Effects of serum proteins on corrosion behavior of ISO 5832–9 alloy modified by titania coatings

Stainless steel ISO 5832–9 type is often used to perform implants which operate in protein-containing physiological environments. The interaction between proteins and surface of the implant may affect its corrosive properties. The aim of this work was to study the effect of selected serum proteins (albumin and γ-globulins) on the corrosion of ISO 5832–9 alloy (trade name M30NW) which surface was modified by titania coatings. These coatings were obtained by sol– gel method and heated at temperatures of 400 and 800 °C. To evaluate the effect of the proteins, the corrosion tests were performed with and without the addition of proteins with concentration of 1 g L−1 to the physiological saline solution (0.9 % NaCl, pH 7.4) at 37 °C. The tests were carried out within 7 days. The following electrochemical methods were used: open circuit potential, linear polarization resistance, and electrochemical impedance spectroscopy. In addition, surface analysis by optical microscopy and X-ray photoelectron spectroscopy (XPS) method was done at the end of weekly corrosion tests. The results of corrosion tests showed that M30NW alloy both uncoated and modified with titania coatings exhibits a very good corrosion resistance during weekly exposition to corrosion medium. The best corrosion resistance in 0.9 % NaCl solution is shown by alloy samples modified by titania coating annealed at 400 °C. The serumproteins have no significant effect onto corrosion of investigated biomedical steel. The XPS results confirmed the presence of proteins on the alloy surface after 7 days of immersion in proteincontaining solutions.The investigations were supported by the National Science Centre project No. N N507 501339. The authors gratefully acknowledge Dr. Janusz Sobczak and Dr. hab. Wojciech Lisowski from Institute of Physical Chemistry of PAS for XPS surface analyses

Electrochemical methods for speciation of trace elements in marine waters. Dynamic aspects

The contribution of electrochemical methods to the knowledge of dynamic speciation of toxic trace elements in marine waters is critically reviewed. Due to the importance of dynamic considerations in the interpretation of the electrochemical signal, the principles and recent developments of kinetic features in the interconversion of metal complex species will be presented. As dynamic electrochemical methods, only stripping techniques (anodic stripping voltammetry and stripping chronopotentiometry) will be used because they are the most important for the determination of trace elements. Competitive ligand ex- change-adsorptive cathodic stripping voltammetry, which should be considered an equilibrium technique rather than a dynamic method, will be also discussed because the complexing parameters may be affected by some kinetic limitations if equilibrium before analysis is not attained and/or the flux of the adsorbed complex is in fluenced by the lability of the natural complexes in the water sample. For a correct data interpretation and system characterization the comparison of results obtained from different techniques seems essential in the articulation of a serious discussion of their meaning

Seeing versus Doing: How Businesses Manage Tensions in Pursuit of Sustainability

Management of organizational tensions can facilitate the simultaneous advancement of economic, social, and environmental priorities. The approach is based on managers identifying and managing tensions between the three priorities, by employing one of the three strategic responses. Although recent work has provided a theoretical basis for such tension acknowledgment and management, there is a dearth of empirical studies. We interviewed 32 corporate sustainability managers across 25 forestry and wood-products organizations in Australia. Study participants were divided into two groups: (1) those considered effective at corporate sustainability and (2) a status-quo group. Contrary to current theory, our findings showed that acknowledgment of organizational tensions was widespread in the Australian forestry and wood-products industry and not limited to those managers who are effective at managing corporate sustainability. What differed was the degree to which managers did something about the perceived tensions—with the effective group more consistently acting to manage and resolve paradoxical scenarios. Our findings suggest that existing theoretical constructs of tension management may not adequately capture the individual-level complexity involved with managing tensions in practice

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (VT) size was 500 ml, or 7 to 9 ml kg1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P < 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P < 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high VT and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome

Epidemiology, practice of ventilation and outcome for patients at increased risk of postoperative pulmonary complications: LAS VEGAS - An observational study in 29 countries

BACKGROUND Limited information exists about the epidemiology and outcome of surgical patients at increased risk of postoperative pulmonary complications (PPCs), and how intraoperative ventilation was managed in these patients. OBJECTIVES To determine the incidence of surgical patients at increased risk of PPCs, and to compare the intraoperative ventilation management and postoperative outcomes with patients at low risk of PPCs. DESIGN This was a prospective international 1-week observational study using the ‘Assess Respiratory Risk in Surgical Patients in Catalonia risk score’ (ARISCAT score) for PPC for risk stratification. PATIENTS AND SETTING Adult patients requiring intraoperative ventilation during general anaesthesia for surgery in 146 hospitals across 29 countries. MAIN OUTCOME MEASURES The primary outcome was the incidence of patients at increased risk of PPCs based on the ARISCAT score. Secondary outcomes included intraoperative ventilatory management and clinical outcomes. RESULTS A total of 9864 patients fulfilled the inclusion criteria. The incidence of patients at increased risk was 28.4%. The most frequently chosen tidal volume (V T) size was 500 ml, or 7 to 9 ml kg−1 predicted body weight, slightly lower in patients at increased risk of PPCs. Levels of positive end-expiratory pressure (PEEP) were slightly higher in patients at increased risk of PPCs, with 14.3% receiving more than 5 cmH2O PEEP compared with 7.6% in patients at low risk of PPCs (P ˂ 0.001). Patients with a predicted preoperative increased risk of PPCs developed PPCs more frequently: 19 versus 7%, relative risk (RR) 3.16 (95% confidence interval 2.76 to 3.61), P ˂ 0.001) and had longer hospital stays. The only ventilatory factor associated with the occurrence of PPCs was the peak pressure. CONCLUSION The incidence of patients with a predicted increased risk of PPCs is high. A large proportion of patients receive high V T and low PEEP levels. PPCs occur frequently in patients at increased risk, with worse clinical outcome.</p

Rôle de la Matière Organique Naturelle Dissoute sur la spéciation des métaux en milieu peu eutrophisé

Dans les écosystèmes aquatiques, la matière organique dissoute (MOD) joue un rôle majeur sur le comportement des éléments traces (inorganiques et organiques) et leur biodisponibilité vis-à-vis des micro-organismes, de part ses propriétés de complexation. Bien que la MOD marine représente le principal réservoir organique dans les océans, la caractérisation de ses propriétés reste difficile de part les faibles teneurs en MOD (INF à ppm) associées à des contaminants à l'état de traces (quelques nM). Cette étude présente un protocole expérimental adapté à des concentrations ultratraces de MOD et de métaux, telles que celles rencontrées dans les eaux oligotrophes de l'estuaire de la Krka (Croatie) et de la Mer Ligure (nord-ouest de la méditerranée). Les échantillons obtenus ont été caractérisés par leur teneur en carbone organique dissous (COD), les propriétés de fluorescence de la MOD, ainsi que sa réactivité vis-à-vis du Cu étudiée par voltamétrie. Dans l'estuaire de la Krka, caractérisé par une stratification verticale très marquée, les concentrations en COD et en Cu totales et la fluorescence 3D de la MOD ne sont pas conservatives, impliquant des processus de désorption des métaux ainsi qu'une activité biologique plus importante à l'interface eau douce/eau de mer. Les propriétés de complexation de la MOD ont été déterminées par deux approches complémentaires: "à l'équilibre" et "cinétique". Les paramètres de complexation obtenus montrent que la MOD d'origine marine s'associe plus fortement avec le cuivre que la MOD terrigène. Bien que la concentration en ligands complexant soit plus importante dans la couche de mélange, elle ne suffit pas à tamponner complètement l'augmentation de la teneur en Cu totale. En conséquence, les concentrations de Cu libre dans cette zone dépassent le seuil de toxicité (10 pM) défini par Sunda et al. (1987, Marine Biology) pour les micro-organismes estuariens. De plus, la cinétique d'association/dissociation est considérablement ralentie, indiquant que la spéciation des métaux dans de tels milieux, soumis à des variations hydrodynamiques fréquentes, n'est probablement pas à l'équilibre. En utilisant les paramètres de complexation déterminés, il a été montré qu'une augmentation de la teneur en Cu totale de la couche de surface jusqu'à atteindre 12 nM (valeur observée en été à cause des activités nautiques) conduit à des teneurs en Cu libres dépassant systématiquement le seuil de toxicité. En mer Ligure, des profils verticaux ont été réalisés chaque mois durant l'année 2008, à 12 profondeurs jusqu'à 2200 m (site DYFAMED, nord-ouest de la méditerranée). Les profils de COD présentent un maximum en surface (1 ppm) puis décroissent jusqu'à 0.5 ppm en dessous de 200 m. La spectroscopie de fluorescence, associée à un traitement statistique (PARAFAC) des matrices d'excitation/émission de fluorescence, a permis de déterminer la distribution des composantes protéiniques et humiques de la MOD. Sur deux profils verticaux (été/automne), les propriétés de complexation de la MOD vis-à-vis du Cu ont été modélisés à l'aide de paramètres utilisables dans les codes de spéciation (ex. MINEQL, CHESS). Ces paramètres permettent de calculer la distribution verticale du Cu libre (6.5-1.0 pM) en comparaison au Cu total (2.2-1.4 nM)