Free-form Nature Research Articles

Photocatalysis of functionalised 3D printed cementitious materials

The main objective of this study was to evaluate the photocatalytic behaviour of 3D printed cementitious mortars that were functionalised with TiO2 nanoparticles. This study is one of the few available regarding functionalisation of 3D concrete printing (3DCP) with photocatalytic properties. Despite the fact 3DCP research is swiftly growing, it is still necessary further investigation to fully understand these materials' physicochemical and mechanical properties, which will influence the functionalised properties of the composite. Due to the freeform nature of the 3DCP there are no moulds, therefore the functionalisation through coating can be performed in a much earlier stage than in conventional moulded concrete. The developed smart 3D printed concrete could promote the photodegradation of pollutants for self-cleaning and air purification. In particular, this study investigated the effect of two parameters on photocatalytic behaviour: light power intensity and the coating rate of nano-TiO2 particles. Surface coating was adopted as the functionalisation method, and the Rhodamine B dye degradation efficiency was used as an indicator to evaluate the photocatalytic behaviour. Additionally, the surface roughness and microstructure of the 3D printed cementitious mortar specimens were assessed to distinguish between the reference and TiO2 coated series. Scanning electron microscopy (SEM), X-ray Energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) crystallography were carried out as three techniques to evaluate the morphology, composition, and microstructure of the specimens, respectively. The results indicated successful activation of catalyst particles under illumination, where higher light power intensity increased the degradation efficiency. Furthermore, dye degradation efficiency increased with increasing coating rates of nano-TiO2 particles on the surface of the specimens. The roughness of the 3D printed specimens’ surface was sufficient for settling the nano-TiO2 particles. Finally, microscopy results confirmed the presence and suitable distribution of the nano-TiO2 particles on the surface of the coated specimens.

Application of magnetic field assisted finishing process for nanofinishing of freeform femoral knee joint and performance analysis of finished surface

Finishing of femoral knee joint implant is very cumbersome due to its freeform nature. In the present study, a magnetic field-assisted finishing process is employed to uniformly finish the femoral knee implant over its surface curvature at the nanometer level. Experiments are conducted to analyze the freeform surface finishing capability of magnetic field-assisted finishing tool, which proves the tool’s capability to achieve the required surface properties of a femoral knee implant. A comparative analysis between the performance of the magnetic field assisted finishing process and manually polished surface relative to tibial bearing material, that is, ultra-high molecular weight polyethylene with the help of pin-on-disc tribometer, is carried out. It will help to understand the in vivo performance of a finished femoral component of the knee joint by a magnetic field-assisted finishing process. The wear tests prove that the volume loss of the disc material while considering magnetic field-assisted finished pins (11.79 mm3) are better in all cases than the manually polished pins (27.97 mm3). The tribology test also demonstrates that femoral knee implant polished using magnetic field-assisted finishing process will face fewer problems related to wear debris. It will also reduce the problems that occur due to the mixing of debris in the bloodstream. The polishing tool provides almost uniform nanometer-level surface finishing with a standard deviation of 19.23 along the surface curvature. The minimum achieved surface roughness of the femoral knee joint is 20 nm.

An explorer’s journal for machines: Exploring the case of Cyberpunk 2077

With increasing technological capabilities, video games provide ever more expansive virtual worlds for players to explore. Designers employ various mechanics and level design principles to encourage such exploration. However, what motivates people to explore in virtual environments, and which approaches are successful, is not yet clearly established. Methods for measuring player experience often take place retroactively after a play session, relying on recall, and are thus prone to missing less salient events and their motivations. Journaling events as they occur allow promises to be a suitable method of collecting data, but presents a challenge in aggregating data points due to their freeform nature. This makes it difficult to identify overarching patterns of exploration behaviour. We present an exploratory study in devising a journaling protocol for gathering information during gameplay sessions, focused on documenting moments of exploration in a manner that balances ease of data capture and data evaluation. We describe our efforts in prototyping this journaling method and how we used it to analyse Cyberpunk 2077 and several other game designs. Our results show that exploration occurs in a pattern of event → expectation → resolution. The motivation to explore depends on the expectations that a game raises through its marketing and design. At the same time, exploratory behaviour going unrewarded by the game quickly reduces the desire to explore. When recording instances of exploration, the addition of emotion words is essential in order to properly contextualize the information. This article lays the foundation for documenting exploration in games, as well as other emotional or behavioural constructs that require in-the-moment data collection.

Patient-Specific Patch for an Intra-Atrial Rerouting Procedure Developed Through Surgical Simulation.

In pediatric cardiac surgery, an application of three-dimensional (3D) modeling to develop custom-made prostheses is limited, and currently surgeons use their intraoperative visual estimation to develop 3D complex structures from 2D patch materials. Contemporary 3D designers are developing complex surfaces using surface modeling in other industries, which can be applied to pediatric cardiac surgery. However, its free-form nature may lead to intradesigner variability. A patient with a body weight of 4 kg with partial anomalous pulmonary venous connection and preoperative computed tomography data was selected, and a patient-specific 3D heart model was obtained. Through collaboration with a pediatric cardiologist and a pediatric cardiac surgeon, a 3D designer developed two patient-specific 3D patches for an intra-atrial rerouting procedure (IAR) for the patient using different methods of surface modeling. The shape and size of two flattened patches were analyzed using a geometric morphometrics (GM) approach. Computational fluid dynamics (CFD) analysis was also performed to calculate pressure drop across streamlines and flow energy loss in the right atrium for both patches. The GM analysis showed that the size and shape of the two patches around the systemic vein orifice, crucial to prevent systemic venous obstruction, were almost equivalent. However, the CFD analysis showed that the pressure drop and flow energy loss were almost twice for one patch compared with the other. Our platform of developing a patient-specific 3D patch for an IAR procedure using surface modeling seemed promising, although intradesigner patch variability was not neglectable in our small-sized patient.

Augmenting the Patient Experience: Therapeutic Arts Interventions for Patients Undergoing Chemotherapy/Infusion

Introduction Intravenous infusions and chemotherapy can be a stressful and emotionally-draining process. Prior studies have examined patient perceptions of care and how to improve patient experience during this time. Art interventions have been performed to enhance the patient experience and reduce negative side effects. This patient-centered study investigated the process by which two distinct art modalities - reflective writing and tile painting -- alleviated patients' symptom burden. Methods Chemotherapy patients at The Comprehensive Cancer Center at The Miriam Hospital (Providence, RI) were invited to participate in a therapeutic activity of their choice during their infusions - either painting a wooden tile or engaging in a reflective writing activity. The tile painting consisted of free-form painting with either acrylic paints or pastels. The reflective writing activity consisted of guided or personal reflections on a variety of predefined prompts. Patients completed the Edmonton Symptom Assessment System (ESAS) immediately before and immediately after engaging in their chosen activity, allowing a direct within-subjects comparison of associated symptomatology. Patients also completed a qualitative survey, which allowed them to expand upon their experience in their own words, write recommendations, and reflect upon the process. The activity and surveys were standardized to 30 minutes duration. After the post-activity survey, patients were allowed to continue writing or painting if they so desired. Patients were encouraged to keep the art materials and journal for further therapeutic benefit. Results Twenty-six participants were included in data analysis, with 9 choosing to journal and 17 choosing to paint. In the painting group, there was a significant reduction in the following ESAS measures: tiredness (p = 0.021), anxiety (p = 0.013), shortness of breath (p = 0.016), and a marked increase in feelings of well-being (p = 0.002). In the reflective writing group, there was a significant reduction in anxiety (p = 0.05). Conclusion Overall, both tile painting and reflective writing initiatives resulted in improved patient experience and sense of wellness. The tile painting activity led to a greater number of improved symptoms, whereas reflective writing led to a singular reduction in anxiety, illustrating perhaps the different mechanisms by which these activities foster healing. The tile painting may have served to distract the patient from the gravity of the current illness; its free-form nature allowed participants to be creative with pleasant imagery of their choice, and finishing a work of art perhaps elicited a sense of accomplishment. In comparison, reflective writing may have allowed patients to process their experience of living with their illness and delve deeply into emotional states, fostering a sense of resilience and introspection. Taken together, the specific mechanisms by which these activities provide solace may explain the differential nature of these contrasting yet ultimately beneficial therapies. Disclosures No relevant conflicts of interest to declare.

Magnetically-doped polydimethylsiloxane for artificial muscle applications

Artificial muscle actuators demonstrate great potential for improving the quality of life. Recently, polymer muscle actuators have attracted attention due to their inexpensive and highly versatile methods of fabrication along with decent mechanical properties that can mimic those of natural muscles. The aim of this research is to investigate the usability of a magnetite-doped polymer powder, polydimethylsiloxane (PDMS), for artificial muscle actuators through an inexpensive method of production. PDMS samples doped with different levels of magnetite were fabricated using molds that were produced by additive manufacturing. Subsequently, the samples were magnetically and mechanically characterized by investigation of strength, elastic modulus, failure strain and permittivity, which are vital to meet the load capacity. The test results demonstrated that the mechanical and magnetic properties could be tailored as a function of doping level. Matching the mechanical response of these artificial components to those of artificial muscles will reduce the residual stresses, enhance the artificial muscle life and allow wider use of these materials for biomedical applications. This research rendered fabrication of molds possible for various applications where geometric customization of the actuator is required to meet endure severe loads, thanks to the freeform nature of additive manufacturing.

Logical Family: A Memoir by Armistead Maupin

Reviewed by: Logical Family: A Memoir by Armistead Maupin Robert Kellerman Armistead Maupin, Logical Family: A Memoir. New York: HarperCollins, 2017. Cloth, $27.99; paper, $16.99; e-book, $12.99. Fans of Armistead Maupin’s series of novels collectively known as Tales of the City will find much pleasure in his recent memoir, Logical Family. Like his fiction, it features the incisive characterization, candor, and psychological depth for which Maupin is best known, as well as some of the same wildly improbable plotlines drawn from his own life that have made his novels such compulsive reading. Maupin has met President Nixon, worked for Senator Jesse Helms, had a tour of duty in Vietnam, came out in San Francisco, and began writing the novels for which he is famous as newspaper columns with virtually no plan of how he was going bring the scheme off. Nobody knew, least of all Maupin himself, that these nine novels would become his life work and a mouthpiece for LGBTQ liberation for thousands of devoted readers worldwide. The book’s title is his own phrase, “logical family,” as opposed to “biological family”—that is, the people one chooses to have relationships with as opposed to those one has to by virtue of blood. Maupin is unflinchingly honest about his conservative biological family: his father and brother are distant; his Confederate grandfather looms large in his family mythology; but he finds refuge in his mother, sister, and grandmothers. Interesting as his family is, [End Page 92] his logical family is even more so, including the many people he met as he moved to San Francisco and began his writing career, as well as those he met because of his coming out and subsequent status as a gay public figure: actor Rock Hudson, for example, with whom he had an affair and, following that, a long friendship; actor Ian McKellen; artist Donald Bachardy and his partner, writer Christopher Isherwood. Presumably, Maupin sought to explore how his background created his need for a logical family, and the two subjects—his background and his logical family—do not always connect as clearly as they might. For instance, the chapter Maupin devotes to his stint in Vietnam is fascinating, but it is unclear exactly why its material is important to the larger narrative. There are odd omissions as well. For example, one wonders about his long-term partner Terry Anderson, who is barely mentioned, and about his husband Christopher Turner, who is mentioned often but with no great detail about their relationship: how they met, how their relationship developed, and so on. Given that these would presumably be some of the most important members of Maupin’s logical family, such omissions are puzzling. Perhaps the most surprising omission is one that many readers may be looking for: the development of the nine-novel fictional world he created. There is fascinating material about how the initial six-volume set of novels actually got started but not nearly as much on how it developed and was sustained over time, nor on the final three novels that pick up nearly twenty years after the first six left off. One familiar with his entire corpus might wish the connections between Maupin’s life and his fiction were more fully articulated. These, however, are minor quibbles. One of the attributes of a memoir is its free-form nature, allowing its writer to emphasize what he or she feels is important without necessary regard for logical narrative progression. Alert readers will see the seeds of his greatest character creation, Anna Madrigal, in his grandmother, and his main characters, Mary Ann Singleton and Michael Tolliver, as clearly aspects of his own personality as he came out in San Francisco as a young man: naïve, curious, hopeful, romantic. As his readers know, Maupin is a natural storyteller, and his stories are [End Page 93] well worth hearing. As a panorama of the LGBTQ movement filtered through one man’s experiences, the memoir is a wonderful success in social history. And, as always, Maupin’s humanity and warmth come shining through. As he writes about an intergenerational party of gay men, “This is how the camaraderie of...

Layout and sizing optimization of discrete truss based on continuum

A new method combined continuum topology with discrete truss is proposed for truss optimization. The optimized material distribution is obtained by means of continuum topology optimization and then transformed into initial truss. Based on the element principal stress and 8-neighborhood elements of continuum, force flow path extraction method is presented to obtain the initial truss layout. For section size optimization, criterion is deduced from a mathematical model by Lagrange multiplier method. Leveraging the free-form nature of continuum, this method can avoid the restriction of traditional ground structure. And it can achieve a better solution with less mass, smaller deformation and more uniform stress.

A specific hypoactivation of right temporo-parietal junction/posterior superior temporal sulcus in response to socially awkward situations in autism.

People with autism spectrum disorder (ASD) often have difficulty comprehending social situations in the complex, dynamic contexts encountered in the real world. To study the social brain under conditions which approximate naturalistic situations, we measured brain activity with FUNCTIONAL MAGNETIC RESONANCE IMAGING: while participants watched a full-length episode of the sitcom The Office. Having quantified the degree of social awkwardness at each moment of the episode, as judged by an independent sample of controls, we found that both individuals with ASD and control participants showed reliable activation of several brain regions commonly associated with social perception and cognition (e.g. those comprising the 'mentalizing network') during the more awkward moments. However, individuals with ASD showed less activity than controls in a region near right temporo-parietal junction (RTPJ) extending into the posterior end of the right superior temporal sulcus (RSTS). Further analyses suggested that, despite the free-form nature of the experimental design, this group difference was specific to this RTPJ/RSTS area of the mentalizing network; other regions of interest showed similar activity across groups with respect to both location and magnitude. These findings add support to a body of evidence suggesting that RTPJ/RSTS plays a special role in social processes across modalities and may function atypically in individuals with ASD navigating the social world.

Image-inspired 3D multiphoton excited fabrication of extracellular matrix structures by modulated raster scanning

Multiphoton excited photochemistry is a powerful 3D fabrication tool that produces sub-micron feature sizes. Here we exploit the freeform nature of the process to create models of the extracellular matrix (ECM) of several tissues, where the design blueprint is derived directly from high resolution optical microscopy images (e.g. fluorescence and Second Harmonic Generation). To achieve this goal, we implemented a new form of instrument control, termed modulated raster scanning, where rapid laser shuttering (10 MHz) is used to directly map the greyscale image data to the resulting protein concentration in the fabricated scaffold. Fidelity in terms of area coverage and relative concentration relative to the image data is ~95%. We compare the results to an STL approach, and find the new scheme provides significantly improved performance. We suggest the method will enable a variety of cell-matrix studies in cancer biology and also provide insight into generating scaffolds for tissue engineering.

Thermal Modeling of Direct Digital Melt-Deposition Processes

Additive manufacturing involves creating three-dimensional objects by depositing materials layer-by-layer. The freeform nature of the method permits the production of components with complex geometry. Deposition processes provide one more capability, which is the addition of multiple materials in a discrete manner to create “heterogeneous” objects with locally controlled composition. The result is direct digital manufacturing (DDM) by which dissimilar materials are added voxel-by-voxel (a voxel is volumetric pixel) following a predetermined tool-path. A typical example is functionally-graded material such as a gear with a tough core and a wear resistant surface. The inherent complexity of DDM processes is such that process modeling based on direct physics-based theory is difficult, especially due to a lack of temperature-dependent thermo-physical properties and particularly when dealing with melt-deposition processes. To overcome this difficulty the inverse problem approach is adopted to develop thermal models for multi-material, direct digital melt-deposition. This approach is based on the construction of a numerical-algorithmic framework for modeling anisotropic diffusivity such as that which would occur during energy deposition within a heterogeneous work-piece. This framework consists of path-weighted integral formulations of heat diffusion according to spatial variations in material composition and requires consideration of parameter sensitivity issues.

Thermal Modeling of Direct Digital Melt-Deposition Processes

Additive manufacturing involves creating three-dimensional (3D) objects by depositing materials layer-by-layer. The freeform nature of the method permits the production of components with complex geometry. Deposition processes provide one more capability, which is the addition of multiple materials in a discrete manner to create “heterogeneous” objects with locally controlled composition and microstructure. The result is direct digital manufacturing (DDM) by which dissimilar materials are added voxel-by-voxel (a voxel is volumetric pixel) following a predetermined tool-path. A typical example is functionally gradient material such as a gear with a tough core and a wear-resistant surface. The inherent complexity of DDM processes is such that process modeling based on direct physics-based theory is difficult, especially due to a lack of temperature-dependent thermophysical properties and particularly when dealing with melt-deposition processes. In order to overcome this difficulty, an inverse problem approach is proposed for the development of thermal models that can represent multi-material, direct digital melt deposition. This approach is based on the construction of a numerical-algorithmic framework for modeling anisotropic diffusivity such as that which would occur during energy deposition within a heterogeneous workpiece. This framework consists of path-weighted integral formulations of heat diffusion according to spatial variations in material composition and requires consideration of parameter sensitivity issues.

Variational Bayesian Filtering

The use of the variational Bayes (VB) approximation in Bayesian filtering is studied, both as a means to accelerate marginalized particle filtering and as a deterministic local (one-step) approximation. The VB method of approximation is reviewed, together with restrictions that allow various computational savings to be achieved. These variants provide a range of algorithms that can be used in a principled tradeoff between quality of approximation and computational cost. In combination with marginalized particle filtering, they generalize previously published work on variational filtering and extend currently available methods for speeding up stochastic approximations in Bayesian filtering. In particular, the free-form nature of the VB approximation allows optimal selection of moments which summarize the particles. Other Bayesian filtering schemes are developed by replacing the marginalization operator in Bayesian filtering with VB-marginals. This leads to further computational savings at the cost of quality of approximation. The performance of the various VB filtering schemes is illustrated in the context of a Gaussian model with a nonlinear substate, and a hidden Markov model.

Fast BlockMatching Registration with Entropy-based Similarity

This paper describes the implementation of a multidimensional block-matching nonrigid registration algorithm. The main features of the algorithm are its simplicity, its free form nature, the modularity of the similarity measure, which makes it possible using local entropy-based similarity measures and the avoidance of the optimization module. The algorithm implementation described in this paper is based on the method by Suarez et al. This paper, which has already been submitted to the Insight Journal, is accompanied with the source code, input data, parameters and output data used for validating the algorithm described in it.

Scaffold fabrication by indirect three-dimensional printing

Three-dimensional printing (3DP) has been employed to fabricate porous scaffolds by inkjet printing liquid binder droplets onto particulate matter. Direct 3DP, where the final scaffold materials are utilized during the actual 3DP process, imposes several limitations on the final scaffold structure. This study describes an indirect 3DP protocol, where molds are printed and the final materials are cast into the mold cavity to overcome the limitations of the direct technique. To evaluate the resolution available in this technique, scaffolds with villi features (500 μm diameter, 1 mm height) were produced by solvent casting into plaster molds, followed by particulate leaching. Scanning electron microscope (SEM) showed highly open, well interconnected, uniform pore architecture (∼100–150 μm). The ability of these scaffolds to support intestinal epithelial cell (IEC6) culture was investigated in vitro. IEC6 cells attached to scaffolds uniformly in vitro and grew preferentially in the villi region. To exploit the freeform nature of this technique with large pore size, anatomically shaped zygoma scaffolds with 300–500 μm interconnected pores were produced and characterized. Indirect 3DP provides an alternative method to complement other direct solid freeform fabrication methods.

Measuring Commercial Program SuiteComplexity

COBOL is a very widely-used computer language, even in the 1990s. Its age is reflected in the ease with which poor initial programming practices are possible, even though the language does allow correct structuring. This may be contrasted with those languages of more modern derivation, where encapsulation, abstraction and data-hiding capabilities encourage correct approached. A large burden of maintenance also comes with older and less welldocumented program suites. As more and more modifications are made, the spaghetti nature of its code can become emphasised. To avoid this difficulty, monitoring of the complexity of the code can give early warning of troubles to come. Complexity measurement has generally been undertaken in languages such as FORTRAN, as being more readily available, and more in their approach. A similar approach to a non- scientific language has not, so far as is known, been attempted. The apparently free-form nature of COBOL can, however, be analysed efficiently, and the measurements applied throughout suites of programs. The structure of programs written in ANSI Standard COBOL (1985) 2 is described. The measurement of complexity for individual programs written in COBOL is discussed. The alternatives available for appropriate evaluation of complexity are investigated. The extension of complexity measurements to a suite of associated programs is described. The requirements of meaningful results are evaluated, with the practical and commercial uses to which they may be put. The application of these metrics to an existing program suite are described, with the effects arising from their use. The conclusions relating to their effectiveness, and further refinements to be made, are given. Transactions on Information and Communications Technologies vol 8, © 1994 WIT Press, www.witpress.com, ISSN 1743-3517