Low Pressure Research Articles

Reduction of rejects by combining data from the casting process and automatic X-ray inspection

Automatic inspection of castings with X-rays (radiographic and computed tomography) is widespread for parts that are relevant for safety or have high quality requirements. Examples in the automotive sector are aluminum wheels, chassis parts and new parts within the electric power train. Those parts are automatically inspected, which means that both the image acquisition and the evaluation of the images is done fully automatically. Today, in most industrial implementations, the generated data with a size up to several gigabytes per part is summarized to a simple good or bad decision, according to specification. All other data is dismissed, although this information can be valuable to optimize production processes and thus minimize rejects. This contribution gives an overview about the results of the project Cast Control, which is a collaboration of Fraunhofer Development Center for X-ray Technology EZRT, Fraunhofer Center for Applied Research on Supply Chain Services SCS and industry partner RONAL GROUP. RONAL GROUP is a major aluminum wheel manufacturer, mainly for the OEM market. Within the project we combined serial production data from the low pressure die casting process from a foundry of the RONAL GROUP with the data generated in the automatic X- ray inspection. After collecting a large base of sample data, we were able train a neural network for the prediction of error metrics obtained by X-ray inspection. We apply a combination of layer-wise relevance propagation and dimensionality reduction to find correlations between data of the casting machines (process and sensor) and the characteristics of anomalies detected during X-ray inspection. With this information, it is possible to adjust the casting process in an early stage – even before rejects are produced. This enables the foundry to reduce their rejects rate, which saves costs and energy and results in a better competitiveness.

Adsorption and dissociation of hydrogen molecules over S-vacancies in a Nb-doped MoS2monolayer.

Motivated by the recent interest in the hydrogen energy, we have carried out a complete study of the catalytic activity of a defective molybdenum disulfide monolayer (MoS2) by means of density functional theory (DFT) calculations. The MoS2 monolayer is characterized by a nonreactive basal plane. In principle, its catalytic activity is concentrated at the edges, but an alternative way to increase such activity is obtained by creating active sites where the molecules can dissociate. These defects can be easily produced experimentally by different techniques. In our study, we have performed an atomic, energetic and electronic analysis of a hydrogen molecule adsorbed on a MoS2 monolayer. In a first step, we have found that the H2 molecule remains physisorbed over both doped-free and Nb-doped MoS2 monolayers, showing that the Nb atom does not increase the poor reactivity of the clean MoS2 layer. 
Interestingly, our energetic results suggest that the vacancies will prefer to be formed close to the Nb atoms in the doped monolayer, but the small energy difference would allow the formation in non-doped like sites. Theoretically, we found out the conditions for the molecular dissociation on a S vacancy. In both cases, with and without Nb, the molecule should rotate from the original perpendicular position to an almost parallel orientation jumping an energetic barrier. After that, the atoms are separated binding to the Mo atoms around the missing S atom. Our ab initio molecular dynamics simulations show that for low pressure conditions (using one single molecule in the system) the H2 prefers to desorb from the vacancy, while for larger pressures (when additional H2 molecules are added to the system) the molecule is finally dissociated on the vacancy. Our long simulations confirm the great stability of the structure with the two H atoms binding to the Mo atoms close to the vacancy. 
Finally, the inclusion of a third (or a fourth) H atom in the vacancy leads to the formation and desorption of a H2 molecule, leaving one (or two) atoms in the vacancy.

Comparison of dehydration systems in quality and chemical effects on sunflower seeds

The present work investigates the quality and the chemical effects of dehydration, using a novel dehydration system based on an electromagnetic induction and low pressures technique, comparing it with the thermo-solar drying system. High oleic sunflower seeds, which are an important oil seed crop, were used due to the fact that they have a special place in the food industry. The seed samples were exposed to electromagnetic induction and low pressures by 0.5 and 1 h, then several chemical characterizations were carried out, in the electrophoresis study, it was found that most proteins in the hull were degraded or denatured, some of them were lost during the time in the thermosolar dryer while in kernel keeps 94.9% of the concentration in control proteins. Otherwise, the electromagnetic induction dryer did not lose the most of proteins in the kernel keeping 99.1% in 0.5 h and 98.4% in 1 h, just degrading its concentration. Germination viability results did not show changes after 0.5 h in the electromagnetic fields, but they decreased in 1 h from 66 to 40% until the thermosolar method fell to 24% in 4 h, both analysis results change proportionally with the treatment time and moisture content and the amount of the oxygen.

Adaptive non‐invasive ventilation treatment for sleep Apnea

AbstractThe purpose of this study was to investigate the effectiveness of two non‐invasive mechanical ventilation (NIV) modalities to treat sleep apnea: (1) Average Volume Assured Pressure Support (AVAPS) NIV, and (2) Pressure Support (PS) NIV with Continuously Calculated Average Required Ventilation (CCARV). Two detailed (previously developed and tested) simulation models were used to assess the effectiveness of the NIV modalities. One simulated subjects without chronic obstructive pulmonary disease (COPD), and the other simulated patients with COPD. Sleep apnea was simulated in each model (COPD and Non‐COPD), and the ability of each NIV modality to normalize breathing was measured. In both NIV modalities, a low level continuous positive airway pressure was used and a backup respiratory rate was added to the algorithm in order to minimize the respiratory work rate. Both modalities could help normalize breathing in response to an episode of sleep apnea within about 5 min (during which time blood gases were within safe limits). AVAPS NIV and PS NIV with CCARV have potential value to be used for treatment of sleep apnea. Clinical evaluations are needed to fully assess the effectiveness of these NIV modalities.

Bacterial profile, drug resistance pattern, clinical and laboratory predictors of ascites infection in cirrhosis patients

Ascites is a pathological collection of free fluid in the peritoneal cavity, which is a common complication in patients with cirrhosis, an advanced liver disease. Bacterial infection increases the mortality rate of hospitalized patients with cirrhosis, irrespective of the severity of the liver disease. Around 60% of patients with compensated cirrhosis developed ascites within 10 years during the course of their disease. The in-hospital mortality rate due to spontaneous bacterial peritonitis (SBP) could exceed 90%, but with early diagnosis and prompt antibiotic therapy, this rate has been shown to decrease to 20%. Here, we enrolled adult (age ≥ 18) patients with liver disease with evidence of cirrhosis who developed ascites and assessed the presence of spontaneous ascites fluid infection (SAFI) in these patients. Of the total 218 patients, 22.9% (50/218) develop ascites infection. The liver organ function tests like alanine aminotransferase, aspartate aminotransferase, total bilirubin, and direct bilirubin were found to be significantly (P < 0.05) higher in patients with ascites fluid infection compared to patients with non-ascites fluid infection. Of the gram-negative bacteria, K. pneumonia and E. coli were isolated and found to be 100% resistant to amoxicillin and clavulanate. From the gram-positive bacterial isolates, S. aureus was only resistant to penicillin, whereas Str. viridans was resistant to ceftriaxone, cefotaxime, cefepime, and penicillin. On the other hand, clinical features such as a history of jaundice, low arterial blood pressure, and ultrasound results such as a shrunken liver and enlarged spleen were also independent predictors of spontaneous bacterial peritonitis. In conclusion, given the high probability of death following SAFI, early detection, and treatment, as well as knowledge of the microbial agent, resistance profile, and predictive markers in various contexts, are essential for the timely diagnosis and management of SAFI in these patients.

Sonoprocesses for sustainable textile processing and nanofinishing: a review

The textile sector is widely acknowledged as one of the most environmentally damaging sectors globally, primarily due to its high consumption of water and energy, utilization of chemicals, and the discharge of waste water containing a complex mixture of hazardous substances. The incorporation of nanotechnology, particularly through wet processes involving nano finishes, while enhancing textile functionality, further exacerbates these environmental concerns. Consequently, the exploration and promotion of sustainable methodologies are imperative across all wet treatments in textile processing. Among the potential solutions, sonoprocesses stand out as a promising avenue for mitigating resource consumption, and supporting environmentally friendly synthesis and application of nanomaterials to textiles. Sonoprocesses offer the advantage of carrying processes at low temperature and pressure, and the use of aqueous media instead of organic solvents. This comprehensive review delves into the multifaceted applications of sonoprocesses within the textile realm, with a specific emphasis on the synthesis and application of nanomaterials to textiles. Discussing the diverse applications of sonoprocesses, this study will pave the way for the integration of these techniques within the textile industry, ultimately aiming for widespread adoption on a commercial scale. This will help in promoting sustainable practices and reducing the ecological footprint of the textile sector.

Applying Machine Learning in Numerical Weather and Climate Modeling Systems

Applying Machine Learning in Numerical Weather and Climate Modeling Systems

Experimental study on the combustion and flame propagation characteristics of CH4/O2/N2 premixed turbulent jets

The combustion and flame propagation characteristics of CH4/O2/N2 premixed turbulent jets are investigated experimentally in a constant volume chamber (CVC) under different initial temperature (Tini, 300/400/500/600K) and oxygen fractions (γ, 0.4/0.6/0.8/1.0) conditions using High-speed camera and schlieren system. Four types of jet tip velocity were found: primary vortex motion at the jet top (M-type 1), secondary vortex motion (M-type 2), weaker positive and negative feedback between the flame and the flow field (M-type 3), and stronger positive and negative feedback (N-type 4). With the decrease of γ, the jet acceleration and deceleration mechanism is changed from the top vortex motion mechanism in M-type 1 and M-type 2 to the positive and negative feedback mechanism in M-type 3 and N-type 4. The interaction between the pulsating flow field and the heat release from the pre-chamber transitions to the flow field momentum dissipation. For M-type 1 and M-type 2, there is no significant difference in overpressure dynamics. The N-type 4 exhibits lower peak pressure and pressure rise rates. Moreover, the flame mode was predicted under higher Pini (10 bar ≤ Pini) and lower γ (γ ≤ 0.4) based on empirical equations established by the self-similar analytical model.

Production of Mg thin flakes with enhanced hydrogen storage performance

Flake-like particles are interesting materials for the preparation of alloys and homogeneous nanocomposites, they also have potential use as hydrogen storage materials. However, limited information is available regarding the synthesis of pure magnesium with flake-like morphology. In this study, the successful production of Mg flakes was conducted using a cost-effective and simple method, such as high energy ball milling. Various milling parameters, including different milling times and process control agents, were tested. Optimal conditions led to the formation of coarse flakes with ∼1.72 μm thickness, while a two-step milling process produced thinner flakes with submicron thickness (∼242 nm). Ductilization of the material and a significant reduction in crystal size during the milling process were observed via X-ray diffraction. Isothermal kinetic tests at 350 °C and 20 bar revealed improved hydrogen storage performance for both coarse and thin flakes compared to pristine Mg. Coarse flakes achieved capacities of 4.1 wt% in 60 min while thin flakes reached 4.6 wt% in 6 min, compared to 3.4 wt% achieved in 100 min by pristine Mg. The improved behavior of thin flake-shaped Mg was maintained at 300 °C and 20 bar, with 4.5 wt% of hydrogen absorbed in 6 min. Even at lower testing pressures (10 bar) higher capacities were achieved at the expense of slower kinetics. These findings suggest that thin flake-shaped Mg is a suitable material with enhanced performance for hydrogen storage applications.

Cloud Radiative Effects Associated With Daily Weather Regimes

AbstractUsing high temporal resolution satellite observations and reanalysis data, we classify daily weather into distinct regimes and quantify their associated cloud radiative effect (CRE) to better understand the roles of various weather systems in affecting Earth's top‐of‐atmosphere radiation budget. These regimes include non‐precipitation, drizzle, wet non‐storm, and storm days, which encompass atmospheric rivers (AR), tropical storms (TS), and mesoscale convection systems (MCS). We find that precipitation (wet) days account for roughly 80% (60%) of global longwave (LW) and shortwave (SW) CREs due to their large frequency and high intensity in CRE. Despite being rare globally (13%), AR, TS, and MCS days together account for 32% of global LW CRE and 27% of SW CRE due to their higher intensity in LW and SW CRE. These results enhance our understanding of how various weather systems, particularly severe storms, influence Earth's radiative balance, and will help to better constrain climate models.

Healing of Undisturbed Slide Zone Soil: Experimental Study on the Huaipa Landslide in Sanmenxia City

The occurrence and development of a landslide is a gradual process of destruction, causing huge losses to people’s lives and property. The shear strength of the shear zone gradually decreases to the residual state during the sliding process but it can recover to a certain extent during a relatively stable period. In a landslide, more than one slide usually occurs; however, after the first slide stops, it can enter a dormant period. The sliding surface can then experience a self-healing strength recovery phenomenon; this self-healing phenomenon has a significant impact on the reactivation of the landslide. Relevant studies have shown that the strength of the sliding surface is slightly greater than the residual strength when a landslide is reactivated; however, the explanations provided by these studies have not been sufficiently systematic. In this study, focusing on the undisturbed slide zone soil of the Huaipa landslide in Sanmenxia City, the “shear–pause–shear–pause–shear” test scheme is adopted. The soil is subjected to 3 h, 6 h, 12 h, 24 h, and 72 h healing shear tests, and combined with the SEM microstructure characteristics of the shear surface, to explore the internal mechanism of self-healing. The results show that the landslide soil exhibits strong self-healing strength recovery characteristics; however, these strength recovery characteristics decrease rapidly after experiencing a very small displacement. The strength recovery was strongly correlated with the vertical stress and healing time. With increasing vertical stress, the strength recovery value of the soil increases. Under low pressure, the strength recovery is small, and under high pressure, the strength recovery is obvious. With increasing healing time, the strength recovery increases; however, the increase in the amplitude diminishes and ultimately approaches zero with increasing healing time. A “healing phenomenon” occurs in the shear surface of slide zone soil after a short period of time. A shear strength value greater than the residual strength can be used to check the landslide design, which can effectively reduce costs.

New Sorption Isotherms Derived from a Gamma Distribution of Binding Constants.

New sorption isotherms for heterogeneous sorbents are derived by combining a Gamma distribution of binding constants with a local isotherm defined by a Langmuir or Hill equation. The new "Gamma isotherms" are expressed as Stieltjes transforms of the distribution and involve generalized exponential integrals. The related energy distributions are asymmetric and present a peak corresponding to the mean binding constant. The advantages of the new isotherms are (1) at low pressures or concentrations, with a Langmuir local isotherm, the global "Gamma-Langmuir" isotherm retrieves Henry's law; (2) contrary to the power Freundlich or hypergeometric Freundlich global isotherms, these Gamma isotherms do not need a redefinition of the standard state; (3) with a Hill local isotherm, the global "Gamma-Hill" isotherm allows a separate estimation of the cooperativity and heterogeneity parameters; and (4) the condensation approximation is a good approximation if the local isotherm is Hill and displays a high degree of cooperativity. The Gamma-Langmuir model is applied to three examples from the literature, with rather different Gamma distributions.

Recovery and immune function after low pressure pneumoperitoneum during robot-assisted radical prostatectomy: a randomised controlled trial.

To compare the effectiveness of low intra-abdominal pressure (IAP) facilitated by deep neuromuscular block (NMB) to standard practice in improving the quality of recovery, preserving immune function, and enhancing parietal perfusion during robot-assisted radical prostatectomy (RARP). In this blinded, randomised controlled trial, 96 patients were randomised to the experimental group with low IAP (8 mmHg) facilitated by deep NMB (post-tetanic count 1-2) or the control group with standard IAP (14 mmHg) and moderate NMB (train-of-four 1-2). Recovery was measured using the 40-item Quality of Recovery questionnaire and 36-item Short-Form Health survey. Immune function was evaluated by plasma damage-associated molecular patterns, cytokines, and ex vivo lipopolysaccharide-stimulated cytokine production. Parietal peritoneum perfusion was measured by analysing the recordings of indocyanine-green injection. Quality of recovery was not superior in the experimental group (n = 46) compared to the control group (n = 50). All clinical outcomes, including pain scores, postoperative nausea and vomiting, and hospital stay were similar. There were no significant differences in postoperative plasma concentrations of damage-associated molecular patterns, cytokines, and ex vivo cytokine production capacity. The use of low IAP resulted in better parietal peritoneum perfusion. Despite better perfusion of the parietal peritoneum, low IAP facilitated by deep NMB did not improve the quality of recovery or preserve immune function compared to standard practice in patients undergoing RARP.

3D-printed magnetic-based air pressure sensor for continuous respiration monitoring and breathing rehabilitation

The rapid development of point-of-care testing has made prompt diagnosis, monitoring and treatment possible for many patients suffering from chronic respiratory diseases. Currently, the biggest challenge is further optimizing testing devices to facilitate more functionalities with higher efficiency and performance, along with specificity toward patient needs. By understanding that patients with chronic respiratory diseases may have difficulty breathing within a normal range, a respiration sensor is developed focusing on sensitivities in the lower air pressure range. In contrast to the simpler airflow data, the sensor can provide respiratory air pressure as an output using a magnetic-based pressure sensor. This unconventional but highly reliable approach, combined with the rest of the simple 3D-printed design of the sensor, offers a wide range of tunability and functionalities. Due to the detachable components of the respiration sensor, the device can be easily transformed into other respiratory uses such as an inspiratory muscle training device or modified to cater for higher-ranged deep breathing. Therefore, not only does it reach very low air pressure measurement (0.1 cmH2O) for normal, tidal breathing, but the sensor can also be manipulated to detect high levels of air pressure (up to 35 cmH2O for exhalation and 45 cmH2O for inhalation). With its excellent sensitivities (0.0456 mV/cmH2O for inhalation, -0.0940 mV/cmH2O for exhalation), impressive distinction between inhalation and exhalation, and fully reproducible and convenient design, we believe that this respiration sensor will pave the way for developing multimodal and multifunctional respiration sensors within the biomedical field.

An Experimental Study on the Flash Boiling Characteristics of Liquid Ammonia Spray in a Constant Volume Chamber under High Injection Pressure

The spray characteristics of liquid ammonia under various ambient pressures and temperatures were analyzed in a constant volume chamber to cover a wide range of superheat degrees. The injection pressure was set as 70 and 80 MPa with ambient pressure ranging from 0.2 to 4 MPa. The ambient temperature was 500 K. The results showed that the higher the injection pressure, the greater the kinetic energy obtained. The droplet fragmentation was enhanced, and the phenomenon of gradual separation of the gas–liquid region occurred with increasing injection pressure. Under flash boiling spray conditions, the spray developed faster than non-flash boiling and transition flash boiling spray under the same injection pressure. In addition, the flash boiling spray tip penetration of the gas and liquid increased more than that of cold spray, and the fluctuation of the late stage of the injection was relatively large. Therefore, the injection pressure has a greater effect on the spray tip penetration of flash boiling spray. Moreover, ambient pressure greatly influences the flare flash boiling spray. The spray resistance phenomenon was found during the spray development in the flare flash boiling condition. With the increase in ambient pressure, the spray tip penetration of flash boiling spray decreases due to the reduction in the pressure difference inside and outside the spray hole and the restriction of ambient gas. Meanwhile, owing to the low ambient pressure and ambient density, the liquid penetration in the initial phase of the flare flash boiling spray will be abnormally shorter than that of the non-flash boiling spray.

Mycobacterium tuberculosis is less likely to acquire pathogenic mutations during latent infection than during active disease.

Most people infected with Mycobacterium tuberculosis (Mtb) are believed to be in a state of latent tuberculosis (TB) infection (LTBI). Although LTBI is asymptomatic and not infectious, there is a risk of developing active disease even decades after infection. Here, to characterize mutations acquired during LTBI, we collected and analyzed Mtb genomes from seven Japanese patient pairs, each pair consisting of two active TB patients whose starting dates of developing active disease were >3 years apart; one had a high suspicion of LTBI before developing active disease, whereas the other did not. Thereafter, we compared these genomes with those of longitudinal sample pairs within a host of chronic active TB infections combined with public data. The bacterial populations in patients with LTBI were genetically more homogeneous and accumulated single nucleotide polymorphisms (SNPs) slower than those from active disease. Moreover, the lower proportion of nonsynonymous SNPs indicated weaker selective pressures during LTBI than active disease. Finally, the different mutation spectrums indicated different mutators between LTBI and active disease. These results suggest that the likelihood of the acquisition of mutations responsible for antibiotic resistance and increased virulence was lower in the Mtb population from LTBI than active disease.IMPORTANCEControlling latent tuberculosis (TB) infection (LTBI) activation is an effective strategy for TB elimination, where understanding Mycobacterium tuberculosis (Mtb) dynamics within the host plays an important role. Previous studies on chronic active disease reported that Mtb accumulated genomic mutations within the host, possibly resulting in acquired drug resistance and increased virulence. However, several reports suggest that fewer mutations accumulate during LTBI than during the active disease, but the associated risk is largely unknown. Here, we analyzed the genomic dynamics of Mtb within the host during LTBI. Our results statistically suggest that Mtb accumulates mutations during LTBI, but most mutations are under low selective pressures, which induce mutations responsible for drug resistance and virulence. Thus, we propose that LTBI acts as a source for new TB disease rather than as a period for in-host genome evolution.

Exploring Acute Kidney Injury Following Aortic Dissection: A Comprehensive Review of Machine Learning Models for Predicting Risk, Management Strategies, Complications, and Racial and Gender Disparities.

Both types of aortic dissection (AD), Stanford type A and type B, can result in complications such as acute kidney injury (AKI) and aortic rupture. Renal complications in AD arise from compromised renal perfusion affecting the renal arteries. Understanding the intricate connection between AD and AKI is crucial for navigating the complexities of tailored treatment and formulating specific management plans. Concerning machine learning models, in patients with type A aortic dissection, factors such as decreased platelet count on admission, increased D-dimer level, longer cardiopulmonary bypass duration, elevated white blood cell levels, the need for blood transfusion, longer aortic clamp time, extended surgery duration, advanced age, and an elevated body mass index were positively associated with the development of AKI. For the risk of AKI after type B aortic dissection, elevated Nt-pro brain natriuretic peptide, prolonged activated partial thromboplastin time, elevated admission systolic blood pressure, and a higher contrast agent requirement during operative repair were found to predict the risk. Male gender was associated with a higher risk of AKI, and nonwhite race was linked to a higher risk of AKI, a greater likelihood of requiring more urgent procedures, and lower levels of insurance coverage. The treatment of AKI following AD requires a multifaceted approach. Identifying and addressing the underlying cause, such as low blood pressure, renal artery involvement, or medication-induced injury, is crucial for effective management and preventing further kidney damage. Maintaining proper fluid balance is essential for improving renal perfusion, but careful monitoring is necessary to avoid complications. The evolving landscape of research, particularly in biomarkers and AI programs, reveals a promising role in predicting the risk for and managing AKI post-AD.

Optical measurements of solid nitrogen solubility in hydrogen at cryogenic temperatures

The solubility of impurities in hydrogen at cryogenic temperatures is essential information for the design of liquid hydrogen plants. However, large data scatter and inconsistent predictions of impurity solubility by thermodynamic models mean that expensive engineering design margins are required to avoid blockages in cryogenic equipment. Here we report the combination of a stereomicroscope, commercial cryocooler and pressure cell to directly visualise solid impurity freeze-out and melting in stirred hydrogen at low temperatures and elevated pressures. Scattered literature data for nitrogen's solubility in hydrogen are compared to new solid-fluid equilibrium (SFE) measurements for a 1000 ppm N2 in H2 mixture at (1.8–5) MPa, and (42–52) K. These results were used to improve solubility models implemented in the ThermoFAST software package, achieving a three-fold decrease in the root-mean-square deviations between the SFE predictions and the data, helping lower the risk of impurity freeze-out in hydrogen liquefaction.

Electronic-grade epitaxial (111) KTaO3 heterostructures.

KTaO3 heterostructures have recently attracted attention as model systems to study the interplay of quantum paraelectricity, spin-orbit coupling, and superconductivity. However, the high and low vapor pressures of potassium and tantalum present processing challenges to creating heterostructure interfaces clean enough to reveal the intrinsic quantum properties. Here, we report superconducting heterostructures based on high-quality epitaxial (111) KTaO3 thin films using an adsorption-controlled hybrid PLD to overcome the vapor pressure mismatch. Electrical and structural characterizations reveal that the higher-quality heterostructure interface between amorphous LaAlO3 and KTaO3 thin films supports a two-dimensional electron gas with substantially higher electron mobility, superconducting transition temperature, and critical current density than that in bulk single-crystal KTaO3-based heterostructures. Our hybrid approach may enable epitaxial growth of other alkali metal-based oxides that lie beyond the capabilities of conventional methods.

Comparative evaluation of the sleep quality metrics between a cardboard bed and a camp cot: a randomized controlled crossover study.

Health-beneficial emergency bedding has become increasingly important for dealing with natural disasters such as the anticipated Nankai Trough earthquake in Japan. When the Great East Japan Earthquake occurred, cardboard beds were provided to evacuees. However, there were concerns about lower back pain and sleep disturbances, as cardboard beds offer insufficient pressure distribution. This study aimed to compare the effects of cardboard beds with those of foldable camp cots on sleep quality. A randomized controlled crossover study involving 20 healthy participants aged 18-45 years was conducted between June 2022 and January 2023. Participants were asked to sleep for one night on a camp cot and for another night on a cardboard bed, with a minimum three-day washout period between the two nights. Body pressure distribution and sleep metrics obtained from polysomnography (PSG) and questionnaires were compared between the two-bed types (P < 0.05). The camp cot exhibited better body pressure distribution than a cardboard bed, leading to improved sleep satisfaction, bedding comfort, and reduced morning sleepiness. Nevertheless, polysomnography revealed no notable differences in sleep metrics or sleep architecture between the two types of beds. Our findings indicate that cardboard beds have lower pressure dispersion capabilities than camp cots, leading to an increased number of position changes during sleep. Additionally, subjective sleep quality, such as alertness on waking, sleep comfort, and sleep satisfaction, was lower for cardboard beds, suggesting that camp cots might offer a more comfortable bedding option for evacuees. However, there were no discernible differences between the two-bed types in terms of objective sleep metrics derived from PSG. The potential for sleep disturbances caused by lower back pain from a hard mattress has been noted, and it is possible that a single night's experience in healthy individuals might not be enough for sleep issues to manifest.