Burning Mechanism Research Articles

Influence of turbulent fluctuations on detonation propagation

The present study addresses the reaction zone structure and burning mechanism of unstable detonations. Experiments investigated mainly two-dimensional methane–oxygen cellular detonations in a thin channel geometry. The sufficiently high temporal resolution permitted the determination of the probability density function of the shock distribution, a power law with an exponent of$-3$, and the burning rate of unreacted pockets from their edges – through surface turbulent flames with a speed approximately 3–7 times larger than the laminar one at the local conditions. Numerical simulations were performed using a novel large-eddy simulation method where the reactions due to both autoignition and turbulent transport were treated exactly at the subgrid scale in a reaction–diffusion formulation. The model is an extension of Kerstein and Menon’s linear eddy model for large-eddy simulation to treat flows with shock waves and rapid gas-dynamic transients. The two-dimensional simulations recovered well the amplification of the laminar flame speed due to the turbulence generated mainly by the shear layers originating from the triple points and subsequent Richtmyer–Meshkov instability associated with the internal pressure waves. The simulations clarified how the level of turbulence generated controlled the burning rate of the pockets, the hydrodynamic thickness of the wave, the cellular structure and its distribution. Three-dimensional simulations were found to be in general good agreement with the two-dimensional ones, in that the subgrid-scale model captured the ensuing turbulent burning once the scales associated with the cellular dynamics, where turbulent kinetic energy is injected, are well resolved.

The effect of seasonality on burn incidence, severity and outcome in Central Malawi

IntroductionIn much of the world, burns are more common in cold months. However, few studies have described the seasonality of burns in sub-Saharan Africa. This study examines the effect of seasonality on the incidence and outcome of burns in central Malawi. MethodsA retrospective analysis was performed at Kamuzu Central Hospital and included all patients admitted from May 2011 to August 2014. Demographic data, burn mechanism, total body surface area (%TBSA), and mortality were analyzed. Seasons were categorized as Rainy (December–February), Lush (March–May), Cold (June–August) and Hot (September–November). A negative binomial regression was used to assess the effect of seasonality on burn incidence. This was performed using both the raw and deseasonalized data in order to evaluate for trends not attributable to random fluctuation. ResultsA total of 905 patients were included. Flame (38%) and Scald (59%) burns were the most common mechanism. More burns occurred during the cold season (41% vs 19–20% in the other seasons). Overall mortality was 19%. Only the cold season had a statistically significant increase in burn . The incidence rate ratios (IRR) for the hot, lush, and cold seasons were 0.94 (CI 0.6–1.32), 1.02 (CI 0.72–1.45) and 1.6 (CI 1.17–2.19), respectively, when compared to the rainy season. Burn severity and mortality did not differ between seasons. ConclusionThe results of this study demonstrate the year-round phenomenon of burns treated at our institution, and highlights the slight predominance of burns during the cold season. These data can be used to guide prevention strategies, with special attention to the implications of the increased burn incidence during the cold season. Though burn severity and mortality remain relatively unchanged between seasons, recognizing the seasonal variability in incidence of burns is critical for resource allocation in this low-income setting.

Use of a home vacuum-assisted closure device in the burn population is both cost-effective and efficacious

IntroductionThe vacuum assisted closure device (VAC) improves wound-healing when utilized as a bolster to secure split thickness skin grafts (STSG). Patients typically remain hospitalized for VAC therapy; however, home VACs (hVAC) are now available. Limited studies examine burns treated with hVAC as a STSG bolster. MethodA retrospective study of records from an ABA verified regional burn center was conducted over 23 months. Patients included STSGs for burn. Data points included demographics, burn mechanism and location, graft characteristics, hospital length of stay (LOS), and time to heal. Results and discussionFifty patients were included, with average age of 39 years (range <1–83years). Average burn TBSA was 1.27±1.42 (range 0.05–8.18). Grafted area average was 102.9±128.1cm2. The most commonly treated areas were the leg/foot, thigh, and torso (53%, 16%, and 16%, respectively). Average LOS was 1.1±1.2 days. Mean graft-take was 99.2±2.8% with one patient undergoing repeat STSG. Average post-operative time to heal was 16±6 days. A 5-day inpatient stay with a VAC costs an average of $34,635, compared to $9134 for an hVAC over the same period. ConclusionsThe hVAC is a cost-effective STSG bolster in the burn population for appropriate candidates. Excellent graft-take and low morbidity rates imply that this is an efficacious alternative for STSG bolster.

Burn mortality in patients with preexisting cardiovascular disease

IntroductionBurn shock, a complex process, which develops following burn leads to severe and unique derangement of cardiovascular function. Patients with preexisting comorbidities such as cardiovascular diseases may be more susceptible. We therefore sought to examine the impact of preexisting cardiovascular disease on burn outcomes. MethodsA retrospective analysis of patients admitted to a regional burn center from 2002 to 2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, and length of ICU/hospital stay. Bivariate analysis was performed and Poisson regression modeling was utilized to estimate the incidence of being in the ICU and mortality. ResultsThere were a total of 5332 adult patients admitted over the study period. 6% (n=428) had a preexisting cardiovascular disease. Cardiovascular disease patients had a higher mortality rate (16%) compared to those without cardiovascular disease (3%, p<0.001). The adjusted Poisson regression model to estimate incidence risk of being in intensive care unit in patients with cardiovascular disease was 33% higher compared to those without cardiovascular disease (IRR=1.33, 95% CI=1.22–1.47). The risk for mortality is 42% higher (IRR=1.42, 95% CI=1.10–1.84) for patients with pre-existing cardiovascular disease compared to those without cardiovascular disease after controlling for other covariates. ConclusionPreexisting cardiovascular disease significantly increases the risk of intensive care unit admission and mortality in burn patients. Given the increasing number of Americans with cardiovascular diseases, there will likely be a greater number of individuals at risk for worse outcomes following burn. This knowledge can help with burn prognostication.

The accuracy of burn diagnosis codes in health administrative data: A validation study

BackgroundHealth administrative databases may provide rich sources of data for the study of outcomes following burn. We aimed to determine the accuracy of International Classification of Diseases diagnoses codes for burn in a population-based administrative database. MethodsData from a regional burn center’s clinical registry of patients admitted between 2006–2013 were linked to administrative databases. Burn total body surface area (TBSA), depth, mechanism, and inhalation injury were compared between the registry and administrative records. The sensitivity, specificity, and positive and negative predictive values were determined, and coding agreement was assessed with the kappa statistic. Results1215 burn center patients were linked to administrative records. TBSA codes were highly sensitive and specific for ≥10 and ≥20% TBSA (89/93% sensitive and 95/97% specific), with excellent agreement (κ, 0.85/κ, 0.88). Codes were weakly sensitive (68%) in identifying ≥10% TBSA full-thickness burn, though highly specific (86%) with moderate agreement (κ, 0.46). Codes for inhalation injury had limited sensitivity (43%) but high specificity (99%) with moderate agreement (κ, 0.54). Burn mechanism had excellent coding agreement (κ, 0.84). ConclusionsAdministrative data diagnosis codes accurately identify burn by burn size and mechanism, while identification of inhalation injury or full-thickness burns is less sensitive but highly specific.

Improved Survival of Patients With Extensive Burns: Trends in Patient Characteristics and Mortality Among Burn Patients in a Tertiary Care Burn Facility, 2004-2013.

Classic determinants of burn mortality are age, burn size, and the presence of inhalation injury. Our objective was to describe temporal trends in patient and burn characteristics, inpatient mortality, and the relationship between these characteristics and inpatient mortality over time. All patients aged 18 years or older and admitted with burn injury, including inhalation injury only, between 2004 and 2013 were included. Adjusted Cox proportional hazards regression models were used to estimate the relationship between admit year and inpatient mortality. A total of 5540 patients were admitted between 2004 and 2013. Significant differences in sex, race/ethnicity, burn mechanisms, TBSA, inhalation injury, and inpatient mortality were observed across calendar years. Patients admitted between 2011 and 2013 were more likely to be women, non-Hispanic Caucasian, with smaller burn size, and less likely to have an inhalation injury, in comparison with patients admitted from 2004 to 2010. After controlling for patient demographics, burn mechanisms, and differential lengths of stay, no calendar year trends in inpatient mortality were detected. However, a significant decrease in inpatient mortality was observed among patients with extensive burns (≥75% TBSA) in more recent calendar years. This large, tertiary care referral burn center has maintained low inpatient mortality rates among burn patients over the past 10 years. While observed decreases in mortality during this time are largely due to changes in patient and burn characteristics, survival among patients with extensive burns has improved.

A National Study of the Effect of Race, Socioeconomic Status, and Gender on Burn Outcomes.

Age, burn size, and inhalation injury are the major contributing variables related to burn mortality. While the female gender has been linked to higher mortality, the impact of socioeconomic status has not been well studied. The interplay between these three factors is also unknown. This study sought to clarify the effects of these variables on outcomes in a national sample of patients with burns. A retrospective review of 172,640 patient records of the National Burn Repository (version 8, 2002-2011) data was conducted. Of those records, 36,960 (21.4%) patient entries were excluded for duplicate entries, follow-up visits, readmissions, nonburn injuries, skin diseases, and incompleteness (missing date of admission, date of discharge, race, or TBSA of burn or TBSA). Univariate and multivariate analyses were performed to compare outcomes by race (Caucasian, African-American, and other minority groups). P < .05 was considered significant. The study group included 135,680 patients and was predominately Caucasian (59.0% Caucasian, 19.0% African-American, and 22.0% other minority groups). The African-American race had more females, operations, longer length of stay, ventilator days, septicemia (all P < .001), and urinary tract infections (UTIs, P < .01). Caucasians had the largest burns (9.27 ± 13.22, P <.001) and were more likely to be older, to be intubated, and to have longer intensive care unit stays and higher mortality (all P < .001). Other non-African-American minorities (other minority group) had the second largest burn sizes, most uninsured members, and lowest mortality (P < .001). On multivariate analysis, mortality was related to African-American race, female gender, TBSA, full-thickness burn injury, inhalation injury, uninsured status, and burn mechanism. African-Americans were 50% more likely to have complications (P < .001), 30% more likely to have UTIs (P = .002), and 41% more likely to get septicemia (P < .001). Other racial minority groups had more acute respiratory distress syndrome, pneumonias, septicemia, UTIs, length of stay, and hospital charges when compared with Caucasian patients. Socioeconomic status was related to mortality but inconsistently related to other outcomes. Race appears to play a significant role in burn injury outcomes. Minority groups, especially African-Americans, have a higher risk of morbidity and mortality compared with Caucasian patients with burns. Socioeconomic status and gender also play a significant role in burn outcomes. Future studies should focus on delineating the reasons for this disparity.

The effect of preexisting respiratory co-morbidities on burn outcomes

IntroductionBurns cause physiologic changes in multiple organ systems in the body. Burn mortality is usually attributable to pulmonary complications, which can occur in up to 41% of patients admitted to the hospital after burn. Patients with preexisting comorbidities such as chronic lung diseases may be more susceptible. We therefore sought to examine the impact of preexisting respiratory disease on burn outcomes. MethodsA retrospective analysis of patients admitted to a regional burn center from 2002–2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, smoker status, length of hospital stay, and days of mechanical ventilation. Bivariate analysis was performed and Cox regression modeling using significant variables was utilized to estimate hazard of progression to mechanical ventilation and mortality. ResultsThere were a total of 7640 patients over the study period. Overall survival rate was 96%. 8% (n=672) had a preexisting respiratory disease. Chronic lung disease patients had a higher mortality rate (7%) compared to those without lung disease (4%, p<0.01). The adjusted Cox regression model to estimate the hazard of progression to mechanical ventilation in patients with respiratory disease was 21% higher compared to those without respiratory disease (HR=1.21, 95% CI=1.01–1.44). The hazard of progression to mortality is 56% higher (HR=1.56, 95% CI=1.10–2.19) for patients with pre-existing respiratory disease compared to those without respiratory disease after controlling for patient demographics and injury characteristics. ConclusionPreexisting chronic respiratory disease significantly increases the hazard of progression to mechanical ventilation and mortality in patients following burn. Given the increasing number of Americans with chronic respiratory diseases, there will likely be a greater number of individuals at risk for worse outcomes following burn.

The effect of smoking status on burn inhalation injury mortality

IntroductionThree factors that effect burn mortality are age, total body surface of burn (TBSA), and inhalation injury. Of the three, inhalation injury is the strongest predictor of mortality thus its inclusion in the revised Baux score (age+TBSA+17* (inhalation injury, 1=yes, 0=no)). However, the weighted contribution of specific comorbidities such as smoker status on mortality has traditionally not been accounted for nor studied in this subset of burn patients. We therefore sought to examine the impact of current tobacco and/or marijuana smoking in patients with inhalation injury. MethodsA retrospective analysis of patients admitted to a regional burn center from 2002 to 2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA, pre-existing comorbidities, and smoker status. Bivariate analysis was performed and logistic regression modeling using significant variables was utilized to estimate odds of mortality. ResultsThere were a total of 7640 patients over the study period. 7% (n=580) of the burn cohort with inhalation injury were included in this study. In-hospital burn mortality for inhalation injury patients was 23%. Current smokers (20%) included cigarette smokers and marijuana users, 19% and 3%, respectively. Preexisting respiratory disease (17%) was present in 36% of smokers compared to 13% of non-smokers (p<0.001). Smokers had significantly lower mortality rate (9%) compared to non-smokers (26%, p<0.01). The logistic regression model for mortality outcomes identified statistically four significant variables: age, TBSA, ethnicity, and smoker status (OR=0.41, 95% CI=0.18–0.93). Presence of comorbidities, including preexisting respiratory disease, was not significant. ConclusionIn the sub group of burn patients with inhalation injury, the odds of mortality significantly decreased in pre-existing smokers after adjusting for significant covariates. We postulate that an immune tolerance mechanism that modulates and diminishes the pro-inflammatory response confers a survival advantage in smokers after exposure to acute smoke inhalation injury. Future prospective studies in human and/or animal models are needed to confirm these findings.

The structure of swirl-stabilized turbulent premixed CH4/air and CH4/O2/CO2 flames and mechanisms of intense burning of oxy-flames

The objective of this work is to examine the structure of lean turbulent premixed CH4/air (air-flames) and CH4/O2/CO2 (oxy-flames) in a swirl-stabilized combustor at the large (macro) and small (micro) scales, and to explain why the latter burns more intensely despite its lower laminar burning velocity. Measurements of the instantaneous flame front and flow field using OH-PLIF and PIV, respectively, are analyzed. The CO2 dilution in the oxy-flame was adjusted to achieve the same adiabatic temperature for both flames while keeping the equivalence ratio (=0.65) and Reynolds number (=20,000) the same. Results show that at the large scale, the overall length of the oxy-flame is notably shorter than that of the air-flame. We use a strained flame model with detailed kinetics to show that the strained consumption speed of oxy-flames is lower than that of air-flames, mainly due to the chemical role of CO2, and hence laminar flame properties cannot explain the difference between the two flames in the turbulent case. Instead, the turbulent dynamics properties such as the small scale wrinkling of the flame, its surface area density and radius of curvature are obtained from the data and used to explain the observed trends. Measurements show that the flame surface area density of oxy-flames is higher because more flame segments with smaller radius of curvature appear. This is particularly noticeable downstream, and is consistent with the Lewis number effects, i.e., the response for the flame to thermo-diffusive instability. The local average burning intensity, being high under oxy-combustion conditions, explain the shorter overall average flame length.

Flammability of self-extinguishing kenaf/ABS nanoclays composite for aircraft secondary structure

This study investigates the flammability properties of kenaf fiber reinforced acrylonitrile butadiene styrene (ABS) with nanoclays composites. Natural fiber is one of the potential materials to be used with thermoplastic as a composite due to its attractive properties such as lightweight and strong. In this paper, flammability properties of this material are evaluated through Underwriters Laboratory 94 Horizontal Burning (UL94 HB), which has been conducted for both controlled and uncontrolled conditions, smoke density and limiting oxygen index tests (LOI). These flammability tests are in compliance with the Federal Aviation Regulation (FAR) requirement. The results from UL94 HB and smoke density tests show that the presence of nanoclays with effective composition of kenaf fiber reinforced ABS has enhanced the burning characteristics of the material by hindering propagation of flame spread over the surface of the material through char formation. Consequently, this decreases the burning rate and produces low amount of smoke during burning. On contrary, through LOI test, this material requires less oxygen to burn when exposed to fire, which hinders the enhancement of burning characteristics. This is due to burning mechanism exhibited by nanoclays that catalyzes barrier formation and flame propagation rate over the surface of the biocomposite material. Overall, these experimental results suggest that this biocomposite material is capable of self-extinguishing and possesses effective fire extinction. The observed novel synergism from the result obtained is promising to be implemented in secondary structures of aircraft with significant benefits such as cost-effective, lightweight and biodegradable self-extinguishing biocomposite.

The measured effect magnitude of co-morbidities on burn injury mortality

IntroductionThe ability to better prognosticate burn injury outcome is challenging and historically, most center use the Baux or revised Baux score to help prognosticate burn outcome, however, the weighted contribution of comorbidity on burn mortality has traditionally not been accounted for nor adequately studied. We therefore sought to determine the effect of comorbidities, using the Charlson comorbidity index (CCI) on burn mortality. MethodsThe purpose of this study was to determine the effect of comorbidities on burn injury mortality as determined by the LA50 (lethal TBSA burn at which 50% of the cohort will succumb from the burn injury) in a retrospective analysis of patients admitted to a regional burn center from 2002 to 2012. Independent variables analyzed included basic demographics, burn mechanism, presence of inhalation injury, TBSA (total body surface area), length of hospital stay, and pre-existing comorbidities. Bivariate analysis was performed and logistic regression modeling using significant variables was utilized to estimate odds of death. Results7640 patients were included in this study. Overall survival rate was 96%. 40% of our burn cohort had at least one comorbidity. There was a linear increase in the likelihood of death with an increase in CCI. The logistic regression model for mortality outcomes identified four statistically significant variables: age, TBSA, inhalational injury and the presence of comorbidities (OR=1.59 for each 1 point increase in CCI; 95% CI 1.44–1.77). The unadjusted LA50 was 53% for the entire cohort. Partial adjustment multivariate regression controlling for burn mechanism and inhalation injury only, produced a slight reduction in LA50 for the 0–18 and 19–64 age categories to 76% and 48% TBSA, respectively, but a significant decrease occurred in the ≥65 years age group with a reduced LA50 to 20% TBSA (p<0.001). After full adjustment for all significant covariates, including comorbidities, the independent magnitude of effect of comorbidities on the LA50 was evident in the <65 cohort. The full adjustment showed a LA50 decreased to 61% and 43% TBSA, respectively in the 0–18 and >18–65 age groups respectively (p<0.001), however, in the >65 years age cohort there was no change in the LA50. ConclusionPreexisting comorbidities have a significant effect on burn injury mortality in all age groups, particularly the younger burn population. The measured effect of comorbidities in the >65 yr age cohort was mitigated by the co-linearity between age and comorbidities. The inclusion of CCI is imperative so as to better prognosticate burn outcome and help guide expectations and resource utilization, particularly in the younger burn cohort.

High-resolution transient and permanent spectral hole burning inCe3+:Y2SiO5at liquid helium temperatures

We perform hole burning with a low drift stabilized laser within the zero phonon line of the 4f-5d transition in Ce$^{3+}$:Y$_2$SiO$_5$ at 2K. The narrowest spectral holes appear for small applied magnetic fields and are $6\pm4$ MHz wide (FWHM). This puts an upper bound on the homogeneous linewidth of the transition to $3\pm2$ MHz, which is close to lifetime limited. The spin level relaxation time is measured to $72\pm21$ ms with a magnetic field of 10 mT. A slow permanent hole burning mechanism is observed. If the excitation frequency is not changed the fluorescence intensity is reduced by more than 50$\%$ after a couple of minutes of continuous excitation. The spectral hole created by the permanent hole burning has a width in the tens of MHz range, which indicates that a trapping mechanism occurs via the 5d-state.

ENERGY-SAVING FEATURES OF RAW MATERIAL THERMAL PREPARATION IN TERMS OF PROCESSING OPTIMIZATION

The authors study thermal processes of dense-phase particulates baking and sintering. The article considers an up-to-date research and training problem of these thermally-activated processes optimization on conveyor-based calciners. The study includes the problem of programmable dense-phase warming, considering kiln`s technical restrictions and technology abilities of burning mechanism. The authors establish a task of burning mechanism optimal control, which can be solved by converting into multicriteria optimization. Control parameters: heat-transfer agent`s temperature at dense bed entry and its sweeping velocity. Control criterion: a reacting degree minimum and sintering of raw material. The limitations are set on: heat rate, temperature gradient and others, concerning with technical features of an aggregate. The study reveals a condition, forming a fading because of endothermic physicochemical transformations` heat absorption heat wave, which penetrates into the layer and intensifies decarbonization and sintering prosseses, providing the floor price on power imputs. Considering the obtained results, the authors present the operation conditions of conveyor-based kiln, providing resources and energy saving in particulates thermal preparation technology. The article deals with an applicability as alternative energy source, oxyhydrogen accumulator – a source of power protection.

The impact of socio-economic deprivation on burn injury: A nine-year retrospective study of 6441 patients

IntroductionLow socio-economic status is thought to be associated with increased burn risk, however the significance and generalisability across different populations and cultures has been questioned. MethodsA nine-year retrospective study of burn presentations to a large teaching hospital (2005–2014) was performed to investigate the association between socio-economic status and burns. Demographic and injury data was collected via the trust ‘Information portal’. The Welsh Index of Multiple: Deprivation 2011 was used to score for socio-economic status. Chi-squared test and Odds Ratios were calculated and statistical significance defined as p<0.05 throughout. Results6441 burns were identified, with 755 (11.7%) admitted. Overall incidence rates were the highest published in the UK (0.35/1000/year) with sub group analysis showing the highest rates in under fives and males. Significant relationships between both age and burn mechanism and gender and burn mechanism (p=0.0005) were identified. Scald (67.1%) was the most common mechanism with the upper limb (48%) most commonly burned. Chi square analysis demonstrated a significant relationship between socio-economic deprivation, age and burn incidence (p≤0.0005), with a disproportionately high number of burns in patients under the age of 16 in the most deprived quintile (OR 1.23; 95% CI 1.06–1.44). ConclusionThis study specifically highlights patients under the age of 16 living in poorer socio-economic areas as the most at risk of suffering burns receiving hospital attention. This study demonstrates burns as a significant public health issue, and the results should aid in designing specific burn prevention strategies to target high-risk groups.

Investigation of the Burning Mechanism in an Enclosure Fire with a Horizontal Ceiling Vent

This article adopted the method of numerical simulation to study heat release rate change rule and oxygen concentration variation when different opening size was changed within a small space, where there was a constant source of power in the space and an opening at the top level in the corner. Meanwhile, the constitutive factor affecting the burning mechanism of fire was further explored. As simulation results showed, (1) with the increase of opening size and larger amplitude of heat release rate vibration, In the later periods of the experiment, the frequency of heat release rate vibration is basically consistent with the frequency oxygen concentration changing at the nearby fire source. (2) With the increase of opening size, the amplitude of oxygen concentration changing under the bottom of opening is smaller, replenishment of outside cold air at larger opening is more stable, and oxygen quality replenished in the experimental box is increased. Meantime, oxygen quality replenished in the experimental box and participating in oxygen quality is increased obviously with the opening increase, opening size impacts the fire source combustion in the later period of the experiment directly. The oxygen concentration would decrease after a certain period of time in the fire development, unstable combustion “Ghosting flame” and “Oscillating fire” would happen due to the lack of oxygen when oxygen concentration near the combustion source is lower than 0.14.

Construction of an immunorelated protein–protein interaction network for clarifying the mechanism of burn

Background and aimSevere burn is known to induce a series of pathological responses resulting in increased susceptibility to systemic inflammatory response and multiple organ failure, but the underlying molecular mechanism remains unclear at present. The main aim of this study was to expand our understanding of the events leading to circulating leukocyte response after burn by subjecting the gene expression profiles to a bioinformatic analysis. Materials and methodsComprehensive gene expression analysis was performed to identify differentially expressed genes (DEGs) using the expression profile GSE7404 (Mus musculus, circulating leukocyte, 25% of total body surface area (TBSA), full thickness) downloaded from the Gene Expression Omnibus, followed by the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses. In addition, a postburn protein–protein interaction (PPI) network was constructed to identify potential biomarkers. ResultsMaximum changes in the gene expression profile were detected 1 day post burn. Separate Gene Ontology (GO) functional enrichment analysis for upregulated and downregulated DEGs revealed significant alterations of genes related to biological process such as “response to stimuli,” “metabolic,” “cellular and immune system processes,” “biological regulation,” and “death” in the leukocyte transcriptome after the burn. The KEGG pathway enrichment analysis showed that the upregulated DEGs were significantly enriched in the nodes of immunorelated and signal transduction-related pathways, and the downregulated genes were significantly enriched for the immunorelated pathways. The PPI network and module analysis revealed that, 1 day after the burn, lymphocyte-specific protein tyrosine kinase (Lck) (downregulated), Jun (upregulated), Cd19 (downregulated), Stat1 (downregulated), and Cdk1 (upregulated) were located centrally in both the PPI network and modules. ConclusionsBased on an integrated bioinformatic analysis, we concluded that Lck, Jun, Cd19, Stat1, and Cdk1 may be critical 1 day after the burn. These findings expand our understanding of the molecular mechanisms of this important pathological process. Further studies are needed to support our work, focused on identifying candidate biomarkers with sufficient predictive power to act as prognostic and therapeutic biomarkers for burn injury.

Importance of the slick thickness for effective in-situ burning of crude oil

In order to improve the potential of in-situ burning (ISB), the importance of the oil slick thickness on two pure oils (n-octane and dodecane) and two fresh crude oils (Grane and REBCO) was studied in relation to the regression rate, boilover tendency, mass loss rate, burning efficiency and flame height. The experiments were performed in a new experimental apparatus, the Crude Oil Flammability Apparatus (COFA), which has been developed to study ISB of oil on water in a controlled laboratory environment with large water-to-oil ratios. The regression rate, average mass loss rate and burning efficiency reached a constant maximum value for all oils at slick thicknesses exceeding 10–20mm. For thinner initial slick thicknesses, these values were greatly reduced, most likely due to heat losses to the water. A further increase in the initial slick thickness could not improve the burning efficiency above 75% for the crude oils, showing that it only has a limited effect on the burning efficiency as higher burning efficiencies have been reported for larger scales. Furthermore, the results showed that the burning mechanisms differ for pure and crude oil, indicating that the hydrocarbon mixture in crude oils changes as the burning progresses. This observation merits further research.

Models of neutron star atmospheres enriched with nuclear burning ashes

Low-mass X-ray binaries hosting neutron stars (NS) exhibit thermonuclear (type-I) X-ray bursts, which are powered by unstable nuclear burning of helium and/or hydrogen into heavier elements deep in the NS "ocean". In some cases the burning ashes may rise from the burning depths up to the NS photosphere by convection, leading to the appearance of the metal absorption edges in the spectra, which then force the emergent X-ray burst spectra to shift toward lower energies. These effects may have a substantial impact on the color correction factor $f_c$ and the dilution factor $w$, the parameters of the diluted blackbody model $F_E \approx w B_E(f_c T_{eff})$ that is commonly used to describe the emergent spectra from NSs. The aim of this paper is to quantify how much the metal enrichment can change these factors. We have developed a new NS atmosphere modeling code, which has a few important improvements compared to our previous code required by inclusion of the metals. The opacities and the internal partition functions (used in the ionization fraction calculations) are now taken into account for all atomic species. In addition, the code is now parallelized to counter the increased computational load. We compute a detailed grid of atmosphere models with different exotic chemical compositions that mimic the presence of the burning ashes. From the emerging model spectra we compute the color correction factors $f_c$ and the dilution factors $w$ that can then be compared to the observations. We find that the metals may change $f_c$ by up to about 40%, which is enough to explain the scatter seen in the blackbody radius measurements. The presented models open up the possibility for determining NS mass and radii more accurately, and may also act as a tool to probe the nuclear burning mechanisms of X-ray bursts.

EXPERIMENTAL AND DESIGN CONSIDERATIONS FOR SOLID PROPELLANT GAS GENERATOR

The main vital purpose of gas generator (GG) solid propellant (SP) is, the burning of SP to produce the required gas amount with low temperature and without solid precipitate. Numerous variety of propellants and configurations have been used to create hot gas. A comprehensive study of several important aspects of SPGG design has been investigated in the present work. End burning mechanism, GG solid propellant types, various burning surface configurations, simplified design procedure, insulation evaluation, analysis of experimental works, numerical models have been developed to describe pressure variation with time and performance parameters. Effect of design parameters were also discussed. Good agreement is obtained between experimental firing data and the established models for SPGG parameters performance. Finally; the several design parameters of the SPGG are analyzed and investigated, each design parameter is treated separately while the other parameters are assumed constant.