Detailed Assembly Research Articles

Design of a metal additive manufactured aircraft seat leg using topology optimization and part decomposition

PurposeThe lightweight design of aircraft seats can significantly improve fuel efficiency and reduce greenhouse gas emissions. Metal additive manufacturing (MAM) can produce lightweight topology-optimized designs with improved performance, but limited build volume restricts the printing of large components. The purpose of this paper is to design a lightweight aircraft seat leg structure using topology optimization (TO) and MAM with build volume restrictions, while satisfying structural airworthiness certification requirements.Design/methodology/approachTO was used to determine a lightweight conceptual design for the seat leg structure. The conceptual design was decomposed to meet the machine build volume, a detailed CAD assembly was designed and print orientation was selected for each component. Static and dynamic verification was performed, the design was updated to meet the structural requirements and a prototype was manufactured.FindingsThe final topology-optimized seat leg structure was decomposed into three parts, yielding a 57% reduction in the number of parts compared to a reference design. In addition, the design achieved an 8.5% mass reduction while satisfying structural requirements for airworthiness certification.Originality/valueTo the best of the authors’ knowledge, this study is the first paper to design an aircraft seat leg structure manufactured with MAM using a rigorous TO approach. The resultant design reduces mass and part count compared to a reference design and is verified with respect to real-world aircraft certification requirements.

MouseVUER: video based open-source system for laboratory mouse home-cage monitoring

Video monitoring of mice in the home-cage reveals behavior profiles without the disruptions caused by specialized test setups and makes it possible to quantify changes in behavior patterns continually over long time frames. Several commercial home-cage monitoring systems are available with varying costs and capabilities; however there are currently no open-source systems for home-cage monitoring. We present an open-source system for top-down video monitoring of research mice in a slightly modified home-cage. The system is designed for integration with Allentown NexGen ventilated racks and allows unobstructed view of up to three mice, but can also be operated outside the rack. The system has an easy to duplicate and assemble home-cage design along with a video acquisition solution. The system utilizes a depth video camera, and we demonstrate the robustness of depth video for home-cage mice monitoring. For researchers without access to Allentown NexGen ventilated racks, we provide designs and assembly instructions for a standalone non-ventilated rack solution that holds three systems for more compact and efficient housing. We make all the design files, along with detailed assembly and installation instructions, available on the project webpage (https://github.com/NIH-CIT-OIR-SPIS/MouseVUER).

A 3D printed plant model for accurate and reliable 3D plant phenotyping.

This study addresses the importance of precise referencing in 3-dimensional (3D) plant phenotyping, which is crucial for advancing plant breeding and improving crop production. Traditionally, reference data in plant phenotyping rely on invasive methods. Recent advancements in 3D sensing technologies offer the possibility to collect parameters that cannot be referenced by manual measurements. This work focuses on evaluating a 3D printed sugar beet plant model as a referencing tool. Fused deposition modeling has turned out to be a suitable 3D printing technique for creating reference objects in 3D plant phenotyping. Production deviations of the created reference model were in a low and acceptable range. We were able to achieve deviations ranging from -10 mm to +5 mm. In parallel, we demonstrated a high-dimensional stability of the reference model, reaching only ±4 mm deformation over the course of 1 year. Detailed print files, assembly descriptions, and benchmark parameters are provided, facilitating replication and benefiting the research community. Consumer-grade 3D printing was utilized to create a stable and reproducible 3D reference model of a sugar beet plant, addressing challenges in referencing morphological parameters in 3D plant phenotyping. The reference model is applicable in 3 demonstrated use cases: evaluating and comparing 3D sensor systems, investigating the potential accuracy of parameter extraction algorithms, and continuously monitoring these algorithms in practical experiments in greenhouse and field experiments. Using this approach, it is possible to monitor the extraction of a nonverifiable parameter and create reference data. The process serves as a model for developing reference models for other agricultural crops.

Projectile seating depth influence on a small arms cartridge performance

In the world of small-arms ammunition, precision reigns supreme. The most significant feature of ammunition for shooters is undoubtedly the repeatability from one shot to the next. This study explores the detailed assembly process of small arms cartridges, leveraging modern machinery and innovative designs employed by cartridge manufacturers. It emphasizes how these tools ensure the fundamental repeatability and precision necessary for the quality of each batch of rounds. Establishing standards for the highest possible quality requires assessing the impact of imprecise cartridge assembly on ballistic performance. Utilizing a free-flight ballistic tunnel, a high-speed camera, light- and target-screen systems, the authors analyzed the effects of varying projectile seating depths thus affecting cartridge overall lengths (COAL) and cartridge base to ogive distance (CBTO) on the initial velocity and bullets’ point of impact at 50 meters. The study was conducted for two types of projectiles, differing in their ogive profiles: secant and tangent ogive. The performance differences between these profiles provided valuable insights for future projectile designs, highlighting that low-drag projectiles are slightly more sensitive to the seating depth than tangent profile bullets, and the importance of it should be considered in mass, military production as well. It is a valuable resource for analyzing the trade-off between producing bullets with a low drag coefficient and ensuring high precision. The research enhances the understanding of internal and external ballistics but most importantly draws attention to the importance of the standards of assembly processes to ensure optimal performance and safety in the field.

Electrolyte‐Controlled Permeability in Nanocellulose‐Stabilized Emulsions

AbstractParticle‐stabilized emulsions, so‐called Pickering emulsions (PEs), are a promising low‐tech avenue to precisely engineered materials for applications in drug delivery, catalysis, or water remediation. The particle assembly at the liquid–liquid interface provides superior stability and an adjustable permeability, which is a key parameter for controllable compound capture and release. However, understanding the complex factors that control the particle assembly in detail is a still‐remaining challenge limiting practical applications of PEs in an industrial framework. In this study, the properties of oil‐in‐water emulsions, stabilized by cellulose nanocrystals (CNCs), are investigated. It is shown how high ionic strength leads to low polydispersity droplets, with restricted permeability across the oil‐water interface due to the dense packing of the CNC layer. In contrast, lower electrolyte concentration enables enhanced uptake through the interface, while providing the required stability for the reusability of the material. The authors continue to study the impact of the electrolyte content on the dynamic responses of the emulsions, leading to a liquid–liquid system with tunable cyclic uptake and release levels. Overall, the results highlight the potential of nanocellulose‐stabilized emulsions as tunable and robust material platform with well‐defined permeability characteristics—made in a simple way.

A modular surgical simulator for microlaryngoscopy using standard instruments and the carbon dioxide laser.

ObjectiveBuild a microlaryngoscopy surgical simulator for endoscopic laryngeal surgery using standard microsurgical instruments and a CO2 laser.Study designAnatomical modeling, CAD design and 3D printed manufacturing.Subjects and methodsWe created a modular design for a microlaryngoscopy simulator in CAD software. Components include plastic and stainless‐steel models of a standard operating laryngoscope and a cassette system for mounting porcine or synthetic models of the vocal folds. All simulator parts, including the metallic laryngoscope model, were manufactured using 3D printing technology. Tumors were simulated in porcine tissue models by injecting a soy protein‐based tumor phantom. Residents and faculty in the Louisiana State University otolaryngology department evaluated the system. Each participant performed microlaryngoscopy with laser resection on a porcine larynx and cold instrument procedures on synthetic vocal folds. Participants scored the simulator using a 5‐point Likert scale.ResultsThe microlaryngeal surgical simulator demonstrated in this project is realistic, economical, and easily assembled. We have included 3D printed parts files and detailed assembly instructions that will enable educators interested in surgical simulation to build the device.Participants in the simulator evaluation session felt that the simulator faithfully represented the procedure to resect vocal fold lesions using a CO2 laser. The synthetic model allows the trainee to develop hand‐eye coordination while using standard laryngeal instruments.ConclusionsThe simulator described herein will enable surgeons to acquire the surgical skills necessary to perform operative microlaryngoscopy prior to operating on live patients.

Activity and weight ratios of cesium, uranium, plutonium, and curium isotopes based on elaborate inventory calculations of Fukushima Dai-ichi NPP units 1 to 3

ABSTRACT For the reactor cores just before the accident of Fukushima Dai-ichi NPP (FDNPP) units 1 to 3, the core average activity ratios of 134Cs/137Cs, 238Pu/(239Pu+240Pu), and 242Cm/(243Cm+244Cm) and the weight ratios of 235U/238U, 240Pu/239Pu, and 241Pu/239Pu were evaluated applying the nuclide inventories calculated with CASMO5 based on the detailed assembly specifications and the assembly-axial burnup histories and correcting the calculated inventories with the biases of the inventory calculations. The obtained activity and weight ratios were compared with those evaluated with the preceding inventory calculations with ORIGEN2.2. The present 134Cs/137Cs activity ratios were smaller by 3% to 5% than those with ORIGEN2.2. The measured results of the activity and weight ratios in the samples taken from the contaminated water in the plant facilities and the soil, dust, and others inside and outside of FDNPP were distributed around the calculated core average values, while some of them were deviated from them. The 240Pu/239Pu weight ratios can be used to distinguish the radioactive materials originating from unit 2 from those from unit 3 assuming that the measured results represent the core average values.

Assembly mechanism of the pleomorphic immature poxvirus scaffold

In Vaccinia virus (VACV), the prototype poxvirus, scaffold protein D13 forms a honeycomb-like lattice on the viral membrane that results in formation of the pleomorphic immature virion (IV). The structure of D13 is similar to those of major capsid proteins that readily form icosahedral capsids in nucleocytoplasmic large DNA viruses (NCLDVs). However, the detailed assembly mechanism of the nonicosahedral poxvirus scaffold has never been understood. Here we show the cryo-EM structures of the D13 trimer and scaffold intermediates produced in vitro. The structures reveal that the displacement of the short N-terminal α-helix is critical for initiation of D13 self-assembly. The continuous curvature of the IV is mediated by electrostatic interactions that induce torsion between trimers. The assembly mechanism explains the semiordered capsid-like arrangement of D13 that is distinct from icosahedral NCLDVs. Our structures explain how a single protein can self-assemble into different capsid morphologies and represent a local exception to the universal Caspar-Klug theory of quasi-equivalence.

Distinctive Adsorption Mechanism and Kinetics of Immunoglobulin G on a Nanoscale Polymer Surface.

Elucidation of protein adsorption beyond simple polymer surfaces to those presenting greater chemical complexity and nanoscopic features is critical to developing well-controlled nanobiomaterials and nanobiosensors. In this study, we repeatedly and faithfully track individual proteins on the same nanodomain areas of a block copolymer (BCP) surface and monitor the adsorption and assembly behavior of a model protein, immunoglobulin G (IgG), over time into a tight surface-packed structure. With discrete protein adsorption events unambiguously visualized at the biomolecular level, the detailed assembly and packing states of IgG on the BCP nanodomain surface are subsequently correlated to various regimes of IgG adsorption kinetic plots. Intriguing features, entirely different from those observed from macroscopic homopolymer templates, are identified from the IgG adsorption isotherms on the nanoscale, chemically varying BCP surface. They include the presence of two Langmuir-like adsorption segments and a nonmonotonic regime in the adsorption plot. Via correlation to time-corresponding topographic data, the unique isotherm features are explained with single biomolecule level details of the IgG adsorption pathway on the BCP. This work not only provides much needed, direct experimental evidence for time-resolved, single protein level, adsorption events on nanoscale polymer surfaces but also signifies mutual linking between specific topographic states of protein adsorption and assembly to particular segments of adsorption isotherms. From the fundamental research viewpoint, the correlative ability to examine the nanoscopic surface organizations of individual proteins and their local as well as global adsorption kinetic profiles will be highly valuable for accurately determining protein assembly mechanisms and interpreting protein adsorption kinetics on nanoscale surfaces. Application-wise, such knowledge will also be important for fundamentally guiding the design and development of biomaterials and biomedical devices that exploit nanoscale polymer architectures.

Synthetic Assembly DNA Cloning of Multiplex Hextuple Luciferase Reporter Plasmids.

Multiplex hextuple luciferase assaying allows monitoring the activity of five experimental pathways against one control at the same time. To perform multiplex hextuple luciferase assaying, six orthogonal luciferase reporter units are needed of which five are pathway-specific and one acts as a control for normalization. To ensure stoichiometric delivery of all six luciferase reporters in every transfected cell, synthetic assembly DNA cloning is used to stitch together all six luciferase reporter units into a single vector. Here, we provide a detailed three-step synthetic assembly DNA protocol to generate multiplex hextuple luciferase reporter plasmids for any five cellular signaling pathways of interest, against a control normalization pathway. A first protocol is provided on how to generate plasmids that contain novel transcription factor-binding motifs for specific transcription factors. A second protocol details on how to couple these novel transcription factor-binding motifs to one of five orthogonal luciferases to obtain specific luciferase reporters for cellular signaling pathways acting upstream of those transcription factor-binding motifs. Finally, a third protocol provides details on how to assemble orthogonal luciferase reporters for five cellular signaling pathways acting upstream of five unique transcription factor-binding motifs together with a control constitutive pathway luciferase reporter that will be used for normalization to obtain a final multiplex hextuple luciferase vector.

Study of Relationships between Ceiling Smoke Leakage Rate and Evacuation Time in the Ward.

With reference to the requirements of CNS 15038 and testing principles, this study proposes a set of equipment for measuring the leakage volume of ceilings and provides detailed assembly specifications for future users. In this study, a total of 405 tests were conducted as part of a set of experiments for measuring the leakage volume of ceilings, using various ceiling materials, ceiling sizes, and construction methods, in conjunction with the principles of fluid mechanics, to propose a method for evaluating the leakage volume of ceilings of various sizes and materials. Two cases—bottom-up airflow and top-down airflow—were considered. According to our research findings, in the case of bottom-up airflow, the pressure difference, panel weight, and panel size were correlated with the leakage volume; the more significant the pressure difference, the larger the leakage volume; the heavier the panel weight, the more minor the leakage volume; and the larger the panel size, the more significant the leakage volume. On the other hand, in the case of top-down airflow, different leakage volumes were observed for different ceiling materials, even if the ceiling size was identical. On the other hand, when the ceiling material was the same, and the ceiling size was different, there was not a positive relationship between the leakage volume and a larger panel size; instead, the leakage volume observed for the largest panel was the smallest. Finally, in this study we propose a volumetric leakage assessment table for assessing a ceiling as a whole, which can be utilized by engineers in the future to calculate the smoke leakage value and to estimate the smoke fall time for ward escape designs.

Unique Optical Periodicity Assembly of Discrete Dendritic Lamellae and Pyramidal Single Crystals in Poly(ε-caprolactone).

A unique zig-zag banded morphology poly(ε-caprolactone) (PCL), crystallized at high Tc = 46-47 °C and confined in thin films (<1 μm), is found to be assembled of parallel cogrowth of two totally crystal entities: edge-on dendritic lamellar protrusion from surfaces and flat-on pyramidal single crystals. The alternating PCL optical bands are assembled as flat-on single crystals aligned as straight dendrites as a valley band in series with edge-on branches as a ridge band, leading to a unique assembly mechanism of periodic optical rings where these two crystal pieces are assembled in series. Detailed assembly mechanisms are proposed to explain how the composite bands in the PCL aggregates are correlated to optical birefringence periodicity. By techniques of melt crystallization via periodic species drainage, PCL single crystals could be prepared and tailor-made to a variety of nanopatterns as templates for applications.

Development and testing of an all-additively manufactured hybrid thruster for smallsats

Background: The design, development, and testing of a small-thruster system with additively-manufacturing key components is presented. The primary issue associated with conventionally-manufactured small thruster systems is the assembly complexity, where the motor case, injector, ignition electrodes, nozzle retainer, nozzle, fuel grain, insulting liner, and other components are fabricated individually and then assembled. For very small thruster systems, this detailed fabrication and assembly process is extremely labor intensive and time-consuming. Proposed "all- additive" designs reduce component fabrication and procurement cycle time, and may significantly reduce overall system complexity. Before committing to hardware, a student-lead design team reduced the trade-space to 2 design-options. Each option employs multiple additively-manufactured components including the oxidizer delivery system attachments, motor cap, motor casing, insulation, and the fuel grain. Components are additively manufactured using one of three different methods, fused-deposition modeling (FDM), stereo lithography (SL), and non-galvanic nickel plating (EN). Both designs feature an FDM-fabricated ABS fuel grain, with 1) a two material combustion chamber assembly fabricated from Veroclear® plastic using Polyjet 3-D SL printing technology, and 2) a chamber/fuel assembly additively fabricated from ABS, but plated with an external nickel coating. For simplicity the student prototype employs gaseous oxygen (GOX) and additively manufactured acrylonitrile-butadiene-styrene (ABS) as propellants. ABS has been previously demonstrated to be a highly efficient hybrid fuel material. The research campaign emphasized multiple objectives including hot and cold material testing burn lifetime survivability, system restart capability, and overall performance. Performance comparisons with hydrazine are presented.

Highly contiguous assemblies of 101 drosophilid genomes.

Over 100 years of studies in Drosophila melanogaster and related species in the genus Drosophila have facilitated key discoveries in genetics, genomics, and evolution. While high-quality genome assemblies exist for several species in this group, they only encompass a small fraction of the genus. Recent advances in long-read sequencing allow high-quality genome assemblies for tens or even hundreds of species to be efficiently generated. Here, we utilize Oxford Nanopore sequencing to build an open community resource of genome assemblies for 101 lines of 93 drosophilid species encompassing 14 species groups and 35 sub-groups. The genomes are highly contiguous and complete, with an average contig N50 of 10.5 Mb and greater than 97% BUSCO completeness in 97/101 assemblies. We show that Nanopore-based assemblies are highly accurate in coding regions, particularly with respect to coding insertions and deletions. These assemblies, along with a detailed laboratory protocol and assembly pipelines, are released as a public resource and will serve as a starting point for addressing broad questions of genetics, ecology, and evolution at the scale of hundreds of species.

Self-contained and modular structured illumination microscope.

We present a modular implementation of structured illumination microscopy (SIM) that is fast, largely self-contained and that can be added onto existing fluorescence microscopes. Our strategy, which we call HIT-SIM, can theoretically deliver well over 50 super-resolved images per second and is readily compatible with existing acquisition software packages. We provide a full technical package consisting of schematics, a list of components and an alignment scheme that provides detailed specifications and assembly instructions. We illustrate the performance of the instrument by imaging optically large samples containing sequence-specifically stained DNA fragments.

Different community assembly of ground beetles and spiders in subalpine forests and alpine scoria deserts of a young volcano, Mt. Fuji

AbstractWhile the colonization processes of arthropods in new volcanoes have attracted our attention, the arthropod assembly process in sites where vegetation reaches climax forests after the Holocene catastrophic eruption is unknown. In this study, ground beetles and spiders were investigated using pitfall traps in 12 sites from the subalpine and alpine areas of Mt. Fuji, which were shaped about 2300 years ago and where undisturbed subalpine climax forests and alpine deserts are formed. We examined how elevation, canopy and forest floor vegetation affected turnover and nestedness structure of these assemblages. The alpine desert and subalpine forest comprised different species for both beetles and spiders. The species from the alpine desert seemed to have high dispersal ability. In the subalpine forest, the beetle assemblage found at higher elevations was a subset of those at lower elevations. This nested structure was generated by the expansion of flightless species from montane forests to subalpine forests. Species tolerance to harsh weather conditions may decide the upper elevational limit. The spider assemblage was affected by forest floor vegetation, where species turnover was observed between different floor types. Subalpine spiders included both species expanding from the montane area and those probably colonizing from distant subalpine areas by ballooning. These results suggest that the assembly process differed between alpine and subalpine areas, and also between different taxa particularly in subalpine forests. Examining the genetic relationship between Mt. Fuji populations and possible source populations in other mountains will elucidate the detailed community assembly process in Mt. Fuji.

Periodic crystal assembly of Poly(3-hydroxybutyric acid-co-3-hydroxyvaleric acid): From surface to interior microstructure

Poly(3-hydroxybutyric acid-co-3-hydroxyl-valeric acid) (PHBV) crystallized in the presence of a polymeric diluent impurity is analyzed at specific crystallization temperatures (Tc) from 60 °C to 80 °C. 3D-dissected interior analysis for ring-banded spherulites evidently reveals that the alternate bands exist in not only top surface but also 3D interiors composted of grating-assembled lamellae. Aggregation of the lamellae, initially from two ends of nucleus sheaf-bundles, packs via crystal-by-crystal mode into either Archimedean single-spirals or Fermat's double-spirals, which constitute the “ridge” bands. Then from the ridge-band lamellae, secondary lamellae then branch out at 60–80° oblique angles, with irregular bending, twisting, or scrolling to accommodate in the confined space, to form the “valley” bands. Each new growth cycle repeats the fractal patterns of previous one. The periodic cycles repeat themselves in a fractal fashion to form a cross-lamellar structure, with “crossbar pitch” equal to its optical band spacing. Periodicity of aggregation in top surface and interior is depicted in detailed 3D assembly, beyond and distinguished from conventional planar analytical approaches, for novel mechanisms.

User‐centered development of a worker guidance system for a flexible production line

AbstractWorker guidance systems are digital assistance systems in production, which provide work‐related information and, thus, guide employees through production processes. This article describes the user‐centered development of such a worker guidance system for a flexible production line in a metrology company. Usage context analysis and requirements analysis illustrate the need for a simple and independent system that can be used voluntarily by employees. After two iterations of the human‐centered design process, an interactive software prototype was created and implemented on a tablet personal computer. In this prototype, all essential process and assembly information in the flexible production line is available to the employees in the form of text descriptions and pictures as step‐by‐step instructions, which can be selected via two‐step navigation. The final evaluation was conducted as a user study with N = 10 assembly workers in the flexible production line under realistic conditions and was also intended to find out at which level of detail the information should be displayed in the system. The system scored well on the system usability scale (between 65.8 and 70.8) and concerning acceptance. Using the worker guidance system, no assembly faults occurred during the user study. Due to the significantly shorter assembly time, but no further significant differences, it was decided to set up the less detailed assembly information as a standard in the system. However, employees can call up more detailed information, if necessary. This system will be used by the company in the future.

Peat-based gnotobiotic plant growth systems for Arabidopsis microbiome research.

The complex structure and function of a plant microbiome are driven by many variables, including the environment, microbe-microbe interactions and host factors. Likewise, resident microbiota can influence many host phenotypes. Gnotobiotic growth systems and controlled environments empower researchers to isolate these variables, and standardized methods equip a global research community to harmonize protocols, replicate experiments and collaborate broadly. We developed two easily constructed peat-based gnotobiotic growth platforms: the FlowPot system and the GnotoPot system. Sterile peat is amenable to colonization by microbiota and supports growth of the model plant Arabidopsis thaliana in the presence or absence of microorganisms. The FlowPot system uniquely allows one to flush the substrate with water, nutrients and/or suspensions of microbiota via an irrigation port, and a mesh retainer allows for the inversion of plants for dip or vacuum infiltration protocols. The irrigation port also facilitates passive drainage, preventing root anoxia. In contrast, the GnotoPot system utilizes a compressed peat pellet, widely used in the horticultural industry. GnotoPot construction has fewer steps and requires less user handling, thereby reducing the risk of contamination. Both protocols take up to 4 d to complete with 4-5 h of hands-on time, including substrate and seed sterilization. In this protocol, we provide detailed assembly and inoculation procedures for the two systems. Both systems are modular, do not require a sterile growth chamber, and cost less than US$2 per vessel.

Beta-strand-mediated dimeric formation of the Ig-like domains of human lamin A/C and B1

Lamins are nuclear intermediate filament proteins that play an essential role in maintaining the nuclear structure by forming a 3-D meshwork. Lamins consist of the N-terminal unstructured head, the coiled-coil rod domain, and the C-terminal tail, which is mostly unstructured except for the Ig-like domain. To date, the Ig-like domain has been characterized as a monomeric structure. Here, we determined the crystal structures of human lamin A/C, including the Ig-like domain and its N- and C-terminal flanking sequences. Interestingly, the structures showed a homodimer formed by beta-strand interactions between the N- and C-terminal flanking sequences. This interaction also provides a molecular implication for the creation of a 3-D meshwork between the 3.5-nm-thick filaments. Furthermore, we determined the crystal structure of the corresponding region of lamin B1. The structure showed a similar dimeric assembly, also formed by beta-strand interactions, albeit the intersubunit distance was much shorter. Since the Ig-like domain contains many genetic hotspots causing lamin-related diseases in lamin A/C, our findings will help understand the detailed assembly of lamins in a 3-D meshwork structure and lamin-related diseases at the molecular level.