Detailed regional deposition of inhaled particles in the human lung is calculated for individual airway generations. The calculations are based on Landahl's deposition model as applied to the morphometric lung model of Weibel. We consider primarily deposition patterns of iron oxide particles with diameters ranging between 1 and 10 micrometers, but we also calculate patterns of deposition for bis(2-ethylhexyl) sebacate particles with diameters as small as 0.2 micrometers. We obtain good agreement between predicted values and observed values for alveolar retention of inhaled iron oxide particles with 64 and 20% of total deposition predicted to occur in nonciliated airways for 2- and 5-micrometer particles, respectively. This is compared with 48 +/- 9 and 27 +/- 10% for the measured values. Calculated values for total lung deposition of small bis(2-ethylhexyl) sebacate particles agree well with experimental data. The calculations show a minimum in deposition occurring for particle diameters of 0.5 micrometers, which is in agreement with observations. A calculation of surface concentration of deposited 7.9-micrometer aerodynamic particles reveals a very large concentration occurring at airway generation four. This observation is considered in light of observations that bronchial carcinomas occur in this vicinity of the lung.

Summary Various finite elements based on mixed formulations have been proposed for the solution of boundary value problems involving strain‐gradient models. The relevant literature, however, does not provide details on some important theoretical aspects of these elements. In this work, we first present the existing elements within a novel, single mathematical framework, identifying some theoretical issues common to all of them that affect their robustness and numerical efficiency. We then proceed to develop a new family of mixed elements that addresses these issues while being simpler and computationally cheaper. The behavior of the new elements is further demonstrated through two numerical examples.

Bei der Restaurierung antiker griechischer Tempel werden einzelne Marmorblöcke zu einem Bauteil, beispielsweise einem Architrav, zusammengebaut. Wegen der Forderung nach Reversibilität der Eingriffe erfolgt dies an der Akropolis von Athen durch Anwendung von in Zementmörtel eingelassenen Titanstäben mit Gewinde in vorgebohrten Löchern. Diese Art der Restaurierung entspricht einer Teil sanierung der Architrave. Im hier vorliegenden Beitrag werden experimentelle Untersuchungen zum Ausziehverhalten dieser Verankerungsstäbe vorgestellt. Die Versuche werden an einer speziell entworfenen Versuchsanordnung durchgeführt. Das Versagen erfolgt bei allen Versuchen an der Grenzfläche zwischen Mörtel und Bohrlochwand. Es zeigt sich, dass die Gewindeform das Tragverhalten entscheidend beeinflusst. Ferner werden mögliche Grenzzustände definiert.

For the development of innovative connections for the restoration of the integrity of structural elements of ancient stone temples, it is imperative, among others, to understand the reasons of the ‘pull‐out’ phenomenon. Pull‐out can be defined as the gradual or abrupt removal of the reinforcing bars from the body of the structural member, without prior failure of neither the marble nor the bars. An analytic solution is not yet available and in this context, a combined experimental and numerical analysis was undertaken in an effort to enlighten the failure mechanisms activated during the phenomenon. The experimental part included a series of pull‐out tests with prismatic specimens made from Dionysos marble in which threaded metallic bars were planted in drilled holes. The adhesion between the marble and the bar was achieved using a suitable cementitious material. The criterion adopted for the design of the connections is to avoid completely the failure of marble. The parameters studied included the depth and the pitch of the thread of the reinforcing bars. The experimental set‐up comprising suitable supporting and measuring systems was improvised, given the absence of a standard, relevant to this particular problem. Based on the experimental results, a design criterion is introduced allowing for a predefined amount of slip between the reinforcing bar–cement interface and the marble body. In addition, a numerical model is developed, calibrated on the basis of the experimental results. It is concluded that the form of the thread influences considerably the carrying capacity: denser pitches lead to higher ultimate load and energy consumption while the coarser ones favour parasitic bending effects and a flexible behaviour. In addition, the medium depth for each pitch leads to a stiffer and stronger behaviour.

Sand-rubber mixture (SRm) behaviour is affected by rubber content (RC) whilst dissipation in sands is caused by inter-particle sliding. Dissipation in SRm is as, or more significant than in sands. However, the mechanisms of dissipation in SRm are not well understood. In this study, onedimensional compression tests on sand samples with RC of 0%, 15%, 30%, 45% and 100% by mass were performed on a standard oedometer. In addition, a SRm with RC of 30% was tested on a minioedometer placed inside an X-ray scanner and 3D images of the internal structure of the material were acquired at three stages during loading and unloading. Image analysis was used to infer particle-scale measurements and provide experimental evidence to help explaining the energy dissipation mechanisms for SRm. It is postulated here that energy dissipation in these mixtures is dominated by inter-particle sliding at initial stages of loading, but once rubber particles fill the voids spaces between the sand, deformation and dissipation mechanisms are dominated by the deformation of the rubber particles.