Dropwise condensation of steam on ion implanted titanium surfaces

Stable dropwise condensation of steam was achieved by ion beam implantation of N⁺ on titanium surfaces stabilized by a preoxidation procedure. It is pointed out that dropwise condensation can be adjusted by ion implantation in spite of increased wettability indicated by contact angle and surface free energy measurements. Our results suggest a nucleation mechanism possibly caused by interactions of nano-scale surface roughness and surface chemistry effects connected with precipitation of nitrides. Measured heat transfer coefficients for dropwise condensation were up to 5.5 times larger than values calculated by Nußelt film theory. No significant influence of the applied ion implantation parameters was found.     

Numerical and Experimental Investigations of Steel Mixing Time in a 130‐t Ladle

This paper presents the experimental determination of variations in the chemical composition of a steel bath after introducing an alloy addition, and a numerical simulation corresponding to the conditions in an industrial ladle furnace. The numerical model and experimental studies aimed to determine the mixing time necessary for achieving the assumed degree of chemical homogenisation under the conditions of operation of the ladle furnace. In addition, through the numerical studies, the metal bath mixing time for a variable position of the porous plug is investigated.     

Product service systems,after-sales service and new product development

After-sales service is a critical element in the successful marketing of many products. Capital goods, for example, manufacturing equipment, require after-sales service such as maintenance and repair in order for customers to get the full value from them. Some manufacturers have started to offer customers an integrated product and service, termed a product-service system in the academic literature. However, in order to deliver such integrated offerings, a different approach to new product development (NPD) is required. This is because the product design influences after-sales service requirements, and so this needs to be considered during NPD. However, researchers have largely ignored the relationship between NPD and service. To address this gap, six in-depth case studies were conducted at leading companies that offer a combined product-service offering, to identify how service requirements are typically evaluated at the design stage. The results show that at companies where after-sales is an important element of the business, service requirements are systematically evaluated during NPD through the involvement of after-sales personnel and the use of field service data to set design goals.     

Measurement of Binary Diffusion Coefficients for Neon–Argon Gas Mixtures Using a Loschmidt Cell Combined with Holographic Interferometry

The paper reports on experimental binary diffusion coefficient data of neon–argon gas mixtures. Measurements were performed in the temperature range between 293.15 K and 333.15 K and for pressures between 1 bar and 10 bar over almost the whole composition range using a Loschmidt diffusion cell combined with holographic interferometry. The thermostated Loschmidt cell is divided into two half-cells, which can be separated and connected by a sliding plate. Prior to the measurements, two different pure gases are filled into the two half-cells. After starting the diffusion process, the temporal change of the partial molar densities, or rather of the refractive index of the gases, is detected in both half-cells using two holographic interferometers. With this apparatus, the temperature, pressure, and concentration dependence of the binary diffusion coefficient can be determined. The relative uncertainty of a diffusion measurement is between 0.4 % and 1.4 % depending on the pressure. The experimental data are compared with data from the literature and with new theoretical data based on quantum-mechanical ab initio calculations combined with the kinetic theory of gases. Due to a systematic error, the concentration dependence determined in the upper half-cell shows deviations from the theoretical values and from most of the literature data. The concentration, temperature, and pressure dependence obtained from the data from the lower half-cell, however, are in very good agreement with available data. The product of the binary gas diffusion coefficient and the molar density of the gas mixture shows no significant dependence on pressure for the studied neon–argon noble gas system.     

The waterborne polyurethane dispersions based on polycarbonate diol: Effect of ionic content

Three water-based polyurethane dispersions (PUD) were synthesized by modified dispersing procedure using polycarbonate diol (PCD), isophorone diisocyanate (IPDI), dimethylolpropionic acid (DMPA), triethylamine (TEA) and ethylenediamine (EDA). The ionic group content in the polyurethane-ionomer structure was varied by changing the amount of the internal emulsifier, DMPA (4.5, 7.5 and 10 wt.% to the prepolymer weight). The expected structures of obtained materials were confirmed by FTIR spectroscopy. The effect of the DMPA content on the thermal properties of polyurethane films was measured by TGA, DTA, DSC and DMTA methods. Increased DMPA amounts result in the higher hard segment contents and in the increase of the weight loss corresponding to the degradation of the hard segments. The reduction of hard segment content led to the elevated temperature of decomposition and to the decrease of the glass transition temperature and thermoplasticity. The atomic force microscopy (AFM), results indicated that phase separation between hard and soft segment of PUD with higher DMPA content is more significant than of PUD with lower DMPA content. The physico-mechanical properties, such as hardness, adhesion test and gloss of the dried films were also determined considering the effect of DMPA content on coating properties.     

Stochastic transitions in a bistable reaction system on the membrane

Transitions between steady states of a multi-stable stochastic system in the perfectly mixed chemical reactor are possible only because of stochastic switching. In realistic cellular conditions, where diffusion is limited, transitions between steady states can also follow from the propagation of travelling waves. Here, we study the interplay between the two modes of transition for a prototype bistable system of kinase–phosphatase interactions on the plasma membrane. Within microscopic kinetic Monte Carlo simulations on the hexagonal lattice, we observed that for finite diffusion the behaviour of the spatially extended system differs qualitatively from the behaviour of the same system in the well-mixed regime. Even when a small isolated subcompartment remains mostly inactive, the chemical travelling wave may propagate, leading to the activation of a larger compartment. The activating wave can be induced after a small subdomain is activated as a result of a stochastic fluctuation. Such a spontaneous onset of activity is radically more probable in subdomains characterized by slower diffusion. Our results show that a local immobilization of substrates can lead to the global activation of membrane proteins by the mechanism that involves stochastic fluctuations followed by the propagation of a semi-deterministic travelling wave.     

Geophysical Diagnosis of Diversion Channel Infiltration in a Uranium Waste Rock Pile

The Osamu Utsumi mine was the first to economically mine uranium ore in Brazil. During its operation, a river valley was buried for the construction of the waste rock pile. The original stream was diverted to the northwest side of the pile and has since flowed into a diversion channel devoid of basal waterproofing, while an acid mine drainage (AMD) source flows at the base of this waste rock pile. This research aims to evaluate the possible relationship between water infiltration of the diversion channel and the AMD resurgence at the base of the pile using electrical resistivity tomography and induced polarization. 2D inversion models and pseudo-3D maps allowed the recognition of low resistivity zones (<?100 Ω·m) with high chargeability areas (10 mV/V). Some of these low-resistivity areas have been interpreted as infiltration zones in segments of the diversion channel into the pile, and in one of them, the flow intercepts a high chargeability area interpreted as a sulfide-rich zone that is expected to contribute to AMD at the base of the pile. Understanding the hydrogeochemical process will help select effective actions to mitigate the generation of AMD at the mine, which is currently in the decommissioning phase.

     

Metallacarborane Derivatives Effective against Pseudomonas aeruginosa and Yersinia enterocolitica

Pseudomonas aeruginosa is an opportunistic human pathogen that has become a nosocomial health problem worldwide. The pathogen has multiple drug removal and virulence secretion systems, is resistant to many antibiotics, and there is no commercial vaccine against it. Yersinia pestis is a zoonotic pathogen that is on the Select Agents list. The bacterium is the deadliest pathogen known to humans and antibiotic-resistant strains are appearing naturally. There is no commercial vaccine against the pathogen, either. In the current work, novel compounds based on metallacarborane cage were studied on strains of Pseudomonas aeruginosa and a Yersinia pestis substitute, Yersinia enterocolitica. The representative compounds had IC₅₀ values below 10 µM against Y. enterocolitica and values of 20–50 μM against P. aeruginosa. Artificial generation of compound-resistant Y. enterocolitica suggested a common mechanism for drug resistance, the first reported in the literature, and suggested N-linked metallacarboranes as impervious to cellular mechanisms of resistance generation. SEM analysis of the compound-resistant strains showed that the compounds had a predominantly bacteriostatic effect and blocked bacterial cell division in Y. enterocolitica. The compounds could be a starting point towards novel anti-Yersinia drugs and the strategy presented here proposes a mechanism to bypass any future drug resistance in bacteria.