Transmitter Positioning of Distributed Large-Scale Metrology Within Line-Less Mobile Assembly Systems

In Line-less Mobile Assembly Systems (LMAS) the mobilization of assembly resources and products enables rapid physical system reconfigurations to increase flexibility and adaptability. The clean-floor approach discards fixed anchor points, so that assembly resources such as mobile robots and automated guided vehicles transporting products can adapt to new product requirements and form new assembly processes without specific layout restrictions. An associated challenge is spatial referencing between mobile resources and product tolerances. Due to the missing fixed points, there is a need for more positioning data to locate and navigate assembly resources. Distributed large-scale metrology systems offer the capability to cover a wide shop floor area and obtain positioning data from several resources simultaneously with uncertainties in the submillimeter range. The positioning of transmitter units of these systems becomes a demanding task taking visibility during dynamic processes and configuration-dependent measurement uncertainty into account. This paper presents a novel approach to optimize the position configuration of distributed large-scale metrology systems by minimizing the measurement uncertainty for dynamic assembly processes. For this purpose, a particle-swarm-optimization algorithm has been implemented. The results show that the algorithm is capable of determining suitable transmitter positions by finding global optima in the assembly station search space verified by applying brute-force method in simulation.

The Complex Architecture of Plant Cuticles and Its Relation to Multiple Biological Functions

Terrestrialization of vascular plants, i.e., Angiosperm, is associated with the development of cuticular barriers that prevent biotic and abiotic stresses and support plant growth and development. To fulfill these multiple functions, cuticles have developed a unique supramolecular and dynamic assembly of molecules and macromolecules. Plant cuticles are not only an assembly of lipid compounds, i.e., waxes and cutin polyester, as generally presented in the literature, but also of polysaccharides and phenolic compounds, each fulfilling a role dependent on the presence of the others. This mini-review is focused on recent developments and hypotheses on cuticle architecture–function relationships through the prism of non-lipid components, i.e., cuticle-embedded polysaccharides and polyester-bound phenolics.

Possible mechanisms underlying the dynamic assembly of calcium entry units: The role of temperature and pH

Skeletal muscle function is regulated by intracellular Ca2+ levels. Two main mechanisms control movements of Ca2+ ions from intracellular stores (i.e., the sarcoplasmic reticulum; SR) and from extracellular space: (1) excitation–contraction (EC) coupling and (2) store-operated Ca2+ entry (SOCE). SOCE allows recovery of extracellular Ca2+ during prolonged muscle activity, when the SR undergoes depletion. We recently discovered that prolonged exercise leads to formation of calcium entry units (CEUs), intracellular junctions located at the I band that are formed by two distinct elements: SR stacks and transverse tubules (TTs). Assembly of CEUs during exercise promotes the interaction between STIM1 and Orai1, the two main proteins that mediate SOCE, and increases muscle resistance to fatigue in the presence of extracellular Ca2+. The molecular mechanisms underlying the exercise-dependent remodeling of SR and TT leading to CEU assembly remain to be fully elucidated. Here, we first verified whether CEUs can assemble ex vivo (in the absence of blood supply and innervation), subjecting excised EDL muscles from mice to an ex vivo incremental fatigue protocol (80 Hz tetanus stimulation lasting 45 min): the data collected demonstrate that CEUs can assemble ex vivo in isolated EDL muscles. We then evaluated if intracellular parameters that are affected by exercise, such as temperature and pH, may influence the assembly of CEUs. We found that higher temperature (36°C versus 25°C) and lower pH (7.2 versus 7.4) promotes formation of CEUs increasing the percentage of fibers containing SR stacks, the number of SR stacks/area, and the elongation of TTs at the I band. Importantly, increased assembly of CEUs at higher temperature (36°C) or at lower pH (7.2) correlated with increased fatigue resistance of EDL muscles in the presence of extracellular Ca2+, suggesting that CEUs assembled ex vivo are functional.

Magnetically tightened form-stable phase change materials with modular assembly and geometric conformality features

Recently, phase change materials (PCMs) have attracted significant attention due to their promising applications in many fields like solar energy and chip cooling. However, the present PCMs seriously suffer inevitable leakage and low thermal conduction. Magnetism can produce invisible field effects in the surrounding space. If there exist magnetic particles within this region, the effects will act on them emerging various fascinating phenomena. Inspired by this, we introduce hard magnetic particles (which can keep the effect after removing the magnetic field) to PCMs synthesizing an unprecedented magnetically tightened form-stable PCMs (MTPCMs), achieving multifunctions of leakage-proof, dynamic assembly and morphological reconfiguration, superior high thermal (increasing of 1400%~1600%) and electrical (>104 S/m) conductivity, and prominent compressive strength. Novel free-standing temperature control and high-performance thermal and electric conversion systems based on MTPCMs are furthermore developed. This work is a significant step toward exploiting a smart PCM for electronics and low-temperature energy storage.

Malat-1-PRC2-EZH1 interaction supports adaptive oxidative stress dependent epigenome remodeling in skeletal myotubes

PRC2-mediated epigenetic function involves the interaction with long non-coding RNAs (lncRNAs). Although the identity of some of these RNAs has been elucidated in the context of developmental programs, their counterparts in postmitotic adult tissue homeostasis remain uncharacterized. To this aim, we used terminally differentiated postmitotic skeletal muscle cells in which oxidative stress induces the dynamic activation of PRC2-Ezh1 through Embryonic Ectoderm Develpment (EED) shuttling to the nucleus. We identify lncRNA Malat-1 as a necessary partner for PRC2-Ezh1-dependent response to oxidative stress. We show that in this pathway, PRC2-EZH1 dynamic assembly, and in turn stress induced skeletal muscle targeted genes repression, depends specifically on Malat-1. Our study reports about PRC2–RNA interactions in the physiological context of adaptive oxidative stress response and identifies the first lncRNA involved in PRC2-Ezh1 function.

Dynamic assembly of the calcium hemostasis modulator 1 channel gates ATP permeation

Calcium hemostasis modulator 1 (CALHM1) is a voltage- and Ca2+-gated ATP channel that plays an important role in neuronal signaling. The currently reported CALHM structures are all in an ATP-conducting state, and the gating mechanism of ATP permeation remains elusive. Here, we report three cryo-EM reconstructions of heptameric CALHM1s with ordered or flexible long C-terminal helices and octameric CALHM1 with flexible long C-terminal helices at resolutions of 3.2 Å, 2.9 Å, and 3.5 Å. Structural analysis revealed that the heptameric CALHM1s are in an ATP nonconducting state in which the pore diameter in the middle is approximately 6.6 Å. Compared with those inside the octameric CALHM1s, the N-helices inside heptameric CALHM1s are in the "down" position to avoid steric clash with neighboring TM1 helices. MD simulations show that the pore size is significantly increased for ATP permeation during the movement of the N-helix from the "down" position to the "up" position. Therefore, we proposed a mechanism in which the "piston-like" motion of the N-helix drives the dynamic assembly of the CALHM1 channel for ATP permeation.

Aberrant Stress Granule Dynamics and Aggrephagy in ALS Pathogenesis

Stress granules are conserved cytosolic ribonucleoprotein (RNP) compartments that undergo dynamic assembly and disassembly by phase separation in response to stressful conditions. Gene mutations may lead to aberrant phase separation of stress granules eliciting irreversible protein aggregations. A selective autophagy pathway called aggrephagy may partially alleviate the cytotoxicity mediated by these protein aggregates. Cells must perceive when and where the stress granules are transformed into toxic protein aggregates to initiate autophagosomal engulfment for subsequent autolysosomal degradation, therefore, maintaining cellular homeostasis. Indeed, defective aggrephagy has been causally linked to various neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). In this review, we discuss stress granules at the intersection of autophagy and ALS pathogenesis.