Self-contained Breathing Apparatus Research Articles

Differences in bacterial community structure and volatile flavor substance of industrial-scale tiger skin chicken feet stored at air packaging and vacuum packaging

The aim of this study was to investigate the differences of quality indexes, bacterial community and volatile organic compounds (VOCs) of industrial-scale tiger skin chicken feet (TSCF) under air packaging (AP) and vacuum packaging (VP). The results showed that the pH, total volatile basic nitrogen, total number of bacterial colony, and sensory scores in VP group changed less than those in AP group during the storage period. Different packaging conditions also had significant effects on bacterial community at the genus levels. Weissella and Lactococcus was the dominant genus in AP group, while Lactiplantibacillus and Pediococcus also had the large proportions in addition to Weissella and Lactococcus in VP group, which also led to the differences in VOCs between the two groups. Several VOCs could be used as potential spoilage indicators, including 2-octanone, ethanol, ethyl acetate and acetic acid in AP-stored TSCF, and 2-octanone, ethanol, ethyl acetate, 2-butyl-1-octanol, (R)-2-butanol, (E)-3-hexenoic acid and 2-butanone in VP-stored TSCF. Correlation analysis showed that these predominance spoilage microorganisms were significantly correlated with these VOCs of TSCF during the storage period. This study can provide a theoretical basis for understanding of the spoilage process of TSCF.

Transcranial doppler to detect high-risk PFO and predict decompression illness in divers

Abstract Background It has not yet been clearly demonstrated whether it is feasible to diagnose patent foramen ovale (PFO) using transcranial doppler (TCD) and to use it in strategies to prevent decompression illness (DCI) in self-contained breathing apparatus (SCUBA) divers. Purpose DIVER-PFO study confirmed that high-risk PFO is associated with an increased risk of DCI in SCUBA divers. In this prespecified post-hoc analysis, we aimed to prospectively evaluate the accuracy of TCD to diagnose high-risk PFO and to predict the occurrence of DCI. Methods Eighty-two consecutive divers (mean age; 41 years, male 80.5%) underwent transesophageal echocardiogram (TEE) and TCD with a saline bubble test to determine the presence of PFO and were subsequently divided into high-risk and low-risk groups by TEE findings. Divers in the high-risk PFO group included those with the following conditions: PFO with atrial septal aneurysm, hypermobility, PFO size ≥2 mm, or right to left shunt at resting state. The enrolled divers were then followed-up using a self-reported questionnaire through e-mail or telephone interview for 3 years, while they were blinded to their PFO status. The primary endpoint of the study was PFO-related DCI, comprising cases of cutaneous or neurologic DCI, DCI symptoms requiring hyperbaric chamber therapy, DCI symptoms within 30 minutes after surfacing, or unexplained death occurring within 2 weeks after diving. Results PFO was detected in 47 (57.3%) and 59 (72.0%) divers by TCD and TEE, respectively. Diagnostic accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of TCD were 68.3%, 67.8%, 69.6% 85.1%, and 45.7% for the diagnosis of PFO, and 65.9%, 82.8%, 56.6%, 51.1% and 85.7% for the diagnosis of high-risk PFO, respectively. PFO-related DCI occurred in 9 divers in the PFO group (PFO vs non-PFO: 6.4 vs 0.7 incidences per 10,000 person dives; p=0.03) during a mean follow-up of 25.6 months. Integrated time-dependent Area Under the Curves for TCD and TEE to predict DCI occurrence using Cox’s proportional hazards regression model were 0.714 and 0.675, respectively. Conclusions TCD was moderately accurate to diagnose high-risk PFO in divers. However, it predicted DCI as much as TEE.Study flowIncidence of DCI in the PFO vs No PFO

Development and evaluation of a novel self-contained breathing apparatus pack to reduce musculoskeletal loads and enhance firefighter comfort

Self‑Contained Breathing Apparatus (SCBA) is an essential piece of personal protective equipment for firefighters, providing essential respiratory support and protection. A major challenge in SCBA research is to reduce musculoskeletal disorders and enhance firefighter comfort while carrying the SCBA. In this study, a novel SCBA pack was designed to reduce SCBA‑related musculoskeletal stress. Ten volunteer firefighters were recruited to participate in the test protocol equipped with a novel SCBA (SCBANovel) and a traditional SCBA (SCBATrad) pack. Surface electromyography and pressure data were collected, and subjective ratings of discomfort using a visual analog scale. The results showed that the SCBANovel significantly reduced trapezius and erector spinae muscle activity. Shoulder and waist pressure were reduced by 19.73%‑32.83% and 18.46%‑41.55%, respectively. In addition, the SCBANovel pack reduced lower back discomfort scores by 59.1%, all compared to the SCBATrad pack. The SCBANovel pack showed a significant reduction in musculoskeletal stress and discomfort in firefighters. Practitioner Summary SCBAs are known to be critical in protecting the health of firefighters, but are often associated with firefighter discomfort and musculoskeletal disorders. We developed the SCBANovel pack and explored the effects on the upper body musculoskeletal system and comfort during walking and running compared to carrying the SCBATrad pack. The SCBANovel pack reduced muscle activity in the trapezius and erector spinae muscles and significantly reduced pressure on the shoulders and lower back.

Firefighter Physiological Responses To Increased Self Contained Breathing Apparatus (SCBA) Weight

Firefighter Physiological Responses To Increased Self Contained Breathing Apparatus (SCBA) Weight

Multi-sensor fusion for biomechanical analysis: evaluation of dynamic interactions between self-contained breathing apparatus and firefighter using computational methods

Understanding the complex three-dimensional (3D) dynamic interactions between self-contained breathing apparatus (SCBA) and the human torso is critical to assessing potential impacts on firefighter health and informing equipment design. This study employed a multi-inertial sensor fusion technology to quantify these interactions. Six volunteer firefighters performed walking and running experiments on a treadmill while wearing the SCBA. Calculations of interaction forces and moments from the multi-inertial sensor technology were validated against a 3D motion capture system. The predicted interaction forces and moments showed good agreement with the measured data, especially for the forces (normal and lateral) and moments (x- and z-direction components) with relative root mean square errors (RMSEs) below 9.4%, 7.7%, 7.7%, and 7.8%, respectively. Peak pack force reached up to 150 N, significantly exceeding the SCBA’s intrinsic weight during SCBA carriage. The proposed multi-inertial sensor fusion technique can effectively evaluate the 3D dynamic interactions and provide a scientific basis for health monitoring and ergonomic optimization of SCBA systems for firefighters.

Microeukaryotic communities varied along the gradient in the seaweed habitats: A case study in a typical reef island in the East China Sea

Seaweeds are ecologically important primary producers, forming unique habitats. Microeukaryotes are pivotal in ecological functioning of seaweeds, but their ecological role and processes in seaweed habitats remain poorly understood due to a lack of field data. Here we presented an innovative insights into the microeukaryotic communities along the seaweed habitat gradients using 18S rDNA sequencing around a typical reef island, Gouqi Island. We set and verified habitat gradients of brown (HB, mainly Sargassum) and green algae (HG, mainly Ulva), and the control site between them (M), with detritus samples collected from collectors by SCUBA (Self-Contained Underwater Breathing Apparatus). Along the seaweed habitats, microeukaryotic biodiversity decreased from the detritus close to the seaweed habitats to surface water with increasing distance from detritus. For the dominant ecological function, clear distinction was also found in detritus and water samples along the seaweed habitat gradient, where phototrophs, mixotrophs and phagotrophs dominated in the detritus of brown algae dominated site, medium site, and green algae dominated site, respectively, responding differently to the environmental factors and seaweeds by Mantel analysis. Furthermore, we found that stochastic processes dominated in microeukaryotic community assembly in the brown seaweed habitat whereas deterministic processes dominated in green algae habitat. Highly varied occupancy was revealed in the green algae habitat by Specificity-Occupancy (SPEC-OCCU) analysis. Our result contributed to a better understanding of the ecological functioning of microeukaryotic communities in seaweed habitats, and further provided data for the bioassessment and conservation of seaweed habitats within marine ecosystems.

Evaluation of the water state and protein characteristics of Tibetan pork under the storage conditions of modified atmosphere packaging: Effect of oxygen concentration

To explore the changes in water status and protein characteristics of Tibetan pork (TP) under modified atmosphere packaging (MAP) with different oxygen concentrations compared to Duroc×Landrace×Yorkshire pork (DLY), the water holding capacity (WHC), water distribution, protein oxidation, and conformation of both types were determined. Results indicate that under MAP, TP pork and DLY pork exhibited higher water retention and lower protein oxidation compared to air packaging. However, with increased oxygen concentration in the MAP, protein oxidation intensified, leading to reduced WHC in the pork. Compared to DLY pork, TP pork in different packaging conditions maintained the integrity of protein secondary and tertiary structures, reducing protein cross-linking aggregation. The lower content of P3 in the two-dimensional relaxation spectra, shorter T1 and T2 relaxation times, and higher proton density suggest better water retention properties in Tibetan pork. These findings support the development of long-distance preservation and transportation technologies for TP pork.

IoT-FAR: A multi-sensor fusion approach for IoT-based firefighting activity recognition

Inadequate training poses a significant risk of injury among young firefighters. Although Human Activity Recognition (HAR) algorithms have shown potential in monitoring and evaluating performance, most existing studies focus on daily activities and have difficulty distinguishing complex firefighting tasks. This study introduces the Internet of things (IoT)-based wearable firefighting activity recognition (IoT-FAR) system which employs a multi-modal sensor fusion approach to achieve comprehensive activity recognition during firefighting training. The IoT-FAR comprises five wearable body sensor nodes and a coordinator node. This study explores the significance of features extracted from the surface electromyography, heart rate, and inertial measurement units in firefighting training activity recognition. A hybrid machine learning (HML)-based network is proposed, which integrates three models: one trained with all features (MA), another with upper body features (MU), and a third with lower body features (ML). The proposed HML-SVM-RBF1-RF2 network achieves superior performance, with a mean recall of 93.94%, mean precision of 90.94%, and a mean accuracy rate of 98.29%. Additionally, the study introduces the specialized firefighting training associated activities (SFTAA) dataset, which includes endurance training activities involving self-contained breathing apparatus (SCBA) conducted by eighteen firefighters. This dataset represents preliminary work towards building a comprehensive dataset covering various events and scenarios for tracking firefighter activities. The IoT-FAR system also demonstrates the potential use of misclassified activities as evaluation metrics for assessing firefighter training performance.

Evaluation of Air Consumption Efficiency in Structural Firefighters.

This study examines variability in air consumption (AC) between firefighters (FF) working at a standardized pace, evaluates the relationship between air consumption efficiency (ACE) and work economy, identifies parameters associated with ACE, and explores the relationship between ACE and self-paced work rate. FF completed randomized trials of an air consumption drill at a standardized pace while breathing through a self-contained breathing apparatus and a gas analyzer. A subsample completed another trial at a self-selected pace. The average AC variability (±1 standard deviation) was ~3.1 min of cylinder usage (13.7%). AC was positively associated with work economy and numerous physiological and anthropometric outcomes. No relationship was found between ACE and self-paced air consumption drill time. FF working at higher internal strain demonstrated poorer ACE. Improving metabolic tolerance may extend the self-contained breathing apparatus' functional duration to enhance productivity and safety.

Assessing the Mental Model State of Emergency Responders in the Context of Radiological Dispersal Device (RDD) Incidents: A Multi-state Study.

Hazardous Materials (HAZMAT) Technicians' notions of mental model, or cognitive representations of their understanding and beliefs regarding Radiological Dispersal Devices (RDDs) incidents, have not been previously explored. A prior study developed an Expected Mental Model State (EMMS) framework specific to RDD incident response for HAZMAT technicians. The work herein presents the development of a derivative of this framework, the EMMS Diagnostic Matrix, to evaluate the actual Mental Model State (MMS) of HAZMAT technicians in the context of RDD incidents. The EMMS Diagnostic Matrix was administered via a survey and simulation activity in four U.S. states representing the Northeast, West, South, and Midwest regions. Data were collected and coded using grounded theory methodology. Reflexive thematic analysis was employed to identify themes across related areas where the notions of mental model for the HAZMAT technician responders' actual MMS differed from the EMMS. The analysis of the collected data revealed four significant themes representing incomplete notions of the mental model spanning various EMMS conceptual domains: Overestimation of Radiation Dose and Health Effects, indicating misunderstandings about the health impacts of radiation exposure, Acute Radiation Syndrome (ARS), particularly in the lower range of radiation doses; Overreliance on Responder Protection [personal protective equipment (PPE)/self-contained breathing apparatus (SCBA)], highlighting gaps in understanding radiation principles and radioactive material dispersal properties from a radiological dispersal device; Misunderstanding Radiation Detection and Units, signifying confusion about radiation units and differentiation between dose rate and accumulated dose; and Incomplete Understanding of Radiation Characteristics and Dispersal Properties, outlining a limited grasp of inhalation risks from radiation and the dispersal traits of a radiological dispersal device. The interconnectedness of these technical misunderstandings can guide the development of a strategic plan to evaluate and modify existing training, aiming at these specific themes to improve the efficiency of HAZMAT technicians in emergency situations and to identify areas for further research.

Impact of Packaging Methods Coupled with High Barrier Packaging Loaded with TiO2 on the Preservation of Chilled Pork.

This study investigated the impact of packaging methods coupled with high barrier packaging loaded with titanium dioxide (TiO2) on the quality of chilled pork. The experiment consisted of three treatment groups: air packaging (AP), vacuum packaging (VP), and vacuum antibacterial packaging (VAP). Changes in total viable count (TVC), pH value, total volatile basic nitrogen (TVB-N) value, sensory attributes, and water holding capacity of pork were analyzed at 0, 3, 6, 9, and 12 d. TVC of the VAP group was 5.85 Log CFU/g at 12 d, which was lower than that of AP (6.95 Log CFU/g) and VP (5.93 Log CFU/g). The antibacterial film incorporating TiO2 effectively inhibited microorganism growth. The VAP group exhibited the lowest pH value and TVB-N value among all the treatment groups at this time. The findings demonstrated that the application of VAP effectively preserved the sensory attributes of pork, the hardness, cohesiveness and adhesiveness of pork in VAP group were significantly superior than those in AP group (p<0.05), but not significantly compared with VP group. On the 12 d, the CIE a* value of pork in VAP group was significantly higher (p<0.05). This exhibited that VAP could effectively maintain the freshness of chilled pork and extend the shelf life for 3 d compared to the AP group. These findings provide empirical evidence to support the practical implementation of TiO2-loaded packaging film in the food industry.

Evaluation of self-contained breathing apparatus (SCBA) weight on firefighter stamina, comfort, and postural stability

Firefighters wear personal protective equipment to protect them from the thermal and chemical environment in which they operate. The self-contained breathing apparatus (SCBA) provides isolation of the airway from the hazardous fireground. National standards limit SCBA weight, however, integration of additional features could result in an SCBA exceeding the current limit. The purpose of this study was to examine the effects of increased SCBA weight on firefighters’ physiological responses, work output, dynamic stability, and comfort. Completion of simulated firefighting activities induced a strong physiological response. Peak oxygen consumption was higher with the lightest SCBA than the heaviest SCBA. Few other physiological differences were noted as SCBA weight increased. Importantly, increased SCBA weight resulted in significantly more negative perceptions by the firefighters and a trend towards significance for the duration of work time prior to reaching volitional fatigue. These results should be considered when assessing changes to existing SCBA weight limits.

Analysis of quality-related proteins in golden pompano (Trachinotus ovatus) fillets with modified atmosphere packaging under superchilling storage

Here, we aimed to study the changes in proteome of golden pompano fillets during post-mortem storage. Tandem mass tags (TMT)-labeled quantitative proteomic strategy was applied to investigate the relationships between protein changes and quality characteristics of modified atmosphere packaging (MAP) fillets during superchilling (-3 ℃) storage. Scanning electron microscopy was used to show that the muscle histology microstructure of fillets was damaged to varying degrees, and low-field nuclear magnetic resonance was used to find that the immobile water and free water in the muscle of fillets changed significantly. Total sulfhydryl content, TCA-soluble peptides and Ca2+-ATPase activity also showed that the fillet protein had a deterioration by oxidation and denaturation. The Fresh (FS), MAP, and air packaging (AP) groups were set. Total of 150 proteins were identified as differential abundant proteins (DAPs) in MAP/FS, while 209 DAPs were in AP/FS group. The KEGG pathway analysis indicated that most DAPs were involved in binding proteins and protein turnover. Correlation analysis found that 52 DAPs were correlated with quality traits. Among them, 8 highly correlated DAPs are expected to be used as potential quality markers for protein oxidation and water-holding capacity. These results provide a further understanding of the muscle deterioration mechanism of packaging golden pompano fillets during superchilling.

Microparticles in Human Perspiration as an Inflammatory Response Index.

A blood component analysis is an early step for evaluating inflammatory disorders, but it can be unfeasible in some settings. This pilot study assessed whether extracellular vesicle (EV) changes in perspiration are parallel to those occurring in blood as an alternative or complementary option to diagnose an inflammatory response. In parallel studies, EVs were analyzed in perspiration and blood obtained before and after five self-contained underwater breathing apparatus (SCUBA) divers at the National Aquarium in Baltimore performed a dive to 3.98 m of sea water for 40 min, and five non-divers performed an exercise routine at ambient atmospheric pressure. The results demonstrated that microparticles (MPs) are present in perspiration, their numbers increase in the blood in response to SCUBA diving, and the interleukin (IL)-1β content increases. In contrast, while blood-borne MPs became elevated in response to terrestrial exercise, no statistically significant increases occurred in perspiration, and there were no changes in IL-1β. There were no statistically significant elevations in the exosomes in perspiration or blood in response to SCUBA diving and few changes following terrestrial exercise. These findings suggest that an MP perspiration analysis could be a non-invasive method for detecting inflammatory responses that can occur due to the oxidative stress associated with SCUBA diving.

Effects of packaging methods and temperature variations on the quality and microbial diversity of grouper (Epinephelus Lanceolatus) during cold storage

Microbial growth and its metabolism are the primary reasons for fish spoilage. In this study, the effects of temperature fluctuations and modified atmosphere packaging (MAP) on the quality and microbial diversity of grouper (Epinephelus lanceolatus) during cold storage were investigated. Fish fillets were packed in air packaging (AP), vacuum packaging (VP), MAP1 (40% CO2/55% N2/5% O2), and MAP2 (60% CO2/35% N2/5% O2), and stored at T1 (4 °C) and T2 (4–8 °C temperature fluctuations), respectively. Total viable counts (TVC), psychrophilic bacteria count, Pseudomonas count, and H2S-producing bacteria count all increased during cold storage. Pseudomonas, Serratia, and Carnobacterium were the dominant genera in AP, VP, and MAP2 at T1 storage, with relative abundances of 82.7%, 54.5%, and 57.3%, respectively. Temperature fluctuations accelerated the spoilage process of the grouper, and increased the relative abundance of Serratia in the samples, but had less effect on the composition of these spoilage bacterial members. The microbial community was more affected by the different gas atmospheres. MAP inhibited the growth of Pseudomonas and increased the relative abundance of Carnobacterium and Psychrobacter in the samples. Low temperature and MAP effectively suppressed the rise of pH, total volatile basic nitrogen (TVB-N), trimethylamine (TMA), thiobarbituric acid reactive substances (TBARs), and K values and maintained the water holding capacity (WHC) and sensory quality of the samples. Grouper had the longest shelf life under MAP2-T1 treatment. The MAP2-T1 samples maintained lower levels of TVB-N (151.8 mg/kg), TMA (7.6 mg/kg), TBARs (0.90 mg MDA/kg), and K value (48.5%) and higher levels of WHC (77.6%) on the 18th day, with a lower degree of spoilage compared to other samples.

A Sustainable Material for Sheep's Cheese Wedges Stored under Different Atmosphere Conditions.

This study is based on the need to improve packaging sustainability in the food industry. Its aim was to assess the performance of a recyclable plastic material for semi-hard sheep's cheese wedges packaging as an alternative to conventional non-sustainable plastic materials. Four different packaging treatments (air, vacuum, and CO2/N2 gas mixtures 50/50 and 80/20% (v/v)) were studied. Changes in gas headspace composition, sensory properties, cheese gross composition, weight loss, pH, colour, and texture profile were investigated at 5 ± 1 °C storage for 56 days. The sensory analysis indicated that vacuum packaging scored the worst in paste appearance and holes, and air atmosphere the worst in flavour; it was concluded that cheeses were unfit from day 14-21 onwards. Air and vacuum packaging were responsible for most of the significant changes identified in the texture profile analysis, and most of these happened in the early stages of storage. The colour parameters a* and b* differentiated the air packaging from the rest of the conditions. As in previous studies using conventional plastic materials, modified atmosphere packaging, either CO2/N2 50/50 or 80/20% (v/v), was the most effective preserving technique to ensure the quality of this type of cheese when comparing air and vacuum packaging treatments.

Thermal degradation of self-contained breathing apparatus facepiece lenses under radiant thermal loads

The self-contained breathing apparatus is one of the most critical components of the firefighting personal protective ensemble providing protection from potentially toxic gases and products of combustion. Three models of self-contained breathing apparatus facepiece lenses meeting various editions of national standards were exposed to radiant thermal loads of 5, 10, 15, and 20 kW/m2 until thermal degradation resulted in hole formation or the test duration reached 30 min. Thermal damage was documented as time to crazing, bubbling, and hole formation. Temperature was recorded within the facepiece. There were significant differences in times to thermal damage between lenses. The facepiece lens model meeting the 2013 edition of National Fire Protection Association 1981 had significantly longer times to thermal degradation than those meeting older editions of the standard. Maximum temperatures were higher in the facepiece model meeting the 2013 edition of National Fire Protection Association 1981, likely because of the extended time the radiant load was applied.

Determination of dynamic air gap thickness and analysis of its relationship with firefighters’ joint movement

ABSTRACT Objectives. The purpose of this study was to calculate the dynamic air gap thickness between the human body and the turnout gear. Relationships between the air gap thickness and joint range of motion (ROM) were also explored. Methods. The air gap thickness and joint ROM of 12 male firefighters walking in a control condition with no self-contained breathing apparatus (SCBA) and three varying-strapped SCBAs were measured using three-dimensional (3D) body scanning and 3D inertial motion capture. The interpolation technique was employed to predict the air gap thickness curve during walking. The dynamic air gap thickness was compared with the joint ROM to see how they relate to the location and percentage of movement restriction. Results. During the walking, the air gap fluctuated as a sine curve. Carrying SCBA reduced the air gap thickness at the trunk most (F = 11.17, p < 0.001, η 2 = 0.63), and adjusting the shoulder strap length altered the air gap distribution at the trunk. The reduced air gap at the pelvis caused an incremental restriction on pelvis rotation. Conclusions. A compatibility design of the shoulder strap and hip belt in SCBA with the turnout jacket is suggested.

Oxy-Inflammation in Humans during Underwater Activities.

Underwater activities are characterized by an imbalance between reactive oxygen/nitrogen species (RONS) and antioxidant mechanisms, which can be associated with an inflammatory response, depending on O2 availability. This review explores the oxidative stress mechanisms and related inflammation status (Oxy-Inflammation) in underwater activities such as breath-hold (BH) diving, Self-Contained Underwater Breathing Apparatus (SCUBA) and Closed-Circuit Rebreather (CCR) diving, and saturation diving. Divers are exposed to hypoxic and hyperoxic conditions, amplified by environmental conditions, hyperbaric pressure, cold water, different types of breathing gases, and air/non-air mixtures. The "diving response", including physiological adaptation, cardiovascular stress, increased arterial blood pressure, peripheral vasoconstriction, altered blood gas values, and risk of bubble formation during decompression, are reported.

Application of bacteriophage MS2 in preliminary simulation of inactivation rate of pathogenic viruses in commercial beef and chicken packaging

SummaryIn response to the growing concern of transmitting pathogenic viruses through food, this research aimed to assess the impact of various factors on the commercial packaging of meat (chicken and beef) on the inactivation of bacteriophage MS2 which was scrutinised by examining the influence of packaging type, bacteriophage spiking levels, temperature, as well as the meat shape and type. The findings revealed that the recovery of bacteriophage MS2 from minced beef was lower in modified atmosphere packaging (MAP) compared with air packaging (AP) at both storage times, spiking levels, and freezing and refrigerating temperatures. On the other hand, the recovery of the bacteriophage from chopped beef was lower in AP than in MAP in refrigerating conditions at both spiking levels during the 3 days of storage. According to our findings, the recovery levels of bacteriophage MS2 from chicken had statistically significant differences in both packaging types at different spiking levels. Storage conditions and packaging type were the most essential parameters in bacteriophage MS2 viability. The lowest bacteriophage viability belonged to MAP.