Magnetically Deployable Robots Using Layered Lamina Emergent Mechanism

The steady rise of deployable structures and mechanisms based on kirigami and origami principles has brought about design innovations that yield flexible and lightweight robots. These robots are designed based on desirable locomotion mechanisms and often incorporate additional materials to support their flexible structure to enable load-bearing applications and considerable efficient movement. One tetherless way to actuate these robots is via the use of magnets. This paper incorporates magnetic actuation and kirigami structures based on the lamina emergent mechanism (LEM). Three designs of magnetic-actuated LEMs (triangular prism, single LEM (SLEM), alternating mirror dual LEM (AMDLEM)) are proposed, and small permanent magnets are attached to the structures’ flaps or legs that rotate in response to an Actuating Permanent Magnet (APM) to yield stick-slip locomotion, enabling the robots to waddle and crawl on a frictional surface. For preliminary characterization, we actuate the three designs at a frequency of 0.6 Hz. We observed the triangular prism, SLEM, and AMDLEM prototypes to achieve horizontal speeds of 4.3 mm/s, 10.7 mm/s, and 12.5 mm/s on flat surfaces, respectively. We further explore how changing different parameters (actuation frequency, friction, leg length, stiffness, compressibility) affects the locomotion of the different mechanisms.

Etnomatematika: Eksplorasi Uma Lengge Untuk Pembelajaran Matematika Di Sekolah

This research was conducted to explore the elements of mathematics (ethnomathematics) contained in the Uma Lengge building that is located in Bima, West Nusa Teggara (NTB), Indonesia. The research used a qualitative method with an ethnographic approach. The data were obtained from literature studies, observation, and documentation. Observation and documentation were used to identify and explore the elements of mathematics (ethnomathematics) contained in the Uma Lengge building, literature studies are used to find out more about the cultural values that exist in the uma lengge building as an application in learning mathematics. The results show elements of mathematics (ethnomathematics) in the uma lengge contain plane figure namely the concept of square, rectangle and triangle, concept of parallel and perpendicular lines, concept of geometry namely triangular prism and concept of similarity in triangle. The implication of this research is that the cultural elements contained in the uma lengge building can be used in mathematics learning applications in schools. Keywords: ethnomathematics, uma lengge, math learning

Asymptotics of sloshing eigenvalues for a triangular prism

We consider the three-dimensional sloshing problem on a triangular prism whose angles with the sloshing surface are of the form ${\pi}/{2q}$ , where q is an integer. We are interested in finding a two-term asymptotic expansion of the eigenvalue counting function. When both angles are ${\pi}/{4}$ , we compute the exact value of the second term. As for the general case, we conjecture an asymptotic expansion by constructing quasimodes for the problem and computing the counting function of the related quasi-eigenvalues. These quasimodes come from solutions of the sloping beach problem and correspond to two kinds of waves, edge waves and surface waves. We show that the quasi-eigenvalues are exponentially close to real eigenvalues of the sloshing problem. The asymptotic expansion of their counting function is closely related to a lattice counting problem inside a perturbed ellipse where the perturbation is in a sense random. The contribution of the angles can then be detected through that perturbation.

Research Part Surface Position Influence on Metal Removal and Steady-State Roughness During Vibro-Abrasive Processing

The paper is devoted to the study of part surface position and its influence on metal removal and steady-state rougness during vibro-abrasive processing. The article raises the differences between vibro-abrasive processing of external and internal part surfaces. Theoretical dependencies analysis for determination on part material removal and surface steady-state roughness is carried out. It is known that available theoretical dependencies do not take into account part surface position for material removal and the steady-state roughness calculation. Experimental researches to determine internal surface material removal with external surface isolation were carried out. The influence of part surface position on the steady-state roughness is investigated. Based on obtained experimental results, the dependence graphs of material removal and roughness on the processing time are constructed. The comparative analysis of the part surface position influence on material removal and the steady-state roughness during vibro-abrasive processing is carried out. The results showed that material removal volume from the internal surface more than from the external for short part length, however material removal volume from the external surfaces grows significantly in case of part length increasing, while from the internal surfaces is not significant. It is established that the internal surface steady-state roughness is ∼1.55 times higher than external surface steady-state roughness after processing in triangular prism 15×15, grit 16.

Shaping in the Third Direction; Synthesis of Patterned Colloidal Crystals by Polyester Fabric-Guided Self-Assembly

A polyester fabric with rectangular openings was used as a sacrificial template for the guiding of a sub-micron sphere (polystyrene (PS) and silica) aqueous colloid self-assembly process during evaporation as a patterned colloidal crystal (PCC). This simple process is also a robust one, being less sensitive to external parameters (ambient pressure, temperature, humidity, vibrations). The most interesting feature of the concave-shape-pattern unit cell (350 μm × 400 μm × 3 μm) of this crystal is the presence of triangular prisms at its border, each prism having a one-dimensional sphere array at its top edge. The high-quality ordered single layer found inside of each unit cell presents the super-prism effect and left-handed behavior. Wider yet elongated deposits with ordered walls and disordered top surfaces were formed under the fabric knots. Rectangular patterning was obtained even for 20 μm PS spheres. Polyester fabrics with other opening geometries and sizes (~300–1000 μm) or with higher fiber elasticity also allowed the formation of similar PCCs, some having curved prismatic walls. A higher colloid concentration (10–20%) induces the formation of thicker walls with fiber-negative replica morphology. Additionally, thick-wall PCCs (~100 μm) with semi-cylindrical morphology were obtained using SiO2 sub-microspheres and a wavy fabric. The colloidal pattern was used as a lithographic mask for natural lithography and as a template for the synthesis of triangular-prism-shaped inverted opals.

Albert Ladenburg (1842-1911) – The Distinguished German Chemist and Historian of Chemistry of the Second Half of the XIX Century (To the 110th Anniversary of His Death)

Albert Ladenburg (1842-1911) was an outstanding German chemist and historian of chemistry of the second half of the 19th century. He ascertained the formula of ozone as O3 and proposed a triangular prism structure for the molecule of benzene. He studied the structure of aromatic hydrocarbons and organic compounds of silicon and tin, and devoted his work to explaining the structure of alkaloids and their synthesis. The purpose of this paper is to familiarize readers with the important events in the life of Ladenburg and his writing and research activities, in particular some of his experimental results, as well as his selected publications.

Micropatterned Fibrous Scaffold Produced by Using Template-Assisted Electrospinning Technique for Wound Healing Application

This paper describes the fabrication of a structural scaffold consisting of both randomly oriented nanofibers and triangular prism patterns on the scaffold surface using a combination technique of electrospinning and collector templates. The polycaprolactone (PCL) nanofibers were electrospun over a triangular prism pattern mold, which acted as a template. The deposited scaffold was removed from the template to produce a standalone structural scaffold of three-dimensional micropatterned nanofibers. The fabricated structural scaffold was compared with flat randomly oriented nanofibers based on in vitro and in vivo studies. The in vitro study indicated that the structural scaffold demonstrated higher fibroblast cell proliferation, cell elongation with a 13.48 ± 2.73 aspect ratio and 70% fibroblast cell orientation compared with flat random nanofibers. Among the treatment groups, the structural scaffold escalated the wound closure to 92.17% on day 14. Histological staining of the healed wound area demonstrated that the structural scaffold exhibited advanced epithelization of the epidermal layer accompanied by mild inflammation. The proliferated fibroblast cells and collagen fibers in the structural scaffold appeared denser and arranged more horizontally. These results determined the potential of micropatterned scaffolds for stimulating cell behavior and their application for wound healing.