3D Plotting Research Articles

Fabrication of porous scaffolds by three-dimensional plotting of a pasty calcium phosphate bone cement under mild conditions

The major advantage of hydroxyapatite (HA)-forming calcium phosphate cements (CPCs) used as bone replacement materials is their setting under physiological conditions without the necessity for thermal treatment that allows the incorporation of biological factors. In the present study, we have combined the biocompatible consolidation of CPCs with the potential of rapid prototyping (RP) techniques to generate calcium phosphate-based scaffolds with defined inner and outer morphology. We demonstrate the application of the RP technique three-dimensional (3D) plotting for the fabrication of HA cement scaffolds. This was realized by utilizing a paste-like CPC (P-CPC) which is stable as a malleable paste and whose setting reaction is initiated only after contact with aqueous solutions. The P-CPC showed good processability in the 3D plotting process and allowed the fabrication of stable 3D structures of different geometries with adequate mechanical stability and compressive strength. The cytocompatibility of the plotted P-CPC scaffolds was demonstrated in a cell culture experiment with human mesenchymal stem cells. The mild conditions during 3D plotting and post-processing and the realization of the whole procedure under sterile conditions make this approach highly attractive for fabrication of individualized implants with respect to patient-specific requirements by simultaneous plotting of biological components.

Drug release from biodegradable polyesterurethanes with shape-memory effect

Three dimension (3D) printing has been increasingly used to make tissue engineering scaffolds. However, polyester-based scaffolds made through traditional 3D printing such as fused deposition modeling (FDM) lack of bioactivity as biomolecules cannot be directly blended with inks to achieve an in situ delivery. In addition, with increasing demand of reducing surgical trauma, implanting scaffolds through a minimally invasive way is of great importance. Here, surface porous tissue engineering scaffolds were made from novel poly(D,L-lactic acid-co-trimethylene carbonate)-based water-in-oil emulsions through a cryogenic 3D plotting. The effects of water content in emulsions on the microstructure of 3D plotted scaffolds were investigated. With heat treatment at 40 °C, scaffolds became soft and can be injected into a catheter. Growth factors can be loaded into the scaffolds in situ and showed a sustained release within 30 days.

Machine design and processing considerations for the 3D plotting of thermoplastic scaffolds

3D plotting by micro-extrusion is a promising layer-wise fabrication method for the production of scaffolds in thermoplastic polymers. It is a solvent-free direct technique which permits extensive control over geometry and porosity. This paper highlights the complications that arise when using this technique for the processing of thermally sensitive polymers. It has been noted that the material is subject to extensive thermal load during processing, which may result in degradation by chain scission. This negatively affects scaffold (mechanical) properties as well as predictability and repeatability of the fabrication technique. A rationale is offered as to the main causes of this thermally induced degradation during processing and tentative ideas towards a solution are equally put forward.

A Matlab Script for Visualizing Structure Contours and Outcrop Patterns in Three Dimensions

Structure contours are one of the most important concepts of geological maps, but students often find it difficult to visualize them in three dimensions (3D). A simple Matlab script is presented, which is intended to assist students in the visualization of structure contours in 3D. The currently available versions of the script produce displays of the following types of geological structures: (i) Planes, (ii) sinusoidal folds, (iii) box- and chevron folds, and (iv) folds exhibiting parasitic folding. For simplicity the Earth's surface is defined using simple cosine functions, whilst structures iii and iv are defined using simplified Fourier series. The script is based on a three-step process: (i) Define the topography, (ii) define the geological structure and (iii) establish whether the geological structure is above (eroded) or below the Earth's surface. The last step provides the outcrop pattern. The topography and geology are displayed in 3D and the associated map pattern is plotted in the same diagram. This combination of 3D and 2D plotting provides a direct link between the 3D nature of the structure and its 2D projection (i.e. the map). The 3D diagrams generated with the script have been used successfully in undergraduate geology mapping exercises.

Method for Automated Discontinuity Analysis of Rock Slopes with Three-Dimensional Laser Scanning

Three-dimensional (3D) laser scanning data can be used to characterize discontinuous rock masses in an unbiased, rapid, and accurate manner. With 3D laser scanning, it is now possible to measure rock faces whose access is restricted or rock slopes along highways or railway lines where working conditions are hazardous. The proposed method is less expensive than traditional manual survey and analysis methods. Laser scanning is a relatively new surveying technique that yields a so-called point cloud set of data; every single point represents a point in 3D space of the scanned rock surface. Because the density of the point cloud can be high (on the order of 5 mm to 1 cm), it allows for an accurate reconstruction of the original rock surface in the form of a 3D interpolated and meshed surface using different interpolation techniques. Through geometric analysis of this 3D mesh and plotting of the facet orientations in a polar plot, it is possible to observe clusters that represent different rock mass discontinu...

Method for Automated Discontinuity Analysis of Rock Slopes with Three-Dimensional Laser Scanning

Three-dimensional (3D) laser scanning data can be used to characterize discontinuous rock masses in an unbiased, rapid, and accurate manner. With 3D laser scanning, it is now possible to measure rock faces whose access is restricted or rock slopes along highways or railway lines where working conditions are hazardous. The proposed method is less expensive than traditional manual survey and analysis methods. Laser scanning is a relatively new surveying technique that yields a so-called point cloud set of data; every single point represents a point in 3D space of the scanned rock surface. Because the density of the point cloud can be high (on the order of 5 mm to 1 cm), it allows for an accurate reconstruction of the original rock surface in the form of a 3D interpolated and meshed surface using different interpolation techniques. Through geometric analysis of this 3D mesh and plotting of the facet orientations in a polar plot, it is possible to observe clusters that represent different rock mass discontinuity sets. With fuzzy k-means clustering algorithms, individual discontinuity sets can be outlined automatically, and the mean orientations of these identified sets can be computed. Assuming a Fisher's distribution, the facet outliers can be removed subsequently. Finally, discontinuity set spacings can be calculated as well.

Rapid prototyping of scaffolds derived from thermoreversible hydrogels and tailored for applications in tissue engineering

In the year 2000 a new rapid prototyping (RP) technology was developed at the Freiburg Materials Research Center to meet the demands for desktop fabrication of scaffolds useful in tissue engineering. A key feature of this RP technology is the three-dimensional (3D) dispensing of liquids and pastes in liquid media. In contrast to conventional RP systems, mainly focused on melt processing, the 3D dispensing RP process (3D plotting) can apply a much larger variety of synthetic as well as natural materials, including aqueous solutions and pastes, to fabricate scaffolds for application in tissue engineering. For the first time, hydrogel scaffolds with a designed external shape and a well-defined internal pore structure were prepared by this RP process. Surface coating and pore formation were achieved to facilitate cell adhesion and cell growth. The versatile application potential of new hydrogel scaffolds was demonstrated in cell culture.

Fully automated diagnostic system development for hydraulic motor performance

In this study, the system that can automatically test comprehensive performance in the hydraulic motor and can be used as test equipments for the development of the hydraulic motor is designed and developed. The effort focuses on the development of test software that analyzes collected data from the hydraulic motor and evaluates its performance, and further on building of test equipments. Test items consists of 12 including the efficiency test, and these tests are carried out full automatically. In particular, the volumetric test is, in general, done by separating the loading part in the hydraulic motor, but here it is carried out through unloading conditions only by controlling the charging pressures in this system. In controlling the test equipment, both open loop and closed loop controls are applied resulting in stable, fast, and accurate test conditions. This system includes not only function of performance test but also capability of calibration and self diagnosis. It also involves 3D graphic contour map plotting and analytical techniques.

Desktop manufacturing of complex objects, prototypes and biomedical scaffolds by means of computer-assisted design combined with computer-guided 3D plotting of polymers and reactive oligomers

Computer-assisted design and image processing were combined with computer-guided one- and two-component air-driven 3D dispensing of hotmelts, solutions, pastes, dispersions of polymers as well as monomers and reactive oligomers to produce solid objects with complex shapes and tailor-made internal structures. During the 3D plotting process either individual microdots or microstrands were positioned in order to construct complex objects, fibers, tubes and scaffolds similar to non-wovens. The resolution was in the range of 200 μm and depended upon inner nozzle diameter, air pressure, plotting speed, rheology, and plotting medium. Plotting in liquid media with densities similar to that of the dispensing liquid eliminated the need for construction of temporary support structures. The design capabilities of this computer-guided 3D plotting process was demonstrated using conventional moisture-curable silicone resin.

Processing of the LH/CG receptor and bound hormone in rat luteal cells after hCG-induced down-regulation as studied by a double immunofluorescence technique in conjunction with confocal laser scanning microscopy.

We developed a double immunofluorescence technique for detection of the rat luteinizing hormone/choriogonadotropin (LH/CG) receptor and bound hCG in the same rat ovarian section and used it in conjunction with confocal laser scanning microscopy (CLSM) to study the fate of the receptor-hormone complex in luteal cells during the hCG-induced down-regulation. Pseudopregnant immature females rats were perfusion-fixed before (0 hr) and 2, 6, 12, 24, or 36 hr after a down-regulating dose of hCG (500 IU IV). The cryosections were stained for the LH/CG receptor and bound hormone by sequential incubations with a polyclonal rabbit antiserum to purified rat LH/CG receptor and a mouse monoclonal antibody (MAb) to hCG, followed by sequential incubation with TRITC- and FITC-conjugated secondary antibodies to rabbit and mouse immunoglobulins, respectively. The results were semiquantitatively analyzed by a pseudo-three-dimensional (3D) plotting of the intensities of the receptor and hormone-specific fluorescence in luteal cells by CLSM. The analysis suggested that the majority of the LH/CG receptors are located on the luteal cells before induction of the down-regulation and that their content seem to vary not only among cells but also on the surface of single cells, thus supporting the previous concept of the functional heterogeneity among the cells and their functional compartmentation. At 2 hr after injection of the down-regulating dose of hCG, the LH/CG receptor-specific and hCG-specific fluorescences clearly co-localized on the luteal cells. Both the LH/CG receptor- and hCG-specific fluorescences disappeared from the luteal cell surfaces in a parallel fashion within 36 hr without a detectable accumulation of either fluorescence deep in the cell interior. These results suggest that the LH/CG receptor and bound hCG do not differ in their manner of in vivo processing in luteal cells. Therefore, the disappearance of the receptor and bound hormone occurs in a parallel fashion and without detectable internalization.