Dimensionality of instructional quality in physical education. Obtaining students' perceptions using bifactor exploratory structural equation modeling and multilevel confirmatory factor analysis.

Background: In research on instructional quality, the generic model of the three basic dimensions is an established framework, which postulates that the three dimensions of classroom management, student support and cognitive activation represent quality characteristics of instruction that can be generalized across subjects. However, there are hardly any studies that examine if the three basic dimensions model could represent a suitable approach to measure instructional quality in physical education. Based on an extended model of the basic dimensions, a measurement model of instructional quality for physical education is presented, which integrates different theoretical approaches from the fields of educational and psychological research as well as different subfields of sports science in order to test the factorial structure of the corresponding measurement model. Methods: 1,047 students from 72 seventh to ninth grade classes from different German-speaking Swiss cantons participated in the study. The conceptualization of the instrument is based on a hybrid approach that integrates generic and subject-specific characteristics. The simultaneous analysis at the individual and class level using MCFA was supplemented by more complex methodological techniques within the relatively new B-ESEM framework at the individual level. Results: The postulated five-factor structure was initially tested using ICM-CFA and showed a good model fit (e.g., χ2/df = 2.32, RMSEA = 0.03, CFI = 0.97, TLI = 0.97, SRMR = 0.04). MCFA revealed a differential factorial structure at both levels of analysis with five factors at the individual level and four factors at the class level (e.g., χ2/df = 2.23, RMSEA = 0.03, CFI = 0.96, TLI = 0.96, SRMR within = 0.04, SRMR between = 0.10). ESEM and B-ESEM outperformed the ICM-CFA and showed an excellent model fit (B-ESEM: χ2/df = 1.19, RMSEA = 0.01, CFI = 1.00, TLI = 1.00, SRMR = 0.01). Inter-factor correlations and factor loadings are largely in line with expectations, indicating arguments for construct validity. Discussion: The study represents a substantial contribution in linking physical education and the generic research on instructional quality. Overall, strong arguments for the factorial structure of the measurement model were demonstrated. The study can be interpreted as a first step in a multi-step procedure in terms of further validity arguments.

Transfer and recovery of DNA and metal particles: A proof-of-concept application of a parallel strategy by DNA and environmental scanning electron microscopy analysis.

According to the principle of Locard "Every contact leaves a trace", when touching a surface, a bi-directional transfer of self and non-self-DNA residing on the hands and touched objects can occur. Metals are commonly encountered in forensic evidence and, during hand contact with these surfaces, a transfer of metal particles could occur together with the transfer of human DNA. This study proposes a proof-concept approach for the original detection of metal particles and touch DNA to track the activity performed by a donor and particularly to assess the metallic substrate touched before the contact with a subsequent surface. To this scope, a scenario of contact events was simulated by three volunteers, who participated in fingerprint deposition firstly on copper and then on plastic and glass surfaces. Twenty-four stubs were collected on the hands of volunteers and the secondary surfaces and then analyzed by environmental scanning electron microscopy (ESEM). DNA was quantified only from copper and plastic surfaces. Ten additional volunteers followed the same protocol of deposition on copper and then on plastic surfaces to evaluate DNA transfer only. On 20 touch DNA samples, the copper surface yielded significantly lower DNA amounts, ranging from 0.001 to 0.129 ng/µl, compared to the secondary touched plastic surface, ranging from 0.007 to 0.362 ng/µl. ESEM-EDS analysis showed that copper particles could be abundantly detected on the hands of the volunteers after contact with the copper surface. Particles containing silicates with copper were shown on plastic, while they were only found in 1/3 of samples on glass. Our proof-of-concept study has shown that ESEM-EDS analysis has the potential to detect copper particles transferred to the hands of volunteers during contact with a copper metallic surface and deposited on secondarily touched items. The results suggest that this original ESEM-DNA parallel approach could potentially allow the tracking of DNA transfer and metal particles at a crime scene, although this represents only a first step and further research on a wider casuistry could help to address the interpretation of results given activity level propositions.

Exploratory Structural Equation Modeling Analysis of the Anxiety Sensitivity Index 3.

Objective: Anxiety sensitivity is associated with the onset and progression of various emotional disorders. The Anxiety Sensitivity Index 3 (ASI-3) is a self-report scale for anxiety sensitivity. This study aims to resolve the ongoing controversy about the factorial structure of the ASI-3 using exploratory structural equation modeling (ESEM), a newly advanced technique. Methods: Confirmatory factor analysis (CFA), ESEM, bifactor-CFA, and bifactor-ESEM were used to investigate the factorial structure of the ASI-3. Three hundred Korean college students (female = 195, age: 21.74 ± 2.34) filled out the ASI-3 and the Distress Intolerance Index. Results: The bifactor-ESEM model exhibited a model fit superior to the 4 alternative models. The general factor showed higher loadings and reliability and explained common variance than the 3 specific factors in the bifactor-ESEM model. Most items reflected the global factor, but 6 items (Items 2, 3, 5, 7, 10, and 17) from the specific factors had insufficient loadings. Moreover, the global factor of the ASI-3 was associated with distress intolerance scores, indicating adequate criterion-related validity. Conclusion: The factorial structure of the ASI-3 is best described as a bifactor-ESEM model for Korean college students. Additionally, the bifactor-ESEM model of the ASI-3 includes a strong global factor that explains a large amount of the observed variance in the ASI-3 items.

Development and validation of the Environmental Confinement Stressors Scale (ECSS-20).

The COVID-19 pandemic has generated a global crisis with severe consequences for public health. There have been negative impacts on people's quality of life and mental health due to various stressors arising in this context, such as physical, social, economic, and psychological challenges. Noteworthy among these are the indirect effects of health measures, especially social distancing and confinement, which have significantly altered people's daily lives and social activities, producing high levels of anxiety, depression, and stress. This study proposes developing and validating a cross-sectional scale called the "Environmental Stressors Scale (ECSS-20)" to address the need to measure the impact of environmental stressors during confinement. The scale, which has been validated following ethical and methodological guidelines, consists of four dimensions: economic stressors (EE), social activities (SA), habitability (H), and exposure to virtual media (EMV). A pilot study (n = 113) and a main study (n = 314) were applied. The results showed that the instrument has a reliable and valid structure, with satisfactory internal consistency and factorial validity. Likewise, gender invariance tests supported its suitability for its applicability to women and men. Overall, the ECSS-20 is a valuable instrument for assessing the impact of confinement and improving the understanding of people's subjective experiences in this situation. Future research could further develop its applicability in different contexts and populations to better understand its usefulness and psychometric properties.

Low-vacuum SEM imaging and viability test of L929 cells exposed to a Euro 6 diesel exhaust gas mixture in a BAT-CELL chamber in comparison with hydrocarbons emission.

Exhaust emissions, which count among the most common causes of premature death worldwide, can cause irreversible changes in cells, leading to their damage or degeneration. In this research, L929 line cells were observed after exposure in the BAT-CELL chamber to exhaust gases emitted from a Euro 6 compression-ignition engine. Real road traffic conditions were simulated, taking into account air resistance while driving at speeds of 50 km/h, 120 km/h and idling engine. Morphological analysis of the cells was performed using an environmental scanning electron microscope. It has been observed that diesel exhaust fumes can cause inflammation, which can induce apoptosis or leads to necrotic cell death. The impact of the vehicle exhaust gases can inhibit cell proliferation by almost three times. Moreover, a correlation has been observed between the speed of the inflammatory reaction in cells and the presence of specific hydrocarbon compounds that determine the toxicity of exhaust gases. Research has shown that the toxicity of the emitted exhaust gases has been the highest at the driving speed of 120 km/h. In order to reduce the harmful effects of exhaust emissions, ecological alternatives and the supplementation of legal provisions regarding the compounds subject to limitation are necessary.

Factor structure and measurement invariance of the Depression anxiety stress scale (DASS-21) in Chinese left-behind and non-left-behind children: an exploratory structural equation modeling approach.

BACKGROUND: Comprehensive data has shown that adolescents often suffer from depression, anxiety, and low self-esteem, and are in a particularly fragile stage of psychological, physiological, and social development. Left-behind children in particular tend to have significantly higher, state anxiety and depression compared to non-left-behind children. The Depression, Anxiety, and Stress Scale (DASS-21) is an effective tool for evaluating depression, anxiety, and stress, and is used to measure levels of depression, anxiety, and stress in groups from a variety of backgrounds. The purpose of this study was to determine the effectiveness, reliability, and measurement invariance of the DASS-21 in Chinese left-behind children. METHOD: The test and re-test method was used (N = 676), and the exploratory structural equation model (Mplus v.8.3) used to verify basic measurement models. For measurement invariance, the configural, weak, strong, and strict models were tested. The reliability of the DASS-21 was also tested using the collected data. RESULTS: Analysis results showed that the DASS-21 had a stable three-factor structure in the sample of left-behind children in China. The measurement invariance test showed that gender and time not only had strong invariance, but also strict invariance. The results of cross left and non-left invariance indicated a lack of strict invariance. Finally, the McDonald's omega coefficient of the DASS-21 total scale was 0.864, and the internal consistency of each subscale was also good. CONCLUSIONS: The DASS-21 is shown to be an effective and reliable tool for measuring depression, anxiety and stress in Chinese left-behind children.

Mathematical-Physics Analyses of the Nozzle Shaping at the Aperture Gas Outlet into Free Space under ESEM Pressure Conditions.

The paper presents a methodology that combines experimental measurements and mathematical-physics analyses to investigate the flow behavior in a nozzle-equipped aperture associated with the solution of its impact on electron beam dispersion in an environmental scanning electron microscope (ESEM). The shape of the nozzle significantly influences the character of the supersonic flow beyond the aperture, especially the shape and type of shock waves, which are highly dense compared to the surrounding gas. These significantly affect the electron scattering, which influences the resulting image. This paper analyzes the effect of aperture and nozzle shaping under specific low-pressure conditions and its impact on the electron dispersion of the primary electron beam.

Osteoinductive and regenerative potential of premixed calcium-silicate bioceramic sealers on vascular wall mesenchymal stem cells.

AIM: The osteogenic potential of new premixed calcium-silicate-containing bioceramic sealers (Ca-Si sealers) was tested with porcine vascular wall-mesenchymal stem cells (pVW-MSCs). METHODOLOGY: Two Ca-Si-containing sealers: Ceraseal (MetaBiomed, Cheong-si, South Korea) and AH Plus Bioceramic (Maruchi, Wonju-si, South Korea), and an epoxy resin sealer (AH Plus; Dentsply, Konstanz, Germany) as a control, were prepared according to the manufacturers' indications. All samples were allowed to set for 100% of their setting time in a sterile humid cabinet at 37°C and 95% relative humidity. pVW-MSC seeding efficiency and osteogenic differentiation were analysed as marker of gene/protein expression for up to 12 days. Mineralization assay and immunofluorescence staining were performed and evaluated over a period of 21 days. Statistical analyses were conducted using one-way analysis of variance (p < .05). Additional samples were prepared and stored under the same conditions and inspected using an environmental scanning electron microscope equipped with an energy dispersive X-ray spectroscopy system. RESULTS: Significantly higher cell seeding efficiency (p < .05) was observed for both Ca-Si sealers from day 8. pVW-MSCs showed a significant shift towards the osteogenic lineage only when seeded in contact with Ca-Si sealers. Gene expression of osteopontin was upregulated significantly. Collagen I and osteocalcin were clearly expressed by cells in contact with Ca-Si sealers. Mineralization granules were observed in Alizarin red assays and confocal laser scanning microscopy analysis of both Ca-Si sealers. No gene expression or granule mineralization were observed on the epoxy resin sealer. CONCLUSIONS: Premixed Ca-Si sealers displayed a higher potential for osteogenic activity on pVW-MSCs. Epoxy resin sealer was unable to induce any osteogenic activity. The properties of both Ca-Si sealers suggest their potential as osteoinductive platforms for vascular MSCs in periapical bone.

Mathematical Physics Analysis of Nozzle Shaping at the Gas Outlet from the Aperture to the Differentially Pumped Chamber in Environmental Scanning Electron Microscopy (ESEM).

A combination of experimental measurement preparations using pressure and temperature sensors in conjunction with the theory of one-dimensional isentropic flow and mathematical physics analyses is presented as a tool for analysis in this paper. Furthermore, the subsequent development of a nozzle for use in environmental electron microscopy between the specimen chamber and the differentially pumped chamber is described. Based on experimental measurements, an analysis of the impact of the nozzle shaping located behind the aperture on the character of the supersonic flow and the resulting dispersion of the electron beam passing through the differential pumped chamber is carried out on the determined pressure ratio using a combination of theory and mathematical physics analyses. The results show that nozzle shapes causing under-expanded gas outflow from the aperture to the nozzle have a worse impact on the dispersion of the primary electron beam. This is due to the flow velocity control. The controlled reduction in the static pressure curve on the primary electron beam path thus causes a significantly higher course of electron dispersion values than variants with shapes causing over-expanded gas outflow.

Condensation or Desublimation: Nanolevel Structural Look on Two Frost Formation Pathways on Surfaces with Different Wettabilities.

Processes of water condensation and desublimation on solid surfaces are ubiquitous in nature and essential for various industrial applications, which are crucial for their performance. Despite their significance, these processes are not well understood due to the lack of methods that can provide insight at the nanolevel into the very first stages of phase transitions. Taking advantage of synchrotron grazing-incidence wide-angle X-ray scattering (GIWAXS) and environmental scanning electron microscopy (ESEM), two pathways of the frosting process from supersaturated vapors were studied in real time for substrates with different wettabilities ranging from highly hydrophilic to superhydrophobic. Within GIWAXS, a fully quantitative structural and orientational characterization of the undergoing phase transition reveals the information on degree of crystallinity of the new phase and determines the ordering at the surfaces and inside the films at the initial stages of water/ice nucleation from vapor onto the substrates. The diversity of frosting scenarios, including direct desublimation from the vapor and two-stage condensation-freezing processes, was observed by both GIWAXS and ESEM for different combinations of substrate wettability and vapor supersaturations. The classical nucleation theory straightforwardly predicts the pathway of the phase transition for hydrophobic and superhydrophobic substrates. The case of hydrophilic substrates is more intricate because the barriers in Gibbs free energy for nucleating both liquid and solid embryos are close to each other and comparable to thermal energy kBT. At that end, classical nucleation theory allows concluding a relation between contact angles for ice and water embryos on the basis of the observed frosting pathway.

Fluorescence microscopic investigation of PCE superplasticiser adsorption in calcined clay blended cement.

Global efforts to minimise carbon dioxide emissions are also leading to attempts to use calcined clays (CC) as a partial substitute for cement in concrete. While the hydration mechanism of such CC blended cements is now well understood, the range of effective admixtures like polycarboxylate ethers (PCE) is limited. There are PCE types that promise relatively high effectiveness, but the mechanisms of action are not yet sufficiently understood. For a detailed understanding of the adsorption of such PCEs, spatially resolved studies of the binder were performed using a combination of fluorescence and scanning electron microscopy. In a comparison of two superplasticisers, the investigations have shown different sites of preferred adsorption in a CC blended system and the results can be correlated with flow tests and setting behaviour. The investigations have shown that a certain PCE type has a higher adsorption on CC and other components of a blended system in comparison to other types.

The Impact of Nozzle Opening Thickness on Flow Characteristics and Primary Electron Beam Scattering in an Environmental Scanning Electron Microscope.

This paper describes the methodology of combining experimental measurements with mathematical-physics analyses in the investigation of flow in the aperture and nozzle. The aperture and nozzle separate the differentially pumped chamber from the specimen chamber in an environmental scanning electron microscope (ESEM). Experimental measurements are provided by temperature and pressure sensors that meet the demanding conditions of cryogenic temperature zones and low pressures. This aperture maintains the required pressure difference between the chambers. Since it separates the large pressure gradient, critical flow occurs on it and supersonic gas flow with the characteristic properties of critical flow in the state variables occurs behind it. As a primary electron beam passes through the differential pumped chamber and the given aperture, the aperture is equipped with a nozzle. The shape of the nozzle strongly influences the character of the supersonic flow. The course of state variables is also strongly influenced by this shape; thus, it affects the number of collisions the primary beam's electrons have with gas molecules, and so the resulting image. This paper describes experimental measurements made using sensors under laboratory conditions in a specially created experimental chamber. Then, validation using mathematical-physical analysis in the Ansys Fluent system is described.

Assessing pragmatic language difficulties using the Revised Children's Communication Checklist-2. Exploratory structural equation modeling and associations with restricted and repetitive behaviors.

In this paper, we investigated the psychometric properties of the Child Communication Checklist-Revised (CCC-R) for the first time with an English-speaking sample. We used a confirmatory application of exploratory structural equation modeling (ESEM) to re-evaluate the CCC-R's psychometric properties. We found strong support for its use as an assessment for pragmatic and structural language. Our second main aim was to explore associations between pragmatic and structural language and restricted and repetitive behaviors (RRBs), two hallmark characteristics of autism. We used the CCC-R and Repetitive Behavior Questionnaire (RBQ-2) to investigate these associations in a diverse non-clinical sample of children, taking a transdiagnostic approach. We intentionally excluded autism and other neurodevelopmental diagnoses to test, (1) the CCC-R in a broad sample and (2) the association between pragmatic language and RRB in children not already selected for that association. The sample comprised two groups of children, one was community sampled (n = 123) and the other (n = 143) included children with non-specific behavioral, emotional and/or cognitive difficulties referred to an assessment unit by schools. We found clear associations between pragmatic language difficulties and RRBs in both groups. Regression analysis showed that pragmatic language was the only significant contributor to RRBs even after Grammatical-Semantic score, age, sex, and socioeconomic status were controlled. The pattern was the same for both recruitment groups. However, the effects were stronger for the school-referred group which also had more pragmatic difficulties, grammatical-semantic difficulties and RRBs. A robust link between pragmatic language and RRBs, established in autism, has continuity across the broader non-clinical population.

Parental mental health and reporting of their child's behaviour: measurement invariance of the French version of the parental strengths and difficulties questionnaire.

Symptomatic effects of mental disorders in parents could bias their reporting on their child's mental health. This study aimed to investigate the measurement invariance of the French version of the parental Strengths and Difficulties Questionnaire (SDQ) across parental mental health in a sample (N = 20,765) of parents of children aged 3 to 17 years in France. Confirmatory factor analysis (CFA) and Exploratory Structural Equation Modelling (ESEM) were used to evaluate the fit of three known alternative SDQ factor structures (five, three, or second-order factor structures). Invariance was tested across parental mental health (present anxiety and depressive symptoms, psychiatric history) and across socio-demographic characteristics (child's age, child's gender, parent's gender, parent's educational level). CFA models showed a poor fit, while all ESEM models achieved acceptable or good fit, with the five-factor model presenting the best fit. Invariance was observed for all characteristics tested, indicating that the SDQ can be used to study the links between parental mental health and their child's mental health without bias. However, ESEM showed that the hyperactivity/inattention and conduct problems dimensions were not well differentiated in the French version of the SDQ.

When and how to use set-exploratory structural equation modelling to test structural models: A tutorial using the R package lavaan.

Exploratory structural equation modelling (ESEM) is an alternative to the well-known method of confirmatory factor analysis (CFA). ESEM is mainly used to assess the quality of measurement models of common factors but can be efficiently extended to test structural models. However, ESEM may not be the best option in some model specifications, especially when structural models are involved, because the full flexibility of ESEM could result in technical difficulties in model estimation. Thus, set-ESEM was developed to accommodate the balance between full-ESEM and CFA. In the present paper, we show examples where set-ESEM should be used rather than full-ESEM. Rather than relying on a simulation study, we provide two applied examples using real data that are included in the OSF repository. Additionally, we provide the code needed to run set-ESEM in the free R package lavaan to make the paper practical. Set-ESEM structural models outperform their CFA-based counterparts in terms of goodness of fit and realistic factor correlation, and hence path coefficients in the two empirical examples. In several instances, effects that were non-significant (i.e., attenuated) in the CFA-based structural model become larger and significant in the set-ESEM structural model, suggesting that set-ESEM models may generate more accurate model parameters and, hence, lower Type II error rate.

Comparative Study of Exsolved and Impregnated Ni Nanoparticles Supported on Nanoporous Perovskites for Low-Temperature CO Oxidation.

This study investigated the redox exsolution of Ni nanoparticles from a nanoporous La0.52Sr0.28Ti0.94Ni0.06O3 perovskite. The characteristics of exsolved Ni nanoparticles including their size, population, and surface concentration were deeply analyzed by environmental scanning electron microscopy (ESEM), transmission electron microscopy-energy dispersive X-ray spectroscopy (TEM-EDX) mapping, and hydrogen temperature-programmed reduction (H2-TPR). Ni exsolution was triggered in hydrogen as early as 400 °C, with the highest catalytic activity for low-temperature CO oxidation achieved after a reduction step at 500 °C, despite only a 10% fraction of Ni exsolved. The activity and stability of exsolved nanoparticles were compared with their impregnated counterparts on a perovskite material with a similar chemical composition (La0.65Sr0.35TiO3) and a comparable specific surface area and Ni loading. After an aging step at 800 °C, the catalytic activity of exsolved Ni nanoparticles at 300 °C was found to be 10 times higher than that of impregnated ones, emphasizing the thermal stability of Ni nanoparticles prepared by redox exsolution.

Electron Beam-Modified Collagen Type I Fibers: Synthesis and Characterization of Mechanical Response.

Ten MeV electron beam treatment facilitates a biomimetic introduction of cross-links in collagenous biopolymer systems, modifying their viscoelastic properties, mechanical stability, and swelling behavior. For reconstituted collagen type I fibers, electron-induced cross-linking opens up new perspectives regarding future biomedical applications in terms of tissue and ligament engineering. We demonstrate how electron irradiation affects stiffness both in low-strain regimes and in postyield regimes of biocompatible reconstituted rat tail collagen type I fibers. Stress-strain tests show a dose-dependent increase in modulus in the nonlinear elastic response, indicating a central role of induced cross-links in mechanical stability. Environmental scanning electron microscopy after fiber rupture reveals aligned distributed collagen fibril domains under the fiber surface for as-prepared fibers, accompanied by a ductile fracture behavior, whereas, in tensile tests imaged by light microscopy after 10 MeV electron treatment, isotropic network topologies are observed until the occurrence of a brittle type of rupture. Based on the biomimicry of the process, these findings might pave the way for a novel type of synthesis of tailored tendon or ligament substitutes.

Assessing the Two Sources of Construct-Relevant Psychometric Multidimensionality of the Nomophobia Questionnaire: The Integrated Framework of Bifactor Exploratory Structural Equation Modeling.

The current study aimed at investigating the two sources of construct-relevant psychometric multidimensionality of the Nomophobia Questionnaire (NMP-Q), applying the newly developed bifactor exploratory structural equation modeling (B-ESEM) approach. We first contrasted several CFA and ESEM models to test the psychometric multidimensionality due to the fallibility of indicators. Then, we compared the first-order structures with those specifying both global and specific factors to test the coexistence of hierarchically ordered factors. Results from 469 participants to the 20-item questionnaire showed the superiority of a B-ESEM representation with a well-defined G-factor and four weaker S-factors. On a methodological level, our findings provide additional support for the utility of using B-ESEM's integrative perspective to better capture the complexity of multidimensional constructs.

The structure of the Symptom Checklist-90-Revised: Global distress, Somatization, Hostility, and Phobic Anxiety scales are reliable and robust across community and clinical samples from four European countries.

While the reliability of SCL-90-R subscales is often questioned, five relatively recent European studies have examined the factor structure of SCL-90-R using a bifactor model and concluded that most of these subscales are reliable. However, examination of their results shows that three subscales, Somatization, Hostility, and Phobic Anxiety, consistently had significantly higher reliability than the other six across clinical and community samples recruited in three very different European countries, Greece, Hungary, and the Netherlands. The objective of this study was to examine whether this "top-3″ would be found in a sample from a fourth European country, France. To do this, we had 696 university students (387 women, 56 %) complete the SCL-90-R and we examined the reliability of the scales of this questionnaire by testing a bifactor model using Exploratory Structural Equation Modeling (ESEM). Our results confirmed that, in our sample, the three scales presented a higher reliability than the other six scales. It therefore seems that there exists, at least in the European cultural area, a stable structure of the SCL-90-R comprising a global distress factor and three reliable and robust specific factors: Somatization, Hostility, and Phobic Anxiety.

Comparative Analysis of Supersonic Flow in Atmospheric and Low Pressure in the Region of Shock Waves Creation for Electron Microscopy.

This paper presents mathematical-physics analyses in the field of the influence of inserted sensors on the supersonic flow behind the nozzle. It evaluates differences in the flow in the area of atmospheric pressure and low pressure on the boundary of continuum mechanics. To analyze the formation of detached and conical shock waves and their distinct characteristics in atmospheric pressure and low pressure on the boundary of continuum mechanics, we conduct comparative analyses using two types of inserted sensors: flat end and tip. These analyses were performed in two variants, considering pressure ratios of 10:1 both in front of and behind the nozzle. The first variant involved using atmospheric pressure in the chamber in front of the nozzle. The second type of analysis was conducted with a pressure of 10,000 Pa in front of the nozzle. While this represents a low pressure at the boundary of continuum mechanics, it remains above the critical limit of 113 Pa. This deliberate choice was made as it falls within the team's research focus on low-pressure regions. Although it is situated at the boundary of continuum mechanics, it is intentionally within a pressure range where the viscosity values are not yet dependent on pressure. In these variants, the nature of the flow was investigated concerning the ratio of inertial and viscous flow forces under atmospheric pressure conditions, and it was compared with flow conditions at low pressure. In the low-pressure scenario, the ratio of inertial and viscous flow forces led to a significant reduction in the value of inertial forces. The results showed an altered flow character, characterized by a reduced tendency for the formation of cross-oblique shockwaves within the nozzle itself and the emergence of shockwaves with increased thickness. This increased thickness is attributed to viscous forces inhibiting the thickening of the shockwave itself. This altered flow character may have implications, such as influencing temperature sensing with a tipped sensor. The shockwave area may form in a very confined space in front of the tip, potentially impacting the results. Additionally, due to reduced inertial forces, the cone shock wave's angle is a few degrees larger than theoretical predictions, and there is no tilting due to lower inertial forces. These analyses serve as the basis for upcoming experiments in the experimental chamber designed specifically for investigations in the given region of low pressures at the boundary of continuum mechanics. The objective, in combination with mathematical-physics analyses, is to determine changes within this region of the continuum mechanics boundary where inertial forces are markedly lower than in the atmosphere but remain under the influence of unreduced viscosity.