Active Disassembly Research Articles

Abstract A016: Mechanism of hypoxia-induced centrosome loss in early prostate cancer

Abstract PURPOSE: We aim to understand cellular and microenvironmental determinants of chromosomal instability in prostate cancer and use these findings as prognostic biomarkers portending aggressive disease. Disease transitions during prostate cancer progression are accompanied by bursts of chromosomal instability (CIN), including chromosomal translocations, oncogene amplifications, and chromothripsis. While high CIN correlates with most metrics of aggressive disease, we lack a mechanistic understanding of how CIN originates in prostate cancer. Recently, we discovered that low Gleason score, primary prostate tumors lack centrosomes, cytoplasmic organelles that ensure the fidelity of chromosome segregation by organizing the shape of the mitotic spindle. Experimental elimination of centrosomes in immortalized, non-tumorigenic prostate cell lines was sufficient to generate extensive CIN resulting in oncogenic transformation of these lines when sub-cutaneously injected into NSG mice. Because we identified centrosome loss as a potential driver of CIN, we sought to understand mechanisms that can trigger centrosome loss in the prostate. Although centrosome loss naturally occurs during the development of some tissues, for example centrosome elimination during oogenesis, the mechanisms that trigger loss are not known. Therefore, we first investigated microenvironmental changes in early prostate cancer as a potential cause. Hypoxia, pathologically low oxygen concentration, is common in the aging prostate due to loss of vasculature and is associated with poor prostate cancer prognosis and high CIN. Therefore, we hypothesized that hypoxic exposure induces centrosome loss in prostate cells. Indeed, we found that exposure to 1% oxygen concentrations leads to progressive centrosome loss in non-tumorigenic, immortalized prostate epithelial cell lines. Using functional assays in cultured cells, we found that hypoxia-induced centrosome loss is an active disassembly process mediated by confluence-dependent Hippo signaling but independent of Hypoxia-Inducible Factor (HIF) transcription. We conclude that hypoxia-induced centrosome disassembly is a plausible driver of CIN in early prostate cancer. At present, we are developing immunohistochemistry assays to identify centrosome loss and hypoxia in biopsy samples to confirm these discoveries. Recently, we have described a combinatorial staining pattern (GLUT3/GLUT1/CA-9) that reliably identifies hypoxic tissue in patient-derived xenografts from prostate tumors. We are coupling this with a new assay to identify the structural component of the centrosome, called the centriole, which is identifiable during both mitosis and interphase. Together, our in situ assays will allow us to determine the penetrance of hypoxia-induced centrosome loss and its association with aggressive prostate cancer. Citation Format: John M. Ryniawec, Gregory C. Rogers, Anne E. Cress. Mechanism of hypoxia-induced centrosome loss in early prostate cancer [abstract]. In: Proceedings of the AACR Special Conference: Advances in Prostate Cancer Research; 2023 Mar 15-18; Denver, Colorado. Philadelphia (PA): AACR; Cancer Res 2023;83(11 Suppl):Abstract nr A016.

Targeted DNA integration in human cells without double-strand breaks using CRISPR-associated transposases.

Conventional genome engineering with CRISPR-Cas9 creates double-strand breaks (DSBs) that lead to undesirable byproducts and reduce product purity. Here we report an approach for programmable integration of large DNA sequences in human cells that avoids the generation of DSBs by using Type I-F CRISPR-associated transposases (CASTs). We optimized DNA targeting by the QCascade complex through protein design and developed potent transcriptional activators by exploiting the multi-valent recruitment of the AAA+ ATPase TnsC to genomic sites targeted by QCascade. After initial detection of plasmid-based integration, we screened 15 additional CAST systems from a wide range of bacterial hosts, identified a homolog from Pseudoalteromonas that exhibits improved activity and further increased integration efficiencies. Finally, we discovered that bacterial ClpX enhances genomic integration by multiple orders of magnitude, likely by promoting active disassembly of the post-integration CAST complex, akin to its known role in Mu transposition. Our work highlights the ability to reconstitute complex, multi-component machineries in human cells and establishes a strong foundation to exploit CRISPR-associated transposases for eukaryotic genome engineering.

Global asymptotic stability of the active disassembly model of flagellar length control.

Organelle size control is a fundamental question in biology that demonstrates the fascinating ability of cells to maintain homeostasis within their highly variable environments. Theoretical models describing cellular dynamics have the potential to help elucidate the principles underlying size control. Here, we perform a detailed study of the active disassembly model proposed in Fai et al. (elife 8:e42599, 2019). We construct a hybrid system which is shown to be well-behaved throughout the domain. We rule out the possibility of oscillations arising in the model and prove global asymptotic stability in the case of two flagella by the construction of a suitable Lyapunov function. Finally, we generalize the model to the case of arbitrary flagellar number in order to study olfactory sensory neurons, which have up to twenty cilia per cell. We show that our theoretical results may be extended to this case and explore the implications of this universal mechanism of size control.

Investigation of Active Disassembly in Large Force Applications

Abstract Active disassembly (AD) is an emerging field of research in design for disassembly that enables a cost-effective nondestructive separation of product components. It is based on using active joints and fasteners that enables the self-disassembly of products without any direct contact between the product and the operator, where these joints and fasteners must be inserted in the product during its design and manufacturing phases. Generally, active joints and fasteners are made of smart materials such as shape memory alloys (SMAs), that can generate the necessary disassembly forces required to separate the different components of the product. Most of the exerted effort in this field of research was focused on separating products requiring small disassembly forces either in the electronic or automotive sectors. All these active disassembly applications were based on using shape memory alloy snap fits, clips, or wires that are characterized by their ability to generate small forces with large displacements. As, up to the authors knowledge, none of the exerted efforts were concerned with investigating the possibility of using the large disassembly forces that could be generated using shape memory alloy actuators in large force active disassembly applications. Consequently, the presented research aims to examine the possibility of applying active disassembly with products requiring large disassembly forces, having tapered surfaces and large mechanical structure. By presenting two case studies to validate the possibility of using active disassembly with large force applications, in addition to investigating the capability of using shape memory alloy actuators assembled either concentric or eccentric with the product structure.

Usage of shape memory alloy actuators for large force active disassembly applications

Shape memory alloys (SMAs) possess inherent superior properties that make their applications in active disassembly an emerging and interesting field of research. This is because extremely large forces can be generated repeatedly using a small compact-sized element, such as an SMA actuator. To ensure the ability of the SMA actuator to generate a repeated large force or withstand repeated load, several factors should be considered. These include factors that affect the value of the generated recovery forces, such as the amount of strain used, activation temperature, activation time, and cross-sectional area of the SMA element. In general, the compressive strain can be considered as the most influential factor that affects the value of the generated recovery force. The present research investigates the possible use of the SMA actuator in large-force active disassembly applications. To the best of the authors' knowledge, all the studies conducted in this field are concerned with implementing active disassembly in applications requiring small disassembly forces. The present research was conducted in three phases. First, the behaviour of the SMA element upon exposure to different repetitive compressive strains was studied, and the generated recovery force and strain hardening induced in the material were considered to ensure the continuous generation of large recovery forces with the least amount of residual strain induced in the material. Second, the optimum value of the compressive strain required to generate the maximum force with the least amount of residual strain induced in the material was estimated. Third, a practical case study was presented to validate the possible implementation of SMA actuators in large force active disassembly applications. The study successfully estimated the optimum compressive strain value that generated the required recovery force to disassemble the conducted case study using active disassembly technique.

Length regulation of multiple flagella that self-assemble from a shared pool of components.

The single-celled green algae Chlamydomonas reinhardtii with its two flagella-microtubule-based structures of equal and constant lengths-is the canonical model organism for studying size control of organelles. Experiments have identified motor-driven transport of tubulin to the flagella tips as a key component of their length control. Here we consider a class of models whose key assumption is that proteins responsible for the intraflagellar transport (IFT) of tubulin are present in limiting amounts. We show that the limiting-pool assumption is insufficient to describe the results of severing experiments, in which a flagellum is regenerated after it has been severed. Next, we consider an extension of the limiting-pool model that incorporates proteins that depolymerize microtubules. We show that this 'active disassembly' model of flagellar length control explains in quantitative detail the results of severing experiments and use it to make predictions that can be tested in experiments.

Programmable Disassembly of Polymer Nanoparticles through Surfactant Interactions

The disassembly of well-defined random copolymer nanoparticles to unimers at precise times can be programmed through the strong interaction with the surfactant, sodium dodecyl sulfate (SDS). The random copolymers consisted of thermoresponsive and self-degradable monomer units, rapidly self-assembled in water above the lower critical solution temperature of the thermoresponsive polymer component into SDS-stabilized polymer nanoparticles at a high weight fraction of polymer, a fully reversible process. Increasing the SDS concentration resulted in an increase in the nanoparticle size from ∼60 to ∼500 nm while maintaining a very narrow particle size distribution. These particles once formed were stable even under highly dilute conditions (i.e., an ∼10-fold dilution). Due to the self-catalyzed hydrolysis of the (N,N-dimethylaminoethyl acrylate) (DMAEA) to acrylic acid within the polymer, the nanoparticles rapidly disassembled back to unimers when the LCST of the hydrolyzed polymer was equal to or greater than the set solution temperature of 37 °C. The time to disassembly from nanoparticle to unimer was programmed through the amount of hydrophobic (butyl acrylate or styrene) units in the copolymer in combination with the amount of SDS. The higher hydrophopic content in the polymer resulted in longer disassembly times, while the higher SDS concentration reduced the disassembly time. Importantly, the self-catalyzed hydrolysis property of PDMAEA was not affected by SDS, allowing precise tunability of the time required for disassembly of the polymer nanoparticles. This active disassembly of nanoparticles provides a unique system that responds without an external trigger (e.g., light, heat, etc., ...) and could find applications where timed-release of compounds or timed activation of enzymes and other biocomponents is required.

Economic and environmental evaluation of design for active disassembly

Prior research has demonstrated that a disassembly based end-of-life (EoL) treatment for electronic products is characterized by the highest recovery rates for precious metals (PMs) and non-commodity plastics, such as flame retardant plastics. Nonetheless, EoL electronic products are nowadays also commonly recycled without disassembly in different types of size-reduction based treatments or in an integrated PM smelter-refinery. This disparity of recycling processes adopted worldwide resulted in a high uncertainty on the EoL treatment processes that will be adopted for discarded electronic products. As a result, governments, original equipment manufacturers and recycling companies struggle to determine the economic and environmental value of design for disassembly. For this reason, a methodology is presented to calculate the Composite Rate of Return (CRR) on investing in design for disassembly and the resulting environmental impacts. This methodology is applied to evaluate the economic and environmental benefits of implementing three types of active fasteners for eleven electronic products which are available in both a product service system (PSS) and a traditional sales oriented business model. The performed analyses demonstrate that the preferred EoL treatment, as well as the economic and environmental benefits of implementing design for active disassembly, strongly depends on several product properties and boundary conditions. Based on the performed sensitivity analysis, the application of active pressure and temperature sensitive fasteners is expected to be only economically viable for products placed on the market in a PSS context, in which they will be separately collected with a high collection rate. Furthermore, impulse sensitive elastomer based fasteners are characterized with the highest rate of return and considered to be suited for both products sold in a traditional sales oriented business model and for products used in a PSS.

Mechanism of ciliary disassembly.

As motile organelles and sensors, cilia play pivotal roles in cell physiology, development and organ homeostasis. Ciliary defects are associated with a class of cilia-related diseases or developmental disorders, termed ciliopathies. Even though the presence of cilia is required for diverse functions, cilia can be removed through ciliary shortening or resorption that necessitates disassembly of the cilium, which occurs normally during cell cycle progression, cell differentiation and in response to cellular stress. The functional significance of ciliary resorption is highlighted in controlling the G1-S transition during cell cycle progression. Internal or external cues that trigger ciliary resorption initiate signaling cascades that regulate several downstream events including depolymerization of axonemal microtubules, dynamic changes in actin and the ciliary membrane, regulation of intraflagellar transport and posttranslational modifications of ciliary proteins. To ensure ciliary resorption, both the active disassembly of the cilium and the simultaneous inhibition of ciliary assembly must be coordinately regulated.

Pressure-sensitive fasteners for active disassembly

This paper presents a number of novel active fasteners developed to significantly lower disassembly costs during reconditioning, remanufacturing, and recycling of products. In the initial stage of the fastener development process, the applicability of distinct trigger signals for active disassembly (AD) is evaluated. Based on this evaluation, the high robustness of using a pressure increase or decrease as a nondestructive trigger for AD is demonstrated. Since previously proposed pressure-sensitive fasteners face considerable drawbacks upon implementation in electronic products due to the ongoing trend of miniaturization, a second generation of pressure-based active fasteners is developed. Evaluation of these fasteners by means of axiomatic design techniques and prototyping demonstrates that the presented snap-fits, which make use of a closed-cell elastomer foam, are most robust. Subsequently, the contraction forces that closed-celled foams can exert as a function of an increase in ambient air pressure are experimentally determined. Furthermore, the implementation of pressure-sensitive foam-based snap-fits in both a modem and a payment terminal is described. Results of these experiments demonstrate that the contraction force of a cross-linked metallocene polyethylene closed-cell foams can reach up to 6 N/cm2 at an overpressure of 2 bar and that the foam-based snap-fits can be released at a pressure increase of 2 bar.

Economic and Environmental Evaluation of Fasteners for Active Disassembly: A Case Study for Payment Terminals

Prior research has demonstrated that design for disassembly enables higher recovery rates for precious and critical metals, as well as flame retardant plastics from End-of-Life (EoL) electronics. However, small EoL electronic products are nowadays commonly recycled in a size-reduction based treatment or can be directly treated in an integrated Precious Metal (PM) smelter-refinery. In this article, a methodology is described to calculate the Rate of Return (RoR) on investing in fasteners which can be simultaneously released by the application of an external trigger, following the principle of active disassembly. This methodology is used in the presented case study to calculate the ROR of implementing a pressure sensitive snap-fit in an electronic payment terminal which is sold in a product service system business model. In addition, the economic and environmental performances of an active disassembly based EoL treatment is compared with those of a manual disassembly and a size-reduction based treatment, as well as direct treatment in an integrated PM smelter-refinery. Results of the presented case study demonstrate that the ROR on investing in active fasteners for the case study product is 27%.

Shape memory technology for active assembly/disassembly: fundamentals, techniques and example applications

Purpose – This paper aims to present a review on utilizing shape memory technology (SMT) for active assembly/disassembly, i.e. assembly/disassembly without physically touching. Design/methodology/approach – The fundamentals behind the shape memory effect (SME) in materials, in particular shape memory alloys (SMAs) and polymers, which are the cornerstones of SMT, are introduced, together with the possible approaches to implement this effect in active assembly/disassembly. Example applications for not only active assembly/ disassembly, but also programmed active disassembly are presented. Findings – The advantages of utilizing SMT over conventional assembly/disassembly techniques are identified. Originality/value – The paper introduces the fundamentals behind the SME and the basic approaches to implement the SMT in not only active assembly/disassembly, but also programmed active assembly.

Second Generation of Pressure Sensitive Fasteners for Active Disassembly

Reversible fasteners suited for Active Disassembly (AD), which can be simultaneously released by an increase in ambient air pressure, have been developed in prior research. However, the implementation of these active fasteners in electronic consumer products is hampered as a result of the ongoing trend of miniaturization. Therefore, a second generation of pressure based fasteners was developed in line with the evolutionary TRIZ trends. This paper presents a novel pressure sensitive snap-fit for electronic products which makes use of closed cell elastomer foam and releases at an overpressure of 2bar.

Proof of Concept of an Elastomer based Fastener Enabling Rapid Disassembly

Cost efficient disassembly operations require the simultaneous release of multiple fasteners without the need to identify the location of every individual fastener. Despite the availability of a number of Active Disassembly concepts which offer significant potential to make systematic product disassembly economically viable, the stage of mass industrial implementation has not yet been reached. A novel fastener concept has been developed in an attempt to overcome some of the barriers that impede implementation of Active Disassembly in electronic consumer products. This fastener concept is based on the mechanical properties of elastomer materials and is triggered by an external force applied on the product housing.

Shape Memory Polymer Nanocomposites for Application of Multiple-Field Active Disassembly: Experiment and Simulation

Active disassembly (AD) uses innovative materials that can perform a designed disassembly action by the application of an external field. AD provides improvements over current disassembly processes by limiting machine or manual labor and enabling batch processing for end-of-life products. With improved disassembly operations, more reuse of components and purer recycling streams may be seen. One problem with AD, however, has been with the single-field actuation because of the probability of accidental disassembly. This presentation will discuss the application of shape memory polymer (SMP) nanocomposites in a new AD process. This novel AD process requires multiple-field actuation of the SMP nanocomposite fastener. In the analysis of this AD process, thermal and magnetic field tests were performed on the SMP nanocomposite. From these tests, finite-element analysis was performed to model and simulate the multiple-field AD process. The results of the simulations provide performance variables for the AD process and show a better performance time for the SMP nanocomposite fastener than for a comparable SMP fastener.

Design method of active disassembly structure triggered by temperature-pressure coupling

Active disassembly products often use active disassembly structures triggered by single temperature or pressure field as reversible joints. These structures can be triggered automatically in extreme or accidental circumstances, thus causing the low reliability of products. For improving the reliability of active disassembly products, working mechanisms of active disassembly structure triggered by temperature-pressure coupling is presented in this article. Through analyzing some typical active disassembly structures, this article presents the design criteria and methods of active disassembly structure triggered by temperature-pressure coupling. The feasibility of these design methods is proved by a case analysis. The results of research shows that the reliability of active disassembly structures triggered by temperature-pressure coupling is improved greatly, which can lay the foundation for the industrial applications of active disassembly methods.

Shape memory polymer actuated hollow snap-fit design analysis

With the increasing environmental requirements for recycling technologies at the end of product lifecycle, active disassembly is becoming more and more important especially for electric and electronic product recycling. Active disassembly using smart material (ADSM) has been studied in the past decade. However, ADSM have not been widely applied due to the cost, material properties, and limited supply. Shape memory polymer (SMP) actuated hollow snap-fit may become one of the possible alternatives in ADSM, which will reduce the usage of smart materials and increase the mechanical properties of snap-fit. This research is aimed to fully investigate the SMP-actuated hollow snap-fit design and propose some guidelines for its future implementation. The correlation between design parameters and two major design objectives, maximum deflection and mating force, were analyzed using FEA software. Furthermore, an approach to search the optimal design values for given design requirements was presented. In order to maximize the recovery force generated by SMP in active disassembly process, an investigation of magnifying the deformation stress by engineering actuator’s shape design was completed. The methods and conclusion presented in this paper could be used as reference for hollow snap-fit development and application.

Design Methods of Active Disassembly Structure Based on Thermoplastic Hot Melt Adhesive

Design Methods of Active Disassembly Structure Based on Thermoplastic Hot Melt Adhesive

Design methodology for active disassembly based on the decapitated head method

Due to the characteristic that shape memory materials can quickly return to their original shape and have large deformation, such materials can be used as the connection in active disassembly devices. However, existing active disassembly devices typically require two moulding steps and complicated machining processes that result in high manufacturing cost. The active disassembly device based on the proposed decapitated head method has only one moulding step and lower manufacturing cost. Its disassembly mode is local damage disassembly, which can decrease the active disassembly cost and improve disassembly efficiency. This paper describes the active disassembly theory and the design methodology based on the decapitated head method, and then analyses the design criteria and feasibility of this method with a real case study.

Poly(methyl methacrylate) for active disassembly

This paper focuses on the applications of poly(methyl methacrylate) (PMMA), one of the most commonly used engineering polymers, for active disassembly (AD). PMMA was first characterized by a series of thermo-mechanical tests to find the suitable programming temperatures and its shape memory characteristics. Four releasable fasteners were then developed, and tested, i.e. active screw, active joint, active snap-fit and active tab. It was successfully demonstrated that PMMA is a promising candidate for AD. Moreover, programmed AD has been achieved as well through a series of temperature-activated actions during the disassembly process. These techniques are applicable to other engineering polymers for AD and programmed AD.