State of the Surface of Antibacterial Copper in Phosphate Buffered Saline

The state was investigated of the copper surface in phosphate buffered saline (PBS; 140 mM Cl-, 10 mM phosphate; pH 7) by a combination of cyclic voltammetry (CV) and chronoamperometry (CA) with in situ spectroscopic ellipsometry and Raman spectroscopy. After polarization, samples were analyzed ex situ. In agreement with expectations on the basis of the Pourbaix diagram, Cu2O and Cu4O3 were observed when polarizing the system above approximate to-0.05 V vs. Ag vertical bar AgCl vertical bar 3M KCl. The formation of Cu2O did not lead to a passivation of the system. Rather, the system dissolved under formation of soluble square planar CuCl42-, identified by its strong Raman peak approximate to 300 cm(-1). During dissolution, spectroscopic ellipsometry showed a film with a stable steady state thickness. Energy electron loss spectroscopy (EELS) analysis of a cross section of the oxide after removal from the electrolyte showed that the oxide was Cu2O. It is suggested that Cl-replaces oxygen vacancies in the oxide layer. As soon as oxidation to Cu-II becomes dominant, the dissolution proceeds to soluble CuII species. The outer surface of copper under these conditions is hence a Cu2O-like surface, with CuII complexes present in solution. (C) The Author(s) 2017. Published by ECS. All rights reserved

State of the Surface of Antibacterial Copper in Phosphate Buffered Saline

The state was investigated of the copper surface in phosphate buffered saline (PBS; 140 mM Cl-, 10 mM phosphate; pH 7) by a combination of cyclic voltammetry (CV) and chronoamperometry (CA) with in situ spectroscopic ellipsometry and Raman spectroscopy. After polarization, samples were analyzed ex situ. In agreement with expectations on the basis of the Pourbaix diagram, Cu2O and Cu4O3 were observed when polarizing the system above approximate to-0.05 V vs. Ag vertical bar AgCl vertical bar 3M KCl. The formation of Cu2O did not lead to a passivation of the system. Rather, the system dissolved under formation of soluble square planar CuCl42-, identified by its strong Raman peak approximate to 300 cm(-1). During dissolution, spectroscopic ellipsometry showed a film with a stable steady state thickness. Energy electron loss spectroscopy (EELS) analysis of a cross section of the oxide after removal from the electrolyte showed that the oxide was Cu2O. It is suggested that Cl-replaces oxygen vacancies in the oxide layer. As soon as oxidation to Cu-II becomes dominant, the dissolution proceeds to soluble CuII species. The outer surface of copper under these conditions is hence a Cu2O-like surface, with CuII complexes present in solution. (C) The Author(s) 2017. Published by ECS. All rights reserved

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Background: Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. // Methods: We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung's disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. // Findings: We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung's disease) from 264 hospitals (89 in high-income countries, 166 in middle-income countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in low-income countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. // Interpretation: Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between low-income, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Cyclodextrin for zinc corrosion protection

Die Arbeit beschäftigt sich mit der Anwendung von Cyclodextrin (CD) für den Korrosionsschutz von Zink. CDe sind cyclische Oligosaccharide, welche durch ihre Struktur die Bildung von Wirt-Gast-Komplexen ermöglichen. Es wurden CD-Komplexe mit organischen Korrosionsinhibitoren hergestellt und charakterisiert. Diese wurden in eine organische Modellbeschichtung eingemischt, und das Verhalten der Beschichtung in Kontakt mit einem Defekt mittels der Raster-Kelvin-Sonde untersucht. Dabei wurde gezeigt, dass durch CD die Verfügbarkeit der Inhibitoren aus der Beschichtung an der Metalloberfläche verbessert wird, was zu einer Reduzierung der Delminationsrate und zur Passivierung des Defektes führt. Darüber hinaus hat sich gezeigt, dass CD auch als Korrosionsinhibitor wirken kann. CD adsorbiert hierbei auf den Korrosionsprodukten und ändert deren elektronischen Eigenschaften. Die Inhibierung ist stark von der Zusammensetzung des Elektrolyten abhängig

Metallische Verbunde durch Fließpressen

Fließpressen eignet sich, mechanische und metallurgische Verbindungen von Stahl und Aluminium zu erzeugen. Die genaue Ausprägung des Verbundes auf submikroskopischer Ebene ist bisher jedoch nicht verstanden. Ferner sind die mechanischen Kontaktbedingungen, welche für die Erzeugung dieser Verbindung notwendig sind, unbekannt. Im Rahmen des vorliegenden Beitrages werden die Mechanismen, welche zu einer Verschweißung von Aluminium und Stahl führen, aufgezeigt. Sowohl bei kalt als auch halbwarm umgeformten Proben werden keine großflächig ausgeprägten intermetallische Phasen ausgebildet. Dennoch bilden sich auch im kalt geformten Zustand erste Ansätze von Reaktionsschichten, so dass die Diffusion zur Erzeugung einer kaltpressgeschweißten Verbindung signifikant beiträgt

Metallische Verbunde durch Fließpressen

Fließpressen eignet sich, mechanische und metallurgische Verbindungen von Stahl und Aluminium zu erzeugen. Die genaue Ausprägung des Verbundes auf submikroskopischer Ebene ist bisher jedoch nicht verstanden. Ferner sind die mechanischen Kontaktbedingungen, welche für die Erzeugung dieser Verbindung notwendig sind, unbekannt. Im Rahmen des vorliegenden Beitrages werden die Mechanismen, welche zu einer Verschweißung von Aluminium und Stahl führen, aufgezeigt. Sowohl bei kalt als auch halbwarm umgeformten Proben werden keine großflächig ausgeprägten intermetallische Phasen ausgebildet. Dennoch bilden sich auch im kalt geformten Zustand erste Ansätze von Reaktionsschichten, so dass die Diffusion zur Erzeugung einer kaltpressgeschweißten Verbindung signifikant beiträgt

Comparison of cathodic delamination of poly(n-alkyl methacrylates) on iron

Cathodic delamination is measured on iron surfaces covered with different poly(n-alky methacrylates), where the alkyl is an n-CnH2n + 1 (n = 1, 4, 18) group. The polymers are prepared by free radical polymerization in solution and spin coated individually on iron. The materials were characterized by infrared (IR) spectroscopy, ellipsometry, and contact angle measurements. Barrier properties in potassium chloride were obtained by electrochemical impedance spectroscopy (EIS). Artificial defects in the polymer model coatings were exposed to 1 M potassium chloride as corrosive medium, and cathodic delamination was measured by a scanning Kelvin probe. The surface wettability decreases as the size of the pending alkyl group in the backbone increases. The same chemical feature shows also an effect on the cathodic delamination and on the electrochemical impedance results. Delamination is roughly twice as fast when n = 1, compared to n = 4 and n = 18. The difference in delamination rate between the latter two polymers is small

Effect of the primary heat treatment on the bond formation in coldwelding of aluminum and steel by cold forging

Cold forging enables the manufacturing of high strength monolithic components. When used as joiningtechnology it can also be extended to an enabler of multi-material product design. The contact conditionsat the interface between the components during the cold forging process play a crucial role. The joining oftwo billets of steel and aluminum is investigated by a finite element analysis with regard to the materialdistribution and the effect of a primary heat treatment of both materials. These parameters affect thesurface enlargement and the contact normal stress which are decisive parameters for the formation of asound bond between aluminum and the hardly cold weldable steel. The experimental results present theeffect of a primary heat treatment on the bond formation. Microscopic analyses of the bond formationallow a deeper insight into the bonding mechanism. Thus, the results lead to process design guidelinesfor cold welding by cold forging

Mechanisms of inhibitor action - passivation and self-healing

In this chapter, we will briefly review the systematics of corrosion inhibitors and the classical mechanisms of action of corrosion inhibitors, the latter with an emphasis on inhibitors interacting with the material surface. The different roles corrosion inhibitors have in protecting materials surfaces will be described – with examples from applications in the oil and gas sector, but also more general. We will discuss in some detail the interaction of an imidazoline‐based surfactant inhibitor with mild steel and the interaction of 2‐mercaptobenzothiazole (MBT) with copper and zinc. By adsorbing to surfaces, molecules in general block sites for metal dissolution. Good inhibitors furthermore react with dissolution products to form insoluble films, in analogy to the formation of conversion coatings. Furthermore, inhibitors may interfere with the kinetics of the cathodic reaction. Over decades, a challenge for the use of inhibitors has been leaching into the environment of inhibiting molecules. Modern triggered release concepts ensure that inhibitors become available only if a corrosion attack has begun. Such triggered release systems have successfully been used for the self‐healing of coatings, and we will discuss one example of the interaction of a cyclodextrin with MBT to see how this works for inhibitors. Future applications in the oil and gas sector may consider the use of intelligent coatings

Delamination kinetics of thin film poly(acrylate) model coatings prepared by surface initiated atom transfer radical polymerization on iron

Living radical polymerization is often considered as an unsuitable method of surface modification for reactive metals such as iron. Necessary noble metal catalyst systems may react with the surface to be modified, causing deactivation of the catalyst. Here, surface-initiated atom transfer radical polymerization (SI-ATRP) using the typical CuI-based catalyst was used to synthesize well-defined poly(methyl methacrylate) thin films grafted on iron. Alkoxy- and chloro-silane initiators were anchored to the metal surface via Si-O-Fe bonds in a metal pretreatment step, yielding a thin cross-linked multilayer sol/gel coating. Except for the precursor’s leaving group, the resulting 10s of nm thick polymer layers were almost identical. Assessment of the delamination kinetics of the model coatings by scanning Kelvin probe (SKP) showed the average delamination to be ≈ 40 % lower in the systems with alkoxy-precursor compared to those with chloro-precursor. In addition, the spread of the measured delamination rates decreased to 1/3 in the alkoxy system, despite identical polymers. The higher delamination rate in the case of chloro-precursors was attributed to residual chloride at the interface. Initiator surface coverage differences may also contribute to stability differences. The ATRP-CuI-catalyst is consequently also suitable for surface modification of non-noble metals after appropriate pretreatment.publishedVersion© The Author(s) 2018. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited