Behavior of oil-based modeling clay at medium strain rates

The modeling clay is an oil-based soft, flowable, and pliable material made from waxes and oils. Besides its primary use for making sculptures, the modeling clay is commonly used to evaluate bulletproof vests and simulate metal manufacturing processes by conformation. In ballistic tests, the clay is used to retain the deformation of the rear face of body armors; and in the study of metal forming processes, it is used as a physical model to provide information on the plastic flow. However, its mechanical dynamic behavior is not entirely understood. In this study, Plastilina Roma No. 1 modeling clay was mechanically characterized using the power-law constitutive model at medium strain rates [Formula: see text]. The material parameters were determined using a penetration model based on the Cavity Expansion Theory and an inverse technique involving the comparison of the model with experimentation. The optimum set of constitutive parameters was found by reducing the difference of the calculated penetration profile and the measurements from a drop test. This optimization process was programmed on the MATLAB–Simulink environment. The determined material parameters were validated by comparing the results from a computational model with three test set-ups. Finite element model results show good concordance with experimental measurements.

Who said that we do not see? An inclusion strategy for students with visual impairment using cell models and a modeling-clay-based evaluation method

Currently, there is a great need for inclusive practices and materials for visually impaired students (SVIs), especially from Biology. Thus, we developed two-dimensional (2D) and three-dimensional (3D) didactic models about cytology as well as a modeling-clay-based evaluation method. The two-dimensional tactile atlas included the representation of organelles with an explanatory text in two formats (written and Braille), whereas the 3D human cell model was made with a colorful polymer clay pasta. These models were tested by students of public schools, with and without visual impairment as well as by teachers of science/biology. Their perceptions were analyzed by using questionnaires, whereas the modeling clay-based evaluation method was used with the SVIs to identify their level of understanding about the cellular structures presented to them. According to all participants including SVIs, both materials facilitated the understanding of cell organelles. Interestingly, the modeling clay-based evaluation method confirmed that this blind audience could see (distinguish) as many details as those who have no visual impairment. Our results strengthen the fact that this blind public depends on the accessibility level that, apparently, is offered by our 2D and 3D models to them. In agreement with that conclusion, all teachers pointed this strategy as helpful to this public especially during teaching these overly complex topics.

Techniques of hollow maxillary dentures: a literature review

Clinically, the management of severy atrophic maxilla might represent a significant challenge for the attending dentists and surgeons to successfully perform and achieve fabricated complete maxillary dentures. Making a hollow denture base for these defects has also been previously reported as a valid approach that can be used to decrease the weight of the maxillary prosthesis. Many modalities have been proposed for these procedures with favorable outcomes, and variable events of disadvantages and adverse events. This literature review aims to collect enough evidence regarding the different reported techniques of the hollow maxillary denture, according to the different studies. Many techniques have been previously reported as using magnets, using implants, intramucosal inserts, springs, suction disks, lightweight dentures, and modified impression techniques. Many materials have been previously used with the 3D spacers of the lightweight denture techniques as dental stone, silicon putty, cellophane-wrapped asbestos, light-body coated gauze, modeling clay, salt, thermocol, caramel, and glycerine soap. Favoring one of the modalities over the other requires the inauguration of future studies with an adequate sample size to validate the efficacy and safety of these modalities. All of this information is furtherly discussed within the manuscript based on the collected evidence from the different studies in the literature.

STEAM Learning in Public Libraries: A “Guide on the Side” Approach for Inclusive Learning

Children and their families are practicing STEAM (Science, Technology, Engineering, Arts, and Math) skills through a library program. Hand-crank generators and LED bulbs are set out on each of the tables, along with two types of dough—conductive play dough and insulating modeling clay.

Expanding the Teaching of Single Frequency Vibration Absorption to Broadband Attenuation using Subordinate Oscillator Arrays via Fettuccine Pasta

Dynamic vibration absorbers (DVAs) and tuned mass-dampers (TVAs) have wide-spread applications in the aerospace industry, the automotive sector, and in civil engineering structures. There are numerous designs of active and passive vibration attenuators or absorbers that isolate structural vibrations at or around the desired frequency. All these design approaches are fundamentally different ways to modify and tune the placement of the resonant frequencies of the host structure. The current work presents a novel method to passively attenuate vibration over a broad frequency bandwidth in the presence of uncertainty. An array of linear oscillators, also referred to as subordinate oscillator arrays (SOAs), are attached to a two-degrees-of-freedom structure to produce an attenuated broadband frequency response around a target frequency. SOAs can also be interpreted as an array of DVAs and in some categories, they can be considered as an approach to meta-structures. Another objective of the current work is to develop a hands-on approach to extend classroom teaching of vibration-isolation using SOAs made out of fettuccine strands and modeling clay. The frequencies of the oscillators in the array are tuned by varying the length of each strand and the mass of the modeling clay attached to its tip. Uncertainty in dynamic properties of such oscillators often results in mistuned SOAs with non-uniform frequency response function. Therefore, designing and testing fettuccine-based SOAs allows students to handle cases when structural uncertainties arise in engineering systems. Additionally, some of the work in the field of meta-structures can be modeled and represented by SOAs and this will provide a straight forward way to teach students some of these contemporary concepts.

An Affordable Knee Arthroscopy Simulator

Introduction: The objective of this study is to describe a model of knee arthroscopy simulator that is affordable, low-cost and easily reproducible, aiming to enable the diffusion of more effective active teaching and training methodologies. Methods: For the creation of the arthroscopic camera, an endoscopic camera for mobile phones and computers model SXT-5.0M manufactured by KKMOON were used. The camera was introduced in a metal tube, which was coupled to a set of three 20 mm PVC hydraulic connectors to simulate the handle and sleeve of the arthroscope. The camera has a resolution of 1280 x 720 pixels and is equipped with six built-in white LED lamps, simulating and eliminating the need to use an additional light source. The knee model was developed using a PVC pipe fixed on a wooden support, to which synthetic femur and tibia models were affixed. Four three-centimeter diameter holes, compatible with the standard arthroscopic portals, were made in the body of the PVC pipe. For the menisci, a model was made out of modeling clay (Corfix®), until the anatomical structures were close to the real ones. The model consists of both menisci and the intercondylar eminence, simulating the proximal tibial articular surface. The model made out of modeling clay was the basis for the production of a thin Crystal Polyester Resin mold. Using the resin mold, the meniscal models were made of Silicone Rubber Type II, widely used in industry and crafts. Results: A functional and reproducible simulator was obtained, consisting of a knee model and an arthroscopic camera. The simulator works adequately adapted to a TV, monitor or computer, and allows the simulation of diagnostic procedures, meniscectomy and meniscoplasty. Conclusion: It is possible to develop a knee arthroscopy simulator, with components available in local and electronic commerce, at a cost of approximately R$ 300.

Prophylactic Treatments of Cycas Stem Wounds Influence Vegetative Propagation

Cycad stem cuttings will develop adventitious roots if the open wound is first treated with a sealant to protect the exposed parenchyma tissue. The commercial pruning wound sealant that is often employed for this purpose is not available in many locations. We used commonly available products as a prophylactic sealant on Cycas edentata , Cycas micronesica , and Cycas nitida cuttings to determine efficacy for sealing the wound and enabling adventitious root formation. Success was quantified after 7 months in a sand propagation substrate. Mortality was 100% for control cuttings with no wound sealant and about 60% for cuttings with candle wax as the sealant. Cuttings that received petroleum jelly, lanolin paste, modeling clay, honeycomb wax, or commercial pruning sealant exhibited 100% survival. Success in adventitious root formation ranged from 75% to 92% among the five successful prophylactic treatments and did not differ among the species. The results indicated that four of the products we evaluated were as effective as commercial pruning sealant for treating the exposed parenchyma on Cycas stem cuttings and enabling asexual propagation success. The candle wax was less effective because it was brittle and cracked to expose the stem’s parenchyma tissue.

Um Simulador de Artroscopia de Joelho Acessível

Introduction: The objective of this study is to describe a model of knee arthroscopy simulator that is affordable, low-cost and easily reproducible, aiming to enable the diffusion of more effective active teaching and training methodologies. Methods: For the creation of the arthroscopic camera, an endoscopic camera for mobile phones and computers model SXT-5.0M manufactured by KKMOON were used. The camera was introduced in a metal tube, which was coupled to a set of three 20 mm PVC hydraulic connectors to simulate the handle and sleeve of the arthroscope. The camera has a resolution of 1280 x 720 pixels and is equipped with six built-in white LED lamps, simulating and eliminating the need to use an additional light source. The knee model was developed using a PVC pipe fixed on a wooden support, to which synthetic femur and tibia models were affixed. Four three-centimeter diameter holes, compatible with the standard arthroscopic portals, were made in the body of the PVC pipe. For the menisci, a model was made out of modeling clay (Corfix®), until the anatomical structures were close to the real ones. The model consists of both menisci and the intercondylar eminence, simulating the proximal tibial articular surface. The model made out of modeling clay was the basis for the production of a thin Crystal Polyester Resin mold. Using the resin mold, the meniscal models were made of Silicone Rubber Type II, widely used in industry and crafts. Results: A functional and reproducible simulator was obtained, consisting of a knee model and an arthroscopic camera. The simulator works adequately adapted to a TV, monitor or computer, and allows the simulation of diagnostic procedures, meniscectomy and meniscoplasty. Conclusion: It is possible to develop a knee arthroscopy simulator, with components available in local and electronic commerce, at a cost of approximately R$ 300.