Search Results (106)

In the high-temperature cooking process of Chinese-style catering, the oil fume accumulates on the inner wall of the flue during the cooling process, forming grease stains, which can easily trigger flue fires and cause a kitchen fire. Statistics indicate flue fires are a primary cause of kitchen fires in China. The changes in the composition of grease stains are due to different freezing points, which will adhere to different parts of the flue and be repeatedly heated and cooled if not cleaned in time. This leads to changes in combustion performance, subsequently affecting the progression of flue fire propagation. This paper takes grease deposits with different deposition times and locations in the flue of commercial kitchens as the research object. The research selected a medium-sized commercial kitchen flue (kitchen chimney) in Langfang City, with deposition times of the parts of the inlet and outlet for 2 months and grease in the inlet for a deposition time of 7 days, 60 days, and more than 1 year. This paper analyzed the grease deposits at different deposition positions at the flue inlet and outlet using a thermogravimetric analyzer and a gas-mass spectrometer. It is found that the primary components of the grease at the outlet have low molecular weight, thermal decomposition starting temperature ignition temperature, and activation energy in the first stage and will catch fire first; the grease at the inlet has a high comprehensive combustion performance, and the combustion is violent with little effect from the oxygen supply. Then, the pyrolysis analysis of grease stains located at the entrance of the flue is performed at different deposition times under air and nitrogen atmosphere. The results showed that the pyrolysis process of grease stains with a more than 1 year deposition time consists of two stages. One stage is the first weightlessness stage, which has the lowest activation energy, the longest combustion process, and the greatest fire risk; the other is the pyrolysis combustion process of grease stains with a deposition time of 7 days. Its activation energy is the highest, and the fire risk is the smallest. The research results can be a reference for the setting of the fire dampers and the cleaning time for the flue. Full article

Background/Objectives: The adverse effects of low gravity on human physiology are well documented; however, much of the literature is directed at changes which occur in microgravity (µg: weightlessness) with relatively less documented on changes in hypogravity (<1 g; >µg: gravity less than Earth’s but more than microgravity). Somatosensation and neuromuscular control may be of particular importance for astronauts as they prepare for future missions to walk on the Moon. This study aimed to explore the effect of reduced weight bearing (to simulate conditions of hypogravity) on ankle somatosensation, lower-limb muscle activity, tone, and stiffness, compared to full weight bearing. Methods: Participants completed an ankle somatosensory acuity task (active movement extent discrimination assessment [AMEDA]) in two body positions: (1) upright standing (1 g), and (2) in a head-elevated supine, semi-weight bearing (0.16 g) position using a custom-built inclined “wedge bed”. The second position induced ~16% body weight on to the plantar aspect of the feet, simulating that of lunar gravity. We compared the AMEDA scores between the two positions. Lower-limb muscle activity was recorded via surface EMG throughout the AMEDA task for both positions. The ankle AMEDA has five depths of ankle inversion. We compared muscle activity between the body positions, and muscle activity between inversion depths “1” and “5” (within each position). Lower-limb muscle tone and muscle stiffness were assessed at rest in both body positions using the MyotonPRO. Results: Fifty-five participants between the ages of 18 and 65 (28 females, 27 males; mean age of 40 years) completed the study. The AMEDA scores, muscle tone and stiffness were reduced when the participants were on the lunar wedge bed, compared to upright standing (p = 0.002; p < 0.001; p < 0.001). Some lower-limb muscles exhibited less activity in the lunar wedge-bed position compared to upright standing (tibialis anterior, peroneus longus, vastus lateralis, rectus femoris; p < 0.05) but others were unchanged (gastrocnemius, vastus medialis; p > 0.05). Muscle activity was unchanged between the AMEDA depths (p = 0.188). Conclusions: The results provide insight into how the somatosensory and neuromuscular systems respond to reduced weight bearing and potentially lunar gravity conditions, thereby informing how to target interventions for future missions. Full article

The adverse effects of weightlessness on the human cardiovascular system greatly hinder the process of long-term and long-distance space exploration. Succinylation is an important type of protein post-translational modification. However, whether succinylation modification is able to play a role in altered vascular endothelial cell function under microgravity or simulated microgravity has not been reported. This study aims to investigate the quantitative global proteome and the changes in lysine succinylation in related proteins, seeking to facilitate a better understanding of the protein post-translational modification in cardiovascular deconditioning under microgravity. LC-MS/MS combined with bioinformatics analysis were used to quantitatively detect the perspectives at the global protein level. Immunoprecipitation and Western blot analysis were conducted to further verify the alterations of related proteins and lysine succinylation. A total of 132 differentially expressed proteins and 164 differentially expressed lysine succinylation sites were identified in human umbilical vein endothelial cells (HUVECs). Bioinformatics analysis indicates that lysine succinylation may play a potential role in energy metabolism. In addition, desuccinylase SIRT5 was downregulated and regulated succinylation modification levels of HUVECs under simulated microgravity. Notably, the overexpression of SIRT5 effectively protected HUVECs from apoptosis induced by simulated microgravity. And the succinylation of Lys396 in ERO1A was significantly increased in HUVECs under simulated microgravity. Mechanistically, the knockdown of SIRT5 was found to induce the apoptosis of HUVECs through the succinylation of Lys396 in ERO1A. These results can provide new ideas for elucidating the molecular mechanism of cardiovascular dysfunction in microgravity environments, and provide key molecular targets for scientific protective measures against microgravity in space. Full article

Background/Objectives: Long-term spaceflight in a microgravity environment frequently results in gastrointestinal dysfunction, presenting substantial challenges to astronauts’ health. Hericium erinaceus, a plant recognized for its dual use as food and medicine, contains a key functional component called Hericium erinaceus polysaccharide (HEP), which is purported to promote gastrointestinal health. This study aims to investigate the protective effects of HEP against gastrointestinal disturbances induced by simulated weightlessness and to elucidate its regulatory mechanisms. Methods: Sprague Dawley rats subjected to a tail suspension model were administered either a standard diet or a diet supplemented with 0.125% HEP over a period of 4 weeks (the intake of HEP is approximately 157.5 mg/kg bw/d, n = 8), metagenomics and targeted metabolomics to investigate the effects of HEP on gastrointestinal hormone secretion disorders, gut microbiota dysbiosis, and intestinal barrier damage induced by simulated weightlessness. Results: Dietary supplementation with HEP was observed to significantly alleviate weightlessness-induced gastrointestinal hormone disruptions, enhancing motility and intestinal barrier function while reducing inflammation. In addition, HEP improved gut microbiota by boosting beneficial bacteria as Oscillibacter sp.1-3, Firmicutes bacterium ASF500, and Lactobacillus reuteri, while reducing harmful bacteria like Escherichia coli and Mucispirillum schaedleri at the species level. Furthermore, HEP altered the serum metabolic profile of the rats, reducing inflammation by upregulating the tryptophan metabolism pathway and enhancing the production of short-chain fatty acids. Conclusions: HEP effectively protects against gastrointestinal dysfunction induced by simulated weightlessness by regulating hormone secretion and maintaining intestinal homeostasis. Full article

Research into the mechanisms by which gravity influences spermatozoa has implications for maintaining the species in deep space exploration and may provide new approaches to reproductive technologies on Earth. Changes in the speed of mouse spermatozoa after 30 min exposure to simulated weightlessness (by 3D-clinostat) and 2 g hypergravity (by centrifugation) were studied using inhibitory analysis. Simulated microgravity after 30 min led to an increase in the speed of spermatozoa and against the background of an increase in the relative calcium content in the cytoplasm. This effect was prevented by the introduction of 6-(dimethylamino) purine, wortmannin, and calyculin A. Hypergravity led to a decrease in the speed of spermatozoa movement, which was prevented by sodium orthovanadate and calyculin A. At the same time, under microgravity conditions, there was a redistribution of proteins forming microfilament bundles between the membrane and cytoplasmic compartments and under hypergravity conditions—proteins forming networks. The obtained results indicate that even a short exposure of spermatozoa to altered gravity leads to the launch of mechanotransduction pathways in them and a change in motility. Full article

Robots are becoming an integral part of space facilities construction and maintenance, and may need to move to and from different work locations. Robotic arms that are widely employed, which are mounted on fixed bases, have difficulty coping with increasingly complex missions. The challenge discussed in this paper is the problem of the efficient locomotion of robotic systems. Inspired by the gliding motion of a flying snake launched from a tree and combined with the weightlessness of the space environment, we design similar motions for the robot, including the following three steps. First, the robot folds its body like a snake and initiates flight by accelerating the global center of mass (CM), focusing on the movement direction and generating suitable momentum. Then, during the flight (free-floating) phase, the joint motions are planned using a nonlinear optimization technique, considering the nonholonomic constraints introduced by the momentum conservation and the system states at the initial and final states of the floating. Meanwhile, the difficulties caused by long-distance flights are addressed to reduce the motion computational cost and energy consumption by introducing the phase plane analysis method. Finally, the landing motion is designed to avoid rigid collisions and rollover on the radial plane. The numerical simulations illustrate that the three phases of maneuvers are smooth and continuous, which can help the space robots efficiently traverse the environment. Full article

Herein, we take an underground natural gas storage in the Ordos Basin as an example to explore the influence of temperature, CO₂ flow rate, CO₂ partial pressure, and chloride ion concentration on the corrosion rate of N80 and P110 steels in CaCl₂ brine type. Meanwhile, in order to reduce the amount of chemical corrosion inhibitors and improve performance, a novel corrosion inhibitor with a quinoline quaternary ammonium structure named YS-QB was synthesized from 1-methyl-1,2,3,4-tetrahydroisoquinoline, epichlorohydrin, and oleic acid amide propyl dimethylamine. Under normal and high-pressure environments, YS-QB exhibits a superior corrosion inhibition effect to the market product of CX-1. In order to further reduce the amount of corrosion inhibitor and improve the corrosion inhibition effect, orthogonal experiments were conducted to optimize the formula system, and the optimal composite system was finally obtained by forming YS-QB, propargyl alcohol, hexamethylenetetramine, and isopropanol in a mass ratio of 12:1:1:2. At 80 °C, a dosage of 30 mg/L can suppress the CO₂ corrosion rate below 0.076 mm/a, while a dosage of 60 mg/L can suppress the CO₂ corrosion rate below 0.076 mm/a at a high-pressure environment of 120 °C. Combining weightlessness and electrochemical experiments, it is found that the composite corrosion inhibitor performs best when the dosage reached 100 mg/L, and a further increase in the dosage weakens the corrosion inhibition capacity. Based on the polarization curve changes with the dosage of the composite corrosion inhibitor, it can be determined that the final obtained composite corrosion inhibitor system was a cathodic corrosion inhibitor. Full article

The study aimed at obtaining a precise view of the modification of heart rate variability (HRV) and respiratory rate with the help of “smart clothes” (the Hexoskin Smart Shirt, Hexoskin Smart Sensors & AI, Montreal, QC, Canada) during a 45 min session of “dry” immersion (DI), which is considered a model of Earth-based weightlessness. Eight healthy subjects aged 19 to 21 years participated in the study. Hexoskin Smart Shirt provided a .wav sound file. For analysis, the ecg_peaks function of the neurokit2 library was applied. HRV parameters were calculated within 5 min segments with the help of the pyHRV toolbox. Time-domain (HR and SDNN) and frequency-domain (HF, LF, and VLF) HRV parameters, sample, and approximate entropy were calculated. Thus, the “smart cloth” technology appears as a reliable telemetric instrument to monitor cardiac and respiratory regulation during the DI session. Full article

In most mammals, postural soleus muscles are involved in the maintenance of the stability of the body in the gravitational field of Earth. It is well established that immediately after a laboratory rat is exposed to conditions of weightlessness (parabolic flight) or simulated microgravity (hindlimb suspension/unloading), a sharp decrease in soleus muscle electrical activity occurs. However, starting from the 3rd day of mechanical unloading, soleus muscle electrical activity begins to increase and reaches baseline levels approximately by the 14th day of hindlimb suspension. This phenomenon, observed in the course of rat hindlimb suspension, was named the “spontaneous electrical activity of postural muscle”. The present review discusses spinal mechanisms underlying the development of such spontaneous activity of rat soleus muscle and the effect of this activity on intracellular signaling in rat soleus muscle during mechanical unloading. Full article

The article discusses laboratory methods and the corresponding computational methods verifying compliance with the normative requirements regarding the lateral correction force of the powered roof support. The currently used flat model only allows for checking the normative requirement in relation to the sum of active forces of the correction cylinders installed in the roof support. Determining the required value of the active force of each cylinder is possible due to the simplified FEM model of a powered roof support, described in the research work, treated as a uniform weightless elastic body loaded with a concentrated force recreating the weight of the roof support located on an inclined longwall panel. The third analysed computational method involves determining the reaction in the four correction cylinders of the roof support, creating a spatial, statically indeterminate system of forces. It enables determining the range of variability of the response in the correction cylinders as a function of the distribution of floor pressure on the roof support base. The discussed computational methods were used to determine, for example, the lateral correction force of one of the types of powered supports used in a longwall panel inclined at an angle of 35°. The usefulness of the discussed calculation methods at various stages of the designing process of the powered support and its certification has been confirmed. Full article

The aim of this study was to prevent initial changes in Drosophila melanogaster oocytes under simulated weightlessness and hypergravity at the 2 g level. Phospholipids with polyunsaturated fatty acids in the tail groups (essential phospholipids) at a concentration of 500 mg/kg of nutrient medium were used as a protective agent. Cell stiffness was determined using atomic force microscopy, the change in the oocytes’ area was assessed as a mark of deformation, and the contents of cholesterol and neutral lipids were determined using fluorescence microscopy. The results indicate that the administration of essential phospholipids leads to a decrease in the cholesterol content in the oocytes’ membranes by 13% (p < 0.05). The stiffness of oocytes from flies that received essential phospholipids was 14% higher (p < 0.05) and did not change during 6 h of simulated weightlessness or hypergravity, and neither did the area, which indicates their resistance to deformation. Moreover, the exposure to simulated weightlessness and hypergravity of oocytes from flies that received a standard nutrient medium led to a more intense loss of cholesterol from cell membranes after 30 min by 13% and 18% (p < 0.05), respectively, compared to the control, but essential phospholipids prevented this effect. Full article

Traditional model predictive torque control (MPTC) predicts the torque and flux values for the next time step and selects the voltage vector that minimizes the cost function as the optimal vector to apply to the inverter. This control approach is straightforward and allows for multi-objective control, but it has some issues in terms of the dynamic steady-state performance and parameter robustness. Therefore, this paper proposes a weightless model predictive control method based on an extended state observer (ESO). By designing an improved ESO to observe and compensate for motor parameter disturbances in real time, and employing a novel 2-D switching table and voltage vector sector selection diagram, the method evaluates three out of eight voltage vectors based on the torque and stator flux error signals. This reduces the computational load while increasing the number of candidate voltage vectors. Finally, a cost function without weighting factors is designed to lower the computational complexity. The simulation results show that the proposed new control method effectively reduces the torque and flux ripple and improves the current waveform compared to traditional MPTC. Full article

In this article, I develop a critique of Chantal Mouffe’s leftist populism and its construction of ‘the people’ against an opposed ‘them’, from a perspective informed by the thought of Didier Eribon. I draw on both his public interventions and his theoretical work, employing his concepts of return, society as verdict, and his two principles of critical thinking to question the desirability of crafting ‘the people’ in the first place. I contend that Eribon’s critique renders Mouffe’s proposal problematic on three accounts. First, her approach is too politically volatile; its instability leaves it devoid of a critical analysis of the differences between concrete social positions, struggles, and subjectivities within ‘the people’. Consequently, the political becomes merely a function of the social. Yet, the social and its determining power remain mostly unaddressed by her framework. Second, its simplistic opposition of an overly generalised ‘the people’ against ‘the oligarchy’ is susceptible to right-wing populist appropriations. Third, for a shot at hegemony and a general appeal, it eclipses plurality and dissensus within ‘the people’. In contrast, Eribon encourages a connection between the social and the political by suggesting that a self-critical analysis be mutually intertwined with social analysis. Instead of merely mobilising affects, they must be critically interrogated. Instead of summoning ‘the people’, a return to their respective genesis must be attempted. Unless both principles of critical thinking, the insights of return, and societal verdicts are deployed to come to terms with the social determinisms at hand, the ‘people’s’ mobilisation against an opposed ‘them’ risks sacrificing pluralism and equality alike and neglecting the criteria of the desirability of specific changes in favour of a “whatever it costs” attempt at hegemony. Full article

In order to study the influence of modular filled and composite material forms on the axial crushing and energy absorption properties of structures, modular filled composite structures were constructed, and innovatively applied to the inner side of double-hat beam (DHB) structures in automobiles. The modular filled structures comprise hexagonal, quadrilateral, and triangular sections. By analyzing the collision performance of modular filled DHB structures, significant enhancements were observed in both the sectional characteristics and the specific Mean Crushing Force of modular filled DHBs compared to the conventional double-hat beam structure. These advancements notably improved the plastic deformation characteristics of the structures. Additionally, dynamic weightlessness experiments were conducted to validate the accuracy of the simulation model. Among the proposed schemes, namely QU-5, HE-5, and TR-5, notable improvements in crashworthiness were identified. Specifically, crashworthiness indicators increased by 32.54%, 78.9%, and 116.53%. Compared with other thin-walled structures, modular filled composite DHBs have advantages in axial crushing and energy absorption. By optimizing layout characteristics, the modular filled structures will achieve significant lightweight and energy absorption performance improvements. This work has clear reference value for automotive engineers and scholars to further explore the axial crash safety, platform modularization, and lightweight design of vehicles. Full article

Changes in the structure of bone can occur in space as an adaptive response to microgravity and on Earth due to the adaptive effects to exercise, to the aging of bone cells, or to prolonged disuse. Knowledge of cell-mediated bone remodeling on Earth informs our understanding of bone tissue changes in space and whether these skeletal changes might increase the risk for fractures or premature osteoporosis in astronauts. Comparisons of skeletal health between astronauts and aging humans, however, may be both informative and misleading. Astronauts are screened for a high level of physical fitness and health, are launched with high bone mineral densities, and perform exercise daily in space to combat skeletal atrophy as an adaptive response to reduced weight-bearing function, while the elderly display cellular and tissue pathology as a response to senescence and disuse. Current clinical testing for age-related bone change, applied to astronauts, may not be sufficient for fully understanding risks associated with rare and uniquely induced bone changes. This review aims to (i) highlight cellular analogies between spaceflight-induced and age-related bone loss, which could aid in predicting fractures, (ii) discuss why overreliance on terrestrial clinical approaches may miss potentially irreversible disruptions in trabecular bone microarchitecture induced by spaceflight, and (iii) detail how the cellular effects of the bisphosphonate class of drugs offer a prophylactic countermeasure for suppressing the elevated bone resorption characteristically observed during long-duration spaceflights. Thus the use of the bisphosphonate will help protect the bone from structural changes while in microgravity either along with exercise or alone when exercise is not performed, e.g. after an injury or illness. Full article