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In this work, we investigate single-pulse laser ablation of bulk stainless steel (AISI304), aluminium (Al) and copper (Cu) and its dependence on the pulse duration. We measured the reflectivity, ablation thresholds and volumes under the variation of pulse duration and fluence. The known drop of efficiency with increasing pulse duration is confirmed for single-pulse ablation in all three metals. We attribute the efficiency drop to a weakened photomechanically driven ablation process and a stronger contribution of photothermal phase explosion. The highest energetic efficiency and precision is achieved for pulse durations below the mechanical expansion time of 3-5 ps, where the stress confinement condition is fulfilled.

Bentonite-bonded molding sand is one of the most common mold materials used in metal casting. The high casting temperatures cause dehydration and alteration of the molding sand, thereby degrading its reusability. Neutron radiography and neutron diffraction were applied to study these processes by using pure bentonite-quartz-water mixtures in simulation casting experiments. The aim of the experiments was to compare the dehydration behavior of raw and recycled mold material in order to assess possible causes of the limited reusability of molding sands in industrial application. Neutron radiography provided quantitative data for the local water concentrations within the mold material as a function of time and temperature. Dehydration zones, condensation zones, and areas of pristine hydrated molding sand could be established clearly. The kinematics of the zones was quantified. Within four cycles of de- and rehydration, no significant differences in water kinematics were detected. The data, therefore, suggest that the industrial handling (molding-sand additives and the presence of metal melt) may have greater effects on molding-sand reusability than the intrinsic properties of the pure bentonite–quartz–water system.

Bioinspired 3D microfluidic systems that combine vascularization with extracellular matrix architectures of organotypic geometry, composition and biophysical traits can help advance our understanding of microorgan physiology. Here, two-photon stereolithography is adopted to fabricate freestanding perfusable 3D cell scaffolds with micrometer resolution from gelatin methacryloyl hydrogel derived from extracellular matrix protein. As a proof of concept, we introduce an ultracompact bio-hybrid chip layout to demonstrate perfusion and cell seeding of double-digit μm proteinaceous channels. This perfusion chip consists of a standardized microfluidic interface fabricated from standard resin and a GM10 bioink channel printed atop of this interface. In addition, we demonstrate that algorithmic design synthesis can recapitulate intact alveoli and capillary networks with tunable design parameters to implement vascularized alveolar tissue models. This approach will allow for a systematic investigation of cell-cell and tissue dynamics in response to defined structural, mechanical and bio-molecular cues and is ultimately scalable to fabricate organ-on-a-chip systems.