Influence of Ca ions and temperature on the corrosion behavior of WC–Co hardmetals in alkaline solutions

The effect of temperature and Ca ions on the corrosion behavior of hardmetals was investigated in 0.1 M NaOH and 0.05 M Ca(OH)₂ alkaline electrolytes using impedance spectroscopy, potentiodynamic polarization and surface analytical techniques. It was found that calcium containing alkaline solutions efficiently decrease the anodic currents up to 5 times by forming a calcium containing deposit on the top of the WC–Co hardmetal surface, which remains stable even at higher temperatures (40 °C and 60 °C). This positive influence of Ca ions is predominant under polarization in the range from 0 to +0.85 V (Ag/AgCl) but is not apparent under OCP conditions. In NaOH, however, the corrosion resistance strongly decreases at higher temperatures as compared with the room temperature. At the slightly elevated temperature in 0.1 M NaOH the Co binder phase loses its passivity and is almost completely washed out of the compound material. A WC skeleton remains on the surface and hence the ductility in the hardmetal is lost. In the end, the material could completely fail under such operating conditions. Also the Ni alloyed binder loses its strong passivation ability at the elevated temperatures.     

Effect of fuel injection pressure on a heavy-duty diesel engine nonvolatile particle emission

The effects of the fuel injection pressure on a heavy-duty diesel engine exhaust particle emissions were studied. Nonvolatile particle size distributions and gaseous emissions were measured at steady-state engine conditions while the fuel injection pressure was changed. An increase in the injection pressure resulted in an increase in the nonvolatile nucleation mode (core) emission at medium and at high loads. At low loads, the core was not detected. Simultaneously, a decrease in soot mode number concentration and size and an increase in the soot mode distribution width were detected at all loads. Interestingly, the emission of the core was independent of the soot mode concentration at load conditions below 50%. Depending on engine load conditions, growth of the geometric mean diameter of the core mode was also detected with increasing injection pressure. The core mode emission and also the size of the mode increased with increasing NOx emission while the soot mode size and emission decreased simultaneously.     

Phase State and Deliquescence Hysteresis of Ammonium-Sulfate-Seeded Secondary Organic Aerosol

The phase state of secondary organic aerosol (SOA) has an impact on its lifetime, composition, and its interaction with water. To better understand the effect of phase state of SOA on climate interactions, we studied the SOA phase state and the effect of its history and report here the phase state and the humidity-induced phase hysteresis of multicomponent-seeded SOA particles produced in a large, continuously stirred tank reactor. We determined the phase state of the particles by their bounced fraction impacting on a smooth substrate in a low-pressure impactor. The particles were composed of ammonium sulfate ([NH₄]₂SO₄) seed and a secondary organic matter (SOM) shell formed from oxidized α-pinene or isoprene. The ammonium sulfate (AS) seed dominated the deliquescence of the α-pinene SOM multicomponent particles, whereas their efflorescence was strongly attenuated by the SOM coating. Particles coated with isoprene SOM showed continuous phase transitions with a lesser effect by the AS seed. The results agree with and independently corroborate contemporary research.

Copyright 2015 American Association for Aerosol Research     

Influence of the Co/Ni Ratio and Dendritic Segregations on the High-Temperature Oxidation Resistance of Multinary Co-Rich Superalloys at 850 °C and 1050 °C

Metallurgical and Materials Transactions A - Excellent inherent oxidation resistance is a prerequisite for the use of superalloys in many high-temperature applications. To achieve this goal,...     

Influence of W Content on the Oxidation Behaviour of Ternary $$\gamma ^{\prime }$$ γ ′ -Strengthened Co-Based Model Alloys Between 800 and $$900\,^{\circ }{\hbox {C}}$$ 900 ∘ C

Oxidation of Metals - The oxidation behaviour of ternary Co–Al–W alloys with W contents between 7 and 10 at. $$\%$$ was investigated in detail. Continuous thermogravimetry was...     

Affinity purification of the major bovine allergen by a novel monoclonal antibody

A monoclonal antibody was developed to the 20 kd major allergen of cow by immunizing mice with crude dander extract. The monoclonal antibody did not exhibit cross-reactivity to cat, dog, and horse dander extracts when studied by ELISA inhibition. The antibody was used in affinity chromatography for the purification of the 20 kd allergen from cow dander extract. Purity of the allergen was estimated to be 88%, and allergenic reactivity was verified by IgE immunoblotting and skin prick tests. After further purification with size-exclusion chromatography, the allergen was almost 100% pure. The isoelectric point of the double-purified allergen was determined to be 4.1. The amino acid composition was characterized by the predominance of acidic amino acids.     

Neonatal Candida parapsilosis outbreak with a high case fatality rate

A Candida parapsilosis outbreak of 58 cases in a neonatal intensive care unit lasted for 55 months. Patients infected by or colonized with C. parapsilosis were mainly very low birth weight infants (birth weight < 1500 g). Their mean birth weight was 817 g and their mean gestational age was 28 weeks. Statistical analysis including logistic regression confirmed that prematurity was the main risk factor. The analysis also suggested that C. parapsilosis infection (or colonization) was associated with a poor prognosis. In infants with gestational age < 29 weeks the risk for death in C. parapsilosis-infected patients was 16-fold greater than in those with no C. parapsilosis infection. The case fatality rate of C. parapsilosis patients was higher than that of the controls (9 of 23 vs. 1 of 40; P < 0.0001). The outbreak was most likely a result of cross-infection because C. parapsilosis could be isolated only from the patients and from the hands of four nurses immediately after they had cared for a colonized patient. Cessation of the outbreak was temporally associated with long term parenteral fluconazole (6 mg/kg/day) prophylaxis.     

Context-Sensitive Visibility

An improvement to the so-called visual verification approach is presented. Visual verification is a method for checking the correctness of the behaviour of a reactive or concurrent system. It shares a great deal of common ground with ordinary formal state space verification, but is more user-friendly. This is because the user does not need to specify in detail the properties that the system must satisfy to be correct. Instead, the user only lists the atomic actions that are relevant for the property. Computer tools are used to obtain a graphical representation which is a summary of all possible alternative behaviours of the system, and the user then analyses the result. The improvement presented in this article allows the user to pick a region of the graphical representation and investigate it in more detail, without being overwhelmed by the details outside the region. The improvement is illustrated by analysing the livelocks in a model of the alternating bit protocol.