Cambrian lobopodians shed light on the origin of the tardigrade body plan.

Phylum Tardigrada (water bears), well known for their cryptobiosis, includes small invertebrates with four paired limbs and is divided into two classes: Eutardigrada and Heterotardigrada. The evolutionary origin of Tardigrada is known to lie within the lobopodians, which are extinct soft-bodied worms with lobopodous limbs mostly discovered at sites of exceptionally well-preserved fossils. Contrary to their closest relatives, onychophorans and euarthropods, the origin of morphological characters of tardigrades remains unclear, and detailed comparison with the lobopodians has not been well explored. Here, we present detailed morphological comparison between tardigrades and Cambrian lobopodians, with a phylogenetic analysis encompassing most of the lobopodians and three panarthropod phyla. The results indicate that the ancestral tardigrades likely had a Cambrian lobopodian-like morphology and shared most recent ancestry with the luolishaniids. Internal relationships within Tardigrada indicate that the ancestral tardigrade had a vermiform body shape without segmental plates, but possessed cuticular structures surrounding the mouth opening, and lobopodous legs terminating with claws, but without digits. This finding is in contrast to the long-standing stygarctid-like ancestor hypothesis. The highly compact and miniaturized body plan of tardigrades evolved after the tardigrade lineage diverged from an ancient shared ancestor with the luolishaniids.

Scaphopoda is the sister taxon to Bivalvia: Evidence of ancient incomplete lineage sorting.

The almost simultaneous emergence of major animal phyla during the early Cambrian shaped modern animal biodiversity. Reconstructing evolutionary relationships among such closely spaced branches in the animal tree of life has proven to be a major challenge, hindering understanding of early animal evolution and the fossil record. This is particularly true in the species-rich and highly varied Mollusca where dramatic inconsistency among paleontological, morphological, and molecular evidence has led to a long-standing debate about the group's phylogeny and the nature of dozens of enigmatic fossil taxa. A critical step needed to overcome this issue is to supplement available genomic data, which is plentiful for well-studied lineages, with genomes from rare but key lineages, such as Scaphopoda. Here, by presenting chromosome-level genomes from both extant scaphopod orders and leveraging complete genomes spanning Mollusca, we provide strong support for Scaphopoda as the sister taxon of Bivalvia, revitalizing the morphology-based Diasoma hypothesis originally proposed 50 years ago. Our molecular clock analysis confidently dates the split between Bivalvia and Scaphopoda at ~520 Ma, prompting a reinterpretation of controversial laterally compressed Early Cambrian fossils, including Anabarella, Watsonella, and Mellopegma, as stem diasomes. Moreover, we show that incongruence in the phylogenetic placement of Scaphopoda in previous phylogenomic studies was due to ancient incomplete lineage sorting (ILS) that occurred during the rapid radiation of Conchifera. Our findings highlight the need to consider ILS as a potential source of error in deep phylogeny reconstruction, especially in the context of the unique nature of the Cambrian Explosion.

Cambrian explosion condensed: High-precision geochronology of the lower Wood Canyon Formation, Nevada.

The geologically rapid appearance of fossils of modern animal phyla within Cambrian strata is a defining characteristic of the history of life on Earth. However, temporal calibration of the base of the Cambrian Period remains uncertain within millions of years, which has resulted in mounting challenges to the concept of a discrete Cambrian explosion. We present precise zircon U-Pb dates for the lower Wood Canyon Formation, Nevada. These data demonstrate the base of the Cambrian Period, as defined by both ichnofossil biostratigraphy and carbon isotope chemostratigraphy, was younger than 533 Mya, at least 6 My later than currently recognized. This new geochronology condenses previous age models for the Nemakit-Daldynian (early Cambrian) and, integrated with global records, demonstrates an explosive tempo to the early radiation of modern animal phyla.

On the Resolution Limit of Electrohydrodynamic Redox 3D Printing.

Additive manufacturing (AM) will empower the next breakthroughs in nanotechnology by combining unmatched geometrical freedom with nanometric resolution. Despite recent advances, no micro-AM technique has been able to synthesize functional nanostructures with excellent metal quality and sub-100 nm resolution. Here, significant breakthroughs in electrohydrodynamic redox 3D printing (EHD-RP) are reported by directly fabricating high-purity Cu (>98 at.%) with adjustable voxel size from >6µm down to 50 nm. This unique tunability of the feature size is achieved by managing in-flight solvent evaporation of the ion-loaded droplet to either trigger or prevent the Coulomb explosion. In the first case, the landing of confined droplets on the substrate allows the fabrication of high-aspect-ratio 50 nm-wide nanopillars, while in the second, droplet disintegration leads to large-area spray deposition. It is discussed that the reported pillar width corresponds to the ultimate resolution achievable by EHD printing. The unrivaled feature size and growth rate (>100 voxel s-1) enable the direct manufacturing of 30 µm-tall atom probe tomography (APT) tips that unveil the pristine microstructure and chemistry of the deposit. This method opens up prospects for the development of novel materials for 3D nano-printing.

Two Notorious Nodes: a Critical Examination of Relaxed Molecular Clock Age Estimates of the Bilaterian Animals and Placental Mammals.

The popularity of relaxed clock Bayesian inference of clade origin timings has generated several recent publications with focal results considerably older than the fossils of the clades in question. Here we critically examine two such clades: the animals (with focus on the bilaterians); and the mammals (with focus on the placentals). Each example displays a set of characteristic pathologies which, although much commented on, are rarely corrected for. We conclude that in neither case does the molecular clock analysis provide any evidence for an origin of the clade deeper than what is suggested by the fossil record. In addition, both these clades have other features (including, in the case of the placental mammals, proximity to a large mass extinction) that allow us to generate precise expectations of the timings of their origins. Thus, in these instances the fossil record can provide a powerful test of molecular clock methodology, and why it goes astray; and we have every reason to think these problems are general.

Rethinking Porosity-Based Diffusivity Estimates for Sorptive Gas Transport at Variable Temperatures.

The detection of noble gas radioisotopes following a suspected underground nuclear explosion is the surest indicator that nuclear detonation has occurred. However, the accurate interpretation and attribution of radioisotopic signatures is only possible with a complete understanding of transport processes occurring between the nuclear cavity and surface. In the far-field, diffusive forces contributing to gas transport are impacted by temperature gradients and subsurface lithology. In the current study, we investigate diffusive transport of xenon (Xe), krypton (Kr), and sulfur hexafluoride (SF6) through intact Bandelier tuff at elevated temperatures using a newly developed high temperature diffusion cell. Diffusion coefficients determined using Finite Element Heat and Mass transfer code simulations and the Parameter ESTimation tool range from 2.6-3.1 × 10-6 m2/s at 20 °C, 3.4-5.1 × 10-6 m2/s at 40 °C, and 4.3-7.0 × 10-6 m2/s at 70 °C. Sorption was found to be an important transport mechanism at ambient temperatures (20 °C). Most critically, our study shows that empirical porosity-based diffusion estimates for these gases through tuff captured neither the magnitude nor trends relative to a nonsorbing sandstone. These new insights highlight the importance of experimental transport investigations and will be used to improve models for subsurface gas propagation relevant to proliferation detection and environmental contamination.

Cellular self-organization: An overdrive in Cambrian diversity?

During the early Cambrian period metazoan life forms diverged at an accelerated rate to occupy multiple ecological niches on earth. A variety of explanations have been proposed to address this major evolutionary phenomenon termed the "Cambrian explosion." While most hypotheses address environmental, developmental, and ecological factors that facilitated evolutionary innovations, the biological basis for accelerated emergence of species diversity in the Cambrian period remains largely conjectural. Herein, we posit that morphogenesis by self-organization enables the uncoupling of genomic mutational landscape from phenotypic diversification. Evidence is provided for a two-tiered interpretation of genomic changes in metazoan animals wherein mutations not only impact upon function of individual cells, but also alter the self-organization outcome during developmental morphogenesis. We provide evidence that the morphological impacts of mutations on self-organization could remain repressed if associated with an unmet negative energetic cost. We posit that accelerated morphological diversification in transition to the Cambrian period has occurred by emergence of dormant (i.e., reserved) morphological novelties whose molecular underpinnings were seeded in the Precambrian period.

Application of root cause analysis and TEAMSTEPPS post intravesical gas explosion during transurethral resection of the prostate: a rare case report.

BACKGROUND: An intravesical gas explosion is a rare complication of transurethral resection of the prostate (TURP). It was first reported in English literature in 1926, and up to 2022 were only forty-one cases. Injury from an intravesical gas explosion, in the most severe cases appearing as extraperitoneal or intraperitoneal bladder rupture needed emergent repair surgery. CASE PRESENTATION: We present a case of a 75-year-old man who suffered an intravesical gas explosion during TURP. The patient underwent an emergent exploratory laparotomy for bladder repair and was transferred to the intensive care unit for further observation and treatment. Under the medical team's care for up to sixty days, the patient recovered smoothly without clinical sequelae. CONCLUSIONS: This case report presents an example of a rare complication of intravesical gas explosion during TURP, utilizing root cause analysis (RCA) to comprehend causal relationships and team strategies and tools to improve performance and patient safety (TeamSTEPPS) method delivers four teamwork skills that can be utilized during surgery and five recommendations to avoid gas explosions during TURP to prevent the recurrence of medical errors. In modern healthcare systems, promoting patient safety is crucial. Once complications appear, RCA and TeamSTEPPS are helpful means to support the healthcare team reflect and improve as a team.

How state firework restrictions affect the incidence of paediatric firework injuries in the USA.

OBJECTIVES: State laws dictate firework access in the USA, and the association between state laws and paediatric firework injuries has not been investigated. We hypothesise that states with fewer firework restrictions will have a higher incidence of paediatric firework injuries. METHODS: A retrospective review (2012-2020) of paediatric patients who sustained a fireworks-related injury was conducted using the Pediatric Health Information System. Inclusion criteria were age less than 18 years and International Classification of Diseases code for fireworks-related injury. States were classified as 'unrestrictive' or 'restrictive' based on permitted fireworks. Case number, demographics and injury severity were evaluated. A negative binomial regression was used to evaluate independent variables predictive of firework injuries, with the dependent variable being the number of injuries. Independent variables that were predictive of number of injuries were subsequently evaluated with a Mann-Whitney test to determine the significance of the differences between 'unrestrictive' and 'restrictive' states. RESULTS: During the study period, 2299 fireworks-related injuries were reported. Mean age was 9.2±4.8 years (range 0-17). Most injuries, based on raw numbers, were in 'unrestrictive' states (72.6%). When normalised measures were used for comparison, based on paediatric state population, there was a statistically significant difference with a higher percentage of injuries in unrestricted states (p=0.002). The mean number of cases per million pediatric-aged individuals was higher in the 'unrestrictive' states versus the 'restrictive' states (p=0.003). CONCLUSIONS: States with fewer firework restrictions had a higher incidence of fireworks-related injuries in children. Restricting fireworks may protect children from fireworks-related injuries.

A systematic review of otologic injuries sustained in civilian terrorist explosions.

PURPOSE: Determine the prevalence of otological symptoms and tympanic membrane perforation, healing rates of tympanic membrane perforation with surgical and conservative management, and hearing function in civilian victims of terrorist explosions. METHODS: A systematic review was conducted with searches on Medline, Embase, EMCare and CINAHL for publications between the 1st January 1945 and 26th May 2023. Studies with quantitative data addressing our aims were included. This review is registered with PROSPERO: CRD42020166768. Among 2611 studies screened, 18 studies comprising prospective and retrospective cohort studies were included. RESULTS: The percentage of eardrums perforated in patients admitted to hospital, under ENT follow up and attending the emergency department is 69.0% (CI 55.5-80.5%), 38.7% (CI 19.0-63.0%, I2 0.715%) and 21.0% (CI 11.9-34.3%, I2 0.718%) respectively. Perforated eardrums heal spontaneously in 62.9% (CI 50.4-73.8%, I2 0.687%) of cases and in 88.8% (CI 75.9-96.3%, I2 0.500%) of cases after surgery. Common symptoms present within one month of bombings are tinnitus 84.7% (CI 70.0-92.9%, I2 0.506%), hearing loss 83.0% (CI 64.5-92.9%, I2 0.505%) and ear fullness 59.7% (CI 13.4-93.4%, I2 0.719). Symptomatic status between one and six months commonly include no symptoms 57.5% (CI 46.0-68.3%), hearing loss 35.4% (CI 21.8-51.8%, I2 0.673%) and tinnitus 15.6% (CI 4.9-40.0%, I2 0.500%). Within one month of bombings, the most common hearing abnormality is sensorineural hearing loss affecting 26.9% (CI 16.9-40.1%, I2 0.689%) of ears 43.5% (CI 33.4-54.2%, I2 0.500) of people. CONCLUSION: Tympanic membrane perforation, subjective hearing loss, tinnitus, ear fullness and sensorineural hearing loss are common sequelae of civilian terrorist explosions.

Acute Neurobehavioral and Glial Responses to Explosion Gas Inhalation in Rats.

Military personnel, firefighters, and fire survivors exhibit a higher prevalence of mental health conditions such as depression and post-traumatic stress disorder (PTSD) compared to the general population. While numerous studies have examined the neurological impacts of physical trauma and psychological stress, research on acute neurobehavioral effects of gas inhalation from explosions or fires is limited. This study investigates the early-stage neurobehavioral and neuronal consequences of acute explosion gas inhalation in Sprague-Dawley rats. Rats were exposed to simulated explosive gas and subsequently assessed using behavioral tests and neurobiological analyses. The high-dose exposure group demonstrated significant depression-like behaviors, including reduced mobility and exploration. However, neuronal damage was not evident in histological analyses. Immunofluorescence revealed increased density of radial glia and oligodendrocytes in specific brain regions, suggesting hypoxia and axon damage induced by gas inhalation as a potential mechanism for the observed neurobehavioral changes. These findings underscore the acute impact of explosion gas inhalation on mental health, highlighting the habenula and dentate gyrus of hippocampus as the possible target regions. The findings are expected to support early diagnosis and treatment strategies for brain injuries caused by explosion gas, offering insights into early intervention for depression and PTSD in affected populations.

Explosion Detection Using Smartphones: Ensemble Learning with the Smartphone High-Explosive Audio Recordings Dataset and the ESC-50 Dataset.

Explosion monitoring is performed by infrasound and seismoacoustic sensor networks that are distributed globally, regionally, and locally. However, these networks are unevenly and sparsely distributed, especially at the local scale, as maintaining and deploying networks is costly. With increasing interest in smaller-yield explosions, the need for more dense networks has increased. To address this issue, we propose using smartphone sensors for explosion detection as they are cost-effective and easy to deploy. Although there are studies using smartphone sensors for explosion detection, the field is still in its infancy and new technologies need to be developed. We applied a machine learning model for explosion detection using smartphone microphones. The data used were from the Smartphone High-explosive Audio Recordings Dataset (SHAReD), a collection of 326 waveforms from 70 high-explosive (HE) events recorded on smartphones, and the ESC-50 dataset, a benchmarking dataset commonly used for environmental sound classification. Two machine learning models were trained and combined into an ensemble model for explosion detection. The resulting ensemble model classified audio signals as either "explosion", "ambient", or "other" with true positive rates (recall) greater than 96% for all three categories.

Lightweight Detection Methods for Insulator Self-Explosion Defects.

The accurate and efficient detection of defective insulators is an essential prerequisite for ensuring the safety of the power grid in the new generation of intelligent electrical system inspections. Currently, traditional object detection algorithms for detecting defective insulators in images face issues such as excessive parameter size, low accuracy, and slow detection speed. To address the aforementioned issues, this article proposes an insulator defect detection model based on the lightweight Faster R-CNN (Faster Region-based Convolutional Network) model (Faster R-CNN-tiny). First, the Faster R-CNN model's backbone network is turned into a lightweight version of it by substituting EfficientNet for ResNet (Residual Network), greatly decreasing the model parameters while increasing its detection accuracy. The second step is to employ a feature pyramid to build feature maps with various resolutions for feature fusion, which enables the detection of objects at various scales. In addition, replacing ordinary convolutions in the network model with more efficient depth-wise separable convolutions increases detection speed while slightly reducing network detection accuracy. Transfer learning is introduced, and a training method involving freezing and unfreezing the model is employed to enhance the network's ability to detect small target defects. The proposed model is validated using the insulator self-exploding defect dataset. The experimental results show that Faster R-CNN-tiny significantly outperforms the Faster R-CNN (ResNet) model in terms of mean average precision (mAP), frames per second (FPS), and number of parameters.

Oxygen accumulation and associated dangers in rescue helicopters.

BACKGROUND: At the time of the COVID-19 pandemic, devastating incidents increased due to frequent oxygen administration to patients. The dangers associated with the use of oxygen, especially through local enrichments and formation of "oxygen clouds", have been well understood for years. Nevertheless, dramatic incidents continue to occur, since fire hazard increases exponentially with oxygen concentrations above 23%. Rescue helicopters are at a particular high risk, because of technical reasons such as oxygen use in a very small space, surrounded by kerosene lines, electronic relays and extremely hot surfaces. METHODS: In this study three different sized rescue helicopter models (Airbus H135, H145 and MD902) were examined. Oxygen enrichment in the cabin was measured with an oxymeter during a delivery rate of 15 l/min constant flow for 60 min. Furthermore, the clearance of the enriched atmosphere was tested in different situations and with different ventilation methods. To make the airflow visible, a fog machine was used to fill the helicopter cabin. RESULTS: Oxygen accumulation above 21% was detected in every helicopter. After 10-15 min, the critical 23% threshold was exceeded in all three aircrafts. The highest concentration was detected in the smallest machine (MD902) after 60 min with 27.4%. Moreover, oxygen clouds persisted in the rear and the bottom of the aircrafts, even when the front doors were opened. This was most pronounced in the largest aircraft, the H145 from Airbus Helicopters. Complete and rapid removal of elevated oxygen concentrations was achieved only by cross-ventilation within 1 min. CONCLUSIONS: Oxygen should be handled with particular care in rescue helicopters. Adapted checklists and precautions can help to prevent oxygen accumulation, and thus, fatal incidents. To our knowledge, this is the first study, which analyzed oxygen concentrations in different settings in rescue helicopters.

Rapid and Green Electric-Explosion Preparation of Spherical Indium Nanocrystals with Abundant Metal Defects for Highly-Selective CO2 Electroreduction.

Electrochemical conversion of CO2 into high-value-added chemicals has been considered a promising route to achieve carbon neutrality and mitigate the global greenhouse effect. However, the lack of highly efficient electrocatalysts has limited its practical application. Herein, we propose an ultrafast and green electric explosion method to batch-scale prepare spherical indium (In) nanocrystals (NCs) with abundant metal defects toward high selective electrocatalytic CO2 reduction (CO2RR) to HCOOH. During the electric explosion synthesis process, the Ar atmosphere plays a significant role in forming the spherical In NCs with abundant metal defects instead of highly crystalline In2O3 NCs formed under an air atmosphere. Analysis results reveal that the In NCs possess ultrafast catalytic kinetics and reduced onset potential, which is ascribed to the formation of rich metal defects serving as effective catalytic sites for converting CO2 into HCOOH. This work provides a feasible strategy to massively produce efficient In-based electrocatalysts for electrocatalytic CO2-to-formate conversion.

Secondary Atomization and Micro-Explosion Effect Induced by Surfactant and Nanoparticles on Enhancing the Combustion Performance of Al/JP-10/OA Nanofluid Fuel.

Aluminum/tetrahydrodicyclopentadiene/oleic acid (Al/JP-10/OA) nanofluid fuel is considered a potential fuel for aircraft powered by aviation turbine engines. However, an optimized formula for an Al/JP-10/OA system inducing a secondary atomization and micro-explosion effect and improving the burning performance needs to be developed. With this aim, in this work, the combustion characteristics of pure JP-10, JP-10/OA, JP-10/Al, and Al/JP-10/OA were experimentally tested, and a comparative analysis was conducted. Specifically, the influence of the surfactant and nanoparticle concentrations on the combustion characteristics of Al/JP-10/OA nanofluid fuel, including the flame structure, the flame temperature, the burning rate, the secondary atomization and micro-explosion effect, etc., were evaluated in detail. The results demonstrate that the addition of OA surfactant and Al nanoparticles had a significant effect on the burning rate of fuel droplets. The OA had an inhibition effect, while the Al nanoparticles had a promotion effect. As both OA and Al nanoparticles were added to the JP-10, the synergetic effect had to be considered. At the optimum ratio of OA to Al for the best suspension stability, there is a critical Al concentration of 1.0 wt.% from promotion to inhibition with increases in the Al concentration. The addition of OA and Al nanoparticles induced the secondary atomization and micro-explosion, resulting in an unsteady combustion and chaotic flame structure. The transient flame temperature of hundreds of Kelvins increased, the high-temperature flame zone widened, and thus, the energy release was elevated. Therefore, the combustion performance and energy release of Al/JP-10/OA nanofluid fuel can be improved through the secondary atomization and micro-explosion effect induced by the surfactant and nanoparticles.

Effects of steam explosion pretreatment on the digestive properties and gut microbiota of Laminaria japonica polysaccharide.

BACKGROUND: Laminaria japonica polysaccharide, which is an important bioactive substance of Laminaria japonica with anti-inflammatory and antioxidant effects. In this study, the molecular weight, functional groups and surface morphology were investigated to evaluate the digestive properties of Laminaria japonica polysaccharide before and after steam explosion. RESULTS: The results indicated that the Laminaria japonica polysaccharide entered the large intestine to be utilized by the gut microbiota after passing through the oral, gastric and small intestinal. Meanwhile, Laminaria japonica polysaccharide of steam explosion promoted the growth of beneficial bacteria Phascolarctobacterium and Intestinimonas, and increased the content of acetic, propionic and butyric acids, which was 2.29-folds, 2.60-folds and 1.63-folds higher than the control group after 48 h of fermentation. CONCLUSION: This study reveals that the effect of steam explosion pretreatment on the digestion in vitro and gut microbiota of Laminaria japonica polysaccharide will provide a basic theoretical basis for the potential application of Laminaria japonica polysaccharide as a prebiotic in the food industry. © 2024 Society of Chemical Industry.

Steam explosion-assisted grinding improves the functional properties and antioxidant activity of Java tea-leaf powders (Clerodendranthus spicatus).

BACKGROUND: Java tea is widely consumed and has multiple health effects. This study established a steam explosion (SE) pretreatment method to prepare Java tea-leaf powders. The physicochemical, functional properties, phenolic extraction, and antioxidant activity of Java tea-leaf powders produced by simple and SE-assisted milling methods were investigated. RESULTS: In comparison with simple milling, SE pretreatment broke the cell wall effectively and reduced the particle size of Java tea-leaf powders. Steam explosion-treated powders showed higher values for sensory signals, bulk and tap density, and for the water solubility index. After SE treatment, the adsorption capacities to glucose, soybean oil, and cholesterol of leaf powders were increased by up to 55, 95, and 80% respectively. The extracts from SE-treated powders also showed higher total polyphenol content and antioxidant activity. CONCLUSION: Steam explosion treatment is helpful for the improvement of functional properties and antioxidant activity, which can benefit the development and application of Java tea-leaf powders. © 2024 Society of Chemical Industry.

Effect of postharvest storage time on quality characteristics of explosion puffing dried whole shiitake mushroom (Lentinula edodes) crisps.

BACKGROUND: Non-fried shiitake mushroom (Lentinula edodes) crisps fabricated by explosion puffing drying (EPD) are receiving worldwide attention because of their crispness, convenience, nutrition and health functions. The quality of mushroom crisps varies with storage time of fresh L. edodes. Therefore, the effect of postharvest storage time (ranging from 0 to 14 days) of fresh L. edodes on quality characteristics of EPD- processed mushroom crisps was evaluated. RESULTS: The weight loss and total color difference of fresh L. edodes were increased to 2.95% and 24.66, but moisture content, firmness and lightness were reduced by 6.14%, 40.70% and 43.57%, respectively, after 14 days storage. The puffing degree of mushroom crisps was initially increased to its highest value (55.95%) on the 4th day storage and thereafter decreased. The highest rehydration ratio (2.36) and crispness (63.67), and lowest hardness (102.95 N) of mushroom crisps were fabricated with L. edodes on the 4th day of storage. Free water was predominant in fresh L. edodes, which was decreased for fresh L. edodes, whereas it increased initially to the maximum value and decreased thereafter for osmotic dehydrated and heat pump pre-dried L. edodes with increasing storage time. Principal component analysis and hierarchical cluster analysis confirmed that fresh L. edodes stored at different times had a remarkable effect on quality characteristics of mushroom crisps. CONCLUSION: Fresh L. edodes stored at 4 ± 1 °C for 4 days is recommended for fabrication of mushroom crisps with superior quality. This study provides a theoretical basis for selection of a suitable storage time for fresh L. edodes before EPD of crisps. © 2023 Society of Chemical Industry.

Comparison of numerical calculations and ALOHA modeling in consequence assessment of chlorine gas emissions from ethylene dichloride reactors.

Incidents involving chemical storage tanks in the petrochemical industry are significant events with severe consequences. Within the petrochemical industry, EDC is a sector that produces ethylene dichloride through the reaction of chlorine and ethylene. The present research was conducted to evaluate the consequences of chlorine gas released from the EDC reactor in a petrochemical industry in southern Iran. Data regarding reactor specifications were obtained from the factory's technical office, while climatic data was acquired from the Meteorological Organization. The consequences of chlorine gas release from the reactor were assessed in four predefined scenarios using numerical calculation methods and modeling with the ALOHA software. The numerical calculation method involved thermodynamic fluid path analysis, discharge coefficient calculations, and wind speed impact analysis. The hazard radius was determined based on the ERPG1-2-3 index. Results showed that in the scenario of chlorine gas release from EDC reactors, according to the ALOHA model, an increase in wind speed from 3 to 7 m/h led to an expanded dispersion radius. At a radius of 700 m from the reactor, the maximum outdoor concentration reached 3.12 ppm, decreasing to 2.27 ppm at 800 m and further to 1.53 ppm at 1000 m. The comparison of numerical calculations and modeling using the ALOHA software indicates the desirable conformity of the results with each other. The R2 coefficient for evaluating the conformity of the results was 0.9964, indicating the desired efficiency of the model in evaluating the consequences of the release of toxic gasses from the EDC tank. The results of this research can be useful in designing the site and emergency response plan.