Rapid Decompression Research Articles

Numerical Study of the Effects of Fluid Conductance and the Capacity of Negatively Pressured Cabin to the Process of Explosive Decompression

Explosive decompression is the rapid decompression process of aircraft in the sky caused by the damage of cabin which challenges the safety of people and equipment. The explosive decompression tester usually uses negative pressure reserve cabin technology. Numerical study was conducted to analyse the influence of the throttling and negative pressure reserve cabin volume on the explosive decompression process. The results show that as the throttle opening, the explosive decompression time decreases and the fluctuation amplitude of the two chambers after the pressure balance is enhanced; the volume of the negative pressure reserve cabin has little effects on the rate of explosive decompression and has no obvious influence on the fluctuation.

Modelling distributed crewing in commercial aircraft with STAMP for a rapid decompression hazard

Changes to crewing configurations in commercial airlines are likely as a means of reducing operating costs. To consider the safety implications for a distributed crewing configuration, system theoretic accident model and processes (STAMP) was applied to a rapid decompression hazard. High level control structures for current operations and distributed crewing are presented. The CONOPS generated by STAMP-STPA for distributed crewing, and design constraints associated with unsafe control actions (UCAs) are offered to progress in the route to certification for distributed crewing, and improve safety in current operations. Control loops between stakeholders were created using system-theoretic process analysis (STPA). The factors leading to the Helios 255 incident demonstrated the redundancy that a ground station could offer without the risk of hypoxia, during a decompression incident. STPA analysis also highlighted initial UCAs that could occur within the hypothetical distributed crewing configuration, prompting consideration of design constraints and new CONOPS for ground station design.Practitioner Summary: SPO in commercial aircraft is likely as a means to reduce costs. This paper makes a case for distributed crewing using STAMP-STPA. Comparing current operations with a distributed crewing configuration, the redundancy offered by a ground station is demonstrated. Design constraints and new CONOPs for distributed crewing, and current operations are proposed.

Xenocrysts and megacrysts of alkali olivine-basalt-basanite-nephelinite association makhtesh ramon (israel): interaction with transporting magmas and morphological adjustment

Xenocrysts and megacrysts hosted in the rocks of Early Cretaceous olivine-basalt-basanite-nephelinite association that outcropped in erosion crater of Makhtesh Ramon (Natural Reserve of Mishmar ha-Nagev, Israel) are the topic of the current research. Magmatic rock association contains the wide spectrum of xenoliths trapped at different crustal levels. These are upper mantle, lower, and upper crustal xenoliths. Mantle xenoliths are represented by peridotites, olivine clinopyroxenites, clinopyroxenites, olivine websterites, websterites and their amphibole-bearing analogs. Lower crustal xenoliths are mafic granulites, such as metagabbros and plagioclasites, upper crustal xenoliths are the fragments of Neoproterozoic tuffs. Xenocrysts and megacrysts are fragments of xenoliths that chipped from them during their transportation to the surface. Different rate of xenoliths, xenocrysts, and megacrysts alteration by host magma and late fluids is a common petrographic particularity. The fluid alteration occurred at phreatomagmatic stage of magma crystallization. Alteration is observed by the appearance of new textures and products of reactional interaction. Xenocrysts and megacrysts are mainly represented by minerals that compatible with rock magmatic association. These are olivine, clinopyroxene, amphibole, nepheline, plagioclase, anorthoclase, apatite, magnetite, and spinel. Xenocrysts of quartz and orthopyroxene are incompatible to host rock magmatic association under-saturated in SiO 2 . Main reasons determining interaction between magma and xenolith are rapid decompression, metamorphism and metasomatism. Xenocrysts are subjected to metamorphism that corresponds to high-temperature facies of contact metamorphism, up to the partial melting of xenocrysts. Metasomatism is smoothing out the composition of xenocrysts to the composition of the same minerals that crystallized from host melt. There are several important criterions, which permit to identify xenocrysts and divide them from phenocrysts. These are partial melting, solid-state decomposition, recrystallization of primary (before-trapping) textures, recrystallization and self-faceting of initially anhedral grains into the crystals with perfect habit. Chemical composition of xenocrysts has both mineral - geochemical indications of xenogenic origin and new-formed sings of alteration.

A Rare Complication of Chronic Subdural Hematoma Evacuation: Brain Stem Hemorrhage: A Case Report

Abstract Chronic subdural hematoma (CSDH), which commonly affects the elderly, is one of the most frequent, but also benign neurosurgical pathologies. Burr hole drainage is the standard surgical modality for evacuation of a CSDH. This technique is known to be safe, with low morbidity and mortality rates. However, postoperative complications have occasionally been reported. We report the case of a 70-year-old man who presented a fatal brain stem hemorrhage after burr-hole drainage for unilateral chronic subdural hematoma. Asymmetrical and rapid decompression were thought to be leading to vascular disruption or sudden increase in cerebral blood flow, was probably responsible for the secondary brain stem bleeding. Therefore, a slow rate of evacuation of chronic subdural hematomas, as well as rigorous postoperative reanimation, are recommended in order to prevent serious complications.

White Matter Status of Participants in Altitude Chamber Research and Training.

Magnetic resonance imaging (MRI) brain scans of U.S. Air Force (USAF) altitude workers show increased white matter hyperintensities (WMH) that appear related to decompression stress. Relevant exposure thresholds are unknown. This MRI survey compares the white matter status of UK participants (UKP) in altitude chamber research and training with USAF cohorts having background and increased WMH. UKP (N = 20) comprised 13 research subjects and 7 military altitude chamber instructors ages 33 to 50 yr (16 men, 4 women), encompassing 1417 decompressions over a 15,000-ft (4572 m) pressure altitude (range 11-189; median 50). High resolution MRI reproduced USAF sequences and data were analyzed at the University of Maryland to validate comparison with age-matched USAF control (DOC; N = 85) and aerospace operational physiologist (PHY; N = 55) cohorts. UKP data are dichotomous: 17 subjects (85%) had normal scans (total 19 WMH) and three outliers had excess (>15) WMH (total of 83 lesions). WMH were not associated with metrics of decompression history (total exposures, rapid decompression, pressure breathing, hypoxia familiarization, decompression sickness, or exposure intensity). Ranked data indicate that UKP have fewer WMH than PHY but not DOC. UKP outliers' excess WMH are attributable to past mild traumatic brain injury. WMH in UKP are unrelated to subjects' low intensity (brief, infrequent) experience of altitude chamber decompression, encompassing occasional hypobaric hypoxia and mild decompression sickness, even with cumulative experience over many years. Such low intensity hypobaric exposure appears 'subthreshold' for promotion of WMH.Connolly DM, Lee VM, Hodkinson PD. White matter status of participants in altitude chamber research and training. Aerosp Med Hum Perform. 2018; 89(9):777-786.

The effect of rapid decompression on barotrauma and survival rate in swallowtail seaperch (Anthias anthias): Defining protocols for mitigating surfacing mortality

Swallowtail seaperch, Anthias anthias, is a popular fish in the public aquaria industry worldwide, but is subject to barotrauma and high mortality rates if an appropriate decompression profile is not used. Here, we analyze behavioral response to pressure reductions in swallowtail to define protocols for mitigating surfacing mortality. Four different pressure reduction rates were tested (15%, 25%, 35%, and 45%) in several lifting steps from an initial depth of 30 m. Decompression using this procedure was done with 12 and 24 h acclimation duration at each step allowing fish to recover from the pressure reduction. Fish condition was assessed based on swimming behavior, immediately after each new pressure reduction also after each acclimation time. Additionally, fish condition was monitored in a post-decompression trial for 14 days. During decompression, both conditions - initial and final - showed statistically significant differences in the reduction rates tested but showed no differences in acclimation times, and no interaction of the two factors. Neither pressure nor acclimation time affected the condition of the animal in post-decompression trials. Ascension steps near the surface are associated with larger decreases in neutrally buoyant fish compared to deeper decompression steps. Close monitoring of the effect of decompression on A. anthias in the control group, showed that a 29% reduction in pressure could indicate an approximate value of the free vertical range of this species, while swimbladder rupture can occur between 63 and 70% of pressure reduction. The optimal protocol for mitigating surfacing mortality combines two decompression profiles used in this experiment with a total duration of 84 h and comprising 4 lifting steps. The protocol developed to mitigate surfacing mortality was designed for conditions where oceanic cages or containers can be lifted gradually.

Acute decompression following simulated dive conditions alters mitochondrial respiration and motility.

While barotrauma, decompression sickness, and drowning-related injuries are common morbidities associated with diving and decompression from depth, it remains unclear what impact rapid decompression has on mitochondrial function. In vitro diving simulation was performed with human dermal fibroblast cells subjected to control, air, nitrogen, and oxygen dive conditions. With the exception of the gas mixture, all other related variables, including absolute pressure exposure, dive and decompression rates, and temperature, were held constant. High-resolution respirometry was used to examine key respiratory states. Mitochondrial dynamic function, including net movement, number, and rates of fusion/fission events, was obtained from fluorescence microscopy imaging. Effects of the dive conditions on cell cytoskeleton were assessed by imaging both actin and microtubules. Maximum respiration was lower in fibroblasts in the air group than in the control and nitrogen groups. The oxygen group had overall lower respiration when compared with all other groups. All groups demonstrated lower mitochondrial motility when compared with the control group. Rates of fusion and fission events were the same between all groups. There were visible differences in cell morphology consistent with the actin staining; however, there were no appreciable changes to the microtubules. This is the first study to directly assess mitochondrial respiration and dynamics in a cell model of decompression. Both hyperbaric oxygen and air dive conditions produce deleterious effects on overall mitochondrial health in fibroblasts.

An experimental investigation of the roles of water content and gas decompression rate for outburst in coal briquettes

The coal and gas outburst has become a worldwide challenge and is still not fully understood. In this study, an experimental investigation was carried out for outburst evolution. Coal briquettes were fabricated based on less than 0.6 mm pulverized coal particles of Tunliu Coal Mine. CO2 was used to simulate outbursts by saturating coal briquettes in varying gas pressures (0.2, 0.4 and 0.6 MPa). The outbursts of coal briquettes were induced when rapid gas decompression was performed. The results indicate the outbursts depend on the gas pressure, water content and the rate of gas decompression. The differential pressure between the gas inside and outside the coal briquette is essential to outbursts and varies for different water contents while other parameters affect the initiation and intensity of outbursts as well. The higher gas pressure the more intense outburst occurs. It is worth noting that low rate of gas decompression cannot activate any outburst in the experiments even for a high gas pressure. The water content affects the outburst strongly. The critical minimum gas pressure in the coal briquettes with high water content becomes much higher than that in the coal briquettes with low water content. The major energy of the outbursts in the experiments is the expansion energy of the free state gas inside the coal briquettes. This study clearly demonstrates the progressive fragmentation of outbursts due to gas decompression.

Juvenile Chinook Salmon Survival When Exposed to Simulated Dam Passage after Being Implanted with a New Microacoustic Transmitter

AbstractThe current minimum size for tagging Chinook Salmon Oncorhynchus tshawytscha in the Columbia River basin with acoustic transmitters is ≥95 mm FL. Using a newly developed cylindrical microacoustic transmitter (AT; weight in air, 0.22 g), our objective was to evaluate the minimum size of Chinook Salmon for tagging. We measured Chinook Salmon survival and the retention of transmitters and viscera after their exposure to rapid decompression (n = 399) or shear forces (n = 308) that simulated dam passage. Fish (69–107 mm FL) were implanted with an AT (AT‐only) or an AT and a PIT tag (weight in air = 0.10 g; AT+PIT) through a 3‐mm incision with no sutures, or did not receive an incision or tag (untagged control fish). Tag burden averaged 2.9% (range, 1.4–6.2%) in the AT‐only group and 4.2% (range, 2.0–7.9%) in the AT+PIT group. Proportional survival and the retention of transmitters and viscera was significantly lower for AT‐only (0.70) and AT+PIT (0.54) fish than for untagged fish (0.85) after their exposure to pressure change scenarios. No transmitters were fully expelled, but 9% of AT‐only and 22% of AT+PIT salmon had protruding viscera or transmitters. Following shear exposure, the proportional survival and retention of transmitters and viscera was significantly lower for AT‐only (0.70) and AT+PIT (0.61) fish than for untagged fish (0.98). Visceral expulsion was attributed to 90% and 93% of mortal injuries in AT‐only and AT+PIT fish, respectively. In both tests the tagged fish suffered more mortal injuries and death than did untagged fish over the range of tag burdens tested, and no tag burden threshold below which tagged and untagged fish performed similarly was found. As such, a generalized linear model that included tag burden as a predictor variable provided the best fit to the survival data. Without a significant tag burden threshold, we recommend the minimum size for tagging Chinook Salmon using the transmitters and PIT tags evaluated, applied with a 3‐mm incision and no sutures, should remain at 95 mm FL.

Symptomatic cord compression by paraspinal musculature following cervical laminectomy: rare complication.

Cervical laminectomy is an effective treatment for multilevel cervical compressive myelopathy. Symptomatic spinal cord compression (SSCC) by paraspinal musculature (PSM) following cervical laminectomy is rarely reported. The aim of this study was to evaluate the frequency and pathogenesis of this complication after cervical laminectomy. Between 2007 and 2016, the medical records of 1309 cervical laminectomy patients were reviewed. From these 1309 records, seven patients (five men and two women; average age, 64.12years; range 48-78years) with SSCC by PSM following cervical laminectomy were identified. The incidence and possible risk factors of this rare condition were evaluated. The frequency of SSCC by PSM following cervical laminectomy was 0.53%. Presenting symptoms included paralyses and paresthesias, depending on the level and severity of cervical spinal cord compression. The initial onset of neurologic deterioration varied from 12h to 21days after operation. Most patients recovered well after surgical management with an average Barthel index of 74.3 at 6months after surgery. In comparison with 63 controls, this rare complication was associated with preoperative cervical kyphosis, prior antiplatelet therapy, and posterior decompression with prone position. SSCC by PSM is a rare but devastating complication following cervical laminectomy, especially in those patients with preoperative kyphosis, prior antiplatelet treatment, and decompression with prone position. MRI is an ideal tool to identify this complication. Rapid cervical cord decompression and avoidance of recurrent compressive events can achieve a good clinical outcome. These slides can be retrieved under Electronic Supplementary Material.

Assessment of injury and mortality from rapid decompression on crucian carps

Knowledge of barotrauma injury mechanisms is required in the fish-friendly turbine design. Rapid decreases in pressure is one of the main reasons that cause injury and mortality to fish that pass through hydropower machines. A steel tank and related pressure regulation components were designed to study the barotrauma injury thresholds of crucian carps. Decompression from 700 kPa to 6 kPa in 0.3 s was implemented in this system with dozens of yearling and subyearling crucian carps. The fish swim bladder and other organs were observed to find the main reason for injury after the rapid decompression. The tested fish were kept for at least 48 hours to study the physiological status in different observation periods. The direct and indirect decompression induced mortality after the test was observed and analyzed.

SubCAS: A Portable, Submersible Hyperbaric Chamber to Collect Living Mesophotic Fishes

Accompanying the recent technological innovations in remotely operated vehicles, submersibles, technical SCUBA, and closed-circuit rebreather diving gear, new discoveries are being made on mesophotic coral ecosystems around the world. However, collecting live fishes from mesophotic depths (60-150m) is challenging, given the difficulty of accessing the habitat, catching the fishes, and the barotrauma that can result from rapid decompression during their transport to the surface. Here, we designed and tested the performance of a portable, submersible hyperbaric chamber, the SubCAS, which we used to safely surface reef fishes from mesophotic depths. During six expeditions between 2014 and 2017 to the Philippines, Vanuatu, Palau and Pohnpei, we assessed the survival of 174 fishes caught between 60 and 150 m depth and decompressed using this chamber. A total of 155 (89.1%) fishes survived decompression, and 143 of 148 specimens shipped (96.6%) survived air cargo transport from remote field sites to the Steinhart Aquarium at the California Academy of Sciences. Survival was significantly related to taxonomic family, with Pomacentridae and Apogonidae showing the highest mortality. Collection depth, fish body size, and length of decompression had no relation to survivorship. Significant interactions between individual decompression events and both fish body size and taxonomic family indicate that low survival was associated with specific SubCAS trials. The SubCAS has allowed us to reliably surface charismatic fishes previously unknown to science and maintain them in aquaria for research and public engagement purposes. This opportunity facilitates a direct connection between our more than one million annual visitors and the wonders of exploration and the science of mesophotic coral ecosystems.

Induced material degradation of elastomers in harsh environments

The elastomeric components used in oil drilling operations, especially sealing solutions, are experiencing hardships from high pressure, high temperature and in contact with fluids. Therefore, the present work contributes to identifying the behaviour of hydrogenated nitrile butadiene rubber (HNBR) in contact with solvents and gases, and the ageing effect on resistance to rapid gas decompression (RGD). The swelling behaviour of HNBR was measured in different solvents and the tensile properties in different swollen conditions, i.e., un-swollen, swollen and de-swollen, were tested. RGD resistance was investigated in virgin and aged conditions. Deteriorated properties were observed in swollen states and the degradation magnitude was correlated with the degree of swelling; in fully de-swollen states, the un-swollen properties were regained. In RGD measurements, a relatively lower gas permeation was seen in swollen samples as well as the lowest volume increase during the decompression phase. However, crack observation based NORSOK ranking rates the RGD resistance in thermo-oxidative aged HNBR to be best followed by swollen and virgin samples, respectively.

Decoupling of bilayer leaflets under gas supersaturation: nitrogen nanobubbles in a membrane and their implication in decompression sickness

Decompression sickness (also known as diver’s sickness) is a disease that arises from the formation of a bubble inside the body caused by rapid decompression from high atmospheric pressures. However, the nature of pre-existing micronuclei that are proposed for interpreting the formation and growth of the bubble, as well as their very existence, is still highly controversial. In this work, atomistic molecular dynamics simulations are employed to investigate the nucleation of gas bubbles under the condition of nitrogen supersaturation, in the presence of a lipid bilayer and lipid micelle representing other macromolecules with a smaller hydrophobic region. Our simulation results demonstrate that by crossing a small energy barrier, excess nitrogen molecules can enter the lipid bilayer nearly spontaneously, for which the hydrophobic core serves as a potential well for gas enrichment. At a rather low nitrogen supersaturation, gas molecules in the membrane are dispersed in the hydrophobic region of the bilayer, with a slight increase in membrane thickness. But as the level of gas supersaturation reaches a threshold, the accumulation of N2 molecules in the bilayer center causes the two leaflets to be decoupled and the formation of nanobubbles. Therefore, we propose a nucleation mechanism for bubble formation in a supersaturated solution of inert gas: a cell membrane acts as a potential well for gas enrichment, being an ideal location for forming nanobubbles that induce membrane damage at a high level of gas supersaturation. As opposed to previous models, the new mechanism involves forming gas nuclei in a very low-tension hydrophobic environment, and thus a rather low energy barrier is required and pre-existing bubble micronuclei are not needed.

Gas nucleus growth in high-viscosity liquid under strongly non-equilibrium conditions

The present paper describes the growth dynamics of a gas bubble formed as a result of nucleation in a highly-viscous gas-saturated liquid under rapid decompression. The mathematical model presented combines both dynamical and diffusion problems. The half-analytical solution for the dissolved gas concentration profile, bubble growth rate and the rate of bubble mass change is found. In contrast to previously reported solutions, it can be applied at all stages of the process in a wide range of supersaturation. The half-analytical solution is in good agreement with the results of numerical simulations and with known solutions for limiting cases.

Sr isotope zoning in plagioclase from andesites at Cabo De Gata, Spain: Evidence for shallow and deep contamination

Plagioclase crystals in andesites from the Cabo De Gata region show generally radiogenic Sr isotope compositions and consistent core to rim increases in 87Sr/86Sr that are indicative of open system processes in the lithosphere and crustal contamination during crystallization. High-grade metamorphic rocks of the Alpujárride and Nevado-Filábride complexes represent the most likely crustal contaminants. The plagioclases are characterized by subtly zoned and resorbed calcic cores (An73–86). These cores also have radiogenic 87Sr/86Sr (0.7127–0.7129), although typically less radiogenic than plagioclase rims, groundmass plagioclase and whole rock compositions (up to 87Sr/86Sr = 0.7135). These cores are interpreted to represent early crystallization of plagioclase from hydrous melts emplaced into the lower crust. The parental melts to these andesites must therefore have already inherited their radiogenic Sr isotope compositions prior to entering the lower crust and before the onset of crystallization of plagioclase, which is inconsistent with previous models suggesting that the generally radiogenic nature of Sr in these volcanics reflects large amounts of crustal contamination. Instead, the isotope systematics are consistent with models invoked significant addition of a subducted sediment component to the mantle source. The high-An% plagioclase cores are characterized by resorption textures, which are consistent with dissolution during rapid decompression and/or devolatisation during magma migration from the lower crust into upper crustal magma chambers.

SCUBA Diving in Pregnancy.

Obstetrical care providers may occasionally encounter women with questions about the safety of Self-Contained Underwater Breathing Apparatus (SCUBA) diving in pregnancy. This article provides an overview of safety issues associated with basic SCUBA diving and offers guidance to practitioners about how to evaluate and counsel pregnant women about the associated maternal and fetal risks. Basic diving physiology is reviewed and the implications of SCUBA diving during pregnancy are discussed. A literature review examined available animal and human data about the potential adverse effects of the physiological changes of pregnancy on divers, the impact of pressure changes during diving, and possible consequences of hyperbaric gas exposure and rapid decompression on mother and fetus. Studies were found by searching the terms "scuba diving," "pregnancy," "fetus," "decompression illness," "hyperbaric medicine," and "animal studies" in the databases Medline, Pubmed, and Embase. Reference lists from existing articles and reports from identified diving magazines were also reviewed. Studies were limited to the English language and included publications until 2016. All relevant human studies were selected. Five retrospective studies and one prospective study assessing the antenatal and postnatal outcomes of women who participated in SCUBA diving while pregnant were reviewed. Published data was limited in both quantity and quality. The authors' experience with SCUBA diving together with a background in obstetrics allowed themes to be explored and recommendations developed. In addition to established risks of SCUBA diving, pregnant women are at increased risk due to changes in body habitus (affecting equipment fitting and balance). Animal data suggest possible adverse fetal effects due to fetal decompression illness (DCI) and hyperbaric oxygen exposure. Human data, though generally reassuring, are of poor quality and thus do not completely exclude adverse outcomes. In general, women should be cautioned to avoid diving during pregnancy, but inadvertent exposure to recreational diving in early pregnancy is not a reason for pregnancy termination.

Causes of fragmented crystals in ignimbrites: a case study of the Cardones ignimbrite, Northern Chile

Broken crystals have been documented in many large-volume caldera-forming ignimbrites and can help to understand the role of crystal fragmentation in both eruption and compaction processes, the latter generally overlooked in the literature. This study investigates the origin of fragmented crystals in the > 1260 km3, crystal-rich Cardones ignimbrites located in the Central Andes. Observations of fragmented crystals in non-welded pumice clasts indicate that primary fragmentation includes extensive crystal breakage and an associated ca. 5 vol% expansion of individual crystals while preserving their original shapes. These observations are consistent with the hypothesis that crystals fragment in a brittle response to rapid decompression associated with the eruption. Additionally, we observe that the extent of crystal fragmentation increases with increasing stratigraphic depth in the ignimbrite, recording secondary crystal fragmentation during welding and compaction. Secondary crystal fragmentation aids welding and compaction in two ways. First, enhanced crystal fragmentation at crystal-crystal contacts accommodates compaction along the principal axis of stress. Second, rotation and displacement of individual crystal fragments enhances lateral flow in the direction(s) of least principal stress. This process increases crystal aspect ratios and forms textures that resemble mantled porphyroclasts in shear zones, indicating lateral flow adds to processes of compaction and welding alongside bubble collapse. In the Cardones ignimbrite, secondary fragmentation commences at depths of 175–250 m (lithostatic pressures 4–6 MPa), and is modulated by both the overlying crystal load and the time spent above the glass transition temperature. Under these conditions, the existence of force-chains can produce stresses at crystal-crystal contacts of a few times the lithostatic pressure. We suggest that documenting crystal textures, in addition to conventional welding parameters, can provide useful information about welding processes in thick crystal-rich ignimbrites.

Investigation of the effect of thermal aging on rapid gas decompression (RGD) resistance of nitrile rubber

Thermal aging is possibly the most significant factor affecting the rapid gas decompression (RGD) resistance of rubber. In this study, NBR vulcanizates by different sulfur curing systems such as conventional (CV), semi-efficient (SEV), and efficient (EV) were thermally aged for 7 days at 100 °C. The effect of thermal aging on RGD resistance, and physico-mechanical properties has been evaluated by changes in the rating of RGD and properties before and after aging. The presented results show that thermal aging of NBR vulcanizates strongly depends on crosslink density and mechanical properties. Thermal aging of nitrile rubber samples increased the crosslink density and decreased tensile and tear strength which lead to lower RGD resistance. The significant changes of RGD resistance were in the CV > SEV > EV system order during aging. The results obtained indicate that the SEV system might be a suitable selection for engineering applications with middle physico-mechanical properties and good thermal aging and RGD resistance.

Experimental evidence of low-density liquid water upon rapid decompression

Water is an extraordinary liquid, having a number of anomalous properties which become strongly enhanced in the supercooled region. Due to rapid crystallization of supercooled water, there exists a region that has been experimentally inaccessible for studying deeply supercooled bulk water. Using a rapid decompression technique integrated with in situ X-ray diffraction, we show that a high-pressure ice phase transforms to a low-density noncrystalline (LDN) form upon rapid release of pressure at temperatures of 140-165 K. The LDN subsequently crystallizes into ice-Ic through a diffusion-controlled process. Together with the change in crystallization rate with temperature, the experimental evidence indicates that the LDN is a low-density liquid (LDL). The measured X-ray diffraction data show that the LDL is tetrahedrally coordinated with the tetrahedral network fully developed and clearly linked to low-density amorphous ices. On the other hand, there is a distinct difference in structure between the LDL and supercooled water or liquid water in terms of the tetrahedral order parameter.