Degree Of Charring Research Articles

Development of a Supervised Learning Model to Predict Permeability of Porous Carbon Composites

Predicting the permeability of porous thermal protection system (TPS) materials is essential for understanding their performance during high-speed entry. High-fidelity formulation of Klinkenberg permeability for TPS materials is intractable because unique parameters are needed at each temperature, for various gaseous species, and at every stage of decomposition of resin in the porous material. A supervised learning model based on support vector machine is developed to predict the permeability of TPS materials and is found to be a robust technique to capture the complex relationship between temperature, average pressure, porosity, and permeability of the material. The ability of different gaseous species to permeate through the material is captured through the supervised learning model by constructing an input variable called species identifier, which relates the molecular weight and viscosity of the gaseous species. The model is also extended to capture the permeability of the full composite, which includes both the fibers and the resin. It is demonstrated that the new model captures the nonlinear relationship between permeability and degree of char during the decomposition of the resin in the porous material. The supervised learning model of the physical simulations offers a robust approach for predicting permeability of porous materials in both continuum and noncontinuum flow regimes.

Chemical Characterization of Waterlogged Charred Wood: The Case of a Medieval Shipwreck

In 2008, a medieval wooden shipwreck was discovered at the port of Rhodes, Greece. The shipwreck was party burned, presenting a challenge for conservators, as uncharred, semi-charred and charred waterlogged wood were often encountered on the same piece of timber. In seeking the most appropriate conservation method for this unusual material, its chemical characterization was considered necessary. This study examined the chemistry of the three dominant wood conditions found in the wreck. Fourier transform infrared spectroscopy and X-ray diffraction analysis were implemented in comparison to reference samples. Energy dispersive analysis was also used for assessing the inorganic composition of each condition. Moreover, for charred and semi-charred wood, proximate analysis was undertaken. Results obtained regarding the organic moieties of the waterlogged archaeological material, demonstrated that charred samples were chemically comparable to charcoals, semi-charred material showed similarity to thermally modified wood, whereas uncharred waterlogged wood was proven to have an analogous chemistry to biodeteriorated wood. Elemental analysis results also diversified among the three shipwreck’s conditions. Sulfur, iron, and oxygen decreased in charred areas, whereas carbon increased. Proximate analysis showed that ash and fixed carbon content increased with charring, whereas volatile mater decreased. This work proved major chemical differences among shipwreck timbers’ conditions owing to different degree of charring. These are anticipated to influence not only conservation methods’ efficacy, but also the post-treatment behavior of the material. Further investigation is needed for correlating the chemistry of the archaeological material to its physical properties in order to contribute to practical aspects of conservation.

Comparative analysis of extraction methods in distilled drinks production

The paper presents the results of studying the extraction process in the technology of distilled drinks production at the stage of their aging with the use of oak chips, which reduces the duration of the technological process and reduces technological losses. At the engineering center “FOOD ENGINEERING” of Kemerovo State University, two extraction methods were selected for studying: 1) using a batch extractor for the “solid - liquid” system with exposure to oxygen, and 2) extraction based on the effects of microwave radiation. A comparative analysis of these processing methods has shown that the method of exposure to oxygen is more effective, taking into account the increase in optical density. The degree of oak chip charring was found to affect the color of the product significantly. Microwave radiation contributes to a more intensive accumulation of polyphenols, especially while using the chips with strong charring. When exposed to oxygen, the degree of charring had little influence on the content of polyphenols; still, exposure to oxygen intensified the process of phenolic compound extraction. The content of extractive solid compounds is higher in the samples exposed to oxygen and microwave radiation compared to the control sample, with little difference between different varieties of oak chips. In this regard, it has been planned to conduct further studies of the joint effect of these intensification methods on the extraction process.

BROADLEAVED TREE TRUNKS CHARRING DURING FOREST FIRES WITHIN THE UKRAINIAN ROZTOCHYA

Introduction. On the territory of Ukrainian Roztochya and Male Polissya (Zhovkva part of Roztochya included) fires often occur in natural ecosystems – forest fires, meadow vegetation burning, stubble, landfills, and peatlands. Such fires, in addition to the destruction of property, cause significant emissions of incomplete combustion products and smoke into the air. Charring of broadleaved species, along with conifers, needs more detailed research, as the territory of the Ukrainian Roztochya is dominated by hornbeam-oak-pine, mixed oak, and beech forests.Aim. The object of the paper is to investigate the degree of tree trunks charring of the main forest-forming species in the Ukrainian Roztochya during forest fires based on experimental data.Research methods. Freshly cut trees were exposed to heating for 10 minutes, at periods of 1 minute, 3, and 5 minutes, checking the degree of damage to the trunk (charring, mm). Repeatability of the experiment – three times. Basing on received data the charring of broadleaved tree trunks in the Ukrainian Roztocze was determined. The flame temperature was measured by a GM1150A non-contact pyrometer. The level of burnout was measured by a ruler made following GOST 17435-72. A stopwatch was used to record the time of burning. Results and discussion. The experiments were performed in the fresh air under close-to-natural conditions. The fire source was an artificial open flame. Freshly cut tree trunks were installed vertically, right in the burning zone. Cutting residues, fallen dry leaves, straw, dry grass was used as flammable material. It was found that the lowest degree of charring is inherent to oak, which has burned by 38 mm during 10 minutes (with log thickness of 124 mm). Species such as hornbeam and maple completely burned out in 10 minutes (in diameters of 129 mm and 140 mm).Conclusions. Investigations of temperature effects on the main forest-forming species of the region have shown that they all differ in charring during forest fires. Three species grown in Ukrainian Roztochya were selected – hornbeam (Carpinus betulus), oak (Quercus robur), and maple (Acer platanoides). To prevent fires in forests, fire lanes should be planned with oak plantations on the edge of the forest.

Optimization of Parameters for the Cutting of Wood-Based Materials by a CO2 Laser

This article deals with the laser cutting of wood and wood composites. The laser cutting of wood and wood composites is widely accepted and used by the wood industry (due to its many advantages compared to, e.g., saw cutting). The goal of this research was to optimize the cutting parameters of spruce wood (Pices abies L.) by a low-power CO2 laser. The influence of three factors was investigated, namely, the effect of the laser power (100 and 150 W), cutting speed (3, 6, and 9 mm·s−1), and number of annual rings (3–11) on the width of the cutting kerf on the top board, on the width of the cutting kerf on the bottom board, on the ratio of the cutting kerf width on the top and bottom of the board, on the width of the heat-affected area on both sides of the cutting kerf (this applies to the top and bottom of the board), and on the degree of charring. Analysis of variance (ANOVA) and correlation and regression analysis were used for developing a linear regression model without interactions and a quadratic regression model with quadratic interactions. Based on the developed models, the optimization of parameter settings of the investigated process was performed in order to achieve the final kerf quality. The improvement in the quality of the part ranged from 3% to more than 30%. The results were compared with other research dealing with the laser cutting of wood and wood composites.

Effects of Pyrolysis Atmosphere and Temperature on Coal Char Characteristics and Gasification Reactivity

AbstractCoal chars are usually produced under complex atmospheres in industrial production. However, most of the research about char characteristics and gasification reactivity uses the coal char samples prepared under an inert atmosphere. In this study, the influences of the pyrolysis atmosphere and temperature on coal char characteristics and gasification reactivity were investigated. A Shanxi bituminous coal was pyrolyzed in a bubbling fluidized bed to produce char samples. A mixture of hydrogen (H2), carbon dioxide (CO2), carbon monoxide (CO), and methane (CH4) was used as simulated pyrolysis gas (SPG). The coal was pyrolyzed in the SPG and N2 atmospheres, respectively. SEM, Raman spectroscopy, and FTIR spectroscopy were used to study the influences of the pyrolysis atmosphere and temperature on the coal char characteristics. The char–H2O and char–CO2 gasification reactivities were measured by using a modified thermogravimetric analysis (TGA) system. The experimental results indicate that the SPG atmosphere has no obvious influence on the coal char morphology, but it has significant influences on the carbon structures and surface chemical groups. The SPG char samples have lower gasification reactivity. The disproportionation reaction of CO, the decomposition reaction of CH4, and the loss of oxygen‐containing structures induced by H2 lead to a higher‐ordered degree of char, and the graphite generated from the disproportionation reaction and the decomposition reaction can decrease the specific surface area of the coal char. These two reasons result in the lower gasification reactivity of SPG char.

An Emerging Complimentary Medicine-Yolk Oil Made from Heating Method

Yolk oil is common in Asia. According to the Flora Sinensis, yolk oil is a multipurpose medicine, with specific dermatological and fever indications. Nowadays, it is generally used as a complimentary medicine for heart diseases. Yolk oil can be made from heating or chemical extraction method. It is generally believed that yolk oil made from heating (YOheat) method is more effective as a medicine than that from extraction (YOext). The technical details of the heating method remain an issue of argument, including the degree of char and the threat of carcinogens formed during the heating process. Most yolk oil related studies used YOext as research material. Nevertheless, animal studies have showed that YOheat reduced triglycerides and total cholesterol in rodent liver. It is expected an easy-to-make complimentary medicine like YOheat may become even more common and thus evidence based studies should be conducted to verify its pharmacological effects and safety.

Direct Current Combined With Bipolar Radiofrequency Ablation: An Ex Vivo Feasibility Study

The combination of radiofrequency ablation (RFA) with direct current (DC) is a promising strategy to improve the efficiency of RFA. However, DC-enhanced monopolar RFA is limited by electrolytic injury at the positive-electrode site. The aim of this study was to investigate the feasibility of the DC-enhanced bipolar RFA. To obviate the need for the subcutaneous positive electrode, the DC circuit was combined with a commercially available bipolar RFA system, in which both poles of the DC circuit are connected to a single RF probe. DC was applied for 15 min and followed by RFA in bovine livers using the following various DC currents: (1) no DC (control), (2) 3V continued until the end of RFA, (3) 5V continued until the end of RFA, (4) 10V continued until the end of RFA, (5) 5V continued in the circuit with reversed pole, (6) 3V stopped after initiation of RFA, and (7) 5V stopped. Coagulation volume, temperatures at a distance of 5, 10, and 15 mm from the RF probe, mean amperage, ablation duration, applied energy, minimum impedance, and degree of tissue charring were assessed and compared (analysis of variance, Student-Newman-Keuls test). All combined DC and RFA groups did increase coagulation volume. The 10V continued group showed significantly lower applied energy, shortest ablation duration, highest minimum impedance, and highest degree of charring with the lowest coagulation volume (p<0.05). DC-enhanced bipolar RFA with both poles of the DC circuit on a single probe appears to be ineffective.

Nature and reactivity of charcoal produced and added to soil during wildfire are particle-size dependent

Charcoal added to soil by wildfires is usually considered to be part of the most stable pool of soil organic matter (SOM). It consists of a continuum of slightly burned plant residues to completely charred material. We sampled the macroscopic charcoal pool produced by a moderate intensity wildfire in a pine coastal forest in Tuscany (Central Italy) with the aim of assessing the relationship between its particle size and chemical composition as well as its reactivity. Our conceptual approach included particle size separation by dry sieving and analysis of four size fractions (>2 mm, 2–1 mm, 1–0.5 mm and <0.5 mm) for elemental composition. The composition of the charcoal fractions was studied using solid-state 13C nuclear magnetic resonance (NMR) spectroscopy, diffuse reflectance Fourier transform infrared (DRIFT) spectroscopy, analytical pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) and CuO oxidation. The reactivity of the fractions was assessed using acid dichromate oxidation, while the morphology was observed using scanning electron microscopy (SEM). There were clear differences in chemistry and reactivity between the fractions. The different fractions are probably the result of both type of original plant material and the fire conditions. In fact, wood-derived charcoal largely prevalent in the largest fraction, while pine needles and herbs were most probably precursors of charcoal in the smallest fractions. The degree of charring was greatest for the coarse fraction, which represented 56% of the total charcoal, and decreased gradually to the finest fraction. The composition was completely aromatic for the coarsest fraction, whereas the finest fraction showed a greater contribution from aliphatic C- and N-containing components. The greatest reactivity was found for the smallest fraction, which represented 24% of the total charcoal. It is particularly rich in N and potentially susceptible to microbial decomposition. The study demonstrates that properties of charcoal added to soil during wildfires may be reliably discriminated on the basis of particle size.

Charring of woods by volcanic processes: An example from the Taupo ignimbrite, New Zealand

One of the most violent and explosive eruptions in historic times was that of the Taupo volcano in New Zealand 1800 years ago. This culminated in emplacement of the Taupo ignimbrite, laid down by a single vent-generated pyroclastic density current that entombed and preserved abundant plant material. The ignimbrite consists of two layers, generated by processes within the concentrated part of the density current (flow, sensu stricto) and where the current interacted with the atmosphere and the pre-eruptive vegetative cover. Eighty-four wood samples were collected from eight localities representing both layers, at varying distances from the vent, including the previously described Pureora Fossil Forest. Samples were studied by light, scanning electron and reflectance microscopy in order to determine their systematic affinity (angiosperm or conifer), degree of charring and reflectance values. Most samples (59) were conifer, probably derived from podocarps that are known to have been common in the pre-eruptive vegetation. Samples ranged from uncharred, through incompletely charred to fully charred woods. The variation in degrees of charring and reflectance values implies that the entrained charcoal did not equilibrate with the flow temperature. Minimum charring temperatures, interpreted from the mean of the three highest maximum reflectance values, showed no major differences between ignimbrite layers and were generally low, ranging from 269 to 398 °C. Both ignimbrite layers also show a trend of increasing deposit temperature away from the vent, consistent with estimates from palaeomagnetic techniques.

Determination of T1 ρH Relaxation Rates in Charred and Uncharred Wood and Consequences for NMR Quantitation

The performance of three different techniques for determining proton rotating frame relaxation rates ( T 1 ρ H ) in charred and uncharred woods is compared. The variable contact time (VCT) experiment is shown to over-estimate T 1 ρH , particularly for the charred samples, due to the presence of slowly cross-polarizing 13C nuclei. The variable spin (VSL) or delayed contact experiment is shown to overcome these problems; however, care is needed in the analysis to ensure rapidly relaxing components are not overlooked. T 1 ρH is shown to be non-uniform for both charred and uncharred wood samples; a rapidly relaxing component ( T 1 ρH =0.46–1.07 ms) and a slowly relaxing component ( T 1 ρH =3.58–7.49) is detected in each sample. T 1 ρH for each component generally decreases with heating temperature (degree of charring) and the proportion of rapidly relaxing component increases. Direct T 1 ρH determination (via 1H detection) shows that all samples contain an even faster relaxing component (0.09–0.24 ms) that is virtually undetectable by the indirect (VCT and VSL) techniques. A new method for correcting for T 1 ρH signal losses in spin counting experiments is developed to deal with the rapidly relaxing component detected in the VSL experiment. Implementation of this correction increased the proportion of potential 13C CPMAS NMR signal that can be accounted for by up to 50% for the charred samples. An even greater proportion of potential signal can be accounted for if the very rapidly relaxing component detected in the direct T 1 ρH determination is included; however, it must be kept in mind that this experiment also detects 1H pools which may not be involved in 1H– 13C cross-polarization.

Temperature and time effects on mutagen production in cooked lamb meat.

Basic extracts isolated from lamb meat treated at various temperatures were tested for mutagenicity in Salmonella typhimurium strain TA98 in the presence of S9 mix. Samples of ground lamb patties were cooked for 10 min per side at 100, 150, 200, 250 and 300 degrees C. Low cooking temperatures resulted in products with low levels of mutagenicity. At temperatures greater than 150 degrees C the mutagenic activity of the cooked meat increased to reach a maximum at 300 degrees C. In another series of experiments, lamb patties were cooked at 250 degrees C for 2, 4, 6, 8, 10 and 12 min. Short cooking times (rare products) caused no mutagenic activity and uncooked ground meat showed no activity. Prolonged cooking appeared to increase the mutagenicity of the products with a maximum value at 10 min. The results indicate that the formation of mutagens depends on both cooking temperature and cooking time. The level of mutagenicity tends to increase with the degree of charring.