Yellow Tip Research Articles

A new genus and species of nudibranch-mimicking Syllidae (Annelida, Polychaeta)

Nudibranch mollusks, which are well-known for their vivid warning coloration and effective defenses, are mimicked by diverse invertebrates to deter predation through both Müllerian and Batesian strategies. Despite extensive documentation across different taxa, mimickers have not been detected among annelids, including polychaetes, until now. This study described a new genus and species of polychaete living on Dendronephthya octocorals in Vietnam and Japan. Belonging to Syllidae, it exhibits unique morphological adaptations such as a low number of body segments, simple chaetae concealed within the parapodia and large and fusiform antennae and cirri. Moreover, these appendages are vividly colored, featuring an internal dark red area with numerous terminal white spots and bright yellow tips, effectively contributing to mimicking the appearance of a nudibranch. This discovery not only documents the first known instance of such mimicry among annelids, but also expands our understanding of evolutionary adaptation and ecological strategies in marine invertebrates.

Mixing and Combustion of Methane-Oxygen Flame in a Coaxial Dual-Shear Jet Nozzle

In this study, a coaxial dual-shear jet nozzle is designed to enhance mixing and establish stable methane–oxygen combustion. The characteristics of mixing and combustion of methane–oxygen flames are experimentally investigated in nonreacting and reacting cases by varying the outer-to-middle velocity ratio ru from 1.1 to 5.7. In the nonreacting cases, acetone–planar-laser-induced fluorescence technology is applied to experimentally study the mixing behavior near the nozzle exit. Since the coaxial dual-shear configuration generates a sandwich structure, a flow structure near the exit, including three potential cores and three mixing layers, is established. Two mixture fraction fields divided by a critical velocity ratio ruc are observed, in which the stoichiometric contours have different appearances. Based on the mixing characteristics, a mixing model and a linear scaling relation were presented to predict the stoichiometric mixing length in both nonreacting and reacting flows. Besides, the coaxial dual-shear jets yield more compact flames in cases of ru<2.9, while the conventional coaxial jets produce longer flames with yellow tips. This shows the improvement of the coaxial dual-shear nozzle in mixing and combustion efficiency due to the formation of two shear layers near the nozzle exit. Furthermore, the OH* distribution indicates that the coaxial dual-shear flames produce a lower thermal load on the nozzle, preventing the combustor from experiencing the hazards of ablation.

Effect of different irrigation activation systems using continuous chelating irrigation protocol on the removal of smear layer in the apical third of root canals: An in vitro scanning electron microscope study

Aim: Continuous chelation is a novel irrigation regimen popular as a single solution for irrigation of the root canal system during root canal therapy, especially for the removal of the smear layer. This study aimed to compare the effectiveness of three different irrigation activation systems in removing the smear layer from the apical third in single-rooted mandibular premolars using a scanning electron microscope (SEM). Methods: Fifty-six extracted single-rooted mandibular premolars were decoronated, and canals prepared till #30/0.09, with Chloroquick (3% NaOCl + 9% HEBP) as the working solution. Teeth were randomly divided into four groups based on the final irrigant activation protocol; Group A - (control group) conventional syringe irrigation with a 30-gauge single-side vented needle. Group B - (passive ultrasonic irrigation method) passive ultrasonic irrigation (PUI) with #20-Irrisafe ultrasonic files activated for 1 min. Group C - (sonic activation) EndoActivator system using the yellow tip (#20/0.04) activated for 1 min. Group D - Tornado Disinfection Kit using GF-brush for 20–30 s as per manufacturer’s instructions. The canals were dried, samples were hemi-sectioned, and the amount of remaining smear layer was scored according to the Tabrizizadeh criteria (2015) with SEM images at ×2500 by two blinded operators. The collected data were analyzed statistically using the Chi-square test (P &lt; 0.05). Results: The results showed statistically significant differences in terms of smear removal among the groups (P &lt; 0.05) with the Gentlefile group performing better, followed by PUI, EndoActivator, and the conventional group. Conclusion: Within the limitations of the study, continuous chelation with Gentlefile activation could be a viable and efficient protocol for the removal of the smear layer from the apical third of root canals.

Micropipette tip intubation in rats as a replacement for conventional endotracheal tube intubation.

Endotracheal intubation is often necessary in the course of animal experiments, especially in craniofacial surgery. However, endotracheal intubation can be a major burden in this context. The authors performed simple and cost-saving method using a 200 μL yellow micropipette tip, and the success of this method was demonstrated by X-ray and autopsy. We used a total of 30 rats. After the rats were fixed with a plaster, the trachea and vocal cords were visualized with the tongue pulled back. Under direct visualization of the vocal cords, a curving micropipette tip was advanced into the trachea. This method can be learned quickly and applied successfully by general experimenters. We successfully intubated all 30 rats without any complications. The success rate of micropipette tip intubation was 100%. This procedure was performed by one experimenter within 2 to 3 minutes after induction of anesthesia. We demonstrated its superiority by X-ray and autopsy. Herein, we describe endotracheal intubation of rats using micropipette tips. To the best of our knowledge, this method is novel and represents the simplest and most efficient means of intubation in rats, providing an alternative to conventional endotracheal intubation.

A new species of Luisia (Orchidaceae) from Shan State, Myanmar

A new species, Luisia verrucosaKurzweil, Nob.Tanaka &amp; Ormerod, from Shan State in Myanmar is described and illustrated. It is very distinct in the genus, characterised by (1) light pinkish and purple-marked navicular sepals which are coarsely verrucose on the outside, especially in their distal part, (2) light pinkish and irregularly pink-dotted lorate-elliptic petals with yellow tips, and (3) a lip with a comparatively large, oblong-elliptic, maroon-purple epichile with prominent callosities in the form of massive bulges. Because its lip does not have a constriction or prominent boundary line between hypochile and epichile, it is superficially similar to Luisia brachystachys (Lindl.) Blume, but the new species differs by having considerably larger flowers with verrucose sepals and pronounced lip ornaments.

Use of magnesium in bareroot pine nurseries

Pines with visible magnesium (Mg) deficiencies (i.e. yellow tips on needles) occur in bareroot nurseries throughout the world. The occurrence of “yellow-tips” is rare when soil pH is above 6.5 but they have occurred on sands (pH &lt; 6.0) with less than 25 μg g-1 Mg. If yellow-tips occur in the summer, the foliar content of yellow tips is usually less than 1,000 μg g-1 Mg. Some nurseries do not produce “yellow-tip” seedlings when irrigation water contains sufficient Mg. Factors favoring a deficiency include low soil pH, high calcium in irrigation water, frequent fertilization with nitrogen and potassium and applying too much gypsum. Although various Mg fertilizers are available, many nursery managers apply dolomite or potassium-magnesium sulfate before sowing seeds and a few also apply magnesium sulfate in July or August. Soil tests are used to determine when to fertilize before sowing and foliage tests determine when to apply Mg to green seedlings. Nursery managers who follow S.A. Wilde’s forest-based soil recommendations may apply magnesium sulfate to green seedlings even when seedbeds contain adequate levels of Mg. When deficiency is minor, chlorosis on needle tips usually disappears before the fall equinox and, when applied at this time, Mg fertilizers have little or no effect on height growth. This paper reviews some of the past and current uses of Mg in bareroot nurseries and highlights a need for additional research.

Re-Description of Sillago malabarica, Silver Whiting from Southern Indian Waters

Sillaginids possess similar taxonomic characters, which make the specific identification difficult, and many true species may be hidden in the synonymy of wide-ranging species. There are currently 36 valid species of sand whitings in the family Sillaginidae. Thirteen valid species are reported from Indian waters and six species are reported from the Arabian Sea. Investigations into the sillaginid diversity off the west coast of India revealed the presence of a species from the Arabian seawhich, on examination, proved to be very similar to the types of Sciaena malabarica. Based on conventional taxonomic analysis and DNA barcoding, we therefore raise Sillago malabarica (new combination) from the synonymy of S. sihama and re-describe it here. Distinctive characteristics of the species include XI-XII spines in the first dorsal fin; I, 21–24 rays in the 2nd dorsal fin; 3–4/7–8 gill rakers on 1st gill arch, Head length 25.2–30.4; Snout length 39.4%–46.8% HL; post-orbital length 34%–37.5% HL, 34 total vertebrae (abdominal: 13, haemal: 4 and caudal: 17); single sharp spine on the opercular edge; swim-bladder with eight or nine lateral processes extending from entire lateral surface of main body of swim bladder; golden silvery body, dorsal and anal fins hyaline, with yellow tips and the absence of a mid-lateral streak or dark bands. Apart from re described species S. malabarica, original S. sihama is also recorded from Indian waters, in our studies.

Structure of CH4–Air Inverse Diffusion Flames in a Multi-slit Burner

Inverse diffusion flame (IDF) configurations have shown to be robust to changes in fuel feed and combining desired characteristics of both diffusion and premixed flames. In this work, methane IDFs are characterized in a multi-slit burner. To this end, a multi-technique experiment with photography, particle image velocimetry, and flame chemiluminescence through spectroscopy is conducted. The flames studied encompass a range of conditions (0 ≤ Vr ≤ 100) with laminar flow at two different power outputs (238 and 476 W). Four characteristic IDF structures were identified and denominated as types A, B, C, and D. Type A do not exhibit IDF-like characteristics and behave like normal diffusion flames. Types B, C, and D were found to exhibit a dual nature, with regions varying from a diffusion-like regime to a premixed-like regime. The velocity ratio Vr was found to be the most important parameter when characterizing IDF, whereas the use of a global equivalence ratio ϕg can be misleading because it does not offer insight in actual reaction stoichiometry. Type C flames displayed ideal characteristics for the application in appliances as a result of its stability and absence of undesired yellow tips.

An integrative description of a newCephalothrixspecies (Nemertea: Palaeonemertea) from the South China Sea.

A new nemertean species of the genusCephalothrixfrom intertidal calcareous red algae off the Vietnam coast is described based on histological sections, confocal laser scanning microscopy, and nucleotide sequences of three nuclear (18S rRNA, 28S rRNA, H3) and two mitochondrial (COI, 16S rRNA) DNA fragments.Cephalothrix sunisp. nov. is characterized by a unique body colour pattern consisting of transverse brown on ventral body side. A molecular phylogenetic analysis of the family Cephalotrichidae using a multigene approach has identifiedthree clades for Cephalothrix: Cephalothrix, Procephalothrix, and interstitial cephalotrichids. The new species belongs to clade Procephalothrix sensu Chernyshev Kajihara 2019 and a subclade of species with red, orange, or dark yellow anterior tip.

S2324 Multimodality Endoscopic Treatment of Boerhaave Syndrome

INTRODUCTION: We present a case of Boerhaave syndrome successfully treated with endoscopic suturing followed by esophageal stent placement. CASE DESCRIPTION/METHODS: A 54-year-old male presented with chest pain after repeated episodes of retching. CT showed pneumomediastinum and pleural effusions. The patient went into septic shock requiring vasopressors and mechanical ventilation. Bilateral chest tubes were placed. Fluid draining from the chest tubes was high in amylase. An urgent EGD was performed at the bedside in the ICU. Endoscopy revealed a 6 cm esophageal perforation (Figure 1). The patient was deemed a poor surgical candidate secondary to hemodynamic instability, and thus we proceeded with endoscopic treatment. Given the large defect size, we attempted primary closure with endoscopic suturing using three interrupted sutures and achieved excellent tissue apposition (Figure 2). This was followed by placement of a 15 cm × 20 mm, through the scope, fully covered self-expanding metal stent across the sutured defect site. The upper flare of the stent was then sutured endoscopically to the esophageal wall to minimize the risk of distal migration. An esophagram two weeks later showed no leakage of contrast. The patient improved clinically, tolerated a soft diet, and was discharged. Repeat EGD was performed 3 months later to remove the stent. The perforation site had healed (Figure 3). DISCUSSION: We used a combination of endoscopic techniques to successfully treat a patient with Boerhaave syndrome. Temporary placement of esophageal stents have been reported for this condition. This works not by directly closing the perforation site but rather by preventing oral and GI secretions from passing through the defect and thereby allowing a natural inflammatory response to ultimately seal the perforation. We were concerned that the large size of the defect may not allow the esophageal stent to sufficiently appose the entire defect. We believe that endoscopic suturing mimics primary surgical closure and also facilitates stent fixation, which may minimize the risk of stent migration. We advocate that if endoscopic suturing tools and expertise are available and if endoscopic suturing is considered for stent fixation, efforts should be made to primarily close the defect by endoscopic suturing before placing and anchoring the esophageal stent. Finally, this case also highlights that this procedure can be performed at the ICU bedside without the need for fluoroscopy, which may be ideal in unstable patients.Figure 1.: The endoscopic view reveals a large 6 cm perforation in length.Figure 2.: Endoscopic view showing complete closure of the defect using OverStitch Endoscopic Suturing System (Apollo Endosurgery. Austin, TX) prior to placement of a through the scope, fully covered self-expanding metal stent (Taewong Medical. Seoul, Korea) across the sutured defect site. Yellow triangle tip at the level of the most proximal suture.Figure 3.: Endoscopic view after stent removal. The perforation site has completely closed 3 months after the initial intervention.

SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTIONIN STOVE PLATES. PART 2. STANDARD BASIS AND METHODOLOGY OF EVALUATION THE POWER EFFICIENCY AND ECOLOGICAL CHARACTERISTICS OF DOMESTIC GAS DEVICES

Gas stoves belong to the number of the most wide — spread domestic devices. Research activity concerning these appliances has been stopped in Ukraine some decades ago despite an increase of the natural gas using in municipal economy.&#x0D; Operation data, power efficiency characteristics and pollution indicators related to on air state by gas combustion in the living accommodation are regulated by the normative documents: national and international standards, regional technical (engineering) conditions of Ukraine, EU countries, Russia, USA, China and other states.&#x0D; Practically any gas stove is equipped with an atmospheric ejection burner. The principal characteristics of the gas burners, operation peculiarities peculiarities for the atmospheric burners are systematized and analyzed in the presented paper. The following qualitative and quantitative indicators of the atmospheric burners have been considered in this paper: the fuel types to be used (natural gas, liquefied gas), working gas pressure ahead of stove, nominal heat capacity, limit range of operation adjustment, noise by burner operation.&#x0D; Gas burning under the atmospheric burners operation makes the two-stage process. The physical background of the stable combustion have been considered along with the specific reasons and generalized criteria of the unstable combustions modes: flash-back, blow-off, appearance of the «yellow tips» in the flame.&#x0D; The atmospheric burners possess both the power and environmental advantages in comparison with the burners of total preliminary mixing of fuel gas and combustion air. Application of primary air excess lpr &lt; 1.0, provides higher efficiency of the burners and need for lower gas pressure ahead of the domestic stoves while the two-stage combustion makes one of the principle techniques of environmentally benign combustion technologies. It has been shown that energetic experiences in ejection burners are proportional to the cube of the air access coefficient, in case of the atmospheric burners — are raised two the third power: ea ~ l3a,pr.&#x0D; An original methodology experimental researchers for the atmospheric burners of various design and of different companies — manufacturers has been proposed. The methods of the tests performing fully meet to Ukrainian norms and international standards. The computerized firing rig stand with a diagnostic facility has been created providing both power and environmental research of the atmospheric burners with definition of the boundaries of stable operation and breach the combustion stability. An example of the water heating thermogram within the test vessel has been presented providing an opportunity to evaluate the peculiarities of head transfer process by time and space for the system «atmospheric burner – the vessel to be heated and liquid to be boiled». Bibl. 31, Fig. 7, Tab. 5.

A mitogenomic phylogeny of pierid butterflies and complete mitochondrial genome of the yellow tip Anthocharis scolymus (Lepidoptera: Pieridae)

The yellow tip butterfly Anthocharis scolymus (Lepidoptera: Pieridae) has a circular mitochondrial genome of 15,230 bp in size. It consists 13 protein-coding genes, 22 tRNAs, two ribosomal RNA genes, and an AT-rich control region. Using whole mitogenome alignments, we reconstructed the phylogenetic relationships of 28 pierid butterflies. The maximum-likelihood (ML) tree topology was consistent with previous studies.

Lifting and yellow tip characteristics of small-scale partially premixed combustor burning pipeline natural gas and liquefied natural gas

In this article, a small-scale partially premixed combustor was designed with 1.5 kW heat input rate. Through altering premixing ratio of gas and air, the lifting and yellow tip characteristics were experimentally tested with the burner head material of cast-iron and copper–aluminum respectively. Combined with burner head temperature influences, the lifting and yellow tip characteristics of small-scale partially premixed combustor are discussed when natural gas is substituted. It is found that when lifting and yellow tip occur, the cast-iron burner shows a slow tendency of temperature change, but the temperature of copper–aluminum burner fluctuates sharply. Yellow tip is related to gas properties and burner structure, and is more likely to appear with the increase of the Wobbe index and heavy hydrocarbon fraction, while lifting is very likely to appear when temperature fluctuates. Yellow tip characteristic can be predicted by Wobbe index, but this method is unsuitable for lifting prediction.

Branchiostegus biendong, a New Tilefish from Vietnam (Perciformes: Branchiostegidae).

A new tilefish, Branchiostegus biendong, is described on the basis of three specimens (181-209 mm in standard length [SL]) collected from a local fish market of Quy Nhon on the South China Sea coast of central Vietnam. It can be distinguished from 17 congeners in having the following combination of characters: six diagonal scale rows exposed on cheek; cheek scales moderately large (diameter 2.2-2.5% SL); predorsal ridge black; cheek almost silver with an oval-shaped, yellow blotch along ventral margin of eye; dorsal fin translucent yellowish with narrow black margin overlapping stronger yellowish coloration dorsally; upper lobe of caudal fin with 5-6 yellow stripes and tip with black blotch; and lower lobe of caudal fin navy blue. A key to five species of Branchiostegus from Vietnamese waters is provided.

Identification of wheat blue dwarf phytoplasma effectors targeting plant proliferation and defence responses

The identification of effectors from pathogenic microbes is one of the most important subjects for elucidating infection mechanisms. Wheat blue dwarf (WBD) phytoplasma causes dwarfism, witches' broom, and yellow leaf tips in wheat plants, resulting in severe yield loss in northwestern China. In this study, 37 candidate effector proteins were transiently expressed in Nicotiana benthamiana. Plants expressing the SAP11‐like protein SWP1 exhibited typical witches' broom. Interestingly, another protein, SWP11, induced both cell death and defence responses, including H2O2 accumulation and callose deposition. Analysis by qRT‐PCR was used to show that a marker gene of the hypersensitive response, HIN1, and three pathogenesis‐related genes, PR1, PR2 and PR3, were significantly up‐regulated in leaves of N. benthamiana expressing SWP11. In addition, SWP12 and SWP21 (TENGU‐like) were shown to suppress SWP11‐, BAX‐, and/or INF1‐induced cell death. These results indicated that SWP21 has a distinct role in virulence compared with TENGU and that WBD phytoplasma possesses effectors that target plant proliferation and defence responses. The ability of these effectors to trigger or suppress plant immunity provides new insights into the phytoplasma–plant interaction.

On the genus Armina (Gastropoda: Heterobranchia: Nudibranchia) in Thailand

The marine sea slug heterobranch fauna from Thailand is composed of a total of 240 species, and Armina semperi is the only representative of the genus Armina recorded in the country. This species, described in the Philippines in the nineteenth century, has an uneasy taxonomic history and appears to be part of a complex of morphologically similar species, which has made its real identity difficult to determine. Comparison of samples of the genus Armina from Thailand with the original description of A. semperi showed that they were different. Furthermore, additional sampling allowed the discovery of a second species of the genus, similar to the so-called A. semperi and living in sympatry with it. In this paper, the taxonomic history of A. semperi is summarized and both species from Thailand are described as new to science. Armina scotti n. sp. is characterized by its black dorsum with pale yellowish notal ridges, widened forming three rounded blotches, not divergent posteriorly, not bifurcated; oral veil white, with a pale blue submarginal band and yellow edge; white rhinophores with a black subterminal band, which is pale blue on the inner-front sides, orange tips, and a black stripe running to the sides of the oral veil. The cutting edge of the jaws with up to four rows of denticles; radular formula 28 x 20.1.1.1.20; rachidian tooth with 5–6 strong denticles on each side of the median cusp; lateral teeth denticulate to smooth. Hermaphrodite duct very thin. Ampulla very long and wide; bursa copulatrix absent; prostate not differentiated; and penis proportionally very large and unarmed. Armina occulta n. sp. is characterized by its black dorsum with white notum narrowed forming two transverse dark bands, divergent and bifurcated posteriorly; orange mantle edge; black foot with a thick marginal band of deep blue; rhinophores deep blue with yellow tips, and a black subterminal band. The radular formula is 50 x 29.1.1.29; broad rachidian teeth, bearing 4–6 strong denticles only on the left side of the median cusp; a very thin hermaphrodite duct; very long and wide ampulla; undifferentiated prostate; large bursa copulatrix; and a penis bearing a stylet.

SCIENTIFIC AND ENGINEERING PRINCIPLES OF EFFICIENT FUEL USE AND ENVIRONMENTALLY FRIENDLY GAS COMBUSTION IN STOVE PLATES. PART 1. MODERN STATE-OF-THE-ART AND DIRECTIONS FOR IMPROVEMENT THE GAS BURNING IN DOMESTIC GAS COOKERS

Natural gas NG consumption in industry and energy of Ukraine, in recent years falls down as a result of the crisis in the country’s economy, to a certain extent due to the introduction of renewable energy sources along with alternative technologies, while in the utility sector the consumption of fuel gas flow rate enhancing because of an increase the number of consumers. The natural gas is mostly using by domestic purpose for heating of premises and for cooking. These items of the gas utilization in Ukraine are already exceeding the NG consumption in industry. Cooking is proceeding directly in the living quarters, those usually do not meet the requirements of the Ukrainian norms DBN for the ventilation procedures. NG use in household gas stoves is of great importance from the standpoint of controlling the emissions of harmful components of combustion products along with maintenance the satisfactory energy efficiency characteristics of NG using. The main environment pollutants when burning the natural gas in gas stoves are including the nitrogen oxides NOx (to a greater extent — highly toxic NO2 component), carbon oxide CO, formaldehyde CH2O as well as hydrocarbons (unburned UHC and polyaromatic PAH). An overview of environmental documents to control CO and NOx emissions in comparison with the proper norms by USA, EU, Russian Federation, Australia and China, has been completed. The modern designs of the burners for gas stoves are considered along with defining the main characteristics: heat power, the natural gas flow rate, diameter of gas orifice, diameter and spacing the firing openings and other parameters. The modern physical and chemical principles of gas combustion by means of atmospheric ejection burners of gas cookers have been analyzed from the standpoints of combustion process stabilization and of ensuring the stability of flares. Among the factors of the firing process destabilization within the framework of analysis above mentioned, the following forms of unstable combustion/flame unstabilities have been considered: flashback, blow out or flame lifting, and the appearance of flame yellow tips. Bibl. 37, Fig. 11, Tab. 7.

Bacterial diseases of wheat caused by Xanthomonas sp. in the Southern Ural: Identification issues

The identification of pathogenic agents isolated from infected wheat seeds and plants, collected in the Southern Ural and characterized by an atypical manifestation of bacterial infection (yellow leaf tips), has been carried out by direct microbiological and molecular methods. In addition, an indirect identification by the hypersensitive reaction (HR) approach has been performed simultaneously with the pathogenicity assessment of isolates using an indicator plant Plectranthus australis R. Br. Isolated samples have been microbiologically identified as Xanthomonas sp. According to the results of the PCR identification with species-specific primers, isolated samples represent Xanthomonas translucens; the reliability of the obtained results is corroborated by the hypersensitive reaction approach used also to assess the pathogenicity of isolates. Winter wheat, especially cv. Pionerskaya 23, where both X. translucens and Pantoea agglomerans were found, suffered more severe symptoms than spring wheat that was only affected by strains of X. translucens. To improve the reliability of the primary diagnostics of a bacterial character of seed infection, the provoking of the pathogen development by temperature or pH stress is proposed.

Primary air ratio change and gas interchangeability index correct for domestic gas cooker burning multi-source natural gases

In this paper, the influences of burner head temperature and gas properties on primary air ratio change of domestic gas cooker were studied, when natural gases interchange. Then though experimental test, the equation of AGA Lifting Index was modified and its interchangeability limits for Chinese natural gas interchangeability prediction was redefined. From results, when natural gases interchange, the original calculation equation of primary air ratio change should be corrected by temperature. The temperature correction coefficient m values1.1, when poor gas substitutes rich gas. As well as m values 0.9 when rich gas substitutes poor gas. And m values 1.0 when similar quality gases interchange. No flash-back and yellow tip were observed for all 17 domestic gas cookers under 11 test natural gases. Unfortunately, there were about half substitute natural gases appearing lifting, but all these gases were in the limit of AGA Lifting Index. Hence it verified that AGA Lifting Index IL can't be totally suitable when it's used to predict Lifting for Chinese natural gas interchangeability. According to natural gas interchangeability experiment on Chinese domestic gas cookers, it corrected the interchangeable limit of AGA Lifting Index IL as follows: total interchangeable, IL ≤ 1.09; interchangeable, 1.09＜IL＜1.13; un-interchangeable, IL ≥ 1.13.

Effects of oxidizer flexibility and bluff-body blockage ratio on flammability limits of diffusion flames

Concerns about global warming have encouraged the interest in hydrocarbon combustion techniques that allow easy capture of carbon dioxide. One technique for achieving this objective is through the use of pure oxygen instead of air for combustion or what is called oxy-combustion carbon capture technology. The main goal of the manuscript is to study flammability limits, visual flame appearance and exhaust emissions of diffusion flame stabilized over a bluff body over ranges of operating and design conditions. The operating conditions include flow Reynolds number, equivalence ratio and oxidizer composition. The design parameter considers the change of blockage ratio (BR) of the bluff body namely, BR=0.36, 0.5, 0.67 and 0.82. Based on this, three sets of experiments were performed utilizing compressed natural gas (CNG) as a fuel to be burned with three different oxidizers including air, oxygen-enriched-air and oxy-fuel mixtures (O2 plus CO2 with a controlled oxygen fractions, OF). The three sets of experiments were performed to identify ranges for stable flame operation considering different oxidizers under different operating conditions. Stability limits, visual flame appearance and extinction limits of these flames are quantified and analyzed. Furthermore, three different regions were observed; precisely, jet flames, central-jet dominated flames and recirculation zone flames, depending on the ratio between oxidizer and fuel momentum. The flame color changed from yellow for air combustion, to bright white for oxygen-enriched-air combustion and finally to blue with yellow tips for oxy-combustion. The flame length was the highest for air combustion, then lower for oxy-combustion and the lowest for oxygen-enriched-air combustion. This was attributed to the effect of oxygen-enrichment which results in increase in the flame speed making flame length shorter. For the sake of comparison, the flammability limits of the three sets were reported and the results revealed that oxygen-enriched-air-flames have higher stability than air-flames and oxy-flames, respectively.