OH Ratio Research Articles

Chemiluminescence diagnosis of oxygen/fuel ratio in fuel-rich jet diffusion flames

Equivalence ratio is one of key parameters associated with various flame characteristics such as flame structure and heat release rate. Chemiluminescence diagnosis of equivalence ratio has received extensive attention but not yet perfected, especially for fuel-rich diffusion flames. In this paper, the feasibility for evaluating molar equivalence ratio of oxygen to fuel in the fuel-rich conditions based on radical chemiluminescence diagnosis was explored. The sensitivity of the spontaneous luminescence intensity to the change of the nominal oxygen/fuel ratio in co-flow CH4-O2 jet diffusion flames was quantitatively studied. In addition, the two-dimensional distributions of the intensity ratios of CH* to CO2* and OH* to CH* were further analyzed, and local oxygen/fuel ratios were reconstructed. The results show that OH* chemiluminescence is more sensitive to changes in nominal oxygen/fuel ratio than CH* and CO2*. The sensitivity of CH* to oxygen/fuel ratio increases with the rise of CH4 flow rate, while the sensitivity of CO2* decreases. The reconstructed value of local oxygen/fuel ratio according to the two-dimensional intensity ratio of CH* to CO2* is underestimated, while based on the intensity ratio of OH* to CH* it is overestimated. Combined with these two intensity ratio distributions, the local oxygen/fuel ratio can be roughly determined.

Uticaj različito umrežavanih polimernih veziva na reološka svojstva plastičnih eksploziva

Plastic Explosive Compositions consisting of HMX and liquid polyurethane binder were prepared in order to determine influence of differently cured polymeric binders on rheological properties of plastic explosives. First, a set of polymeric binders was prepared in polyaddition reaction between HTPB and IPDI, with varying NCO:OH ratio and examined through the standard and non-standard rheological tests on a dynamic rotational rheometer. Viscosity curves of polymeric binders show viscosity increase with NCO:OH ratio increase, as expected. Amplitude sweep tests reveal liquid-like structure of PEs, with structure strength increase with higher NCO:OH ratio of polymeric binder used, and limiting values of LVER vary from 10-3 to 10-2 strain. Results of creep test reveal that with increase of NCO:OH ratio of polymeric binder in PE zero-shear viscosity increase and viscous portion deformation decrease. Also, penetration decrease with increase of NCO:OH ratio. The obtained results indicate that initial rheology testing is crucial in plastic explosive formulation regarding their processability and physical properties.

Understanding the Surface Characteristics of Biochar and Its Catalytic Activity for the Hydrodeoxygenation of Guaiacol

Biochar (BCR) was obtained from the pyrolysis of a palm-oil-empty fruit bunch at 773 K for 2 h and used as a catalyst for the hydrodeoxygenation (HDO) of guaiacol (GUA) as a bio-oil model compound. Brunauer–Emmet–Teller surface area analysis, NH3 and CO2-temperature-programmed desorption, scanning electron microscope–dispersive X-ray spectroscopy, CHN analysis and X-ray fluorescence spectroscopy suggested that macroporous and mesoporous structures were formed in BCR with a co-presence of hydrophilic and hydrophobic sites and acid–base behavior. A combination of infrared, Raman and inelastic neutron scattering (INS) was carried out to achieve a complete vibrational assignment of BCR. The CH–OH ratio in BCR is ~5, showing that the hydroxyl functional groups are a minority species. There was no evidence for any aromatic C–H stretch modes in the infrared, but they are clearly seen in the INS and are the majority species, with a ratio of sp3–CH:sp2–CH of 1:1.3. The hydrogen bound to sp2–C is largely present as isolated C–H bonds, rather than adjacent C–H bonds. The Raman spectrum shows the characteristic G band (ideal graphitic lattice) and three D bands (disordered graphitic lattice, amorphous carbon, and defective graphitic lattice) of sp2 carbons. Adsorbed water in BCR is present as disordered layers on the surface rather than trapped in voids in the material and could be removed easily by drying prior to catalysis. Catalytic testing demonstrated that BCR was able to catalyze the HDO of GUA, yielding phenol and cresols as the major products. Phenol was produced both from the direct demethoxylation of GUA, as well as through the demethylation pathway via the formation of catechol as the intermediate followed by deoxygenation.

Investigation on the OH*and CH* chemiluminescence characteristics of single coal particle flames under O2/CO2 atmosphere

Here, the OH* and CH* chemiluminescence characteristics of a single coal particle flame combustion in a visual drop-tube furnace (VDTF) for different oxygen fraction, Xi,O2, in O2/CO2 atmosphere were investigated using an optical diagnostic technique. The results indicate that the combustion of single coal particles is composed of a volatile reaction stage followed by a volatile-char reaction stage. During volatile reaction stage, the single coal particle burns in an enveloped flame. The flame becomes brighter and the flame length increases gradually. In addition, the OH* and CH* intensity shows peak values with axial distance along the furnace, with that of OH* appearing earlier as the oxygen fraction increases. In the volatile-char reaction stage, the flame length fluctuates slightly, and OH* and CH* peak position are spread over a smaller range of distance. The value of Xi,O2 affects the reaction rate as it promotes the diffusion of oxygen to the interior of coal particle, as the intensity of OH* and CH* increasing rapidly for Xi,O2 > 0.4. This indicates that the rate of reaction is controlled by Xi,O2. Furthermore, the peak intensity ratio of OH* and CH* increases linearly with Xi,O2.

A high-productivity process for mass-producing Fe3O4 nanoparticles by co-precipitation in a rotating packed bed

Fe3O4 nanoparticles were mass-produced using a rotating packed bed (RPB) and the role of stoichiometric ratio and the effects of the FeCl2 and FeCl3 concentrations, aging temperature, and Fe2+ and Fe3+ sources on the characteristics of the obtained Fe3O4 nanoparticles were examined. A high-productivity process for mass-producing Fe3O4 nanoparticles with a rate of approximately 23 kg/day was developed with an FeSO4 concentration of 0.15 mol/L, an FeCl3 concentration of 0.3 mol/L, an NaOH concentration of 1.2 mol/L, a production temperature of 25 °C, an aging temperature of 25 °C, a rotational speed of 1800 rpm, a flow rate of aqueous FeSO4/FeCl3 of 0.5 L/min, and a flow rate of aqueous NaOH of 0.5 L/min. The thus mass-produced Fe3O4 nanoparticles had a mean diameter of 8.4 nm and exhibited superparamagnetism with a saturation magnetization of 61 emu/g. Since the RPB provides excellent micromixing and overcomes the difficulty of mass-production that is associated with traditional co-precipitation in a batch process, Fe3O4 nanoparticles that are mass-produced in an RPB are smaller than Fe3O4 nanoparticles that are batch-produced in a batch reactor, and so have a greater adsorption capacity to remove Reactive Red 2 from water. The results in this work demonstrate that an RPB can mass-produce Fe3O4 nanoparticles at a production temperature of 25 °C and an aging temperature of 25 °C with a low molar ratio of OH− to Fe2+ (8:1). Accordingly, a high-productivity process for mass-producing Fe3O4 nanoparticles can be implemented using an RPB with co-precipitation.

Simulation of continuous catalytic conversion of glycerol into lactic acid in a microreactor system: A CFD study

Hand in hand with the flourish of the biodiesel industry, glycerol (GLY) as an inconvenient by-product has generated environmental and sustainability concerns. Devising measures for efficient transformation of GLY into value-added products is a promising solution. In this contribution, the transformation of GLY to lactic acid (LA) as a valuable chemical was investigated in a continuous process for industrial applications. In this regard, a catalytic method using heterogeneous Cu nanoparticles in NaOH solution was studied in a microreactor by a CFD simulation. A seven-inlet micromixer comprising an optimized mixing unit was incorporated for uniform distribution of the species. The effects of various parameters upon the process performance were considered and the optimum points were determined. Also, the extent of the influence of each variable on LA yield was evaluated using sensitivity analysis techniques. While higher LA yield could be obtained at extreme scenarios, optimum values of the Re and temperature for obtaining the maximum performance under sensible operating conditions were determined to be 0.108 and 510.1 K which led to the optimum yields of 67.8% and 59.5%, respectively. Moreover, the sensitivity analysis revealed that the molar ratio of OH−/GLY and temperature were the most and least significant parameters, respectively.

Flame Retardant Waterborne Polyurethanes: Synthesis, Characterization, and Evaluation of Different Properties

A series of flame retardant waterborne polyurethanes (WBPUs) with varying NCO:OH mole ratio, i.e., isocyanate:hydroxyl groups, was synthesized using phosphorus-based polyester polyol and isophorone diisocyanate (IPDI). The phosphorus moiety was kept in the polymeric chain, which improves flame retardancy of the WBPU films. The prepolymer mixing process was adopted for the synthesis route of WBPU systems. The presence of structural-functional groups was confirmed by Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. The thermal stability and percentage char yield were observed by TGA analysis. As a consequence of the existence of phosphorous moiety, these WBPUs also exhibit flame retardancy, which was examined by limiting oxygen index (LOI) and UL-94 test. All the samples show an increment in thermal stability with an increase in NCO:OH ratio. Maximum flame retardancy was obtained in FWP5 and FWP6 systems with LOI value of 32%.

Bio-Based Polyurethane Networks Derived from Liquefied Sawdust.

The utilization of forestry waste resources in the production of polyurethane resins is a promising green alternative to the use of unsustainable resources. Liquefaction of wood-based biomass gives polyols with properties depending on the reagents used. In this article, the liquefaction of forestry wastes, including sawdust, in solvents such as glycerol and polyethylene glycol was investigated. The liquefaction process was carried out at temperatures of 120, 150, and 170 °C. The resulting bio-polyols were analyzed for process efficiency, hydroxyl number, water content, viscosity, and structural features using the Fourier transform infrared spectroscopy (FTIR). The optimum liquefaction temperature was 150 °C and the time of 6 h. Comprehensive analysis of polyol properties shows high biomass conversion and hydroxyl number in the range of 238–815 mg KOH/g. This may indicate that bio-polyols may be used as a potential substitute for petrochemical polyols. During polyurethane synthesis, materials with more than 80 wt% of bio-polyol were obtained. The materials were obtained by a one-step method by hot-pressing for 15 min at 100 °C and a pressure of 5 MPa with an NCO:OH ratio of 1:1 and 1.2:1. Dynamical-mechanical analysis (DMA) showed a high modulus of elasticity in the range of 62–839 MPa which depends on the reaction conditions.

The effects of ring-shaped porous inert media on equivalence ratio oscillations in a self-excited thermoacoustic instability

Gas turbine operation increasingly relies on lean premixed (LPM) combustion to reduce harmful emissions, which is susceptible to thermoacoustic instabilities. Most combustion systems are technically premixed and exhibit a degree of equivalence ratio inhomogeneity. Thermoacoustic pressure oscillations can couple with the heat release oscillations through the generation of equivalence ratio fluctuations at fuel injection sites, which are then convected to the flame front. Previous experimental studies have shown that porous inert media (PIM) can passively mitigate these instabilities by adding acoustic damping and by reducing the thermoacoustic feedback mechanism. To understand the role of PIM on these equivalence ratio oscillations, spatially resolved, phased averaged equivalence ratio fluctuations are measured using the ratio of OH*/CH* chemiluminescence. Spatial imaging of OH* or CH* radicals produce integrated line of sight intensity values and an Abel transformation is used to obtain spatially resolved values. Phase averaged images are synced with dynamic pressure measurements, and an axisymmetric atmospheric burner is used to study the effects of ring-shaped PIM on the spatially resolved equivalence ratio field with self-excited thermoacoustic instabilities. The results show that PIM significantly reduces these fluctuations, and the effects on the stability of the system are discussed.

Elevated levels of OH observed in haze events during wintertime in central Beijing

Abstract. Wintertime in situ measurements of OH, HO2 and RO2 radicals and OH reactivity were made in central Beijing during November and December 2016. Exceptionally elevated NO was observed on occasions, up to ∼250 ppbv. The daily maximum mixing ratios for radical species varied significantly day-to-day over the ranges 1–8×106 cm−3 (OH), 0.2–1.5×108 cm−3 (HO2) and 0.3–2.5×108 cm−3 (RO2). Averaged over the full observation period, the mean daytime peak in radicals was 2.7×106, 0.39×108 and 0.88×108 cm−3 for OH, HO2 and total RO2, respectively. The main daytime source of new radicals via initiation processes (primary production) was the photolysis of HONO (∼83 %), and the dominant termination pathways were the reactions of OH with NO and NO2, particularly under polluted haze conditions. The Master Chemical Mechanism (MCM) v3.3.1 operating within a box model was used to simulate the concentrations of OH, HO2 and RO2. The model underpredicted OH, HO2 and RO2, especially when NO mixing ratios were high (above 6 ppbv). The observation-to-model ratio of OH, HO2 and RO2 increased from ∼1 (for all radicals) at 3 ppbv of NO to a factor of ∼3, ∼20 and ∼91 for OH, HO2 and RO2, respectively, at ∼200 ppbv of NO. The significant underprediction of radical concentrations by the MCM suggests a deficiency in the representation of gas-phase chemistry at high NOx. The OH concentrations were surprisingly similar (within 20 % during the day) in and outside of haze events, despite j(O1D) decreasing by 50 % during haze periods. These observations provide strong evidence that gas-phase oxidation by OH can continue to generate secondary pollutants even under high-pollution episodes, despite the reduction in photolysis rates within haze.

Study of Secondary Organic Aerosol Formation from Chlorine Radical-Initiated Oxidation of Volatile Organic Compounds in a Polluted Atmosphere Using a 3D Chemical Transport Model.

The impact of chlorine (Cl) chemistry on the formation of secondary organic aerosol (SOA) during a severe wintertime air pollution episode is investigated in this study. The Community Multiscale Air Quality (CMAQ) model v5.0.1 with a modified SAPRC-11 gas-phase mechanism and heterogeneous reactions for reactive chlorine species is updated to include the formation of chlorine radical (Cl•)-initiated SOA (Cl-SOA) from aromatic compounds, terpenes, and isoprene. Reported SOA yield data on Cl-SOA formation from environmental chamber studies are used to derive the mass yield and volatility data for the two-product equilibrium-partitioning model. The heterogeneous reaction of particulate chloride (pCl-) leads to a significant increase in the Cl• and hydroxyl radical (OH) concentrations throughout the domain. Monthly Cl-SOA concentrations range from 0.7 to 3.0 μg m-3, with increasing anthropogenic Cl emissions leading to higher Cl-SOA concentrations. Indirectly, this also leads to an increase of monthly SOA by up to 2.5-3.0 g μm-3 from the traditional OH oxidation pathways as well as the surface uptake of glyoxal and methylglyoxal. Increased OH concentrations, however, do not always lead to higher overall SOA concentrations in the entire domain. High OH reduces the lifetime of glyoxal/methylglyoxal (GLY/MGLY), making them less available to form SOA. In the Sichuan Basin (SCB) and part of Southwest China where high O3 concentrations meet high pCl emissions, a higher Cl•/OH ratio leads to net O3 loss from the Cl• + O3 reaction, thus reducing SOA formation from the O3 oxidation of volatile organic compounds (VOCs). Also, the competition between Cl• and OH for VOCs could lead to lower overall SOA because the molar yields of the semivolatile products in Cl-VOC reactions are lower than their OH + VOC reaction counterparts. When Cl• concentrations are further increased with higher emissions of Cl, precursor gases can be depleted and become the limiting factor in SOA formation. This study reveals the direct and indirect impacts of chlorine chemistry on SOA in polluted winter conditions, which are greatly affected by the Cl emissions, the ambient O3 level, and the availability of SOA precursors.

Investigation of Waste Biogas Flame Stability Under Oxygen or Hydrogen-Enriched Conditions

Increasing production rates of the biomethane lead to increased generation of waste biogases. These gases should be utilized on-site to avoid pollutant emissions to the atmosphere. This study presents a flexible swirl burner (~100 kW) with an adiabatic chamber capable of burning unstable composition waste biogases. The main combustion parameters and chemiluminescence emission spectrums were examined by burning waste biogases containing from 5 to 30 vol% of CH4 in CO2 under air, O2-enriched atmosphere, or with the addition of hydrogen. The tested burner ensured stable combustion of waste biogases with CH4 content not less than 20 vol%. The addition of up to 5 vol% of H2 expanded flammability limits, and stable combustion of the mixtures with CH4 content of 15 vol% was achieved. The burner flexibility to work under O2-enriched air conditions showed more promising results, and the flammability limit was expanded up to 5 vol% of CH4 in CO2. However, the combustion under O2-enriched conditions led to increased NOx emissions (up to 1100 ppm). Besides, based on chemiluminescence emission spectrums, a linear correlation between the spectral intensity ratio of OH* and CH* (IOH*/ICH*) and CH4 content in CO2 was presented, which predicts blow-off limits burning waste biogases under different H2 or O2 enrichments.

Development of spiropyran bonded bio-based waterborne polyurethanes for mechanical-responsive color-variable films

Waterborne polyurethanes (WPUs) use water as the solvent to reduce volatile organic compounds emissions and are widely increased because they are environment friendly. Vegetable oil-based polyol is a potential environmental protection material and can replace petroleum-based polyols for WPUs synthesis. In this work, we synthesized new mechanical-responsive soybean oil (SBO)-based WPUs, and their corresponding responsive behaviors were regulated by the flexibility and rigidity of the polymer chains. Soybean oil polyols (MESOs) were firstly synthesized from soybean oils, which were used to synthesize waterborne polyurethanes (SP-MSPUs). Spiropyran (SP) as a mechanophore was bonded to polyurethane chains, and the color of polyurethane films would be changed under the action of stress, which shown the stress-sensitive behavior of polyurethane membrane. The double hydroxyl spiropyran diol (SP2) and the control single hydroxyl spiropyran (SP1) were synthesized and bonded into the SP-MSPU molecular chains, respectively. The SP-MSPU polymer films appeared a translucent light yellow in visible light, and the purple color of polyurethane films was observed under stress tension. Soybean oil polyols with triglyceride bonds are implanted into the polymer to regulate the flexibility and rigidity of the films. From SP- MSPU-115 to SP-MSPU-172 of the polymer samples, the stress required ranged from 1 MPa to 4 MPa when the polymerization tensile deformation was 200%. At the same time, under the same deformation, the UV absorption of polyurethane films synthesized from the same polyol (MESO-134) showed a trend of enhancement with the increase of the molar ratio of NCO and OH in polymer chains. Therefore, excellent mechanical response behavior of a solid SP-MSPU membrane can be obtained. This mechanical responsive SP-MSPU would be used in a variety of applications, such as multi-responsive probe materials, decorative coatings, and anti-falsification technology.

Analyzing OH*, CH*, and C2* chemiluminescence of bifurcating FREI propane-air flames in a micro flow reactor

An experimental investigation of spontaneous flame chemiluminescence of OH*, CH*, and C2* radicals was conducted for premixed propane-air flames in a micro flow reactor. Equivalence ratios from 0.7 to 1.4 were examined and correlated well to the ratio of OH*/CH* and C2*/CH* (R2 > 0.999 for C2*/CH* power fit). The OH*/CH* ratio better correlated with equivalence ratio for lean flames, while the C2*/CH* ratio better correlated with rich flames. The equivalence ratio model was used to calculate the axial local equivalence ratio for a rich propane-air flame (ϕ of 1.5) exhibiting strong bifurcating FREI behavior, resulting in three visible flame fronts. The measured intensities of OH*, CH*, and C2* chemiluminescence, as well as the calculated local equivalence ratio along the reactor axis support the numerical model explanations of the observed bifurcating FREI flames available in the literature. This work highlights the novel application of this diagnostic technique in the context of micro flow reactors.

Curing acceleration of cyanate ester resin by a phenolic compound having a tertiary amino group at the ortho-position

To develop a novel organic catalyst that can effectively cure cyanate ester resins, the effects of incorporating various phenolic compounds on the curing of bisphenol A dicyanate (BADCY) was investigated. Differential scanning calorimetry (DSC) and Fourier transform infrared (FT-IR) spectroscopy analyses revealed that o-(dimethylamino)methylphenol (o-DAMP) was a highly effective catalyst for accelerating the curing of BADCY, and the addition of o-DAMP reduced the final curing temperature of BADCY to 180 °C. The promoting effect of o-DAMP was found to be due to the presence of an acidic phenolic OH group and a basic (dimethylamino)methyl group at the ortho-positions of the molecule. The addition of o-DAMP improved the modulus, strength and fracture toughness (KIC) of the cured BADCY resins. The mechanical and thermal properties of the cured resins could be adjusted by changing the amount of o-DAMP. The investigation of the effects of incorporating various phenolic compounds on the curing of bisphenol A dicyanate (BADCY) revealed that o-(dimethylamino)methylphenol (o-DAMP) was a very effective catalyst, which reduced the final curing temperature to 180 °C. The promoting effect of o-DAMP was due to the presence of a phenolic OH and a (dimethylamino)methyl groups at the ortho-positions of the molecule. The addition of o-DAMP improved the mechanical properties of the cured BADCY resins, and the most balanced properties were obtained when the ratio of OH to OCN was 0.05.

Experimental studies of the effects of global equivalence ratio and CO2 dilution level on the OH* and CH* chemiluminescence in CH4/O2 diffusion flames

Focusing on the chemiluminescent properties of the flame is an effective way to study the flame structure and reaction mechanism. In this paper, based on the CCD camera imaging system, the chemiluminescent distributions of OH* and CH* in CH4/O2 diffusion flames with different global equivalence ratios and CO2 dilution levels were obtained. The changes in the reaction zones of OH* layer and CH* layer were further compared. The peak intensity ratios of OH* and CH* were used to quantitatively characterize the global equivalence ratio and the CO2 dilution level. The results show that variations in the global equivalence ratio and the CO2 dilution level do not obviously alter the shape and thickness of the CH* layer. The distribution and intensity changes of the OH* layer are much more significant than those of the CH* layer when the experimental conditions are varied. For the flame with a low dilution level, the CH* layer is located on the inner rim of the OH* layer, and the radial positions of two peaks are not much different. The increase of the CO2 dilution level leads to the displacement of the OH* peak, which becomes closer to the flame axis. In addition, due to the narrowing of the OH* layer, the CH* layer eventually becomes at the outer rim of the OH* layer. The peak intensity ratio of OH* and CH* decreases linearly with the rise of the global equivalence ratio, and changes as a power function with the increasing CO2 dilution level.

Nitrogen isotopic analysis of nitrate in aquatic environment using cadmium-hydroxylamine hydrochloride reduction.

The nitrogen isotopic ratio of nitrate (δ15 N-NO3 - value) is a critical parameter for understanding nitrogen biogeochemical cycling in aquatic systems. Current approaches to the determination of δ15 N-NO3 - values involve time-intensive handling procedures, the use of toxic chemicals and complicated microbial incubation. A chemical reduction method for measuring the δ15 N-NO3 - values of aquatic samples was established. Nitrate was first quantitatively reduced to nitrite in a column filled with copper-coated cadmium granules, and the produced nitrite further reduced to nitrous oxide gas with hydroxylamine hydrochloride. The nitrogen isotope ratio of the produced nitrous oxide was measured using a continuous-flow isotope ratio mass spectrometer coupled with a purge and cryogenic trap system. The optimized experimental conditions were: solution acidity, H+ concentration of 0.46 M, pH = 0.34; dosage of hydroxylamine, molar ratio of NH2 OH to NO2 - of 4; reaction temperature, 45°C; and reaction time, 14-16 h. No salt effect was found for this method. The reproducibility of the δ15 N-NO3 - value for the laboratory standard was better than 0.3‰ for long-term measurements (20 nmol NO3 - requirement). This method provides a reliable approach for the determination of δ15 N-NO3 - values at natural abundance. It provides (1) high measurement accuracy, (2) ease of operation, (3) environmental-friendly procedure (less toxic regents used), and (4) suitability for both freshwater and saline water samples.

Two-Dimensional Tomographic Simultaneous Multi-Species Visualization—Part I: Experimental Methodology and Application to Laminar and Turbulent Flames

In recent years, the tomographic visualization of laminar and turbulent flames has received much attention due to the possibility of observing combustion processes on-line and with high temporal resolution. In most cases, either the spectrally non-resolved flame luminescence or the chemiluminescence of a single species is detected and used for the tomographic reconstruction. In this work, we present a novel 2D emission tomographic setup that allows for the simultaneous detection of multiple species (e.g., OH*, CH* and soot but not limited to these) using a single image intensified CCD camera. We demonstrate the simultaneous detection of OH* (310 nm), CH* (430 nm) and soot (750 nm) in laminar methane/air, as well as turbulent methane/air and ethylene/air diffusion flames. As expected, the reconstructed distributions of OH* and CH* in laminar and turbulent flames are highly correlated, which supports the feasibility of tomographic measurements on these kinds of flames and at timescales down to about 1 ms. In addition, the possibilities and limitations of the tomographic approach to distinguish between locally premixed, partially premixed and non-premixed conditions, based on evaluating the local intensity ratio of OH* and CH* is investigated. While the tomographic measurements allow a qualitative classification of the combustion conditions, a quantitative interpretation of instantaneous reconstructed intensities (single shot results) has a much greater uncertainty.

Effect of soft segment molecular weight and NCO:OH ratio on thermomechanical properties of lignin-based thermoplastic polyurethane adhesive

During the last decades lignin has been largely applied on development of reactive polyurethanes. More recently, significant efforts were dedicated to synthesizing lignin-based thermoplastic polyurethanes (LTPUs). However, the relationship between molecular structure, properties and feasible LTPU applications still lacks in the literature. Aiming to overcome this absence, kraft lignin was chemically modified by partial acetylation in order to reduce the reactive sites and avoid the formation of a highly cross-linked structure. The extent of the functionalization reaction was properly investigated by Fourier transformed infra-red spectroscopy (FTIR-ATR) and quantitative 31P nuclear magnetic resonance analysis and the results revealed that the hydroxyl content from the parental lignin could be reduced by half in a controlled manner. In the second stage of this research, lignin-based thermoplastic polyurethanes (LTPUs) were successfully synthesized using the partially acetylated Kraft lignin macromonomer as the polyol to form a stable and thermo-formable polymer. The effect of lignin content, soft segment molecular weight, and the NCO:OH ratio on chemical, thermal, and mechanical properties were investigated. At last, LTPUs were applied as hot-melt adhesive for wood and their mechanical behavior evaluated by single lap shear tests. The results elucidated how those parameters influence LTPU properties and might be used as a design tool to tune LTPUs properties, supporting the development of industrial LTPU application.

Comparative otolith morphology and species identification of clupeids from Japan

The amount of interspecific and ontogenetic variation in otolith shape among clupeid fishes from Japan was investigated to create a key to identify otoliths of these species found in the stomach contents of piscivorous predators, fossiliferous beds, and archaeological sites. The interspecific comparison with 12 species (Clupea pallasii, Etrumeus micropus, Herklotsichthys quadrimaculatus, Ilisha elongata, Konosirus punctatus, Nematalosa come, Nematalosa japonica, Sardinella aurita, Sardinella melanura, Sardinella zunasi, Sardinops melanostictus, and Spratelloides gracilis) revealed morphological variation in otolith shape, OL:OH and AL:RL ratios, rostrum, marginal structures, and features of the crista superior. Intraspecific changes were analyzed in two species (E. micropus and S. melanostictus), revealing ontogenetic changes in OL:OH ratio and consequently otolith shape as well as changes in marginal features. Overall, this study shows that the key morphological features can be used as diagnostic features for identification of clupeid otoliths.