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Humanned exploration and extended stay on the Moon are the hottest challenges today. We report highly robust materials by microwave heating under high-vacuum conditions (10− 3 Pa) from a basaltic regolith simulant (FJS-1) to ensure the feasibility of lunar infrastructure construction. The violent degassing dynamics were revealed by monitoring vacuum pressure during heating and analyzing the compounds evolved from basaltic silicate compounds: thermal pyrolysis of silicate compounds became more pronounced above 1000 oC, leading to a catastrophic deformation accompanied by forming countless pores of several hundred µm sizes. The preferential formation of the magnetite phase in vacuum heating dominantly caused the radical change in microwave absorption capacity compared with conventional heating routes using an electrical furnace in atmospheric conditions. Besides, the in-situ measurement of dielectric properties during microwave vacuum heating clarified the increase in one order of magnitude from 100 to 1000 oC. Based on the presumed phenomena during microwave-vacuum heating for basaltic regolith, we propose a new thermal design concept to overcome the practical limitations of microwave technology. The multi-step temperature profile successfully fabricated a highly robust product that demonstrated world-class mechanical performance, equivalent to the compressive strength of 65 MPa without any vigorous hydrostatic cold press as a pre-treatment. [ABSTRACT FROM AUTHOR]

In this paper, we study the initial‐boundary value problem of three‐dimensional viscous, compressible, and heat conductive magnetohydrodynamic equations. Local existence and uniqueness of strong solutions are established with any such initial data that the initial compatibility conditions do not be required. The analysis is based on some suitable prior estimates for the strong coupling term u·∇H$$ u\cdotp \nabla H $$ and strong nonlinear term curlH×H$$ \operatorname{curl}\kern0.1em H\times H $$. Our proof of the existence and uniqueness of solutions is in the Lagrangian coordinates first and then transformed back to the Euler coordinates. [ABSTRACT FROM AUTHOR]

This article considers the zero‐pressure gas dynamics governed by the conservation laws of mass, momentum, and energy with time‐dependent source terms. By adopting the vanishing viscosity method, we propose a viscous system to prove the stability of non‐self‐similar Riemann solutions including the delta shock wave and vacuum. [ABSTRACT FROM AUTHOR]

In this study, three distinct low-temperature glass fillers for vacuum-assisted joining of reaction-bonded silicon carbide (RB-SiC) were designed. Additionally, the physical properties, microscopic morphologies and joints strength of these glass fillers were investigated. The results indicate that Zinc Borosilicate (ZBS) glass filler is the most effective for joining RB-SiC under the specified conditions. ZBS demonstrates optimal glass skeleton for joining, a compatible coefficient of thermal expansion, and superior wettability compared to the other tested powders. Notably, the shear strength of the RB-SiC joints with ZBS reached 80 MPa, markedly surpassing that of Lead zinc borate (PZB) and Lead borosilicate (PBS) by 381 % and 400 %, respectively. [ABSTRACT FROM AUTHOR]

The osmotically dehydrated orange juice sacs can serve as materials for heterogeneous 3D printing. Moreover, physical field-assisted such as ultrasound and vacuum, along with their combined application, were employed to enhance the impregnation of green tea polyphenol (GTP) and ascorbic acid (AA) during osmotic dehydration of orange juice sacs. This innovative approach not only compensates for the loss of water-soluble bioactive substances but also enhances the functional properties of heterogeneous 3D-printed food. The study assessed the impregnation effect of ultrasound (UOD), vacuum (VOD), and their synergistic pretreatment (UVOD) on the osmotic dehydration of orange juice sacs. Results indicated that the VOD-treated product exhibited the highest AA impregnation at 294.20 mg/100 g, while the UVOD-treated product demonstrated the best retention of phenolic compounds at 29.55 mg/g and also with best antioxidant activity. Quality attribute evaluation revealed that the UOVD-treated product displayed the lowest water content (66.44%), the softest texture, and superior color and aroma retention compared to the untreated orange juice sacs. In printing experiments, it was observed that the addition of 1–3% orange juice sacs resulted in successful printing using a 2.5 mm printing nozzle, achieving high precision and aesthetically pleasing outcomes. [ABSTRACT FROM AUTHOR]

We discuss in this short note the local-in-time strong well-posedness of the compressible Navier–Stokes system for non-Newtonian fluids on the three dimensional torus. We show that the result established recently by Kalousek, Mácha, and Nečasova in can be extended to the case where vanishing density is allowed initially. Our proof builds on the framework developed by Cho, Choe, and Kim in for compressible Navier–Stokes equations in the case of Newtonian fluids. To adapt their method, special attention is given to the elliptic regularity of a challenging nonlinear elliptic system. We show particular results in this direction, however, the main result of this paper is proven in the general case when elliptic W 2 , p -regularity is imposed as an assumption. Also, we give a finite time blow-up criterion. [ABSTRACT FROM AUTHOR]

In this study, the tribological characteristics of TiN, AlTiN, and AlTiCrN coatings sliding against a SUS420J1 stainless steel pin were investigated in atmospheric and vacuum environments. The coatings were deposited on SUS440C substrates using the arc-physical vapor deposition technique. The friction and wear behavior of the coatings were evaluated based on the systematic analyses of the friction coefficient data as well as the physical and chemical state of the wear track. The results revealed that the friction coefficients of the SUS440C specimen and AlTiCrN coatings increased, whereas those of the TiN and AlTiN coatings decreased when the environment was changed from atmospheric to vacuum. It was confirmed that the formation of an oxide layer and adsorption of oxides on the surface were dominant factors that influenced the tribological behavior in the atmospheric environment. On the other hand, the compatibility, oxidation inhibition, and droplets of the surface mainly affected the frictional characteristics in the vacuum environment. The results of this work are expected to aid in the selection of proper coating materials for tribological systems operating in a vacuum. [ABSTRACT FROM AUTHOR]

The aim of this paper is to study the hydrodynamic limit of Boltzmann equations for a gas mixture containing two kinds of particles, where one is assumed to be near a vacuum and the other is near a Maxwellian equilibrium state. By the method of Hilbert expansion, we could derive the compressible Euler systems together with the terms of Boltzmann equations according to the different orders of the Knudsen number. Next, we truncate the expansion and establish the uniform estimates of the remainder term by using $ L^2 \,- \, L^{\infty } $ L 2 − L ∞ estimate. [ABSTRACT FROM AUTHOR]

Objective: To determine the trends of instrumental vaginal delivery (IVD) and cesarean section (CS) at the Lagos University Teaching Hospital (LUTH), Nigeria, over 16 years, from 2002 to 2017. Methods: A retrospective cross‐sectional study. The case records of all women who had IVD and CS during the study period were reviewed. The trends in the IVD and CS rates were evaluated using join point regression modeling. The average annual percent change (AAPC) and annual percent change (APC) with associated 95% confidence interval of segmental trends were calculated. Results: The overall IVD rate was 1.36%. Vacuum delivery rate was higher than forceps (0.79% vs 0.57%). The CS rate was 44.9 per 100 deliveries; the rate increased by about 3.7% per annum. CS rates were 7.1–89.9 times the IVD rates within the study period. The number of IVDs performed in the hospital declined by about 83.02%, from 53 cases in 2002 to nine cases in 2017. Forceps delivery declined at a faster rate than vacuum delivery between 2002 and 2017 (AAPC for forceps: −12.6% [−17.5 to −7.5], P < 0.001 vs AAPC for vacuum: −6.2% [−14.3 to 2.7], P = 0.200). The commonest indication for IVD was prolonged second stage of labor (47/162, 29.01%) and shortening of the second stage of labor for maternal conditions (47/162, 29.01%). Conclusion: IVD rates are low and declining at LUTH. There is need to train accoucheurs on the safe use of IVDs to potentially reduce the CS rate. Synopsis: The present study corroborates global reports of declining IVD rates and increasing CS rates. There is need to increase IVD use to potentially reduce CS rate. [ABSTRACT FROM AUTHOR]

Oxygen conditioning on a large scale could effectively improve living and working conditions to relieve the hypoxia of plateau environment. Industrial-scale pressure swing adsorption (PSA) and vacuum pressure swing adsorption (VPSA) medical oxygen production systems are designed for supplying oxygen at high altitude of 3800 m areas. The effects of process parameters and key steps on the performance of PSA and VPSA processes have been experimentally compared and analyzed. The results show that the adsorption time, pressure equalization and purge step are key factors of affecting the oxygen production performance. The PSA cycle with pressure equalization of product end and continuous purge could produce ~ 93% O2 with recovery of 45.4% from compressed air and the minimum energy consumption is 1.21 kW·Nm− 3. The VPSA cycle with pressure equalization of product end and intermittent purge could produce ~ 93% O2 with recovery of 54% from super-atmospheric air and the minimum energy consumption is 0.68 kW·Nm− 3. [ABSTRACT FROM AUTHOR]

In this paper, we consider an initial and boundary value problem to the three-dimensional (3D) nonhomogeneous nematic liquid crystal flows with density-dependent viscosity and vacuum. Combining delicate energy method with the structure of the system under consideration, the global well-posedness of strong solutions is established, provided that ‖ ρ 0 ‖ L 1 + ‖ ∇ d 0 ‖ L 2 is suitably small. In particular, the initial velocity can be arbitrarily large. Moreover, the exponential decay rates of the strong solution are also obtained. [ABSTRACT FROM AUTHOR]

Introduction Material and Methods Results Conclusions Cervical laceration is an obstetric injury associated with severe postpartum hemorrhage and subsequent spontaneous preterm birth. While operative vaginal delivery is a known risk factor for cervical laceration, it is unclear whether forceps and vacuum deliveries incur the same risk. The aim of this systematic review was to compare the risk of cervical laceration between operative instruments (forceps vs vacuum).Medline, Embase, Global Health, CENTRAL, Emcare, and Web of Science were searched from inception until August 2024 with terms related to operative vaginal delivery and cervical laceration. Studies comparing the risk of cervical laceration in individuals undergoing forceps or vacuum delivery were included. Two authors conducted screening, data extraction, and quality assessment of all studies. Random‐effects models were used to pool risk ratios across studies and certainty of evidence was assessed using Cochrane methods and the GRADE approach. PROSPERO Registration Number CRD42023421890.Thirteen studies were eligible for inclusion, 3 randomized controlled trials (RCTs) and 10 observational studies. The overall rate of cervical laceration was 0.35% (990/284218 births) where 1.04% of forceps deliveries (456/43817) were complicated by cervical laceration compared to 0.22% of vacuum deliveries (534/240401). The risk of cervical laceration was 2–5 fold greater in forceps deliveries than in vacuum deliveries: pooled unadjusted risk ratio [RR] 4.83, 95% confidence interval [CI] 1.56–14.98 among RCTs and pooled unadjusted RR 1.89, 95% CI 1.59–2.24 among observational studies. The overall quality of evidence was low to moderate mainly due to the lack of attention to confounding in the included literature. The GRADE assessment indicated that the certainty of evidence was very low for observational studies and moderate for RCTs.Low certainty of evidence indicates that forceps deliveries may be associated with an increased risk of cervical laceration compared to vacuum deliveries. [ABSTRACT FROM AUTHOR]

The increased clinical relevance of image-guided procedures, particularly of interventional magnetic resonance imaging (iMRI), highlights the need for advanced devices and robotics to optimize those procedures. To enable a realistic integration of robotics into the clinical workflow, robotic-patient interfaces (RPI) are required to ensure both functionality and usability. However, current concepts have issues with patient accessibility and safety, user handling, or performing interventions on versatile body regions. This work presents a novel silicone-based RPI to flexibly mount the 'Micropositioning Robotics for Image-Guided Surgery' (μRIGS) system on differently shaped body regions through vacuum, regulated with an electronic miniature pump. Maximum holding forces of 60N at −0.1 bar and 66N at −0.2 bar relative vacuum pressure were reached depending on the applied human body area and tensile force angles. MRI with the integrated metasurface indicated up to 200% signal enhancement, enabling improved tissue contrast within the first 20mm in depth. The multifunctional design supported the incorporation of the sterile iMRI workflow concept. This RPI enables a realistic integration of future technologies such as miniature robots, tracking markers, and instrument holders into complex interventional workflows. Further long-term studies are needed to evaluate the effects of vacuum application lasting for 1-2 hours on different skin types. [ABSTRACT FROM AUTHOR]

This paper focuses on investigating the initial-boundary value problem of incompressible heat conducting Navier-Stokes equations with variable coefficients over bounded domains in R 3 , where the viscosity coefficient and heat conduction coefficient are powers of temperature. We obtain the global well-posedness of a strong solution under the assumption that the initial data and the measure of the initial vacuum region are sufficiently small. It is worth mentioning that the initial density is allowed to contain vacuum, and there are no restrictions on the power index of the temperature-dependent viscosity coefficient and heat conductivity coefficient. At the same time, the exponential decay-in-time results are also obtained. [ABSTRACT FROM AUTHOR]

The influence of storage atmosphere on the color development and myoglobin (Mb) redox state of beef was investigated. Beef samples were packaged in 6 different atmospheres including different degrees of vacuum, levels of oxygen, nitrogen, and a mixture with 20% CO2 and stored at 2°C for 14 days. Over this time, color and reflection of the packaged samples were measured. The used method allows quick, easy, and non‐invasive measurement of the packaged samples, without using time consuming chemical assays. The method could be implemented in beef production lines, with potential for automatization. The data was used to illustrate the L*a*b* values for insights regarding qualitative color changes. Quantitative color changes were analyzed by calculation of color difference ΔE2000. Additionally, the relative levels of the deoxymyoglobin (DMb), oxymyoglobin (OMb) and metmyoglobin (MMb) were calculated from reflection spectra. The most important findings are: there is a strong correlation (rsp = 0.80 to 0.99 with one exception at rsp = 0.69 (high vacuum), p ≤ 0.05) between a* values and relative OMb levels. Storage atmospheres containing high oxygen concentrations lead to an attractive meat color, but a decreased overall color and Mb stability (ΔE = 5.02 (synthetic air) and ΔE = 2.23 (high oxygen) after 14 days of storage). Vacuum packaged samples are most stable in regards of color and Mb stability (ΔE = 1.79 (high vacuum) and ΔE = 1.63 (low vacuum) after 14 days of storage), but lack in the vibrant red color desired for sale. The experiments showed that color measurement can be a fast, non‐invasive marker for meat quality. Practical Application: In this research article, six different storage atmospheres are compared regarding their influence on color stability and color quality of beef during storage in packaging. The results suggest which atmospheres to use in various sales‐related scenarios. The method described can easily be applied in the meat industry to quickly monitor changes during storage and wet‐aging without damaging the meat or opening the meat packages. [ABSTRACT FROM AUTHOR]

Pomegranate juice is prone to color fission during processing and storage due to the instability of anthocyanins, resulting in significant economic losses. This study aims to inhibit the browning of pomegranate juice during processing using the combined technology of vacuum and ultrasound for maintaining its color as much as possible. Pomegranate juice was treated with vacuum (0.5 MPa) and ultrasound (300, 600, 900, 1200, and 1500 W; 15, 20, 25, 30, and 35 min), respectively, to investigate the effects on the color, antioxidant capacity, anthocyanin/polyphenol content, and polyphenol oxidase activity of pomegranate juice. The results showed that the combined treatment of vacuum and ultrasound had a better effect on improving the total anthocyanin content of pomegranate juice than vacuum or ultrasound treatment alone. Vacuum combined with ultrasound can reduce the browning during pomegranate juice processing, increasing browning inhibition rates by 46.01% and 46.19%; reduce the activity of PPO enzyme and increase the inhibition rate of PPO enzyme activity by 35.58%; maintain a high total phenolic content, increasing the total phenolic content of pomegranate juice by 29.27% and 33.79%, respectively; and improve the ABTS scavenging rates by 2.89% and 1.92%, and increase DPPH scavenging rates by 1.35% and 3.01%. Moreover, vacuum ultrasound treatment had no significant effect on the odor of pomegranate juice. Vacuum combined with ultrasonic treatment is beneficial for protecting the color of pomegranate juice and improving its antioxidant performance during the processing. Therefore, combined technology of vacuum and ultrasound would be a promising method for future food processing. Practical applications: This study provides a simple and novel method for protecting the color of pomegranate juice during processing. The combination of vacuum and ultrasound has a certain protective effect on the color of pomegranate juice during processing, and also provides new ideas for color protection research. [ABSTRACT FROM AUTHOR]

This paper presents the results of laboratory studies for the distillation of mercury from depleted coal sorbents produced in gold recovery factories using CIP technology. The mercury content in these materials is more than 1%. The developed technology was tested in a large-scale laboratory on a pilot vacuum sublimation electric furnace with the rheological movement of dispersed material. The use of this equipment makes it possible to demercurize various materials with fairly high moisture (up to 20%). It eliminates the use of an additional technological operation—drying the material in a vacuum drying oven. It has been shown that a high degree of mercury distillation is achieved (more than 99.8%) at 350–400 °C in the reaction space and residual pressure in the system of less than 1.33 kPa, with residual mercury content in the material of less than 0.001% (10 mg/kg), which complies with the European environmental standards. Mercury-free coal sorbents are sent for combustion for the additional extraction of precious metal composites. The proposed vacuum technology is characterized by its environmental safety because the process is performed in sealed equipment, eliminating toxic emissions of mercury vapor into the atmosphere. The proposed vacuum technology equipment is characterized by reliability and ease of use. [ABSTRACT FROM AUTHOR]

Piezoelectric actuators provide several advantages, including rapid response time, travel control, high resolution and actuation efficiency. They are a good candidate for actuating mechanical switches designed for electrical circuit breakers. This study investigates the utilisation of an Amplified Piezoelectric Actuator (APA) in Block-Free (B-F) operational mode as an actuation unit for a Fast-Mechanical Switch (FMS) and an Ultra-Fast Disconnector (UFD) to be utilised in a DC Hybrid Circuit Breaker (HCB). Initially, the principle and construction of the piezoelectric actuator actuating scheme were described and illustrated. A Finite Element Analysis (FEA) model was built to simulate and analyse the presented switch/disconnector static and dynamic behaviours. A prototype was constructed based on calculations, and the travel characteristics were experimentally validated. Subsequently, the proposed switch/disconnector was insulated once in a vacuum and later in a nitrogen gas interruption chamber. Both arrangements were integrated into a DC Hybrid Circuit Breaker test platform to investigate their interruption features. Results show that the presented switch/disconnector achieved a total gap of approximately 1 mm in 1.4 ms and interrupted a DC power of 0.6 kV/60 A within 0.85–1.5 ms in vacuum and 0.98–1.45 ms in nitrogen gas. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine, develop mathematical models, and optimize the in-row seed distribution uniformity performance of a vacuum-type seed metering unit in peanut seeding under different operating conditions. The greased belt stand trials based on the Central Composite Design (CCD) were. Quality of feed index, multiple index, miss index, precision, and coefficient of precision were examined as dependent variables, while the peripheral speed of the seed plate, hole diameter of the seed plate, and vacuum pressure were selected as independent variables. Based on the analysis of experimental data from five different levels of each independent variable, performed using the CCD, a meaningful mathematical model was developed in cubic form for the quality of feed index for peanut seeding, and the model was optimized. The ideal conditions were determined from the model as 0.079 ms−1, 6.94 mm, and 7.07 kPa for peripheral speed of the seed plate, hole diameter, and vacuum pressure, respectively. Based on the findings, quality in seeding by selecting the parameters that affect the performance of precision peanut seeding can be enhanced, resulting in valuable information that can be used as a useful guide to farmers, machine manufacturers, and researchers. [ABSTRACT FROM AUTHOR]

In this study, we establish a regular criterion for the 2D compressible micropolar viscous fluids with vacuum that is independent of the velocity of rotation of the microscopic particles. Specifically, we show that if the density verifies ||ρ||L∞(0,T;L∞) < ∞, then the strong solution will exist globally on R² x(0, T). Consequently, we generalize the results of Zhong (Discrete Contin. Dyn. Syst. Ser. B, 25 (2020), no. 12, 4603–4615) to the compressible case. In particular, we don’t need the additional compatibility condition. [ABSTRACT FROM AUTHOR]

The paper presents the results of the study of the processes of self-propagating high-temperature synthesis of Zr-1%B alloy and its refining by electron beam melting. Experiments on the influence of boron's amorphous and crystalline modifications on the safety parameters of the synthesis process of Zr-1%B alloy necessitated the conversion of amorphous boron into crystalline form by electron beam melting, with an increase in its purity from 94% to 99.9%. High efficiency of vacuum induction and electron beam equipment was demonstrated, which provided a high purity of the Zr-1%B alloy of at least 99.9%. The alloy ingots had a uniform distribution of the alloying element (boron) all over the volume. The obtained alloy is suitable for the production of materials with thermal neutron capture cross-sections of up to 40 barns for neutron protection. [ABSTRACT FROM AUTHOR]

Pulsed vacuum drying (PVD) is a novel vacuum drying method that has demonstrated significant potential in improving energy efficiency and product quality in the drying of foods and agricultural products. The current work provides a comprehensive analysis of the latest advancements in PVD technology, including its historical development, fundamental principles, and mechanistic aspects. The impact of periodic pulsed pressure changes between vacuum and atmospheric pressure on heat and moisture transfer, as well as structural changes in foods at micro‐ and macro‐scales, is thoroughly discussed. The article also highlights the influential drying parameters, the integration of novel auxiliary heaters, and the applications of PVD across various fruits, vegetables, and herbs. Furthermore, the review examines the current status and needs for mathematical modeling of PVD processes, identifying key challenges, research opportunities, and future trends for industrial application. The findings suggest that PVD not only enhances drying efficiency and reduces energy consumption but also preserves the nutritional value, color, and texture of dried products better than traditional methods. Future research should focus on optimizing process parameters and integrating advanced control systems to further improve the scalability and applicability of PVD technology in the food industry. [ABSTRACT FROM AUTHOR]

We show that if we assume the existence of a frame in vacuum where the oneway speed of light is c (c is the measured value of the two-way speed of light in vacuum) than for another frame moving with velocity v1 in relation to that frame we can have time dilation, time contraction or no difference of proper times change at all. Therefore, the standard formulation is a result of a misinterpretation of the mathematical expression between the relation of the proper time of the moving frame in relation to the difference of times of Lorentzian clocks, the so-called time dilation. This is an astonishing conflict that standard formulation cannot solve. This result is easily obtained if we assume time dilation in relation to Einstein Frame (EF) the frame where the speed of light is isotropic. [ABSTRACT FROM AUTHOR]

Abstract Humanned exploration and extended stay on the Moon are the hottest challenges today. We report highly robust materials by microwave heating under high-vacuum conditions (10− 3 Pa) from a basaltic regolith simulant (FJS-1) to ensure the feasibility of lunar infrastructure construction. The violent degassing dynamics were revealed by monitoring vacuum pressure during heating and analyzing the compounds evolved from basaltic silicate compounds: thermal pyrolysis of silicate compounds became more pronounced above 1000 oC, leading to a catastrophic deformation accompanied by forming countless pores of several hundred µm sizes. The preferential formation of the magnetite phase in vacuum heating dominantly caused the radical change in microwave absorption capacity compared with conventional heating routes using an electrical furnace in atmospheric conditions. Besides, the in-situ measurement of dielectric properties during microwave vacuum heating clarified the increase in one order of magnitude from 100 to 1000 oC. Based on the presumed phenomena during microwave-vacuum heating for basaltic regolith, we propose a new thermal design concept to overcome the practical limitations of microwave technology. The multi-step temperature profile successfully fabricated a highly robust product that demonstrated world-class mechanical performance, equivalent to the compressive strength of 65 MPa without any vigorous hydrostatic cold press as a pre-treatment.

The article presents an analysis of milk production in Kazakhstan and identifies the reason for its low level, which is due to deficient feed, especially in small farms and in the private sector. The difficulty of saving the limited silage volume is due to the lack of preparation technology for preventing spoilage. The objective of this work is to complete the necessary equipment of a mobile tractor-trailer to reduce the specific energy consumption when preparing silage in flexible containers using a vacuum seal to increase the productivity of dairy cattle farming in smallholder and the private sector of the Republic. The basic rational parameters for sealing the silage by vacuum in the field on a mobile tractor-trailer for ease of transport and storage are obtained: silage weight in a flexible container – 769.6 kg, geometric dimensions of the sealed container by height (0.90 m), width (0.85 m) and length (0.85 m). The efficiency of the specific energy consumption of the proposed method for silage preparation is established at 35% compared with the traditional method. The recommended technology of silage preparation in flexible containers will be possible when conventional tractor-trailers are retrofitted with standard portable equipment (internal combustion engine-based (ICE) electric generator, vacuum pump, film welder).

Precision research and technological equipment, as a rule, is not able to provide its specification characteristics without a high-quality vibration protection system. Active vibration control of an object is provided with the help of an additional source of movement, an actuator. The most promising high accuracy actuators are based on smart materials, such as materials with shape memory, piezoelectric and magnetostrictive materials, electro- and magnetic active fluids and elastomers. Dielectric elastomer is one of the types of electroactive polymers. Actuators based on a dielectric elastomer show high performance in terms of accuracy and speed and operate due to the controllable deformation of the elastomer under the action of a high voltage electric field. The paper provides a comparison of actuators based on sheet and thin film control electrodes. The influence of the quality of the polymer surface and the type of electrodes on the travel range of the actuator and maximum amplitude of vibrations the system can suppress on the basis of a dielectric elastomer is estimated. The formation of the electrode by magnetron sputtering in vacuum makes it possible to create a thin-film layer of copper that covers the elastomer, despite the developed surface. The effect of ion treatment of an elastomer before coating on the quality of the formed electrode is considered. After the ion treatment, the surface of the elastomer acquires a more uniform regular structure. A thin-film electrode layer is formed according to the topology of the elastomer to an accomplished standard.

The lunar surface and its deep layers contain abundant resources and valuable information resources, the exploration and exploitation of which are important for the sustainable development of the human economy and society. Technological exploration and research in the field of deep space science, especially lunar-based exploration, is a scientific strategy that has been pursued in China and worldwide. Drilling and sampling are key to accurate exploration of the desirable characteristics of deep lunar resources. In this study, an in-situ condition preserved coring (ICP-Coring) and analysis system, which can be used to test drilling tools and develop effective sampling strategies, was designed. The key features of the system include: (1) capability to replicate the extreme temperature fluctuations of the lunar environment (−185 to 200 °C) with intelligent temperature control; (2) ability to maintain a vacuum environment at a scale of 10−3 Pa, both under unloaded conditions within a ϕ580 mm × 1000 mm test chamber, and under loaded conditions using a ϕ400 mm × 800 mm lunar rock simulant; (3) application of axial pressures up to 4 MPa and confining pressures up to 3.5 MPa; (4) sample rotation at any angle with a maximum sampling length of 800 mm; and (5) multiple modes of rotary-percussive drilling, controlled by penetration speed and weight on bit (WOB). Experimental studies on the drilling characteristics in the lunar rock simulant-loaded state under different drill bit-percussive-vacuum environment configurations were conducted. The results show that the outgassing rate of the lunar soil simulant is greater than that of the lunar rock simulant and that a low-temperature environment contributes to a reduced vacuum of the lunar-based simulated environment. The rotary-percussive drilling method effectively shortens the sampling time. With increasing sampling depth, the temperature rise of the drilling tools tends to rapidly increase, followed by slow growth or steady fluctuations. The temperature rise energy accumulation of the drill bits under vacuum is more significant than that under atmospheric pressure, approximately 1.47 times higher. The real-time monitored drilling pressure, penetration speed and rotary torque during drilling serve as parameters for discriminating the drilling status. The results of this research can provide a scientific basis for returning samples from lunar rock in extreme lunar-based environments.

The paper presents the results of the study of the processes of self-propagating high-temperature synthesis of Zr-1%B alloy and its refining by electron beam melting. Experiments on the influence of boron’s amorphous and crystalline modifications on the safety parameters of the synthesis process of Zr-1%B alloy necessitated the conversion of amorphous boron into crystalline form by electron beam melting, with an increase in its purity from 94% to 99.9%. High efficiency of vacuum induction and electron beam equipment was demonstrated, which provided a high purity of the Zr-1%B alloy of at least 99.9%. The alloy ingots had a uniform distribution of the alloying element (boron) all over the volume. The obtained alloy is suitable for the production of materials with thermal neutron capture cross-sections of up to 40 barns for neutron protection.

In this paper, we study on the Cauchy problem of one-dimensional compressible viscous two-fluid MHD model and establish the global existence and uniqueness of strong solutions for large initial data. The initial density is permitted to vanish and even can have compact support. By introducing the flow map Lagrangian coordinate, the uniform upper bounds on the density is obtained. [ABSTRACT FROM AUTHOR]

This paper concerns the global regularity of strong solutions to the Cauchy problem of inhomogeneous incompressible Navier–Stokes fluids with vacuum, zero heat conduction, and density–temperature‐dependent viscosity. The existence of global‐in‐time strong solutions is proved when the initial energy is suitably small or the lower bound of the viscosity coefficient is large enough. Moreover, some exponential decay‐in‐time rates of strong solutions are obtained via time‐weighted a priori estimates. [ABSTRACT FROM AUTHOR]

We study an initial and boundary value problem to the two dimensional non-isothermal inhomogeneous nematic liquid crystal flow with non-negative density. It is shown that the strong solution exists globally if the gradient of viscosity satisfies $ \|\nabla \mu(\rho)\|_{L^{\infty}(0, T; L^p)} < \infty. $ As an application, we establish the global well-posedness of strong solution to the two-dimensional non-isothermal inhomogeneous nematic liquid crystal flow with constant viscosity for general large initial data. [ABSTRACT FROM AUTHOR]

RTV 10A silicone rubber composites have many applications in forming many medical products and one of the recent applications is for orthotic insoles. This is because the RTV silicon rubber has excellent flexibility, elasticity, and resistance against splitting. However, these mechanical properties still need improvement when applied in certain medical applications. One way to improve mechanical properties is by adding talc. The process of mixing silicon rubber with talc requires special techniques to prevent the formation of porosity that may lead to unexpected mechanical properties. This porosity occurs due to trapped air during the mixing process or pouring into molds. Efforts to eliminate this porosity include Vacuum Die Casting (VDC) techniques. This study presents the mechanical properties improvement of RTV 10A silicon rubber composite with the addition of using 30% talc. The objective is to achieve a more convenient orthotic insole to reduce the pain in human foot joints during walking due to planar stress. This study aims to reduce the porosity and minimize the trapped air by adding 30% talc into RTV 10A silicone rubber composite using VDC. In the experiment, the pressure variation was determined at -0.04 MPa, -0.06 MPa, -0.08 MPa, and -0.1 MPa through a mold size of 45 mm in diameter and thickness of 7 mm. Fluidity, density, porosity, and hardness were tested during the experiment. The results show that by decreasing vacuum pressure, the density and the hardness increase. This is because the size and distribution of porosity are decreased and more homogeny. Furthermore, it also produces higher fluidity. However, the porosity of the specimen after vacuum casting is not partially filled.

The paper presents a numerical method developed by the authors. The method consists in obtaining a three-dimensional component fatigue surface model according to the results of tests corresponding to two to four values of the operational factor, making it possible to plot the fatigue limit – operational parameter curve. A description of the algorithm of the method is presented, its validity is confirmed. The results show good agreement with outside empirical data for other values of the operational parameters. A model of the fatigue surface is constructed. The model specifies the calculation of strength of aircraft elements operating in rarified atmosphere (e.g. engine compartments of space complexes and upper stages of carrier rockets). The model increases the endurance calculation accuracy and enables structural mass optimization.

In this paper, we are concerned with the three-dimensional nonhomogeneous Bénard system with density-dependent viscosity in bounded domain. The global well-posedness of strong solution is established, provided that the initial total mass ∥ ρ 0 ∥ L 1 is suitably small. In particular, the initial velocity and temperature can be arbitrarily large. Moreover, the exponential decay of strong solution is also obtained. It is worth noting that the vacuum of initial density is allowed. [ABSTRACT FROM AUTHOR]

A vacuum environment is usually preferred for reducing the dwell time and sintering temperature for doped zirconia ceramics. However, for the present work with 10 mol.% CaO‐doped ZrO2 (10CaSZ) ceramics, both hot‐pressing and vacuum sintering techniques yielded ceramics with open pores (ρ ∼ 93%) and significant amounts of the deleterious monoclinic phase (>$ > $50%). This is in stark contrast with the conventionally sintered highly dense (>99%) 10CaSZ ceramics, where only tetragonal and cubic phases were noted. Probing via electron paramagnetic resonance (EPR) depicted the trapping of oxygen vacancies by vacancies generated in vacuum at high temperature. A possible change in the local coordination (of ions) and the subsequent chemical environment was confirmed by the observed asymmetric signal shape and broader linewidth of the EPR signals. Potential loss of oxygen and deviation from stoichiometry (for dopant) was confirmed via EPR analysis along with the support of energy dispersive spectra analysis. Despite no noticeable shift in the XRD pattern for Ca2+ depletion, the observed compositional gradient differences in the calcium elemental mapping suggested dopant segregation at the grain boundaries. The conclusions from the present work point toward specificity of a given materials system for its beneficial densification under hot pressing or vacuum sintering. [ABSTRACT FROM AUTHOR]

Vacuum-Assisted Sorbent Extraction (VASE) is a novel extraction technique that uses vacuum to facilitate the transfer of volatile compounds from the matrix to the sorbent. This technique was explored for extraction of volatiles from cape gooseberry fruit, for both qualitative and quantitative analyses. Selected extraction parameters were tested: sample size, extraction temperature and time, influence of tissue disintegration on release of volatiles, and also addition of Ag+1 ions in the form of AgNO3 to stop enzymatic formation of volatile compounds. For selected conditions (10 g sample, extraction for 30 min. at 40 °C of volatiles from blended fruit) quantitative aspects were explored. Twenty-two compounds of cape gooseberry were tested. The method was characterized with a very good linearity in a range of 10–5000 µg/kg and good reproducibility. The experiments proved the usefulness of VASE in both volatile profiling and quantitative analyses of cape gooseberry and in prospective other fruit. [ABSTRACT FROM AUTHOR]

AbstractThe phenomena of concentration and cavitation in the Riemann solutions of the relativistic Euler equations with non-ideal isothermal dusty gas are considered. The Riemann problem is solved first, and the solutions consisting of rarefaction waves and shock waves are obtained. Then, by the vanishing pressure approach, we investigate the limiting behaviors of Riemann solutions and observe the concentration and cavitation phenomena. It is rigorously proved that as the dusty gas pressure vanishes with double parameters, the solution containing two shock waves and two rarefaction waves respectively converges to the delta-shock wave and vacuum state of the pressureless relativistic Euler equations. [ABSTRACT FROM AUTHOR]

Key Clinical Message: The use of negative pressure therapy in the management of gunshot wound have a favorable outcome, NPT is easy to build, accelerates wound budding, reduces patient's stay in hospital and its low cost. It showed reassuring results in the management of wound with soft tissue lost, comparatively to other dressing. Wounds due to gunshot injuries are common in east of Republic Democratic of Congo and its management should be well known by surgeons and other health practitioners. Reconstruction is possible with simple surgeries using skin grafts and negative pressure therapy (NPT). In this study, we present our results of wounds treatment after gunshot injury with a simple non‐surgical procedure using NPT. We present four patients with soft tissue losses caused by gunshot injury. These patients underwent an average of four to eight sessions of vacuum dressing, the length of hospital stay was decrease and soft tissue losses were reconstructed using at the end skin grafts. [ABSTRACT FROM AUTHOR]

This work aims to investigate the mechanical properties and interfacial characteristics of 6061 Al alloy plates fabricated by hot-roll bonding (HRB) based on friction stir welding. The results showed that ultimate tensile strength and total elongation of the hot-rolled and aged joints increased with the packaging vacuum, and the tensile specimens fractured at the matrix after exceeding 1 Pa. Non-equilibrium grain boundaries were formed at the hot-rolled interface, and a large amount of Mg2Si particles were linearly precipitated along the interfacial grain boundaries (IGBs). During subsequent heat treatment, Mg2Si particles dissolved back into the matrix, and Al2O3 film remaining at the interface eventually evolved into MgO. In addition, the local IGBs underwent staged elimination during HRB, which facilitated the interface healing due to the fusion of grains at the interface. This process was achieved by the dissociation, emission, and annihilation of dislocations on the IGBs. [ABSTRACT FROM AUTHOR]

In this paper, we are concerned with the Cauchy problem of 3D viscous and heat-conducting micropolar fluids with far field vacuum. Compared with the case of non-vacuum at infinity (Huang and Li in Arch Ration Mech Anal 227:995–1059, 2018; Huang et al. in J Math Fluid Mech 23(1):50, 2021), due to (ρ (t , x) , θ (t , x)) → (0 , 0) as | x | → ∞ , we don’t have useful energy equality (or inequality), which is very important to establish a priori estimates in Huang and Li (Arch Ration Mech Anal 227:995–1059, 2018) and Huang et al. (J Math Fluid Mech 23(1):50, 2021). Thus, a new assumption of a priori estimates and more complicated calculations will be needed. On the other hand, we need to deal with some strong nonlinear terms which come from the interactions of velocity and micro-rotation velocity. Finally, we show that the global existence and uniqueness of strong solutions provided that the initial energy is suitably small. In particular, large-time behavior and a exponential decay rate of the strong solution are obtained, which generalizes the incompressible case (Ye in Dicret Contin Dyn Syst Ser B 24:6725–6743, 2019) to the full compressible case. [ABSTRACT FROM AUTHOR]

The energy conservation problem for the reduced‐gravity two‐and‐a‐half layer model remains a challenging open problem, with several recent contributions addressing various aspects of it. In this paper, we establish sufficient conditions on the regularity of weak solutions that guarantee energy conservation even in the presence of a vacuum. Our theorem corresponds to an improvement of some recent results on this problem and contains some well‐known results as a particular case. [ABSTRACT FROM AUTHOR]

In this paper, an initial boundary value problem of the 2D incompressible Bénard system is concerned. The global existence of a unique strong solution is established by the energy method and a key logarithmic interpolation inequality. In particular, the exponential decay rates for the gradients of velocity and temperature field are obtained. [ABSTRACT FROM AUTHOR]

Purpose: Transduodenal surgical ampullectomy (tAMP) with papillary reimplantation is a valid alternative to pancreaticoduodenectomy for lesions of the periampullary region not amenable to endoscopic resection. As tAMP is burdened by high rates of biliopancreatic-enteric anastomotic leak, we tested preventive endoluminal vacuum therapy (eVAC) combined with post-operative continuous perianastomotic irrigation (CPI) to reduce such anastomotic leak. Methods: Between 10/2013 and 09/2023, 37 patients undergoing laparotomic tAMP (with or without jejunal transposition) and papillary reimplantation at Hirslanden Klinik Zurich were retrospectively analysed; of these, 16 received prophylactic eVAC combined with CPI, while the remaining represented the historical cohort. Results: The eVAC-CPI-group and the historical-cohort were homogeneous in demographic characteristics. Surgery in the prophylactic eVAC-CPI-group lasted about 30 min longer due to eVAC application (p = 0.008). The biliopancreatico-enteric anastomotic leak rates were 6.2% in the eVAC-CIP-group vs. 19.0% in the historical-cohort (p = 0.266). Along, a strong trend of less severe post-operative complications in general (p = 0.073), and borderline-significantly less cases of acute pancreatitis (p = 0.057) and tAMP-related re-operations or re-interventions (p = 0.057) in particular, were observed in the eVAC-CPI-group. The only anastomotic leak in the eVAC-CPI-group was successfully managed through repeated cycles of eVAC. The device was well tolerated by all patients; no vacuum/irrigation-related complications or malfunctioning occurred. Conclusion: Our study is the first to provide some technical insights demonstrating the safety and feasibility of a prophylactic approach with eVAC and perianastomotic irrigation to reduce anastomotic leak after tAMP. Increasing the number of subjects will confirm the benefit of our promising results. [ABSTRACT FROM AUTHOR]

This paper presents a mathematical model of a vapour vacuum system, which is a crucial component of steam power plants of critical importance for energy efficiency. This system consists of three stages, with each stage containing a steam ejector and a gas phase separator in the form of an interstage heat exchanger. The primary purpose of this system is to remove inert gases and maintain the appropriate level of vacuum in the power plant condenser. The presented mathematical model can be used to analyse the operation of the vacuum system in a steady state. Preliminary pressure calculations in various components of the vacuum system show the influence of additional measurement orifice resistance on the vacuum drop in the condenser, which can reduce the efficiency of the entire energy system. It is worth noting that the presented model can be used as a tool for analysing elements of the vacuum system in energy systems. [ABSTRACT FROM AUTHOR]

We establish the global existence and uniqueness of strong solutions for nonhomogeneous magnetic Bénard system with far field vacuum in the whole two-dimensional (2D) plane. In particular, the initial data can be arbitrarily large. Our method relies heavily on the structure of the system under consideration and spatial dimension. [ABSTRACT FROM AUTHOR]

Objectives: In recent investigations, there has been increased focus on hip laxity and hip capsular instability, particularly in the setting of hip arthroscopy. The capsule and its internal negative pressure effects have been shown to be major contributors to hip joint stability, however, the relative contributory role of these elements remains unknown. Intraoperatively, improved understanding of hip capsule biomechanics is imperative for optimization of arthroscopic technique to access the central compartment with minimal soft tissue trauma. In turn, this can help reduce the risk of hip instability and maximize patient outcomes. The purpose of this study was to define the stiffness coefficient of the hip capsule and vacuum phenomenon in response to hip axial traction. Our hypothesis was that the vacuum phenomenon would have a greater relative contribution to axial distraction stiffness at mid-range distraction, and that the hip capsule stiffness coefficient would be greater at terminal distraction. Methods: A review of a prospectively collected database of patients undergoing hip arthroscopy was conducted from 1 July 2021 to 31 June 2022. Patients in this database underwent hip arthroscopy for the treatment of femoroacetabular impingement syndrome (FAIS). Inclusion criteria were 1) completion of the study traction protocol and 2) completion of hip joint venting prior to capsulotomy. Exclusion criteria were 1) previous hip surgery and 2) lack of hip distraction at 50 pounds of axial traction. The study traction protocol involved applying axial traction prior to instrumentation (Native State) of the hip using a post-free distraction system. Hips were then vented using a spinal needle and the traction protocol was repeated (Vented State). Traction intervals were 0, 50, and 100 lbs of force. Fluoroscopic images were taken at each traction interval and standardized to preoperative radiographs, which allowed for a calculation of the lateral joint space width at each interval. Overall distraction distance was calculated as the difference between 0 lbs traction and 50 and 100 lbs traction. The stiffness coefficient was calculated as k = traction force interval/distraction distance in both the Native and Vented States. Comparisons using paired-samples t-tests were conducted between the stiffness coefficients of the Native State and Vented State at 50 lbs and at 100 lbs. A p-value of <0.05 was utilized to indicate statistical significance. Results: Twenty-one patients were identified who met inclusion criteria. Mean age was 34.4 ± 13.4 years with 100% female and a mean BMI of 24.2 ± 4.8 points. Mean stiffness coefficient at 50 lbs in the Native State (10.9 ± 3.3) was significantly higher than the Vented State (4.9 ± 0.7, p < 0.001), with similar findings at 100 lbs in the Native State (10.1 ± 1.7) and Vented State (8.7 ± 1.3, p < 0.001). In the Vented State, the stiffness coefficient was significantly greater at 100 lbs (8.7 ± 1.3) than at 50 lbs (4.9 ± 0.7, p < 0.001). Conclusions: Our results provide an objective characterization of the individual contributions of the hip soft tissue restraints and the vacuum phenomenon to hip resistance to axial traction. At 50 pounds of traction, the vacuum effect contributes to ~55% of the axial distraction stiffness (resistance to axial distraction). At 100 pounds of traction force, the vacuum effect contributes only ~14% of the axial distraction stiffness. The resistance of the hip to axial distraction is of substantial clinical significance as minimization of traction force decreases intraoperative soft tissue trauma. This, however, needs to be balanced with obtaining sufficient working space within the hip joint. There is still substantial controversy regarding the biomechanics of the hip and the optimal methods for minimizing traction force related injury (e.g., post-less traction, minimization of traction time, air arthrogram, and joint venting). These data demonstrate that soft tissues have a proportionally greater effect on restraint of the of the hip at terminal distraction (~1 cm distraction), whereas the vacuum effect has a greater influence on mid-range distraction (~0.5 cm distraction). The proposed model for this phenomenon is that the negative pressure and the soft tissue tension work in parallel to restrain the hip joint. The increased influence of the soft tissue tension at end-range distraction may be due to a check rein effect of the soft tissues; once the iliofemoral ligament has been tensioned to its maximum length its stiffness and capacity for transfer of tensile force increases rapidly. In conclusion, at 50 pounds of traction, the vacuum effect contributes to ~55% of the axial distraction stiffness (resistance to axial distraction). At 100 pounds of traction force, the vacuum effect contributes only ~14% of the axial distraction stiffness. These results demonstrate that the vacuum effect is a significant restraint to axial traction applied across the hip at mid-range distraction. Additionally, the hip capsule has a relatively greater contribution to terminal distraction stiffness. [ABSTRACT FROM AUTHOR]

In this work the design and development of a power processing unit for a vacuum arc thruster is presented. The thruster is part of the Seamless Radio Access Networks for Internet of Space (SeRANIS) mission of the University of the Bundeswehr Munich, which will work as first multifunctional laboratory in orbit with public access. In addition to the basic functionality of generating a voltage peak for igniting the thruster, the power processing unit is equipped with techniques for controlling the ignition sequence and monitoring desired key values. The ignition procedure starts with generating the first trigger signal up to the point where a full-blown plasma is established. The PPU guarantees reliable performance by blocking every additional incoming signal while the ignition sequence is under way and the separation of the satellite's power bus before the thruster discharges. The status of the power processing unit is constantly controlled and information is provided whether ignition was successful or not. The functionality of this circuit is based on simulation before assembly and testing. In addition, the presented system was designed to pass a test cycle of mechanical, thermal and electrical tests before being declared ready for the space mission. [ABSTRACT FROM AUTHOR]

RTV 10A silicone rubber composites have many applications in forming many medical products and one of the recent applications is for orthotic insoles. This is because the RTV silicon rubber has excellent flexibility, elasticity, and resistance against splitting. However, these mechanical properties still need improvement when applied in certain medical applications. One way to improve mechanical properties is by adding talc. The process of mixing silicon rubber with talc requires special techniques to prevent the formation of porosity that may lead to unexpected mechanical properties. This porosity occurs due to trapped air during the mixing process or pouring into molds. Efforts to eliminate this porosity include vacuum die casting (VDC) techniques. This study presents the mechanical properties improvement of RTV 10A silicon rubber composite with the addition of using 30% talc. The objective is to achieve a more convenient orthotic insole to reduce the pain in human foot joints during walking due to planar stress. This study aims to reduce the porosity and minimize the trapped air by adding 30% talc into RTV 10A silicone rubber composite using VDC. In the experiment, the pressure variation was determined at -0.04 MPa, -0.06 MPa, -0.08 MPa, and -0.1 MPa through a mold size of 45 mm in diameter and thickness of 7 mm. Fluidity, density, porosity, and hardness were tested during the experiment. The results show that by decreasing vacuum pressure, the density and the hardness increase. This is because the size and distribution of porosity are decreased and more homogeny. Furthermore, it also produces higher fluidity. However, the porosity of the specimen after vacuum casting is not partially filled. [ABSTRACT FROM AUTHOR]