Search

Silicone rubber (SIR) is a crucial insulating material in cable accessories, but it is also susceptible to faults. In practical applications, mechanical pressure from bending or shrinking can impact the degradation of SIR, necessitating the study of its electrical tree and partial discharge (PD) characteristics under such pressure. This work presents the construction of a test platform for electrical trees under varying pressures to observe their growth process. A high-frequency current transformer is used to measure PD patterns during tree growth, enabling analysis of the effect of PD on tree initiation and propagation under pressure. The experimental results demonstrate a significant decrease in tree inception probability and increase in PD inception voltage under pressure. The pressure also influences the tree structure and PD during the treeing process, where the longest tree with a branch-like structure appears under 800 kPa. The effect of pressure on electrical tree and PD characteristics can be attributed to changes in free volume, alterations in air pressure within the tree channels, and the affected charge accumulation. [ABSTRACT FROM AUTHOR]

In this study, the effect of pressurized torrefaction both by gas-pressurized (GP) and mechanical pressure (MP) at 250 °C on the properties of bio-oil was investigated. GP torrefaction enhanced the deoxygenation reactions and resulted in low O/C atomic ratio of torrefied biomass. The GP torrefaction at 4 MPa (GP-4.0) could remove oxygen content by 46.0%. Acids content in bio-oil for GP-4.0 were reduced to 3.6%, while phenols content increased to 46.7%. However, the yield of bio-oil was only 30.5% for GP-4.0. In contrast, MP torrefaction promoted the cross-linking reactions. The combination of MP torrefaction at 40 MPa and pyrolysis at 250 °C for 30 min (MP-40–30) could remove the oxygen content by 28.2%. The yield of bio-oil was as high as 44.7% for MP-40–30. Acids and furans content in bio-oil decreased, while alcohols, phenols, and hydrocarbons content in bio-oil increased for MP-40–30. Moreover, the hydrocarbons content in bio-oil increased to 11.9% for MP-40–30. Results from this study provided necessary information needed for developing the pyrolysis polygeneration from pressurized torrefied biomass. [ABSTRACT FROM AUTHOR]

Silicone rubber (SIR) is a crucial insulating material in cable accessories, but it is also susceptible to faults. In practical applications, mechanical pressure from bending or shrinking can impact the degradation of SIR, necessitating the study of its electrical tree and partial discharge (PD) characteristics under such pressure. This work presents the construction of a test platform for electrical trees under varying pressures to observe their growth process. A high-frequency current transformer is used to measure PD patterns during tree growth, enabling analysis of the effect of PD on tree initiation and propagation under pressure. The experimental results demonstrate a significant decrease in tree inception probability and increase in PD inception voltage under pressure. The pressure also influences the tree structure and PD during the treeing process, where the longest tree with a branch-like structure appears under 800 kPa. The effect of pressure on electrical tree and PD characteristics can be attributed to changes in free volume, alterations in air pressure within the tree channels, and the affected charge accumulation.

Simple Summary: Insects in the order Hymenoptera can produce males from unfertilised eggs. However, unfertilised eggs require a specific signal to become 'activated' and start development. Manually activating eggs is advantageous for numerous fields of research, especially for insect pest management, but has not been conducted for many hymenopteran species. The invasive woodwasp, Sirex noctilio Fabricius (Hymenoptera: Siricidae), is a hymenopteran pest of pine plantations. In this study, we developed a novel egg activation protocol for S. noctilio, allowing eggs dissected from a female wasp to develop further into larvae after activation. These first instar larvae were subsequently reared on an artificial diet. Optimal conditions for the development of activated eggs were determined, which involved treatments with the fungal symbiont of S. noctilio, Amylostereum areolatum (Russulales: Amylostereaceae). The presence of the fungus did not benefit egg development in an artificial laboratory environment. This study forms the basis for new research on S. noctilio that may not only refine our understanding of aspects involving its cryptic lifestyle but also aid in the development of next-generation pest management strategies. In addition, closely related insect species may benefit from the developed protocols. Egg activation is a cellular transition of an arrested mature oocyte into a developing embryo through a coordinated series of events. Previous studies in Hymenoptera have indicated that mechanical pressure can induce egg activation. In this study, we developed the first egg activation protocol for the haplodiploid insect pest, Sirex noctilio (Hymenoptera: Siricidae), from two climatically different regions in South Africa to demonstrate the broad applicability of the method. In addition, activated eggs were exposed to three treatments involving water, pine sawdust, and the fungal symbiont of S. noctilio, Amylostereum areolatum (Russulales: Amylostereaceae), to determine if the symbiotic fungus is a requirement for egg development in an artificial laboratory environment, as the symbiotic fungus has been hypothesised to be necessary for egg and early larval development in a natural environment. A rearing protocol was developed for the first instar larvae using a modified Anoplophora glabripennis (Coleoptera: Cerambycidae) artificial diet. A significant difference between the mean survival rates of activated eggs from the two different regions was observed. Amylostereum areolatum was shown to be unnecessary for egg survival and adversely affected egg eclosion in an artificial laboratory environment. The maximum larval survival duration on the artificial diet was 92 days. The egg activation and rearing protocol developed in this study enables opportunities for research on the physiology, ecology, symbioses, and genetics of S. noctilio, which can be exploited for new genetic pest management strategies. [ABSTRACT FROM AUTHOR]

Fluid clearance mediated by lymphatic vessels is known to be essential for lung inflation and gas-exchange function during the transition from prenatal to postnatal life, yet the molecular mechanisms that regulate lymphatic function remain unclear. Here, we profiled the molecular features of lymphatic endothelial cells (LECs) in embryonic and postnatal day (P) 0 lungs by single-cell RNA-sequencing analysis. We identified that the expression of c-JUN is transiently upregulated in P0 LECs. Conditional knockout of Jun in LECs impairs the opening of lung lymphatic vessels at birth, leading to fluid retention in the lungs and neonatal death. We further demonstrated that increased mechanical pressure induces the expression of c-JUN in LECs. c-JUN regulates the opening of lymphatic vessels by modulating the remodeling of the actin cytoskeleton in LECs. Our study established the essential regulatory function of c-JUN-mediated transcriptional responses in facilitating lung lymphatic fluid clearance at birth. [ABSTRACT FROM AUTHOR]

Egg activation is a cellular transition of an arrested mature oocyte into a developing embryo through a coordinated series of events. Previous studies in Hymenoptera have indicated that mechanical pressure can induce egg activation. In this study, we developed the first egg activation protocol for the haplodiploid insect pest, Sirex noctilio (Hymenoptera: Siricidae), from two climatically different regions in South Africa to demonstrate the broad applicability of the method. In addition, activated eggs were exposed to three treatments involving water, pine sawdust, and the fungal symbiont of S. noctilio, Amylostereum areolatum (Russulales: Amylostereaceae), to determine if the symbiotic fungus is a requirement for egg development in an artificial laboratory environment, as the symbiotic fungus has been hypothesised to be necessary for egg and early larval development in a natural environment. A rearing protocol was developed for the first instar larvae using a modified Anoplophora glabripennis (Coleoptera: Cerambycidae) artificial diet. A significant difference between the mean survival rates of activated eggs from the two different regions was observed. Amylostereum areolatum was shown to be unnecessary for egg survival and adversely affected egg eclosion in an artificial laboratory environment. The maximum larval survival duration on the artificial diet was 92 days. The egg activation and rearing protocol developed in this study enables opportunities for research on the physiology, ecology, symbioses, and genetics of S. noctilio, which can be exploited for new genetic pest management strategies.

Press-pack insulated gate bipolar transistor (IGBT) devices have multiple chips paralleled to enhance their power density. However, the current imbalance among chips limits the increase of the power, which is mainly attributed to external factors, like stray inductance, temperature, and mechanical pressure. Besides, for the difficulties in decoupling multiple external factors, the current imbalance in press-pack IGBT devices has been extensively studied by simulation, and lack of experimental investigations. In this article, a multifactor decoupling experimental approach for the current sharing characteristics is proposed. The stray inductance, temperature, and mechanical pressure of the two parallel branches can be adjusted independently for investigating chips’ current sharing. Then, the experimental platform for the parallel 3.3 kV/50 A IGBT chips under differentiated external factors is implemented. Measured results show that the stray inductance affects the transient current sharing during turn-on greatly, and the maximum current imbalance can reach 25.46%. The temperature mainly affects the steady state and the maximum current imbalance is 11.7%. Otherwise, mechanical pressure is negligible on the steady and transient current imbalances, which are less than 3%. Finally, the influence mechanisms of the external factors are proposed to explain the current sharing characteristics of parallel chips. [ABSTRACT FROM AUTHOR]

Competition of different species or cell types for limited space is relevant in a variety of biological processes such as biofilm development, tissue morphogenesis and tumor growth. Predicting the outcome for non-adversarial competition of such growing active matter is non-trivial, as it depends on how processes like growth, proliferation and the degradation of cellular matter are regulated in confinement; regulation that happens even in the absence of competition to achieve the dynamic steady state known as homeostasis. Here, we show that passive by-products of the processes maintaining homeostasis can significantly alter fitness. Even for purely pressure-regulated growth and exclusively mechanical interactions, this enables cell types with lower homeostatic pressure to outcompete those with higher homeostatic pressure. We reveal that interfaces play a critical role for this specific kind of competition: there, growing matter with a higher proportion of active cells can better exploit local growth opportunities that continuously arise as the active processes keep the system out of mechanical equilibrium. We elucidate this effect in a theoretical toy model and test it in an agent-based computational model that includes finite-time mechanical persistence of dead cells and thereby decouples the density of growing cells from the homeostatic pressure. Our results suggest that self-organization of cellular aggregates into active and passive matter can be decisive for competition outcomes and that optimizing the proportion of growing (active) cells can be as important to survival as sensitivity to mechanical cues. [ABSTRACT FROM AUTHOR]

Muscle morphogenesis is a multi-step program, starting with myoblast fusion, followed by myotube-tendon attachment and sarcomere assembly, with subsequent sarcomere maturation, mitochondrial amplification, and specialization. The correct chronological order of these steps requires precise control of the transcriptional regulators and their effectors. How this regulation is achieved during muscle development is not well understood. In a genome-wide RNAi screen in Drosophila , we identified the BTB-zinc-finger protein Tono (CG32121) as a muscle-specific transcriptional regulator. tono mutant flight muscles display severe deficits in mitochondria and sarcomere maturation, resulting in uncontrolled contractile forces causing muscle rupture and degeneration during development. Tono protein is expressed during sarcomere maturation and localizes in distinct condensates in flight muscle nuclei. Interestingly, internal pressure exerted by the maturing sarcomeres deforms the muscle nuclei into elongated shapes and changes the Tono condensates, suggesting that Tono senses the mechanical status of the muscle cells. Indeed, external mechanical pressure on the muscles triggers rapid liquid-liquid phase separation of Tono utilizing its BTB domain. Thus, we propose that Tono senses high mechanical pressure to adapt muscle transcription, specifically at the sarcomere maturation stages. Consistently, tono mutant muscles display specific defects in a transcriptional switch that represses early muscle differentiation genes and boosts late ones. We hypothesize that a similar mechano-responsive regulation mechanism may control the activity of related BTB-zinc-finger proteins that, if mutated, can result in uncontrolled force production in human muscle. [Display omitted] • The BTB-zinc-finger protein Tono is a muscle-specific transcriptional regulator • Tono is required for myofibril and mitochondria maturation during muscle development • Tono is a mechanosensitive protein that forms droplets upon mechanical pressure • Growing myofibrils and mitochondria build pressure on muscle nuclei that Tono senses Zhang, Avellaneda, et al. identify the BTB-zinc-finger protein Tono as a mechanosensitive transcriptional regulator during flight muscle development in Drosophila. After sarcomere assembly, high compressive forces on the muscle nuclei are sensed by Tono to induce a transcriptional transition that triggers sarcomere and mitochondria maturation. [ABSTRACT FROM AUTHOR]

Apical hook formation is essential for the emergence and stand establishment of cotton plants. Searching for agronomic measures to regulate apical hook formation and clarifying its mechanism are important for full stand establishment in cotton. In this study, cotton seeds were sown at varying seeding rates or depths in sand to determine if and how apical hook formation was regulated by seeding rates or depths. The results showed that deep seeding or low seeding rates increased mechanical pressure and then increased ethylene content by increasing GhACO1 and GhACS2 expression to improve apical hook formation. Silencing of the GhACO1 and GhACS2 genes or exogenous application of 1-methylcyclopropene (1-MCP) decreased the ethylene content and inhibited apical hook formation in the cotton seedlings. Deep seeding, a low seeding rate, or 1-amino cyclopropane-1-carboxylic acid (ACC) treatment increased the expression of GhHLS1 and GhPIF3 genes, but their expression was decreased in theVIGS- ACO1 and VIGS- ACS2 seedlings. Silencing of the GhHLS1 and GhPIF3 genes inhibited apical hook formation, although the expression of GhACO1 and GhACS2 was unchanged. GhPIF3 may act upstream of GhHLS1, as the expression of GhPIF3 in the VIGS- HLS1 seedlings was unchanged, while the expression of GhHLS1 in the VIGS- PIF3 seedlings decreased. These results suggested that raised mechanical pressure could increase ethylene content by inducing GhACO1 and GhACS2 gene expression, which promoted apical hook formation by increasing the expression of GhHLS1. Therefore, adjusting the mechanical pressure through changing the seeding depth or seeding rate is an important means to regulate apical hook formation and emergence. • Mechanical pressure improves apical hook formation of cotton through ethylene. • Mechanical pressure increases ethylene content by increasing ACO1 and ACS2 expression of cotton. • GhHLS1 plays key role in regulating apical hook formation of cotton. [ABSTRACT FROM AUTHOR]

Conductive polymers, integral to advancements in wearable devices, energy storage, healthcare and more, are crafted by integrating polymers with conductive elements like carbon substances, metals, and their particles. Drawing inspiration from natural water movement, this study introduces a method for crafting high-performance conductive composite films. This technique involves regulating the microstructure space of GaIn-based polymers under the mechanical pressure, where the fluid metal improves the internal microstructure gaps of the material. The presence of hydroxyl/carboxyl groups within the polymer enables the bonding with Ga3+ ions from the liquid metal (LM), securing them in place. This innovative process significantly boosts the material's electrical and thermal conductivity, as well as its mechanical integrity. This methodology has been successfully applied to enhance the attributes of GaIn-based composite films, utilizing nanocellulose fibers, chitosan nanofibers, and Kevlar-29 fibers as foundational materials. To demonstrate the method's effectiveness, a durable, highly thermally and electrically conductive GaIn-based MXene/nanocellulose composite film was developed and investigated in detail. This film showcased remarkable electromagnetic shielding with a high SSE/t value of 7718.91 dB cm2 g−1, and its performance mechanism was detailed through finite element analysis. Notably, the inclusion of GaIn endowed the film with excellent opto-electro-thermal conversion and heat-responsive deformation capabilities, highlighting its suitability for smart applications. Therefore, this research establishes a versatile approach for designing conductive films by merging liquid metal with polymers, potentially setting the stage for the creation of highly conductive composites in future. [Display omitted] [ABSTRACT FROM AUTHOR]

A cost-effective and sustainable approach was used to enhance the thermoelectric performance of printable thermoelectric composite films. Using this approach, we are trying to get rid of the highly energy-intensive (high temperature and long duration) and time-consuming process of manufacturing thermoelectric generators. This study presents a unique approach of using an environmental-friendly and naturally occurring binder, a heterogeneous particle size distribution and applied mechanical pressure to fabricate n-type thermoelectric composite films. Recently spotlighted biomaterial, chitosan, was employed as a binder and it provided enough binding strength to the composite thermoelectric films. Bi2Te2.7Se0.3 is an attractive n-type thermoelectric material because of its high thermoelectric performance. In this work, we are using two different (100-mesh and 325-mesh) n-type Bi2Te2.7Se0.3 thermoelectric conductive particles for thermoelectric composite films to understand the role of wide-range particle distribution on thermoelectric composite films. In addition, two different weight ratios (1:2000 and 1:5000) of binders to Bi2Te2.7Se0.3 particle and two different applied pressures (150 MPa and 200 MPa) were used for this study. The application of pressure and the use of a heterogenous particle distribution improves the packing density which leads to well-aggregated and coalesced polycrystal bulk-like structure in chitosan 100-mesh (heterogeneous particle distribution) Bi2Te2.7Se0.3 thermoelectric composite films and hence improves the overall electrical conductivity and power factor. The best performing composite film was made with an ink of a 1:2000 weight ratio of binder to100-mesh Bi2Te2.7Se0.3 and the applied pressure was 200 MPa. The electrical conductivity was 200 ± 7 S cm−1, the Seebeck coefficient was −201 ± 6 µV K−1, the power factor was 808 ± 69.7 μW m−1 K−2, the thermal conductivity was 0.6 W m−1 K−1, and the figure of merit was 0.4 at room temperature. Using energy efficient, sustainable, and cost effective method we achieved ZT of 0.40 for n-type thermoelectric composite films which is comparable to other printed n-type TE composite films. A 2-leg n-type Bi2Te2.7Se0.3 device was fabricated with a power output of 0.48 μW at a closed circuit voltage of 2.1 mV and ∆T of 12 K. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mechanical pressure-mediated formation of Pd active sites in zeolite Y catalysts. • Effect of mechanical compression on the stability of Pd in Y catalysts. • Pdδ+ species inhibited the decomposition of CH 3 ONO into byproducts. • Pd(2+δ)+/Pdδ+ ratio (0 < δ ≤ 2) is responsible for dimethyl carbonate selectivity. • Enhanced adsorption of CO and CH 3 ONO on Pdδ+ species revealed by DFT. The structural transformation of metal-containing zeolite catalysts subjected to mechanical compression is often disregarded in the preparation of catalysts. Herein, the impact of the mechanical compression on the catalytic active sites of Pd/NaY catalysts responsible for the indirect oxidative carbonylation of methanol to dimethyl carbonate (DMC) has been disclosed. The DMC selectivity of the catalysts was found to strongly depend on the mechanical-pressure applied, as the mechanical pressure controlled the ratio of Pd(2+δ)+ and Pdδ+ species (0 < δ ≤ 2) in the catalysts. The mono-dispersed Pd clusters (1.3 nm) in the Pd/NaY catalyst were obtained under mechanical treatment of 300 MPa. This catalyst showed high CO conversion of 89% and DMC selectivity of 83%, that maintained for at least 150 h. Combining experimental and density functional theory studies, we revealed that the Pdδ+ rather than the Pd(2+δ)+ species enhanced the adsorption of CO and CH 3 ONO reactants and inhibited the decomposition of CH 3 ONO reactant into byproducts, and thus enhanced the DMC selectivity. The mechanical pressure applied had a noticeable effect on the structural features of the metal-containing zeolite catalysts, but despite its importance, this aspect has been poorly considered in the field of heterogenous catalysis. [ABSTRACT FROM AUTHOR]

Competition of different species or cell types for limited space is relevant in a variety of biological processes such as biofilm development, tissue morphogenesis and tumor growth. Predicting the outcome for non-adversarial competition of such growing active matter is non-trivial, as it depends on how processes like growth, proliferation and the degradation of cellular matter are regulated in confinement; regulation that happens even in the absence of competition to achieve the dynamic steady state known as homeostasis. Here, we show that passive by-products of the processes maintaining homeostasis can significantly alter fitness. Even for purely pressure-regulated growth and exclusively mechanical interactions, this enables cell types with lower homeostatic pressure to outcompete those with higher homeostatic pressure. We reveal that interfaces play a critical role for this specific kind of competition: there, growing matter with a higher proportion of active cells can better exploit local growth opportunities that continuously arise as the active processes keep the system out of mechanical equilibrium. We elucidate this effect in a theoretical toy model and test it in an agent-based computational model that includes finite-time mechanical persistence of dead cells and thereby decouples the density of growing cells from the homeostatic pressure. Our results suggest that self-organization of cellular aggregates into active and passive matter can be decisive for competition outcomes and that optimizing the proportion of growing (active) cells can be as important to survival as sensitivity to mechanical cues.

Early events occurring at the surface of the female organ are critical for plant reproduction, especially in species with a dry stigma. After landing on the stigmatic papilla cells, the pollen hydrates and germinates a tube, which penetrates the cell wall and grows towards the ovules to convey the male gametes to the embryo sac. In self-incompatible species within the Brassicaceae, these processes are blocked when the stigma encounters an incompatible pollen. Based on the generation of self-incompatible Arabidopsis lines and by setting up a live imaging system, we showed that control of pollen hydration has a central role in pollen selectivity. The faster the pollen pumps water from the papilla during an initial period of 10 min, the faster it germinates. Furthermore, we found that the self-incompatibility barriers act to block the proper hydration of incompatible pollen and, when hydration is promoted by high humidity, an additional control prevents pollen tube penetration into the stigmatic wall. In papilla cells, actin bundles focalize at the contact site with the compatible pollen but not with the incompatible pollen, raising the possibility that stigmatic cells react to the mechanical pressure applied by the invading growing tube. [ABSTRACT FROM AUTHOR]

Current advancements in neurovascular biology relates a mechanoceutics treatment, known as cranial osteopathic manipulation (COM), Alzheimer's disease (AD). COM could be used as an evidence-based treatment strategy to improve the symptoms of AD if molecular mechanisms, which currently remain unclear, are elucidated. In the present pilot study, using transgenic rats, we have identified COM mediated changes in behavioral and biochemical parameters associated with AD phenotypes. We expect these changes may have functional implications that might account for improved clinical outcomes of COM treatment. Further investigations on COM will be helpful to establish an adjunct treatment for AD. [ABSTRACT FROM AUTHOR]

Commercialized implementations of anion exchange membrane water electrolysis (AEMWE) require stable operation at high current density. To achieve this, ohmic, electrochemical and concentration polarizations are supposed to be exceedingly suppressed. Among all crucial materials, porous electrodes with catalyst coatings extensively affect the above polarizations, which are highly sensitive to specific mechanical pressure for cell assembly. However, the imposed mechanical pressure and its effects on cell performance are rarely reported in AEMWE cells. Here, quantitative characterizations of mechanical pressure and its effects on i) physical properties of catalyst coated electrodes and ii) corresponding single-cell performance are comprehensively investigated. First, the imposed mechanical pressure on membrane electrode assembly (MEA) is controlled by different total thickness gaps between anode/cathode and poly-tetra-fluoroethylene (PTFE) gaskets (Δd = 0, 100, 200, 300 μm). Second, the above resulted distributions of mechanical pressure are quantitatively studied by a mechanical pressure tracking method. Third, the influence of the mechanical pressure on the physical properties of the electrodes and cell performance are demonstrated. It is proved that the mechanical pressure of ca. 0.5 MPa is comprehensively beneficial for suppressing internal resistance (R Ω) and charge transfer resistance (R ct), with slightly increased mass diffusion resistance (R md) and hydrogen crossover. This study unveils the intrinsic effects of mechanical pressure on cell performance and provides critical insights into baseline benchmarking and single-cell even stack optimization. [Display omitted] • Dependence of cell mechanics, mass transport, wettability over contact pressure. • Electrochemical performance and internal resistance in the pressure range 0–6 MPa. • 0.5 MPa is optimal contact pressure to suppress R Ω /R ct and relieve R md. • Membrane thickness (≥50 μm) favorable to prevent membrane damage. • Pre-assembly and gradually increased mechanical pressure are esential for mounting. [ABSTRACT FROM AUTHOR]

Dendritic Li formation is one of the critical reasons for the failure of Li batteries. In order to improve the lithium metal anode performance, a better understanding of the growth mechanisms of Li dendrites is necessary. Due to the malleable nature of lithium metal, mechanical pressure should play an important role in determining the morphology and cycling behaviour of Li anode. Here we investigated the effect of an applied external pressure on the electrochemical deposition of lithium metal. Instead of a highly porous, wire-like Li growth in the absence of pressure, a much more compact Li deposition can be achieved when a pressure is applied to the batteries in the charge/discharge processes. The improved Li deposition/stripping behaviour in the pressed cells yields a 5% higher Coulombic efficiency (~90%) and more than 5-fold longer cycling life than the cells without pressure at a current density of 2 mA/cm 2 . The use of pressure in shaping Li metal is an effective approach to address the Li metal problem and advance Li technologies in the future. [ABSTRACT FROM AUTHOR]

Flower-like inflorescences (pseudanthia) have fascinated botanists for a long time. They are explained as condensed inflorescences implying that the pseudanthium develops from an inflorescence meristem (IM). However, recent developmental studies identified a new form of reproductive meristem, the floral unit meristem (FUM). It differs from IMs by lacking acropetal growth and shares fractionation, expansion and autonomous space filling with flower meristems (FM). The similarity among FUMs and FMs raises the question how far flower-like heads originate from flower-like meristems. In the present paper, pseudanthium development in Davidia involucrata is investigated using scanning electron microscopy. D. involucrata has pincushion-shaped heads composed of densely aggregated, perianthless flowers and associated with two large showy bracts. Early developmental stages show a huge naked FUM. The FMs appear almost simultaneously and lack subtending bracts. With ongoing FUM expansion new space is generated which is immediately used by further FM fractionation. The heads have only staminate flowers or are andromonoecious with staminate and a single perfect flower in oblique position. All FMs lack perianth structures and fractionate a variable number of stamen primordia. The perfect FM is much larger than the staminate FMs and forms a syncarpous gynoecium with inferior ovary. Pseudanthium development in D. involucrata confirms the morphogenetic similarity to FMs as to acropetal growth limitation, meristem expansion and fractionation. It thus should not be interpreted as a condensed inflorescence, but as a flower equivalent. Furthermore as the FUM develops inside a bud, its development is considered to be influenced by mechanical pressure. The oblique position of the perfect flower, the developmental delay of the proximal flowers, and the variable number of stamens which were observed in the pseudanthium development, can be caused by mechanical pressure. Next to the Asteraceae, D. involucrata offers a further example of a pseudanthium originating from a FUM. More knowledge on FUMs is still needed to understand diversification and evolution of flower-like inflorescences. [ABSTRACT FROM AUTHOR]

Although crucial for designing separation processes little is known experimentally about multi-component adsorption isotherms in comparison with pure single components. Very few binary mixture adsorption isotherms are to be found in the literature and information about isotherms over a wide range of gas-phase composition and mechanical pressures and temperature is lacking. Here, we present a quasi-onedimensional statistical mechanical model of binary mixture adsorption in metal-organic frameworks (MOFs) treated exactly by a transfer matrix method in the osmotic ensemble. The experimental parameter space may be very complex and investigations into multi-component mixture adsorption may be guided by theoretical insights. The approach successfully models breathing structural transitions induced by adsorption giving a good account of the shape of adsorption isotherms of CO2 and CH4 adsorption in MIL-53(Al). Binary mixture isotherms and coadsorption- phase diagrams are also calculated and found to give a good description of the experimental trends in these properties and because of the wide model parameter range which reproduces this behaviour suggests that this is generic to MOFs. Finally, a study is made of the influence of mechanical pressure on the shape of CO2 and CH4 adsorption isotherms in MIL-53(Al). Quite modest mechanical pressures can induce significant changes to isotherm shapes in MOFs with implications for binary mixture separation processes. [ABSTRACT FROM AUTHOR]

Pressure application to the lumbar spine is an important assessment and treatment method of low back pain. However, few studies have characterized brain activation patterns in response to mechanical pressure. The objective of this study was to map brain activation associated with various levels of mechanical pressure to the lumbar spine in healthy subjects. Fifteen healthy subjects underwent functional magnetic resonance imaging (fMRI) scanning while mechanical pressure was applied to their lumbar spine with a custom-made magnetic resonance imaging (MRI)-compatible pressure device. Each subject received three levels of pressure (low/medium/high) based on subjective ratings determined prior to the scan using a block design (pressure/rest). Pressure rating was assessed with an 11-point scale (0 = no touch; 10 = max pain-free pressure). Brain activation differences between pressure levels and rest were analyzed. Subjective pressure ratings were significantly different across pressure levels (p < 0.05). The overall brain activation pattern was not different across pressure levels (all p > 0.05). However, the overall effect of pressure versus rest showed significant decreases in brain activation in response to the mechanical stimulus in regions associated with somatosensory processing including the precentral gyri, left hippocampus, left precuneus, left medial frontal gyrus, and left posterior cingulate. There was increase in brain activation in the right inferior parietal lobule and left cerebellum. This study offers insight into the neural mechanisms that may relate to manual mobilization intervention used for managing low back pain. [ABSTRACT FROM AUTHOR]

The physiological root resorption of deciduous teeth is a normal phenomenon, but the mechanisms underlying this process are still unclear. In this study, deciduous dental pulp stem cells (DDPSCs) and permanent dental pulp stem cells (DPSCs) were derived from deciduous teeth and normal permanent teeth at different stages of resorption. In the middle stage of root resorption, DDPSCs exhibited an increase in the ability to induce osteoclast differentiation. Activation of the alpha 7 nicotinic acetylcholine receptor (α7 nAChR) by secretory mammalian Ly-6 urokinase-type plasminogen activator receptor-associated protein 1 (SLURP-1) caused a significant increase in the expression levels of NF-κB, receptor activator of nuclear factor-kappa B ligand (RANKL), and the ratio of RANKL/osteoprotegerin (OPG). These effects were inhibited by alpha-bungarotoxin (α-BTX). Furthermore, the expression levels of RANKL/OPG were significantly reduced following inhibition of NF-κB. High-strength, dynamic positive pressure increased the expression of SLURP-1 and α7 nAChR in DDPSCs in the stable stage. These data indicated that mechanical stress stimulated the expression of SLURP-1 and α7 nAChR in DDPSCs. Additionally, SLURP-1 activated α7 nAChR, thereby upregulating the expression of NF-κB and enhancing its activity, thus regulating RANKL/OPG expression and affecting the ability of DDPSCs to influence osteoclastogenesis, which likely enhances root resorption and leads to the physiological loss of deciduous teeth. [ABSTRACT FROM AUTHOR]

Objective: To investigate the effects of gradient mechanical pressure on chondrocyte proliferation, apoptosis, and the expression of markers of chondrogenesis and chondrocyte hypertrophy. Methods: Mandibular condylar chondrocytes from 5 rabbits were cultured in vitro, and pressed with static pressures of 50 kPa, 100 kPa, 150 kPa and 200 kPa for 3 h, respectively. The chondrocytes cultured without pressure (0 kPa) were used as control. Cell proliferation, apoptosis, and the expression of aggrecan (AGG), collagen II (COL2), collagen X (COL10), alkaline phosphatase (ALP) were investigated. Ultrastructures of the pressurized chondrocytes under transmission electron microscopy (TEM) were observed. Results: Chondrocyte proliferation increased at 100 kPa and decreased at 200 kPa. Chondrocyte apoptosis increased with peak pressure at 200 kPa in a dose-dependent manner. Chondrocyte necrosis increased at 200 kPa. The expression of AGG increased at 200 kPa. The expression of COL2 decreased at 50 kPa and increased at 150 kPa. The expression of COL10 and ALP increased at 150 kPa. Ultrastructure of the pressurized chondrocytes under TEM showed: at 100 kPa, cells were enlarged with less cellular microvillus and a bigger nucleus; at 200 kPa, cells shrank with the sign of apoptosis, and apoptosis cells were found. Conclusions: The mechanical loading of 150 kPa is the moderate pressure for chondrocyte: cell proliferation and apoptosis is balanced, necrosis is reduced, and chondrogenesis and chondrocyte hypertrophy are promoted. When the pressure is lower, chondrogenesis and chondrocyte hypertrophy are inhibited. At 200 kPa, degeneration of cartilage is implied. [ABSTRACT FROM AUTHOR]

Mechanical pressure develops in Li-ion batteries (LIBs) during operation and is critical to battery performance and safety. Detecting pressures in situ is essential to elucidate the operating mechanisms. However, the feasibility and scalability of the current methods face challenges in practical in-situ measurements given the harsh battery internal environment and shell obstruction, especially for large-format LIBs. This study develops an in-situ measurement method for the mechanical pressure of electrode stacks, referred to as jelly rolls, by using embedded thin-film flexible pressure sensors. Pressure sensors are placed inside a prismatic power LIB, and the pressure behaviors are detected. The experiments demonstrate that this method can be used to inspect the mechanical behavior of the jelly roll over a long operation time. The mechanical pressure generated by the volume expansion of the jelly roll is related to the lithiation and delithiation of the graphite cathode. Both reversible and irreversible pressures can be observed using this method, their evolution characteristics are related to spatial location, charging/discharging rate, external pressure, and electrode stack assembly. The proposed method is promising in detecting the pressure state of LIBs and assisting in the evaluation of battery engineering design, manufacturing, and operation monitoring. [Display omitted] • In situ pressure detection in large-format Li-ion batteries (LIBs) via flexible sensors. • The pressure in the jelly roll reflects the LIB mechanical behavior during operation. • Flexible thin-film pressure sensors help to evaluate LIB operation performance. [ABSTRACT FROM AUTHOR]

Mechanical pressure controls the structural, electric, and magnetic order in solid-state systems, allowing tailoring of their physical properties. A well-established example is ferroelastic ferroelectrics, where the coupling between pressure and the primary symmetry-breaking order parameter enables hysteretic switching of the strain state and ferroelectric domain engineering. Here, we study the pressure-driven response in a nonferroelastic ferroelectric, ErMnO 3 , where the classical stress-strain coupling is absent and the domain formation is governed by creation-annihilation processes of topological defects. By annealing ErMnO 3 polycrystals under variable pressures in the MPa regime, we transform nonferroelastic vortex-like domains into stripe-like domains. The width of the stripe-like domains is determined by the applied pressure as we confirm by three-dimensional phase field simulations, showing that pressure leads to oriented layer-like periodic domains. Our work demonstrates the possibility to utilize mechanical pressure for domain engineering in nonferroelastic ferroelectrics, providing a lever to control their dielectric and piezoelectric responses.

Mechanical pressure plays an important role in many physiological and pathological processes. Mimicking the mechanical pressure present in vitro is necessary for related research, but usually requires expensive and complicated equipment. In this study we created a simple pressure culture system based on the transwell culture system. By cutting off the top rim of the transwell insert, the cells were compressed between the insert membrane and the well floor. The new pressure culture system was proven effective in that it induced cell morphological change, integrin β1 upregulation, actin polymerization and growth change in rat retinal ganglion cells, human nasopharyngeal carcinoma cells and mice embryonic fibroblasts. Though the pressure value is immeasurable and inhomogeneous, the easily available culture system still provides a choice for the laboratories that do not have access to the better, but much more expensive pressure culture equipment.

The seeds of terrestrial flowering plants often start their life cycle in subterranean darkness. To protect the fragile apical meristematic tissues and cotyledons from mechanical injuries during soil penetration, dicotyledonous seedlings form an elegant apical hook at the top of the hypocotyl. The apical hook has been considered as an adaption structure to the subterranean environment. However, the role of the apical hook in seedling emergence and the molecular mechanism of apical hook formation under real-life conditions remain highly speculative. Here, we find that HOOKLESS 1 (HLS1), a critical gene in apical hook formation in Arabidopsis thaliana, is required for seedling emergence from the soil. When grown under soil, hls1 mutant exhibits severe emergence defects. By contrast, HLS1 overexpression in the hls1 background fully restores emergence defects and displays better emergence capacity than that of WT. Our results indicate that HLS1 transcription is stimulated in response to the mechanical stress of soil cover, which is dependent on the function of the transcription factors ETHYLENE INSENTIVE 3 (EIN3) and EIN3-LIKE 1 (EIL1). Soil-conferred mechanical stress activates the ethylene signaling pathway to stabilize EIN3 by repressing the activity of the F-box proteins EBF1 and EBF2. These combined results reveal a signaling pathway in which plant seedlings transduce the mechanical pressure of soil covering to regulate apical hook formation accordingly for emerging from the soil.

Currently, metal-organic frameworks (MOFs) are receiving significant attention as part of an international push to use their special properties in an extensive variety of energy applications. In particular, MOFs have exceptional potential for gas storage especially for methane and hydrogen for automobiles. However, using theoretical approaches to investigate this important problem presents various difficulties. Here we present the outcomes of a basic theoretical investigation into methane adsorption in large pore MOFs with the aim of capturing the unique features of this phenomenon. We have developed a pseudo one-dimensional statistical mechanical theory of adsorption of gas in a MOF with both narrow and large pores, which is solved exactly using a transfer matrix technique in the Osmotic Ensemble (OE). The theory effectively describes the distinctive features of adsorption of gas isotherms in MOFs. The characteristic forms of adsorption isotherms in MOFs reflect changes in structure caused by adsorption of gas and compressive stress. Of extraordinary importance for gas storage for energy applications, we find two regimes of Negative gas adsorption (NGA) where gas pressure causes the MOF to transform from the large pore to the narrow pore structure. These transformations can be induced by mechanical compression and conceivably used in an engine to discharge adsorbed gas from the MOF. The elements which govern NGA in MOFs with large pores are identified. Our study may help guide the difficult program of work for computer simulation studies of gas storage in MOFs with large pores.

Pressure application to the lumbar spine is an important assessment and treatment method of low back pain. However, few studies have characterized brain activation patterns in response to mechanical pressure. The objective of this study was to map brain activation associated with various levels of mechanical pressure to the lumbar spine in healthy subjects. Fifteen healthy subjects underwent functional magnetic resonance imaging (fMRI) scanning while mechanical pressure was applied to their lumbar spine with a custom-made magnetic resonance imaging (MRI)-compatible pressure device. Each subject received three levels of pressure (low/medium/high) based on subjective ratings determined prior to the scan using a block design (pressure/rest). Pressure rating was assessed with an 11-point scale (0 = no touch; 10 = max pain-free pressure). Brain activation differences between pressure levels and rest were analyzed. Subjective pressure ratings were significantly different across pressure levels (p < 0.05). The overall brain activation pattern was not different across pressure levels (all p > 0.05). However, the overall effect of pressure versus rest showed significant decreases in brain activation in response to the mechanical stimulus in regions associated with somatosensory processing including the precentral gyri, left hippocampus, left precuneus, left medial frontal gyrus, and left posterior cingulate. There was increase in brain activation in the right inferior parietal lobule and left cerebellum. This study offers insight into the neural mechanisms that may relate to manual mobilization intervention used for managing low back pain.

By reducing current velocity, tidal marsh vegetation can diminish storm surges and storm waves. Conversely, currents often exert high mechanical stresses onto the plants and hence affect vegetation structure and plant characteristics. In our study, we aim at analysing this interaction from both angles. On the one hand, we quantify the reduction of current velocity by Bolboschoenus maritimus, and on the other hand, we identify functional traits of B. maritimus' ramets along environmental gradients. Our results show that tidal marsh vegetation is able to buffer a large proportion of the flow velocity at currents under normal conditions. Cross-shore current velocity decreased with distance from the marsh edge and was reduced by more than 50% after 15 m of vegetation. We were furthermore able to show that plants growing at the marsh edge had a significantly larger diameter than plants from inside the vegetation. We found a positive correlation between plant thickness and cross-shore current which could provide an adaptive value in habitats with high mechanical stress. With the adapted morphology of plants growing at the highly exposed marsh edge, the entire vegetation belt is able to better resist the mechanical stress of high current velocities. This self-adaptive effect thus increases the ability of B. maritimus to grow and persist in the pioneer zone and may hence better contribute to ecosystem-based coastal protection by reducing current velocity. [ABSTRACT FROM AUTHOR]