Interlayer Engineering and Prelithiation: Empowering Si Anodes for Low-Pressure-Operating All-Solid-State Batteries

Silicon (Si) anodes, free from the dendritic growth concerns found in lithium (Li) metal anodes, offer a promising alternative for high-energy all-solid-state batteries (ASSBs). However, most advancements in Si anodes have been achieved under impractical high operating pressures, which can mask detrimental electrochemo-mechanical issues. Herein, we effectively address the challenges related to the low-pressure operation of Si anodes in ASSBs by introducing an silver (Ag) interlayer between the solid electrolyte layer (Li6 PS5 Cl) and anode and prelithiating the anodes. The Si composite electrodes, consisting of Si/polyvinylidene fluoride/carbon nanotubes, are optimized for suitable mechanical properties and electrical connectivity. Although the impact of the Ag interlayer is insignificant at an exceedingly high operating pressure of 70 MPa, it substantially enhances the interfacial contacts under a practical low operating pressure of 15 MPa. Thus, Ag-coated Si anodes outperform bare Si anodes (discharge capacity: 2430 vs 1560 mA h g-1 ). The robust interfacial contact is attributed to the deformable, adhesive properties and protective role of the in situ lithiated Ag interlayer, as evidenced by comprehensive ex situ analyses. Operando electrochemical pressiometry is used effectively to probe the strong interface for Ag-coated Si anodes. Furthermore, prelithiation through the thermal evaporation deposition of Li metal significantly improves the cycling performance.

Study of Low-Pressure Cold Spray Additive Manufacturing: Investigation of Kinematic Spray Parameters on Deposition and Properties

Low-pressure cold spray (LPCS) has broadened the application field of cold spray owing to its portability and low cost. For additive manufacturing (AM) based on LPCS (LPCSAM), it is important to investigate the effects of parameters such as temperature and pressure of the gas, stand-off distance, gun traverse speed, and the number of scanning passes of the gun on the deposition and properties. This study aims to determine the optimal kinematic spray parameters for spraying Cu+Al2O3 powder onto an aluminum substrate through LPCS, so as to prepare for the next AM work. The deposition mass, deposition rate, microhardness, and roughness under different spraying conditions were studied. The best spraying effect, with a high deposition rate and without nozzle clogging, was obtained at a nitrogen pressure of 0.9 MPa and a temperature of 400°C.

Acute low-pressure hydrocephalus in aneurysmal subarachnoid hemorrhage

OBJECTIVE

Acute and chronic hydrocephalus are common pathologies after aneurysmal subarachnoid hemorrhage (SAH). Generally, the presence of acute hydrocephalus is associated with elevated intracranial pressure (ICP) treated with a ventricular drain. Subsequently, however, pronounced hydrocephalus without elevated ICP may develop in some patients with SAH in the postacute phase. This is described as acute low-pressure hydrocephalus (aLPH), and there are very limited data in the literature of this pathology. The aim of this study was to evaluate the rate of and factors associated with aLPH and describe its clinical course.

METHODS

In this retrospective single-center cohort study, the frequency and clinical characteristics of SAH-associated aLPH were investigated. Acute LPH was defined as an increase in ventricular size as measured by the Evans index, ICP within the normal range (< 5 mm Hg) at the time of ventricular enlargement, and timely neurological improvement after indwelling ventricular CSF drainage with negative pressure up to 5 cm H2O below normal level. Demographic and SAH-specific factors in patients with SAH treated using an external ventricular drain were extracted from the electronic medical chart and further analyzed.

RESULTS

From November 2010 to May 2020, 15 (3.7.%) of 406 patients with SAH fulfilled the criteria for aLPH. Acute LPH was diagnosed after an average of 13.1 ± 7.7 days. The presence of IVH and its extension were associated with the occurrence of aLPH. After undergoing the transient phase of aLPH, these patients subsequently developed a chronic, typical malresorptive hydrocephalus requiring a ventriculoperitoneal shunt more often (66.7% vs 17.4%, p < 0.001) and stayed longer in the intensive care unit (27 vs 20.5 days, p = 0.043) and in the hospital (36.4 vs 26.3 days, p = 0.004).

CONCLUSIONS

Acute LPH is a rare pathology in patients with SAH and negatively impacts the clinical course. It should be especially considered in patients with a lack of neurological improvement, an increase in ventricular width, and normal ICP values, so that forced CSF drainage is implemented.

Does Time and Size Matter in Retrograde Intrarenal Surgery? Results Analysis Using a Low-Pressure Technique

PURPOSE

Kidney stone disease affects 5% of the population and is associated with non-negligible morbidity. Retrograde intrarenal surgery and percutaneous nephrolithotomy are the treatments of choice. We analyzed the results from our patients who underwent retrograde intrarenal surgery at controlled pressure.

MATERIALS AND METHODS

We conducted an observational, descriptive, retrospective study of 403 patients who underwent retrograde intrarenal surgery at the Hospital Clínico Universitario Lozano Blesa (Zaragoza, Spain) between January 2013 and December 2019.

RESULTS

The mean surgical time was 111.1 minutes, with a mean stone volume of 3.5 cm³ (maximum volume, 38.3 cm³). A total of 70 patients (17.3%) developed postoperative Clavien-Dindo complications-64 minor (91.4%) and 6 major (8.6%). In addition, 28 patients (6.9%) presented with an early complication (<3 months), with urinary tract infection and pyelonephritis being the most common. The stone-free rate was 69.0%, with a retreatment rate of 4.7%.

CONCLUSIONS

Sex was statistically significantly related to the onset of minor Clavien postoperative complications (p = 0.001). Similarly, corticosteroid use was associated with the onset of major Clavien complications (p = 0.030). Neither surgical time nor stone volume was found to be statistically significantly related to the onset of Clavien postoperative complications or early complications.

Slip Flow Analysis in an Experimental Chamber Simulating Differential Pumping in an Environmental Scanning Electron Microscope

This paper describes the combination of experimental measurements with mathematical-physical analysis during the investigation of flow in an aperture at low pressures in a prepared experimental chamber. In the first step, experimental measurements of the pressure in the specimen chamber and at its outlet were taken during the pumping of the chamber. This process converted the atmospheric pressure into the operating pressure typical for the current AQUASEM II environmental electron microscope at the ISI of the CAS in Brno. Based on these results, a mathematical-physical model was tuned in the Ansys Fluent system and subsequently used for mathematical-physical analysis in a slip flow regime on a nozzle wall at low pressure. These analyses will be used to fine-tune the experimental chamber. Once the chamber is operational, it will be possible to compare the results obtained from the experimental measurements of the nozzle wall pressure, static pressure, total pressure and temperature from the nozzle axis region in supersonic flow with the results obtained from the mathematical-physical analyses. Based on the above comparative analyses, we will be able to determine the realistic slip flow at the nozzle wall under different conditions at the continuum mechanics boundary.

Investigation of Low-Pressure Sn-Passivated Cu-to-Cu Direct Bonding in 3D-Integration

Cu-to-Cu direct bonding plays an important role in three-dimensional integrated circuits (3D IC). However, the bonding process always requires high temperature, high pressure, and a high degree of consistency in height. In this study, Sn is passivated over electroplated copper. Because Sn is a soft material and has a low melting point, a successful bond can be achieved under low temperature and low pressure (1 MPa) without any planarization process. In this experiment, Sn thickness, bonding temperature, and bonding pressure are variables. Three values of thicknesses of Sn, i.e., 1 μm, 800 nm, and 600 nm were used to calculate the minimum value of Sn thickness required to compensate for the height difference. Additionally, the bonding process was conducted at two temperatures, 220 °C and 250 °C, and their optimized parameters with required pressure were found. Moreover, the optimized parameters after the Cu planarization were also investigated, and it was observed that the bonding can succeed under severe conditions as well. Finally, transmission electron microscopy (TEM) was used to observe the adhesion property between different metals and intermetallic compounds (IMCs).

A general method for rapid synthesis of refractory carbides by low-pressure carbothermal shock reduction

Refractory carbides are attractive candidates for support materials in heterogeneous catalysis because of their high thermal, chemical, and mechanical stability. However, the industrial applications of refractory carbides, especially silicon carbide (SiC), are greatly hampered by their low surface area and harsh synthetic conditions, typically have a very limited surface area (<200 m² g^-1), and are prepared in a high-temperature environment (>1,400 °C) that lasts for several or even tens of hours. Based on Le Chatelier's principle, we theoretically proposed and experimentally verified that a low-pressure carbothermal reduction (CR) strategy was capable of synthesizing high-surface area SiC (569.9 m² g^-1) at a lower temperature and a faster rate (∼1,300 °C, 50 Pa, 30 s). Such high-surface area SiC possesses excellent thermal stability and antioxidant capacity since it maintained stability under a water-saturated airflow at 650 °C for 100 h. Furthermore, we demonstrated the feasibility of our strategy for scale-up production of high-surface area SiC (460.6 m² g^-1), with a yield larger than 12 g in one experiment, by virtue of an industrial viable vacuum sintering furnace. Importantly, our strategy is  also applicable to the rapid synthesis of refractory metal carbides (NbC, Mo₂C, TaC, WC) and even their emerging high-entropy carbides (VNbMoTaWC₅, TiVNbTaWC₅). Therefore, our low-pressure CR method provides an alternative strategy, not merely limited to temperature and time items, to regulate the synthesis and facilitate the upcoming industrial applications of carbide-based advanced functional materials.

Integration of Hot Tube Gas Forming and Die Quenching of Ultra-High Strength Steel Hollow Parts Using Low Pressure Sealed-Air

A low pressure sealed-air hot tube gas forming process of ultra-high strength steel tubes was developed not only to change the cross-section of the hollow products by bulging but also to increase the strength of components. Gas-formed components are typically formed by a controlled-gas pressure with extremely high internal pressure, which leads to affected production costs and safety. Moreover, compressing the gas with high pressure requires high energy during its preparation. Therefore, to simplify the internal pressure controlling system and improve the safety factor in gas forming processes, the sealed-air tubes are formed with a quite low initial pressure. The pressure of the sealed air increased with increasing temperature of the air inside the resistance-heated tube, and the bulging deformation was controlled only by axial feeding. The effects of the initial pressure and heating temperature on the bulging deformation and quenchability of the tubes, and the effect of the starting time of axial feeding on the bulging behavior were examined. Consequently, ultra-high strength steel bulged parts were produced even in low initial internal pressure and with the rapid heating of the tubes.

Performance Evaluation of Solar-Blind Gas-Filled Sensors to Detect Electrical Discharges for Low-Pressure Aircraft Applications

Unpressurized aircraft circuits facilitate the initiation of electrical discharges in wiring systems, with consequent damage to related insulation materials and safety hazards, that can and have already caused severe incidents and accidents. Specific sensors and solutions must be developed to detect these types of faults at a very incipient stage, before further damage occurs. Electrical discharges in air generate the corona effect, which is characterized by emissions of bluish light, which are found in the ultraviolet (UV) and visible spectra. However, due to sunlight interference, the corona effect is very difficult to detect at the very initial stage, so the use of solar-blind sensors can be a possible solution. This work analyzes the feasibility of using inexpensive non-invasive solar-blind sensors in a range of pressures compatible with aircraft environments to detect the electrical discharges at a very incipient stage. Their behavior and sensitivity compared with other alternatives, i.e., an antenna sensor and a CMOS imaging sensor, is also assessed. Experimental results presented in this paper show that the analyzed solar-blind sensors can be applied for the on-line detection of electrical discharges in unpressurized aircraft environments at the very initial stage, thus facilitating and enabling the application of predictive maintenance strategies. They also offer the possibility to be combined with existing electrical protections to expand their capabilities and improve their sensitivity to detect very early discharges, thus allowing the timely identification of their occurrence.

DNA Damage Protection for Enhanced Bacterial Survival Under Simulated Low Earth Orbit Environmental Conditions in Escherichia coli

Some organisms have shown the ability to naturally survive in extreme environments, even outer space. Some of these have natural mechanisms to resist severe DNA damage from conditions such as ionizing and non-ionizing radiation, extreme temperatures, and low pressures or vacuum. A good example can be found in Deinococcus radiodurans, which was exposed to severe conditions such as those listed in the Exposure Facility of the International Space Station (ISS) for up to three years. Another example are tardigrades (Ramazzottius varieornatus) which are some of the most resilient animals known. In this study, the survival under simulated Low earth Orbit (LEO) environmental conditions was tested in Escherichia coli. The radiation resistance of this bacteria was enhanced using the Dsup gene from R. varieornatus, and two more genes from D. radiodurans involved in DNA damage repair, RecA and uvrD. The enhanced survival to wide ranges of temperatures and low pressures was then tested in the new strains. This research constitutes a first step in the creation of new bacterial strains engineered to survive severe conditions and adapting existing species for their survival in remote environments, including extra-terrestrial habitats. These strains could be key for the development of environments hospitable to life and could be of use for ecological restoration and space exploration. In addition, studying the efficacy and the functioning of the DNA repair mechanisms used in this study could be beneficial for medical and life sciences engineering.

Growth of Pseudomorphic GeSn at Low Pressure with Sn Composition of 16.7

Group-IV alloy GeSn holds great promise for the high-performance optoelectronic devices that can be monolithically integrated on Si for near- and mid-infrared applications. Growth of GeSn using chemical vapor deposition technique with various Sn and Ge precursors has been investigated worldwide. To achieve relatively high Sn incorporation, the use of higher pressure and/or higher order Ge hydrides precursors were reported. In this work, we successfully demonstrated the growth of high-quality GeSn with Sn composition of 16.7% at low pressure of 12 Torr. The alloy was grown using the commercially available GeH₄ and SnCl₄ precursors via a chemical vapor deposition reactor. Material and optical characterizations were performed to confirm the Sn incorporation and to study the optical properties. The demonstrated growth results reveal a low-pressure growth window to achieve high-quality and high Sn alloys for future device applications.

Inactivation of Enveloped Bovine Viral Diarrhea Virus and Non-Enveloped Porcine Parvovirus Using Low-Pressure Non-Thermal Plasma

As the worldwide population has been experiencing since 2020, viruses represent a serious threat to global well-being. To avoid viral transmission through surgery or medical examination, sterilization of medical material is needed. From emerging sterilization processes, the use of non-thermal plasma (NTP) arises as a promising technique to efficiently reduce microbial burden on medical devices, including new complex polymers as thermosensitive ones. Thus, we evaluated the antiviral efficacy of a low-pressure NTP process taking place in a sealed bag. For this purpose, two different plasmas, O₂ 100% plasma and Ar 80%-O₂ 20% plasma, were tested against two viruses: the bovine viral diarrhea virus and the porcine parvovirus, surrogates of human hepatitis C virus and human parvovirus B19, respectively. The efficacy of both NTP treatments on viral load can be detected after only five minutes. Moreover, the longer the NTP treatments last, the more the load decreases. The most effective load reduction was obtained with a 120-min O₂ plasma treatment inducing a minimum of four-log viral load reduction. So, this process demonstrated strong virucidal capacity inside a sealed bag and represents a very interesting opportunity in the field of fragile medical devices sterilization or disinfection.

Corona Discharge Characteristics under Variable Frequency and Pressure Environments

More electric aircrafts (MEAs) are paving the path to all electric aircrafts (AEAs), which make a much more intensive use of electrical power than conventional aircrafts. Due to the strict weight requirements, both MEA and AEA systems require to increase the distribution voltage in order to limit the required electrical current. Under this paradigm new issues arise, in part due to the voltage rise and in part because of the harsh environments found in aircrafts systems, especially those related to low pressure and high-electric frequency operation. Increased voltage levels, high-operating frequencies, low-pressure environments and reduced distances between wires pose insulation systems at risk, so partial discharges (PDs) and electrical breakdown are more likely to occur. This paper performs an experimental analysis of the effect of low-pressure environments and high-operating frequencies on the visual corona voltage, since corona discharges occurrence is directly related to arc tracking and insulation degradation in wiring systems. To this end, a rod-to-plane electrode configuration is tested in the 20–100 kPa and 50–1000 Hz ranges, these ranges cover most aircraft applications, so that the corona extinction voltage is experimentally determined by using a low-cost high-resolution CMOS imaging sensor which is sensitive to the visible and near ultraviolet (UV) spectra. The imaging sensor locates the discharge points and the intensity of the discharge, offering simplicity and low-cost measurements with high sensitivity. Moreover, to assess the performance of such sensor, the discharges are also acquired by analyzing the leakage current using an inexpensive resistor and a fast oscilloscope. The experimental data presented in this paper can be useful in designing insulation systems for MEA and AEA applications.

Frequency Response of Pressure-Sensitive Paints under Low-Pressure Conditions

The characteristics of fast-response pressure-sensitive paints (PSPs) in low-pressure conditions were evaluated. Three representative porous binders were investigated: polymer-ceramic PSP (PC-PSP), anodized-aluminum PSP (AA-PSP), and thin-layer chromatography PSP (TLC-PSP). For each PSP, two types of luminophores, Pt(II) meso-tetra (pentafluorophenyl) porphine (PtTFPP) and tris(bathophenanthroline) ruthenium dichloride (Ru(dpp)3), were used as sensor molecules. Pressure sensitivities, temperature sensitivities, and photodegradation rates were measured and evaluated using a pressure chamber. The effect of ambient pressure on the frequency response was investigated using an acoustic resonance tube. The diffusivity coefficients of PSPs were estimated from the measured frequency response and luminescent lifetime, and the governing factor of the frequency response under low-pressure conditions was identified. The results of static calibration show that PC-PSP/PtTFPP, AA-PSP/Ru(dpp)3, and TLC-PSP/PtTFPP have high pressure sensitivities that exceed 4%/kPa under low-pressure conditions and that temperature sensitivity and photodegradation rates become lower as the ambient pressure decreases. Dynamic calibration results show that the dynamic characteristics of PSPs with PtTFPP are dependent on the ambient pressure, whereas those of PSPs with Ru(dpp)3 are not influenced by the ambient pressure. This observation indicates that the governing factor in the frequency response under low-pressure conditions is the lifetime for PC-PSP and TLC-PSP, whereas the governing factor for AA-PSP is diffusion.

Insulation Failure Quantification Based on the Energy of Digital Images Using Low-Cost Imaging Sensors

Insulation faults in high-voltage applications often generate partial discharges (PDs) accompanied by corona activity, optical radiation mainly in the ultraviolet (UV) and visible bands. Recent developments in low-cost, small-size, and high-resolution visible imaging sensors, which are also partially sensitive to the UV spectral region, are gaining attention due to their many industrial applications. This paper proposes a method for early PD detection by using digital imaging sensors, which allows the severity of insulation faults to be assessed. The electrical power dissipated by the PDs is correlated to the energy of the acquired visible images, and thus, the severity of insulation faults is determined from the energy of the corona effect. A criterion to quantify the severity of insulation faults based on the energy of the corona images is proposed. To this end, the point-to-plane gap configuration is analyzed in a low-pressure chamber, where digital image photographs of the PDs are taken and evaluated under different pressure conditions ranging from 10 to 100 kPa, which cover the typical pressure range of aeronautic applications. The use of digital imaging sensors also allows an early detection, location and quantification of the PD activity, and thus assessing the severity of insulation faults to perform predictive maintenance tasks, while enabling the cost and complexity of the instrumentation to be reduced. Although the approach proposed in this paper has been applied to detect PDs in aeronautic applications, it can be applied to many other high-voltage applications susceptible of PD occurrence.

Effect of Homogenization at a Lower Pressure on Structural and Functional Properties of Soy Protein Isolate

In this paper, the effects of homogenization at low pressure (1~40 MPa) on structural and functional properties of soy protein isolates (SPI) are investigated. Homogenization at low pressure increase solubility, surface hydrophobicity, emulsification activity and foaming capacity of SPIs, these all functional properties increases and then decreases with the homogenization pressure. Whereas, emulsion stability and foaming stability of SPIs treated by homogenization initially decrease and then increase with homogenization pressure. There is a dramatic decrease in hardness, springiness and cohesiveness of homogenized SPI gels. Generally, homogenization at low pressure do not change the subunit composition of SPIs. It is observed that, when the homogenization pressure is lower than 10 MPa than there is no significant impact on structural change. The content of β-sheet decreased, while unordered structure significantly increased, when the homogenization pressure increased from 10 MPa to 20 MPa. Furthermore, the content of β-sheet increases, when the content of the other structures decreases with the increasing homogenization pressure. The maximum emission wavelength (λmax) for SPIs increases with homogenization pressure increases from 10 Mpa to 20 Mpa, which is attributed to the gradual structural unfolding exposing more hydrophobic residues in protein surface. While, the decreased λmax of SPIs treated with 20 Mpa to 40 Mpa homogenization corresponds to the protein aggregation. It can be deduced that appropriate selection of homogenization pressure is important for improving the functional properties of SPIs.

Low-pressure pulmonary recruitment maneuver: equal to or worse than moderate-pressure pulmonary recruitment maneuver in preventing postlaparoscopic shoulder pain? A randomized controlled trial of 72 patients

Introduction

The pulmonary recruitment maneuver (PRM) has emerged as an effective way of reducing post-laparoscopic shoulder pain (PLSP). However, the optimal lower pressure level for a PRM to reduce PLSP has not yet been investigated.

Aim

To compare the efficacy of the low-pressure PRM with moderate-pressure PRM in preventing PLSP.

Material and methods

Seventy-two ASA I-II patients who were scheduled for gynecologic LS for non-malignant conditions were enrolled in this study. Group 1 included patients who received the PRM at a maximum pressure of 30-40 cm H₂O in a semi-Fowler position and group 2 included patients who received the PRM at a maximum pressure of 15 cm H₂O in a semi-Fowler position. The primary outcome of the study was the difference in PLSP between the two groups.

Results

There were no significant differences in PLSP and wound pain VAS scores between patients receiving the PRM at 30 cm H₂O and 15 cm H₂O during postoperative pain monitoring (p < 0.05). The groups were also similar with respect to ambulation time (p = 0.215), length of hospital stay (p = 0.556) and the height of the pneumoperitoneum measured on chest X-ray (p = 0.151).

Conclusions

The low-pressure PRM (15 cm H₂O pressure) provides similar efficacy as the moderate-pressure PRM (30-40 cm H₂O) in terms of PLSP, wound pain, height of pneumoperitoneum, time of ambulation and length of hospital stay. We suggest that lower maximal inspiratory pressure of 15 cm H₂O might be preferred to avoid the potential complications of the PRM with higher pressures.

Single-Atom Electrocatalysts from Multivariate Metal-Organic Frameworks for Highly Selective Reduction of CO2 at Low Pressures

Single-atom catalysts (SACs) are of great interest because of their ultrahigh activity and selectivity. However, it is difficult to construct model SACs according to a general synthetic method, and therefore, discerning differences in activity of diverse single-atom catalysts is not straightforward. Herein, a general strategy for synthesis of single-atom metals implanted in N-doped carbon (M₁ -N-C; M=Fe, Co, Ni and Cu) has been developed starting from multivariate metal-organic frameworks (MOFs). The M₁ -N-C catalysts, featuring identical chemical environments and supports, provided an ideal platform for differentiating the activity of single-atom metal species. When employed in electrocatalytic CO₂ reduction, Ni₁ -N-C exhibited a very high CO Faradaic efficiency (FE) up to 96.8 % that far surpassed Fe₁ -, Co₁ - and Cu₁ -N-C. Remarkably, the best-performer, Ni₁ -N-C, even demonstrated excellent CO FE at low CO₂ pressures, thereby representing a promising opportunity for the direct use of dilute CO₂ feedstock.

Treatment of starch films with a glow discharge plasma in air and O2 at low pressure

In this study, the effect of different cold plasma treatments was investigated as a novel method for the modification of starch film properties. The films were prepared from wheat starch using a solvent casting method and then treated with air and O₂ glow discharge plasma at different durations (4, 8, and 12 min). A significant increase in the hydrophilicity of the films was observed due to the formation of oxygen-containing groups after plasma treatment. Fourier transform infrared analysis illustrated a decrease in C-H groups that caused an increase in C-O and C-O-C groups in air-treated films and carbonyl groups in O₂-treated films. The surface roughness of the treated films increased from 17.6 nm to 22.5 and 20.6 nm after air and O₂ treatments, respectively. Plasma treatments decreased oxygen permeability of the films but no significant difference in the water vapor permeability was observed. After plasma treatment, tensile strength of films was improved due to crosslinking and etching at the surface, although elongation at break remains unchanged.

Experimental Study of Visual Corona under Aeronautic Pressure Conditions Using Low-Cost Imaging Sensors

Visual corona tests have been broadly applied for identifying the critical corona points of diverse high-voltage devices, although other approaches based on partial discharge or radio interference voltage measurements are also widely applied to detect corona activity. Nevertheless, these two techniques must be applied in screened laboratories, which are scarce and expensive, require sophisticated instrumentation, and typically do not allow location of the discharge points. This paper describes the detection of the visual corona and location of the critical corona points of a sphere-plane gap configurations under different pressure conditions ranging from 100 to 20 kPa, covering the pressures typically found in aeronautic environments. The corona detection is made with a low-cost CMOS imaging sensor from both the visible and ultraviolet (UV) spectrum, which allows detection of the discharge points and their locations, thus significantly reducing the complexity and costs of the instrumentation required while preserving the sensitivity and accuracy of the measurements. The approach proposed in this paper can be applied in aerospace applications to prevent the arc tracking phenomenon, which can lead to catastrophic consequences since there is not a clear protection solution, due to the low levels of leakage current involved in the pre-arc phenomenon.

Alteration of Pressure-Induced Vasodilation in Aging and Diabetes, a Neuro-Vascular Damage

Skin is constantly subjected to pressure at different levels. Pressure-induced vasodilation (PIV) is one of the response mechanisms to low pressure that maintains the homeostasis of the skin. PIV results from the interaction of primary afferent nerves and vascular endothelium of skin vessels. Thanks to this cutaneous neuro-vascular interaction, the cutaneous blood flow increase allows the maintenance of an optimal level of oxygenation and minimizes the lack of vascularization of the skin tissue under low pressure. It seems to be associated with the cutaneous protection mechanisms to prevent pressure ulcers. In some contexts, where microangiopathy and neuropathy can occur, such as aging and diabetes, PIV is impaired, leading to a dramatic early decrease in local skin blood flow when low pressure is applied. In aging, PIV alteration is due to endothelial dysfunction, essentially from an alteration of the nitric oxide pathway. In the inflamm-aging context, oxidative stress increases leading to endothelial cell and nerve damages. An age-related sensory neuropathy will exacerbate the alteration of PIV during the aging process. In diabetes, non-controlled hyperglycaemia leads to an increase in several pathological biochemical pathways that involve oxidative stress and can affect PIV. Sorbinil, alagebrium and alpha-lipoic acid are able individually to restore PIV through a possible oxidative stress reduction. Candesartan, an angiotensin II type 1 receptor blocker, is also able to restore PIV and prevent pressure ulcer formation. The possibility of preventing pressure ulcer associated to diabetes and/or aging with the restoration of PIV seems to be a promising research path.

Portable Low-Pressure Solar Steaming-Collection Unisystem with Polypyrrole Origamis

Solar steaming has emerged as a promising green technology that can address the global issue of scarcity of clean water. However, developing high-performance, cost-effective, and manufacturable solar-steaming materials, and portable solar steaming-collection systems for individuals remains a great challenge. Here, a one-step, low-cost, and mass-producible synthesis of polypyrrole (PPy) origami-based photothermal materials, and an original portable low-pressure controlled solar steaming-collection unisystem, offering synergetic high rates in both water evaporation and steam collection, are reported. Due to enhanced areas for vapor dissipation, the PPy origami improves the water evaporation rate by at least 71% to 2.12 kg m^-2 h^-1 from that of a planar structure and exhibits a solar-thermal energy conversion efficiency of 91.5% under 1 Sun. When further controlling the pressure to ≈0.17 atm in the steaming-collection unisystem, the water collection rate improves by up to 52% systematically and dramatically. Although partial energy is utilized toward obtaining low-pressure, evaluations show that the overall energy efficiency is improved remarkably in the low-pressure system compared to that in ambient pressure. Furthermore, the device demonstrates effective decontamination of heavy metals, bacteria, and desalination. This work can inspire new paradigms toward developing high-performance solar steaming technologies for individuals and households.

Entropy Generation Optimization for Rarified Nanofluid Flows in a Square Cavity with Two Fins at the Hot Wall

Computational Fluid Dynamics (CFD) is utilized to study entropy generation for the rarefied steady state laminar 2-D flow of air-Al₂O₃ nanofluid in a square cavity equipped with two solid fins at the hot wall. Such flows are of great importance in industrial applications, such as the cooling of electronic equipment and nuclear reactors. In this current study, effects of the Knudsen number (Kn), Rayleigh number (Ra) and the nano solid particle’s volume fraction (ϕ) on entropy generation were investigated. The values of the parameters considered in this work were as follows: 0≤Kn≤0.1, 103≤Ra≤106, 0≤ϕ≤0.2. The length of the fins (L_F) was considered to be fixed and equal to 0.5 m, whereas the location of the fins with respect to the lower wall (H_F) was set to 0.25 and 0.75 m. Simulations demonstrated that there was an inverse direct effect of Kn on the entropy generation. Moreover, it was found that when Ra was less than 10⁴, the entropy generation, due to the flow, increased as ϕ increases. In addition, the entropy generation due to the flow will decrease at Ra greater than 10⁴ as ϕ increases. Moreover, the entropy generation due to heat will increase as both the ϕ and Ra increase. In addition, a correlation model of the total entropy generation as a function of all of the investigated parameters in this study was proposed. Finally, an optimization technique was adapted to find out the conditions at which the total entropy generation was minimized.

Basic Salt-Lake Brine: An Efficient Catalyst for the Transformation of CO2 into Quinazoline-2,4(1 H,3 H)-diones

The efficient transformation of CO₂ into value-added chemicals with green, abundant, and cheap catalysts is an interesting and challenging topic in both green and sustainable chemistry. In this study, a series of salt-lake brines were used for the first time to catalyze the reaction of CO₂ and a broad range of 2-aminobenzonitriles to form the corresponding quinazoline-2,4(1 H,3 H)-diones. It was found that the abundant, available, and inexpensive Zhabuye basic salt-lake brine could efficiently promote the reaction of 2-aminobenzonitriles under low pressure of CO₂ . Very high yields of value-added products were obtained. Further studies indicated that the basic carbonate and borate ions in the brine play key roles in accelerating the reactions.

Effects of Low Pressure Treatment on the Mortality of Different Life Stages of Indianmeal moth (Plodia interpunctella) and the Quality of Dried Chinese Jujube

Low pressure technology is a potential non-chemical method to control insects in agriculture products. The purpose of this study was to determine the tolerance of different life stages of indianmeal moth (Plodia interpunctella) to low pressure and to validate the mortality of P. interpunctella when infesting Chinese jujube (Zizyphus jujuba Miller) using a low pressure system. Results showed that larvae were the most tolerant life stage of P. interpunctella, with a minimum exposure time of 41.4 h at 1.3 kPa and 25 °C to obtain 100% mortality. Pupae were the most susceptible life stage, with a lethal time of 12 h under the above low pressure conditions. The survival ratio of P. interpunctella in jujube decreased with increasing exposure time and reached 0% when the jujubes with P. interpunctella larvae were exposed to low-pressure treatment for 41.6 h at 1.3 kPa and 25 °C. Although the color, moisture, soluble solid, and vitamin C contents were slightly changed, there was no significant quality difference in these factors between control and treated jujubes. The information provided by this study is useful in developing effective non-chemical low-pressure treatments for disinfesting agricultural products.

Humidity Measurement in Carbon Dioxide with Capacitive Humidity Sensors at Low Temperature and Pressure

In experimental chambers for simulating the atmospheric near-surface conditions of Mars, or in situ measurements on Mars, the measurement of the humidity in carbon dioxide gas at low temperature and under low pressure is needed. For this purpose, polymer-based capacitive humidity sensors are used; however, these sensors are designed for measuring the humidity in the air on the Earth. The manufacturers provide only the generic calibration equation for standard environmental conditions in air, and temperature corrections of humidity signal. Because of the lack of freely available information regarding the behavior of the sensors in CO₂, the range of reliable results is limited. For these reasons, capacitive humidity sensors (Sensirion SHT75) were tested at the German Aerospace Center (DLR) in its Martian Simulation Facility (MSF). The sensors were investigated in cells with a continuously humidified carbon dioxide flow, for temperatures between −70 °C and 10 °C, and pressures between 10 hPa and 1000 hPa. For 28 temperature–pressure combinations, the sensor calibration equations were calculated together with temperature–dependent formulas for the coefficients of the equations. The characteristic curves obtained from the tests in CO₂ and in air were compared for selected temperature–pressure combinations. The results document a strong cross-sensitivity of the sensors to CO₂ and, compared with air, a strong pressure sensitivity as well. The reason could be an interaction of the molecules of CO₂ with the adsorption sites on the thin polymeric sensing layer. In these circumstances, an individual calibration for each pressure with respect to temperature is required. The performed experiments have shown that this kind of sensor can be a suitable, lightweight, and relatively inexpensive choice for applications in harsh environments such as on Mars.

On Simulating Concurrent Flame Spread in Reduced Gravity by Reducing Ambient Pressure

The flammability of combustible materials in spacecraft environments is of importance for fire safety applications because the environmental conditions can greatly differ from those on earth, and a fire in a spacecraft could be catastrophic. Moreover, experimental testing in spacecraft environments can be difficult and expensive, so using ground-based tests to inform microgravity tests is vital. Reducing buoyancy effects by decreasing ambient pressure is a possible approach to simulate a spacecraft environment on earth. The objective of this work is to study the effect of pressure on material flammability, and by comparison with microgravity data, determine the extent to which reducing pressure can be used to simulate reduced gravity. Specifically, this work studies the effect of pressure and microgravity on upward/concurrent flame spread rates and flame appearance of a burning thin composite fabric made of 75% cotton and 25% fiberglass (Sibal). Experiments in normal gravity were conducted using pressures ranging between 100 and 30 kPa and a forced flow velocity of 20 cm/s. Microgravity experiments were conducted during NASA's Spacecraft Fire Experiment (Saffire), on board of the Orbital Corporation Cygnus spacecraft at 100 kPa and an air flow velocity of 20 cm/s. Results show that reductions of ambient pressure slow the flame spread over the fabric. As pressure is reduced, flame intensity is also reduced. Comparison with the concurrent flame spread rates in microgravity show that similar flame spread rates are obtained at around 30 kPa. The normal gravity and microgravity data is correlated in terms of a mixed convection non-dimensional parameter that describes the heat transferred from the flame to the solid surface. The correlation provides information about the similitudes of the flame spread process in variable pressure and reduced gravity environments, providing guidance for potential on-earth testing for fire safety design in spacecraft and space habitats.

Characterizing the impact of pressure on virus filtration processes and establishing design spaces to ensure effective parvovirus removal

Virus filtration provides robust removal of potential viral contaminants and is a critical step during the manufacture of biotherapeutic products. However, recent studies have shown that small virus removal can be impacted by low operating pressure and depressurization. To better understand the impact of these conditions and to define robust virus filtration design spaces, we conducted multivariate analyses to evaluate parvovirus removal over wide ranges of operating pressure, solution pH, and conductivity for three mAb products on Planova™ BioEX and 20N filters. Pressure ranges from 0.69 to 3.43 bar (10.0–49.7 psi) for Planova BioEX filters and from 0.50 to 1.10 bar (7.3 to 16.0 psi) for Planova 20N filters were identified as ranges over which effective removal of parvovirus is achieved for different products over wide ranges of pH and conductivity. Viral clearance at operating pressure below the robust pressure range suggests that effective parvovirus removal can be achieved at low pressure but that Minute virus of mice (MVM) logarithmic reduction value (LRV) results may be impacted by product and solution conditions. These results establish robust design spaces for Planova BioEX and 20N filters where high parvovirus clearance can be expected for most antibody products and provide further understanding of viral clearance mechanisms. © 2017 The Authors Biotechnology Progress published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers Biotechnol. Prog., 33:1294–1302, 2017

Efficacy of Controlled Atmosphere Treatments to Manage Arthropod Pests of Dry-Cured Hams

Research here explored the use of controlled atmospheres (CA) for managing arthropod pests that infest dry-cured hams. Experiments were conducted with low oxygen (O₂) achieved with low pressure under a vacuum, high carbon dioxide (CO₂), and ozone (O₃). Results showed that both low O₂ and high CO₂ levels required exposures up to 144 h to kill 100% of all stages of red-legged ham beetle, Necrobia rufipes (De Geer) (Coleoptera: Cleridae) and ham mite Tyrophagus putrescentiae (Schrank) (Sarcoptiformes: Acaridae) at 23 °C. In addition, both low O₂ and high CO₂ had no significant mortality against the ham beetle and ham mites at short exposures ranging from 12 to 48 h. Ham beetles were more tolerant than ham mites to an atmosphere of 75.1% CO₂ and low pressure of 25 mm Hg, which imposed an atmosphere estimated at 0.9% O₂. Both low O₂ and high CO₂ trials indicated that the egg stages of both species were more tolerant than other stages tested, but N. rufipes eggs and pupae were more susceptible than larvae and adults to high concentration ozone treatments. The results indicate that O₃ has potential to control ham beetles and ham mites, particularly at ≈166 ppm in just a 24 h exposure period, but O₃ is known from other work to have poor penetration ability, thus it may be more difficult to apply effectively than low O₂ or high CO₂. would be. CA treatment for arthropod pests of dry-cured hams show promise as components of integrated pest management programs after methyl bromide is no longer available for use.

Standoff Detection of Geological Samples of Metal, Rock, and Soil at Low Pressures Using Laser-Induced Breakdown Spectroscopy

Categorized certified reference materials simulating metal, rock, soils, or dusts are used to demonstrate the standoff detection capability of laser-induced breakdown spectroscopy (LIBS) at severely low pressure conditions. A Q-switched Nd:YAG laser operating at 1064 nm with 17.2-50 mJ energy per pulse was used to obtain sample signals from a distance of 5.5 m; the detection sensitivity at pressures down to 0.01 torr was also analyzed. The signal intensity response to pressure changes is explained by the ionization energy and electronegativity of elements, and from the estimated full width half-maximum (FWHM) and electron density, the decrease in both background noise and line broadening makes it suitable for low pressure detection using the current standoff LIBS configuration. The univariate analyses further showed high correlation coefficients for geological samples. Therefore, the present work has extended the current state-of-the-art of standoff LIBS aimed at harsh environment detection.

Design and Application of a High Sensitivity Piezoresistive Pressure Sensor for Low Pressure Conditions

In this paper, a pressure sensor for low pressure detection (0.5 kPa–40 kPa) is proposed. In one structure (No. 1), the silicon membrane is partly etched to form a crossed beam on its top for stress concentration. An aluminum layer is also deposited as part of the beam. Four piezoresistors are fabricated. Two are located at the two ends of the beam. The other two are located at the membrane periphery. Four piezoresistors connect into a Wheatstone bridge. To demonstrate the stress concentrate effect of this structure, two other structures were designed and fabricated. One is a flat membrane structure (No. 2), the other is a structure with the aluminum beam, but without etched silicon (No. 3). The measurement results of these three structures show that the No.1 structure has the highest sensitivity, which is about 3.8 times that of the No. 2 structure and 2.7 times that of the No. 3 structure. They also show that the residual stress in the beam has some backside effect on the sensor performance.

Thermal and tactile interactions in the perception of local skin wetness at rest and during exercise in thermo-neutral and warm environments

The central integration of thermal (i.e. cold) and mechanical (i.e. pressure) sensory afferents is suggested as to underpin the perception of skin wetness. However, the role of temperature and mechanical inputs, and their interaction, is still unclear. Also, it is unknown whether this intra-sensory interaction changes according to the activity performed or the environmental conditions. Hence, we investigated the role of peripheral cold afferents, and their interaction with tactile afferents, in the perception of local skin wetness during rest and exercise in thermo-neutral and warm environments. Six cold-dry stimuli, characterized by decreasing temperatures [i.e. -4, -8 and -15 °C below the local skin temperature (T(sk))] and by different mechanical pressures [i.e. low pressure (LP): 7 kPa; high pressure (HP): 10 kPa], were applied on the back of 8 female participants (age 21 ± 1 years), while they were resting or cycling in 22 or 33 °C ambient temperature. Mean and local Tsk, thermal and wetness perceptions were recorded during the tests. Cold-dry stimuli produced drops in Tsk with cooling rates in a range of 0.06-0.4 °C/s. Colder stimuli resulted in increasing coldness and in stimuli being significantly more often perceived as wet, particularly when producing skin cooling rates of 0.18 °C/s and 0.35 °C/s. However, when stimuli were applied with HP, local wetness perceptions were significantly attenuated. Wetter perceptions were recorded during exercise in the warm environment. We conclude that thermal inputs from peripheral cutaneous afferents are critical in characterizing the perception of local skin wetness. However, the role of these inputs might be modulated by an intra-sensory interaction with the tactile afferents. These findings indicate that human sensory integration is remarkably multimodal.

Low-pressure pneumoperitoneum during laparoscopic donor nephrectomy to optimize live donors' comfort

Nowadays, laparoscopic donor nephrectomy (LDN) has become the gold standard to procure live donor kidneys. As the relationship between donor and recipient loosens, it becomes of even greater importance to optimize safety and comfort of the surgical procedure. Low-pressure pneumoperitoneum has been shown to reduce pain scores after laparoscopic cholecystectomy. Live kidney donors may also benefit from the use of low pressure during LDN. To evaluate feasibility and efficacy to reduce post-operative pain, we performed a randomized blinded study. Twenty donors were randomly assigned to standard (14 mmHg) or low (7 mmHg) pressure during LDN. One conversion from low to standard pressure was indicated by protocol due to lack of progression. Intention-to-treat analysis showed that low pressure resulted in a significantly longer skin-to-skin time (149 ± 86 vs. 111 ± 19 min), higher urine output during pneumoperitoneum (23 ± 35 vs. 11 ± 20 mL/h), lower cumulative overall pain score after 72 h (9.4 ± 3.2 vs. 13.5 ± 4.5), lower deep intra-abdominal pain score (11 ± 3.3 vs. 7.5 ± 3.1), and a lower cumulative overall referred pain score (1.8 ± 1.9 vs. 4.2 ± 3). Donor serum creatinine levels, complications, and quality of life dimensions were not significantly different. Our data show that low-pressure pneumoperitoneum during LDN is feasible and may contribute to increase live donors' comfort during the early post-operative phase.

Effect of Low Pressures on the Room Temperature Transitions of Polytetrafluoroethylene

Between approximately 20 and 30 °C at atmospheric pressure, polytetrafluoroethylene exhibits a phase (denoted as IV), which has not been observed in P-V-T measurements at pressures above 10⁸ Nm^-2 (1 Kilobar). Data are presented to resolve this phase in the temperature range 0 to 50 °C and the pressure range 0 to 0.686 × 10⁸ Nm^-2. The II-IV (20 °C) transition pressure increases with temperature according to the equation P = (-820 + 26.9t + 0.68t ²) × 10⁵ and the IV-I (30 °C) transition according to the equation P = (- 91-57.8t + 1.99t ²) × 10⁵ suggesting a possible triple point near 2.6 × 10⁸ Nm^-2 and 54 °C. However, the IV-I transition probably cannot be resolved by volume measurements at pressures above 2 × 10⁸ Nm^-2 because its volume of transition is small and the two transitions overlap. The enthalpies of the transitions are calculated for different pressures and some thermodynamic properties of phase IV are determined indirectly. It is shown that, if the effect of volume change is subtracted, random reversals of the hand of the helical conformation of the molecule can account for appreciable fractions of the enthalpy and corresponding entropy change for the combined transitions at atmospheric pressure.