What the Ground Says…

Ground, as a body incised by natural and human actions (European Landscape Convention), carries “stories”, going beyond quantitative values. As in a text, it holds the keys to understand what it covers or hides. In its thickness, it shelters “implicit projects”. Understanding its complexity requires a physical and perceptual commitment, challenging the body in space: dimensions gradually forgotten by Environmental Sciences. As a “threshold” between visible and invisible, Underground-Built-Heritage represents the reverse of the emerged world: hollow space, both generator and mirror of open space (cities, landscapes). The focus is on physical and mental relationships between these two worlds. Past and present relationships emerge, allowing hypotheses to reconstitute collective memories, practices, knowledge, and values, which serve territorial development. The “Three Countries Park” is a place for cross-border experimentation to test how UBH can rebuild common links for fragmented environments. The cavities of a geo-park (planned) and the tangles of underground mining architecture are the fragments of a vocabulary whose meaning communities have to relearn. Built undergrounds will, thus, emerge from common stories that revive the imagination of populations who have lost all notion of belonging to a place. UBH will become a vector of new territorial coherence linking the physical and mental perceptions of people.

A hybrid molecular peapod of sp2- and sp3-nanocarbons enabling ultrafast terahertz rotations

The internal hollow space of carbon nanotubes provides a unique nanometre-sized space to capture various molecular entities. The inner space circumfused by sp2-carbon networks can also encapsulate diamondoid molecules to afford sp2/sp3-hybrid nanocarbon peapods that have recently emerged as unique nanostructures. In this study, the sp2/sp3-hybrid peapods have been mimicked by adopting a cylindrical molecule and the smallest diamondoid, i.e., adamantane, to demonstrate the existence of ultrafast rotational motion. The solid-state rotational frequency is measured by NMR spectroscopy to record 1.06 THz that is, to the best of our knowledge, the largest value recorded for solid-state rotations of molecules. Theoretical calculations reveal that multivalent CH-π hydrogen bonds anchored the diamondoid guest on the π-wall of the cylindrical host. The weak hydrogen bonds are prone not only to cleave but also to regenerate at the interfaces, which give freedom to the guest for ultrafast isotropic rotations in the inertial regime.

Fabrication of Hollow Maxillary Complete Denture Using Silicon Putty and Double Flask Technique

This article describes the fabrication of a hollow maxillary complete denture using silicone putty and a double flask technique. A successful complete denture directly depends on retention, stability and support accompanied by good aesthetics. However, in case of atrophic edentulous ridges the challenge lies in the fact that there is a significantly lesser denture bearing area that can lead to a number of problems. The most important of these is an increased interarch space resulting from excessive resorption of upper or lower arch. This can lead to a resulting heavy complete denture that further deteriorates the bone condition due to excessive and continuous load, accelerating bone resorption. Moreover, there is no effective support to deal with any kind of harmful lateral forces and this can lead to dislodgment of the denture. The operator’s efficiency lies in applying the basic principles of fabricating a denture and innovating various steps to counter critical situations. Various methods such as asbestos, silicone putty, modelling clay, thermocol, salt, wax have been used for creating a hollow space inside the denture. Out of the various methods that have been used for fabrication of a hollow space inside a complete denture, silicone putty method is one of the more convenient and accurate method for achieving the objective, thereby rendering a lighter prosthesis. A hollow maxillary denture is highly advantageous as it reduces the weight of acrylic resin, thereby preserving the residual alveolar ridge. It also helps in stability of the denture by indirectly reducing the lateral forces.

Numerical Modeling of Sublimation of Ammonium Carbamate Applied to Supply System of NOx Reductant

Recently, ammonium carbamate (AC) has attracted attention as a substitute for urea, which is a commonly used reductant for NOx emitted from combustion engines. The AC exists as a solid at room temperature, and it is decomposed to NH3 and CO2 gases by heating. Therefore, adequate heat transfer is an essential issue in the design of AC pyrolysis reactor. In this study, a numerical model that describes the sublimation of AC was developed. For modeling, this study considered the three different calculation zones: solid-phase zone, gas-phase zone, and sublimation zone. Additionally, during the sublimation process, collapse of upper solid AC into the hollow space below by the effect of gravity is considered. As a result, it is presented that the modeling shows reasonable information about the AC sublimation in a reactor, such as temperatures in a reactor, pressure of reactor, and flow rate of sublimated gas. However, it is also found that accurate prediction of spatial temperature distribution is challenging because it is related to the accurate prediction of the internal shape of AC and its collapse in a reactor.

Design of a New XY Flexure Micropositioning Stage With a Large Hollow Platform

This paper presents the design of a new flexure-based xy micropositioning stage with a large hollow platform, which is suitable for practical use with a microscope. The designed mechanism has a parallel-kinematic structure and is actuated by two voice coil motors. By employing multistage compound parallelogram flexures, the stage is designed as a four-layer structure, which produces a motion output platform with a large hollow space and large range of motion. Analytical modeling was carried out for parametric design of the stage. Evaluation results show that the designed xy stage exhibits a large safety factor and high natural frequency. Moreover, the large hollow platform is well-suited for practical applications with a microscope.

Numerical Simulation on the Penetration Behavior of the Projectile during the Water Injection Stage of Water-Projectile-Assisted Injection Molding Process

Water-projectile-assisted injection molding (W-PAIM) is a novel molding process for plastic pipes with complicated shape. It utilizes high-pressure water as a power to push a solid projectile to penetrate through the melt to form a hollow space. In order to investigate the penetration behavior of the projectile during the water injection stage of W-PAIM process, numerical simulation of the water injection stage of a W-PAIM pipe with straight and curved segments was carried out. A turbulent flow for the driving water was considered in the motion equation, and the dynamic mesh technology was used to deal with the moving solid projectile. The simulation results, including RWT and the flow fields, were compared with those of water-assisted injection molding (WAIM) pipe with the same outer dimensions. It was found that the residual wall thickness (RWT) of the W-PAIM pipe is much thinner than that of the WAIM pipe. The projectile has a crucial influence on the RWT. The pressure fields of W-PAIM and WAIM are very similar in both straight and curved segments. The velocity field and strain rate field near the penetration front in W-PAIM are quite different from those in WAIM due to the drag flow caused by the projectile penetration.

Cell Injection Millirobot Development and Evaluation in Microfluidic Chip

We propose an innovative design of millirobot, which can achieve donor cell suction, delivery, and injection in a mammalian oocyte on a microfluidic chip. The millirobot body contains a hollow space that produces suction and ejection forces for the injection of cell nuclei using a nozzle at the tip of the robot. Specifically, a controller changes the hollow volume by balancing the magnetic and elastic forces of a membrane along with the motion of stages in the XY plane. A glass capillary attached to the tip of the robot contains a nozzle that is able to absorb and inject cell nuclei. The millirobot provides three degrees of freedom and generates micronewton forces. We demonstrate the effectiveness of the proposed millirobot through an experiment of the absorption and ejection of 20-µm particles from the nozzle using magnetic control in a microfluidic chip.

Experimental investigations on the load bearing behaviour of an innovative prestressed composite floor system in fire

In Germany, regulations for hollow spaces in slab systems require 30 minutes standard fire resistance of the load-bearing steel construction. Within a current national research project a natural fire scenario for the hollow space was developed based on realistic fire loads and ventilation conditions in the hollow space. Assuming this realistic fire scenario in the hollow space, two large scale tests on an innovative composite floor system were performed to evaluate the influence on the load bearing behaviour of the floor system. The integrated and sustainable composite floor system consists of a prestressed concrete slab, an unprotected, bisected hot rolled I-profile with composite dowels either in puzzle or clothoidal shape, and removable floor panels on the top of the I-profile. This floor system ensures the opportunity to adjust the technical building installations in accordance with the use of the building. This integrated and sustainable composite floor system was developed in several research projects. The standard fire resistance R90 for the fire scenario below the slab system has already been proven successfully. In this paper, experimental investigations regarding the heating and load bearing behaviour of the innovative composite floor system under the newly developed natural fire scenario of hollow spaces are presented. In doing so, the special test set-up to realise the fire tests for the fire scenario hollow space will be described in detail. After the fire scenario for the hollow space, the specimen was subjected to the ISO standard fire curve to establish the failure temperature of the unprotected I-profile. In addition to the temperature development and the load bearing behaviour inside the innovative floor during the heating phase, the cooling phase and the influence of a web opening on the load bearing behaviour will be discussed.