Dependence of the lattice parameter of {\gamma '} iron nitride,Fe4N1−x,on nitrogen content; Accuracy of the nitrogen absorption datairon nitride,Fe4N1−x,on nitrogen content; Accuracy of the nitrogen absorption data

Pure iron foils were converted into { \(\gamma ' - Fe_4 N_{1 - x} \) } foils of various compositions by means of nitriding in selected NH₃/H₂ gas mixtures at 803 and 843 K. The lattice parameter and the linear thermal expansion coefficient of { \(\gamma ' - Fe_4 N_{1 - x} \) } nitride and the surrounding gas atmosphere.     

Composition of lime-cement and air-entrained cement mortar as a function of distance to the brick-mortar interface: consequences for masonry

The composition of a lime-cement mortar and an air-entrained cement mortar was studied as a function of distance to the brick-mortar interface. Both mortars had the same cement-to-sand ratio and the same water-to-cement ratio; in the lime-cement mortar the binder-to-sand ratio was highest. The measurements indicate that the mortar composition (i.e. the contents of sand, cured binder and voids) and the contents of chemical substances of the cured binder (i.e. the contents of calcite, portlandite and ettringite) change with distance to the brick-mortar interface. For the mortar composition the tendency of these changes is the same, but for the contents of the chemical substances of cured binder for the two mortar types the tendency of these changes is opposite and also the extent of the changes is significantly different. For the air-entrained cement mortar, the observations are explained by the enrichment of binder towards the brick-mortar interface, resulting from the compaction of fresh mortar. In the lime-cement mortar such an enrichment of binder hardly occurs and the observations are explained by the intense carbonation that takes place. As a result, the contents of the chemical substances in the mortars is very much different. In the air-entrained cement mortar, near the brick-mortar interface the enrichment of cement and the low water content (resulting from the low water retentivity of this mortar), lower the water-to-cement ratio and as a consequence the cement is not fully hydrated. In the lime-cement mortar, as the Ca(OH)₂ content and the water content is higher, near the brick-mortar interface, a carbonated zone is formed which is hardly permeable for CO₂ (and probably water). This does not occur in the air-entrained cement mortar, it remains permeable.     

Treatment of Sjögren’s Syndrome with Mesenchymal Stem Cells: A Systematic Review

Mesenchymal stem cells (MSCs) are ubiquitous in the human body. Mesenchymal stem cells were initially isolated from bone marrow and later from other organs such as fatty tissues, umbilical cords, and gingiva. Their secretory capacities give them interesting immunomodulatory properties in cell therapy. Some studies have explored the use of MSCs to treat Sjögren’s syndrome (SS), a chronic inflammatory autoimmune disease that mainly affects exocrine glands, including salivary and lacrimal glands, although current treatments are only palliative. This systematic review summarizes the current data about the application of MSCs in SS. Reports show improvements in salivary secretions and a decrease in lymphocytic infiltration in salivary glands in patients and mice with SS after intravenous or infra-peritoneal injections of MSCs. MSC injections led to a decrease in inflammatory cytokines and an increase in anti-inflammatory cytokines. However, the intrinsic mechanism of action of these MSCs currently remains unknown.     

The role of the substrate on the mechanical and thermal stability of Pd thin films during hydrogen (de)sorption

In this work, we studied the mechanical and thermal stability of ~100 nm Pd thin films magnetron sputter deposited on a bare oxidized Si(100) wafer, a sputtered Titanium (Ti) intermediate layer, and a spin-coated Polyimide (PI) intermediate layer. The dependence of the film stability on the film morphology and the film-substrate interaction was investigated. It was shown that a columnar morphology with elongated voids at part of the grain boundaries is resistant to embrittlement induced by the hydride formation (α?β phase transitions). For compact film morphology, depending on the rigidity of the intermediate layer and the adherence to the substrate, complete transformation (Pd-PI-SiO₂/Si) or partly suppression (Pd-Ti-SiO₂/Si) of the α to β-phase was observed. In the case of Pd without intermediate layer (Pd-SiO₂/Si), buckling delamination occurred. The damage and deformation mechanisms could be understood by the analysis of the stresses and dislocation (defects) behavior near grain boundaries and the film-substrate interface. From diffraction line-broadening combined with microscopy analysis, we showed that in Pd thin films, stresses relax at critical stress values via different relaxation pathways depending on film-microstructure and film-substrate interaction. On the basis of the in-situ hydriding experiments, it was concluded that a Pd film on a flexible PI intermediate layer exhibits free-standing film-like behavior besides being strongly clamped on a stiff SiO₂/Si substrate.     

On the use of conformal mapping for the computation of hydrodynamic forces acting on bodies of arbitrary shape in viscous flow. Part 1: simply connected body

Some aspects of the force and moment computations in incompressible and viscous flows are revisited. The basic idea was developed in Quartapelle and Napolitano (AIAA J. 21:991–913, 1983). They formulated the way to compute the force and moment without explicitly calculating the pressure. The principle is to project Navier–Stokes equations on a set of functions. Surprisingly these functions have a meaning in potential theory. They are precisely the solutions which give the added masses and added moment of inertia for potential flow. By revisiting this problem for two-dimensional flows in unbounded liquid, a general identity giving the added masses and added moment of inertia is formulated. To this end a conformal-mapping technique is used to transform the fluid domain. Once the potential solution has been obtained, the projection method by Quartapelle and Napolitano is implemented. In addition an a posteriori computation of the pressure is described. Applications illustrate the present study.     

Relation between microstructure and adhesion of hot dip galvanized zinc coatings on dual phase steel

The microstructure of hot dip galvanized zinc coatings on dual phase steel was investigated by electron microscopy and the coating adhesion characterized by tensile testing. The zinc coating consists of a zinc layer and columnar ζ-FeZn₁₃ particles on top of a thin inhibition layer adjacent to the steel substrate. The inhibition layer is a thin compact and continuous layer that consists of η-Fe₂Al_5–xZn_x fine and coarse particles. The coarse faceted particles are on top and fine faceted particles are at the bottom. The steel surface is covered with small fraction manganese oxides, which may impair adhesion of the zinc coating. The adhesion at various interfaces that exist in zinc-coated steel was quantitatively estimated using a so-called “macroscopic atom” model. In addition, the adhesion at the interfaces in zinc-coated steel was qualitatively assessed by examining the fracture and delamination behavior upon tensile testing. In accordance with this model, fracture along zinc grain boundaries preceded fracture along the zinc layer/inhibition layer and ζ-FeZn₁₃ particle/inhibition layer interfaces.     

Structural inhomogeneities of AlSi alloys rapidly quenched from the melt

Hypo- and hyper-eutectic AlSi alloys were rapidly quenched from the melt using the melt-spinning technique with two spinning velocities. Structural differences between the wheel (chill) and upper sides of the melt-spun ribbons were investigated by optical and scanning electron microscopy and X-ray diffraction methods (texture- and size-strain analyses). The Al-rich phase of the hypo-eutectic alloys was textured. The textures observed from both sides of the ribbons were different; in neither case was it of fibre type. For the larger spinning velocity applied, the structural imperfection of the wheel side was larger than that of the upper side for both the Al-rich and the Si-rich phases.     

On the use of conformal mapping for the computation of hydrodynamic forces acting on bodies of arbitrary shape in viscous flow. Part 2: multi-body configuration

Two-dimensional viscous flows around obstacles are considered in an unbounded liquid. The basic idea developed in Part 1 is further extended from a single body to multi-body configurations. This idea follows from the formulation by Quartapelle and Napolitano (AIAA J. 21:991–913, 1983) who proposed computation of the force and moment in incompressible viscous flow without explicitly calculating the pressure. The principle is the projection of Navier–Stokes equations on a set of functions. Surprisingly, these functions have a precise meaning in potential theory. They are the solutions which lead to the added masses and added moment of inertia for the potential flow around the studied arrangement of obstacles. By revisiting this problem, a general identity of the full coupled matrix of added masses and added moment of inertia is formulated. To this end conformal mappings for multi-body configurations are used. Robustness of the proposed algorithms is tested and illustrated. The obtained potential solution is merely a mathematical solution and it does not allow to describe the actual potential flow since the circulation is not accounted for. However, its interest is crucial for implementing the projection technique developed by Quartapelle and Napolitano. The interest of such a method is two-fold. Firstly, it provides a way of computing the force without explicitly calculating the pressure. Consequently and secondly, it offers an alternate way to validate the computation of the loads. In effect, these loads are always available from a direct integration of the Cauchy stress tensor (pressure plus friction). It is worth mentioning that the present technique allows an a posteriori computation of the pressure.     

Electrochemical behavior and performances of Ni-BaZr0·1Ce0·7Y0.1Yb0.1O3−δ cermet anodes for protonic ceramic fuel cell

High performance Ni-BCZYYb cermet anode were prepared at 1300 °C using electrolyte powders prepared by combustion and commercial NiO. The cermets are porous (39 vol% of porosity), show a high electronic conductivity (1097 S cm^?1) and sufficient mechanical properties. The electrochemical behavior of the Ni-BCZYYb/BZCYYb-ZnO/Ni-BCZYYb symmetrical cell elaborated by co-pressing and co-sintering was investigated using electrochemical impedance spectroscopy. The impedance spectroscopy study show that the electrode reaction involves three steps. The total polarization Area Specific Resistance decreases by about one order of magnitude when increasing the temperature from 450 to 600 °C or the H₂ concentration from 5 to 100 vol% to reach 0.049 Ω cm² at 600 °C under pure hydrogen.     

Health and Its Relationship with Residential Relocations of Older People to Institutions versus to Independent Dwellings

Research into older people’s relocations to independent dwellings has largely remained separate from research into moves to institutions. Yet, both types of moves could be a response to health problems and to a certain extent they could be substitutes for each other. Using Litwak and Longino’s model of moves of older people, this study assesses the extent to which three commonly used health measures (limitations in activities of daily living [ADL], self-rated health, and the prevalence of [limiting] chronic conditions) predict older people’s moves to subsidized care institutions and elsewhere, in one multinomial logistic regression model. The data were derived from the POLS survey for the Netherlands (N = 8306) enriched with administrative data on subsequent moves. In line with Litwak and Longino’s model, the findings indicate that older people’s moves to institutions were more likely among those with more severe health problems, whereas moves elsewhere were more likely among those with moderate health problems. Among the three investigated health measures, limitations in ADL had the strongest predictive value, and was the only one for which the difference in effect between relocations to care institutions and relocations elsewhere was statistically significant.