface.

Poly( o -tolidine), PoT, film was prepared by electrochemical oxidation of the monomer, oT, in 0.1 M HCl + 0.1 M KClO 4 . The presence of KClO 4 in the formation medium was found to be essential for the electropolymerization process to proceed. Increasing the upper potential limit up to +1.5 V, instead of +1.0 V, leads to appearance of a new anodic peak at +1.36 V and enhancement of the polymer formation of PoT without changing the film structure. The electrochemical behavior of the formed polymer films was investigated in 1.0 M HClO 4 . The kinetic parameters were calculated from the values of the charge consumed during the electropolymerization process. The rate of the polymerization reaction was found to depend on the concentration of the monomer rather than the electrolyte. The polymerization rate is first order with respect to the monomer concentration and zero order with respect to the electrolyte. The electrolyte plays no active role in the kinetics of the electropolymerization process and its role is most likely limited to polymer doping.

Uniform conducting polymer films of poly(N-(1-Naphthyl) ethylene-diamine dihydrochloride), PNED, were prepared conveniently and reproducibly by the anodic oxidation of the monomer, N-(1-Naphthyl) ethylene-diamine dihydrochloride, NED, in an acidic aqueous solution using the conventional potentiodynamic technique. The different parameters influencing the preparation conditions like monomer concentration, solvent constitution, scan range, scan rate, scan repetition, rotation speed of the working electrode and the type of the substrate were investigated and the optimum preparation conditions are specified. The stability of the prepared films was tested in both aqueous and non-aqueous media. The characteristics of the polymer films and their electrochemical activity towards catalyzing some technologically promising redox reactions were also examined. The films were found to be very stable in aqueous solutions and in some organic solvents like acetone, acetonitrile, and chloroform and dimethyl sulfoxide. The film stability was found to depend on the solution pH. The polymer films were capable of catalyzing the redox processes of several natural products and amino acids e.g. vitamin C and glycine. The polymer film possesses electrochromic properties and the color of the film changes from purple to violet to dark blue and then to brown according to the preparation and/or polarization conditions. The electrochromic properties are related to polaron formation, which subsequently oxidizes to diimine species followed by the oxidation of the aromatic ring. The mechanism of the polymerization process was investigated and discussed. The process involves deprotonation reactions and a head-to-tail coupling of the oxidized monomer with cation radicals.

The optimum conditions for the electrochemical preparation of poly(1-amino-9,10-anthraquinone), PAAQ, films in environmentally safe aqueous solutions were investigated. The conducting polymer films were prepared by electrochemical oxidation of 1-amino-9,10-anthraquinone, AAQ, in sulfuric acid solutions in the potential range from 0.0 to +1.3 V. The influence of scan repetition, scan rate, and monomer concentration on the formation process and the properties of the polymer film were studied. The electrochemical response of the formed polymer film was investigated in both aqueous and non-aqueous media. The polymer films were found to be stable in aqueous acidic media. In non-aqueous solutions, like acetonitrile, dimethyl sulfoxide and dioxin, the polymer films showed remarkable degradation. The best electrochemical response of the PAAQ films was found to be in the potential range between +0.3 and +0.9 V. The presence of quinone units in the polymer film chain suggests promising applications of these conducting polymers in lightweight (rechargeable) batteries, electrochromic display devices, and biosensor and corrosion protection.

The electrochemical behavior of Cu–Ni alloys in acidic chloride medium was investigated. Commercial Cu–Ni alloys were investigated using potentiodynamic techniques, complemented by electrochemical impedance spectroscopy. The influence of alloy composition, chloride ion concentration and immersion time on the electrochemical response of the alloys was analyzed. Results of present investigations with pure metals (Cu and Ni) are also considered in this paper for the sake of comparison. Potentiodynamic measurements reveal that the increase in nickel content decreases the corrosion rate of the alloy and when the nickel content exceeds 30%, an increase in the corrosion rate was recorded. Also, the corrosion current density increases with increasing the concentration of chloride ions up to 0.6 M. The experimental impedance data were fitted to an equivalent circuit model representing the electrode/electrolyte interface. The relevance of the proposed model to the corrosion/passivation phenomena occurring at the electrode/solution interface was discussed.

The corrosion inhibition of Cu–Ni alloys was investigated in aqueous chloride solutions using amino acids as environmentally safe materials. The corrosion rate was calculated in absence and presence of the corrosion inhibitor using polarization and impedance techniques. The inhibition efficiency of the different amino acids was also calculated. The experimental results have shown that a simple amino acid like glycine can be used as efficient corrosion inhibitor for the Cu–Ni alloys in neutral chloride solutions. An inhibition efficiency of about 85% could be achieved at very low concentrations of the amino acid (0.1 mM). For low Ni content alloy (Cu–5Ni), 2.0 mM cysteine shows a remarkable high (∼96%) corrosion inhibition efficiency. The experimental impedance data were fitted to theoretical data according to a proposed equivalent circuit model for the electrode/electrolyte interface, and the mechanism of the corrosion inhibition process was suggested. Different adsorption isotherms were tested and the corrosion inhibition process was found to depend on the adsorption of the amino acid molecules and/or the deposition of corrosion products on the alloy surface. The adsorption free energy of cysteine on Cu–5Ni (−37.81 kJ mol−1) reveals a strong physical adsorption of the inhibitor on the alloy surface.

The corrosion and passivation behaviors of alloys with different Cu–Ni ratios were investigated in acidic sulfate solutions. The corrosion rate was calculated and the corrosion inhibition process was investigated using different amino acids as corrosion inhibitors. For these investigations conventional electrochemical techniques and electrochemical impedance spectroscopy (EIS) were used. Fitting of the experimental impedance data to theoretical values enables understanding of the corrosion inhibition mechanism and the suggestion of a suitable electrical model to explain the behavior of the alloys under different conditions. The investigation of the electrochemical behavior of alloys before and after the corrosion inhibition processes has shown that some amino acids like lysine have promising corrosion inhibition efficiency at very low concentrations. A model for the electrode/electrolyte interface during the corrosion inhibition processes was suggested and the validity of the model for the explanation of the corrosion inhibition phenomena was discussed.

The effect of systematic increase of Ni content on the electrochemical behavior of the Cu–Ni alloys in neutral chloride solutions was investigated. The pitting corrosion behavior of Cu–Ni alloys with different Ni contents, namely, 5, 10, 30 and 65 mass% Ni, in a stagnant 0.6 mol dm−3 NaCl solution of pH 7.0 was studied. The effect of chloride ion concentration on the electrochemical behavior of these alloys was also investigated. The results show that the increase in nickel content decreases the corrosion rate of the alloys in the neutral chloride solution. The increase of chloride concentration up to 0.3 mol dm−3 increases the corrosion rate. At higher concentrations ([Cl−] > 0.3 mol dm−3) the corrosion rate decreases due to the hydrolysis of Cu(I) chloride to form the passive Cu(I) oxide film. The breakdown potential depends on the chloride ion concentration and the nickel content of the alloy. For these investigations conventional electrochemical techniques and electrochemical impedance spectroscopy (EIS) were used. The impedance measurements have shown that the increase of the Ni content and the immersion time of the alloys in the chloride solution increase the corrosion resistance of the alloys. The experimental impedance data were fitted to theoretical values according to a proposed equivalent circuit model.

The corrosion behavior of Cu-Zn alloys in sulfuric acid (H2SO4) solutions was investigated using open-circuit potential measurements, potentiodynamic techniques, and electrochemical impeda...

The electrochemical behaviour of brasses with various Zn content (5.5–38) and brass (Cu–38Zn) with different Pb content (1.3–3.3) in borate solution, pH 9.0, was investigated. The effects of applied potential and the presence of aggressive Cl− ions were also studied. Different electrochemical methods such as open-circuit potential measurements, polarization techniques and electrochemical impedence spectroscopy (EIS) were used. Increase in zinc content decreases the corrosion rate of brass in borate solution exponentially. Long immersion of leaded brasses and alloys with different Zn content improves their stability due to the formation of a passive film. The passive film formation under open-circuit and potentiostatic conditions proceeds via dissolution–precipitation mechanism. The addition of a low concentration of Cl− ion (0.01 M) to the borate solution increases the corrosion rate of Cu–38Zn due to dezincification. Increase in Cl− ion concentration (0.01–0.2 M) decreases the corrosion rate of the brass exponentially due to formation of insoluble CuCl. For Cl− ion concentrations >0.2 M the corrosion rate of the brass increases again due to the formation of the soluble CuCl2− complex.

The effect of Ni content on the corrosion and passivation behaviors of copper-nickel alloys with different Cu to Ni ratios was investigated in neutral sulfate solutions. The influence of working conditions (e.g., immersion time, sulfate ions concentration, and temperature) on the electrochemical behavior of the different alloys was also studied. In this respect, conventional electrochemical methods like open-circuit potential (OCP) measurements, polarization techniques, and electrochemical impedance spectroscopy (EIS) were used. It was found that the initial corrosion resistance is relatively low for alloys with high nickel content. An increase in the nickel content and long immersion time in the neutral sulfate solution increases the corrosion resistance of the alloy and improves its stability. The stability of the alloy was considered to be due to the formation of a stable passive film on its surface. The impedance data were fitted to theoretical data obtained according to an equivalent circuit...

The electrochemical behaviour of copper–nickel alloys with different Ni content (5–65%) in sulphate solutions of pH 12 was investigated. The effects of temperature, immersion time, and concentration of sulphate ions were also studied. Different electrochemical methods such as open-circuit potential measurements, polarization techniques and electrochemical impedance spectroscopy (EIS) were used. Potentiodynamic measurements reveal that the increase in nickel content increases the corrosion rate of the alloy in sulphate solution linearly. Nevertheless, an increase in the nickel content along with increase in immersion time improves the stability of the Cu–Ni alloys due to the formation of a stable passive film. An equivalent circuit model for the electrode/electrolyte interface under different conditions was proposed. The experimental impedance data were fitted to theoretical data according to the proposed model. The relevance of the model to the corrosion/passivation phenomena occurring at the electrode/solution interface was discussed.

Amorphous manganese-rich (67/80 at.%) Mn/Ta/Cr alloy films were prepared by DC magnetron sputtering method. The corrosion behavior and stability of the Mn/Ta/Cr alloy films were examined in chloride-free and -containing 1 M H2SO4. AC and DC electrochemical techniques in combination with XPS analysis were used. Mn/Ta/Cr alloys exhibited very high corrosion resistance and stability up to transpassive dissolution region of chromium. The high corrosion resistance of Mn/Ta/Cr sputtered films is based on the formation of double oxyhydroxide passive film composed mainly of chromium and tantalum. The partial substitution of tantalum with chromium improves the corrosion resistance of the sputter-deposited alloys via accelerating the preferential dissolution of manganese and stabilizing alloy/passive film interface. A change in the passive film structure was observed when the alloys were anodically polarized at potentials higher than 0.6 V (SCE). # 2002 Elsevier Science Ltd. All rights reserved.

Poly(1-amino-9,10-anthraquinone), PAAQ, films were prepared by electrochemical oxidation of the monomer, AAQ, in acetonitrile using LiClO 4 as supporting electrolyte. The influence of scan repetition, scan rate and monomer concentration on the formation of polymer film was studied. The electrochemical behavior of the formed polymer films was investigated in both non-aqueous and aqueous media. The prepared films were found to be more stable in organic solvents than in aqueous solutions. The investigated organic solvents are methanol, ethanol, acetone, carbon tetrachloride, benzene, and chloroform. The polymer film shows electrochemical response in both non-aqueous and aqueous media. In non-aqueous solutions it has a wide potential range of electroactivity (from −1.5 to +1.3 V). In aqueous media the polymer film shows electrochemical response in the potential range between −0.3 and +1.3 V only. The presence of quinone units suggests potential applications in diverse areas such as electrocatalytic processes and lithium ion batteries.

The electrochemical behaviour of brasses with various Zn content (5.5–38) and brass (Cu–38Zn) with different Pb content (1.3–3.3) in borate solution, pH 9.0, was investigated. The effects of applied potential and the presence of aggressive Cl− ions were also studied. Different electrochemical methods such as open-circuit potential measurements, polarization techniques and electrochemical impedence spectroscopy (EIS) were used. Increase in zinc content decreases the corrosion rate of brass in borate solution exponentially. Long immersion of leaded brasses and alloys with different Zn content improves their stability due to the formation of a passive film. The passive film formation under open-circuit and potentiostatic conditions proceeds via dissolution–precipitation mechanism. The addition of a low concentration of Cl− ion (0.01 M) to the borate solution increases the corrosion rate of Cu–38Zn due to dezincification. Increase in Cl− ion concentration (0.01–0.2 M) decreases the corrosion rate of the brass exponentially due to formation of insoluble CuCl. For Cl− ion concentrations >0.2 M the corrosion rate of the brass increases again due to the formation of the soluble CuCl2 − complex.

A 43-year-old man was admitted to the emergency department after a cardiac arrest of unknown etiology. The patient's medical history was unremarkable except for surgery to remove a mediastinal lipoma two years earlier. In the intensive care unit, he was observed to have a mass bulging from the left chest wall. Echocardiography showed cardiac herniation through the chest wall, which was confirmed by thoracic computed tomographic scan.

Despite intensive investigations, the nature of the passive state is one of the most complex and unresolved subjects in the electrochemistry of zinc in alkaline solutions. In this paper, we explore the electrochemistry of the passive state on zinc in 0.1 M sodium borate/1 M sodium hydroxide solution of pH 10.5. During the course of passivation, several characteristic features in the anodic region are observed, including a wide passive range extending over >2 V and a secondary passivation phenomenon that occurs at high anodic potentials. The steady-state current in the passive state is found to be independent of the applied voltage, which is consistent with the barrier layer being an interstitial zinc conductor or an oxygen vacancy conductor (or both) with interstitial zinc being the most likely defect. This model is also consistent with the well-known n-type character of the passive film on zinc.

A 75-year-old patient was admitted to the operating room for an emergency laparotomy for leaking abdominal aortic aneurysm. A pulmonary artery catheter (PAC) was inserted through the right internal jugular vein but it was impossible to advance the catheter lip into the pulmonary artery. We tried to withdraw the catheter but this was also impossible. A postoperative chest radiograph revealed a catheter knot in the right atrium. We succeeded in removing the PAC through a 14-French sheath introducer placed in the femoral vein via fluoroscopy.

The open-circuit potential of the AZ31 alloy in 0.5 M KOH solution (pH 13.5) shifts toward less negative values, showing several falls with steady-state value in the range from -0.6 to -0.55 V (saturated calomel electrode), 1.2 V more positive than the initial potential. The formed film exhibits a superior corrosion resistance. X-ray photoelectron spectroscopy reveals that the film consists of MgO and Mg(OH) 2 with Al enrichment. Scanning electron microscopy shows the formation of a plateletlike layer which probably grows by a dissolution/precipitation mechanism. The dissolution process most likely starts by rupture of the outer layer of the film as a result of the low Pilling-Bedworth ratio of MgO/Mg compared with that of Mg(OH) 2 /Mg.

Amorphous alloys were prepared in a wide composition range by the addition of tantalum to manganese by the sputter deposition method. The effect of alloying tantalum on the corrosion behavior and the stability of sputter-deposited amorphous Mn-Ta alloys was studied. Different techniques such as weight-loss measurements, electrochemical techniques, and X-ray photoelectron spectroscopy (XPS) analysis were used. The addition of Ta remarkably reduces the rate of dissolution of the alloy and Ta passivates spontaneously. No signs of pitting corrosion or transpassive dissolution of Mn were observed. The anodic current density decreases significantly with increasing the tantalum content. XPS studies show a preferential oxidation of Ta in the air-formed (native) oxide. The preferential oxidation was remarkable after immersion in 1 M H 2 SO 4 solution for 30 min. The thickness of the passive film formed on the sputter-deposited Mn-30Ta alloy increases linearly with the applied potential as that observed in valve metals. The formed passive film consists mainly of Ta 2 O 5 . At potentials higher than +0.7 V (standard calomel electrode) high oxidation states of Mn were found to he incorporated in the passive film.