Volatile Yield Research Articles

Development of a comprehensive theoretical and experimental methodology for evaluating the parameters of recycling by pyrolysis of plastic based on polycarbonate and polyethylene

The results of thermogravimetric and Fourier transform infrared (FTIR) analysis of polymer composite materials (PCM) based on polyethylene and polycarbonate are presented and compared to the polymers polyethylene and polycarbonate. Empirical data were obtained for mathematical modeling, including the amount of solid residue upon pyrolysis, volatile yield, and ash content of the studied PCMs and polymers. Results of the mathematical modeling of the pyrolysis process at a temperature of 600 °C are presented to quantitatively assess the composition of the pyrolysis gas.

Trade can buffer climate-induced risks and volatilities in crop supply

Abstract Climate change is intensifying the frequency and severity of extreme events, posing challenges to food security. Corn, a staple crop for billions, is particularly vulnerable to heat stress, a primary driver of yield variability. While many studies have examined climate impact on average corn yields, little attention has been given to the climate impact on production volatility. This study investigates the future volatility and risks associated with global corn supply under climate change, evaluating the potential benefits of two key adaptation strategies: irrigation and market integration. A statistical model is employed to estimate corn yield response to heat stress and utilize NEX-GDDP-CMIP6 climate data to project future production volatility and risks of substantial yield losses. Three metrics are introduced to quantify these risks: Sigma (σ), the standard deviation of year-on-year yield change, which reflects overall yield volatility; Rho (ρ), the risk of substantial loss, defined as the probability of yield falling below a critical threshold; and Beta (β), a relative risk coefficient that captures the volatility of a region's corn production compared to the globally integrated market. The analysis reveals a concerning trend of increasing year-on-year yield volatility (σ) across most regions and climate models. This volatility increase is significant for key corn-producing regions like Brazil and the United States. While irrigated corn production exhibits a smaller rise in volatility, suggesting irrigation as a potential buffer against climate change impacts, it is not a sustainable option as it can cause groundwater depletion. On the other hand, global market integration reduces overall volatility and market risks significantly with less sustainability concerns. These findings highlight the importance of a multidimensional approach to adaptation in the food sector. While irrigation can benefit individual farmers, promoting global market integration offers a broader solution for fostering resilience and sustainability across the entire food system.

Development of an Untargeted Method for the Analysis of the Volatile Profile of Onions via Solid-Phase Microextraction Arrow-Headspace-Gas Chromatography-Mass Spectrometry Using Design of Experiments.

The distinctive aroma of onions, consisting primarily of sulfur-containing compounds, is one of the reasons for the popularity of the vegetable. The rapid enzymatic and chemical reactions that occur after the destruction of onion bulb tissue render the analysis of the volatile profile challenging. Therefore, sample preparation is a crucial step in the analysis of the onion volatilome, but it often does not receive the necessary attention in the literature. In this work, we focused on two aspects: Firstly, we compared different sample preparation approaches to maximize the volatile yield and to enable the description of the onion volatile profile as it would emerge after a solid-phase microextraction (SPME) Arrow sampling procedure. For headspace (HS)-gas chromatography-mass spectrometry analysis, onion juice with the addition of an ammonium sulfate solution proved to be the best option. Secondly, we optimized the HS sampling and desorption parameters (enrichment time, enrichment temperature, agitator speed, desorption time) for onion volatiles using the efficient design of experiments (DoE) approach. The optimal conditions for the analysis with HS-SPME Arrow were an enrichment time of 75min at 60°C with an agitator speed of 713rpm and a desorption time of 120s.

Is the volatility of yields for major crops grown in Germany related to spatial diversification at county level?

Abstract Recent evidence suggests a stabilizing effect of crop diversity on agricultural production. However, different methods are used for assessing these effects and there is little systematic quantitative evidence on diversification benefits. The aim of this study was to assess the relationship between volatility of combined crop yields (denoted as standard deviation) and diversity (denoted as Shannon’s Evenness Index SEI) for standardized yield data of major crop species grown in Germany between 1977 and 2018 (winter wheat, winter barley, silage maize and winter rapeseed) at the county level. Portfolio theory was used to estimate the optimal crop area share for minimizing yield volatility. On average, results indicated a weak negative relationship between volatility and the SEI during the past decades for the case of Germany. Optimizing crop area shares for minimizing volatility reduced yield variance on average by 24 % but was associated with a decrease in SEI for most counties. This was related to the finding that the stability of individual species, i.e., barley and wheat, was more effective in reducing the volatility of combined yields than the asynchronous variation in annual yields among crops. Future studies might include an increased number of crop species and consider temporal diversification effects for a more realistic assessment of the relation between yield volatility and crop diversity and test the relationship in other regions and production conditions.

Microwave vacuum pyrolysis rapidly transforms bamboo into solid biofuel: Predicting fuel performances by response surface methodology

Microwave vacuum pyrolysis presents significant advantages in biochar refining and industrial upgrading. In this study, bamboo charcoal (BC) was produced rapidly by microwave vacuum pyrolysis, the microwave pyrolysis and conventional pyrolysis characteristics of bamboo were compared, and the potential of response surface methodology (RSM) to predict the fuel performances was investigated. The results indicated that microwave pyrolysis significantly reduced the heating time, and also effectively lowered the threshold of thermal decomposition reaction. Besides, as the microwave power and radiation time rose, the fixed carbon, ash, higher heating value, energy density, and fuel ratio of BCs increased, while the yield, H/C, O/C, volatile, and energy yield decreased. The quadratic models have high correlation coefficients for these characteristics, which can be used for the prediction of subsequent BCs production. When the microwave power was 1666 W and the radiation time was 13.3 min, the prepared BC exhibited the highest yield while maintaining a fixed carbon content of over 85 %. This research provided a green way for the transformation and upgrading of BCs industry, and also showed that the most cost-effective production strategy can be formulated through RSM.

Coal chemistry, utilization potential, and coalbed methane (CBM) assessment of some coal deposits in Central Benue Trough, north-central Nigeria

Coalbed methane (CBM), a current global legislative priority for climate change mitigation, is an unconventional and eco-friendly clean source of energy that is considered a veritable alternative to conventional fossil fuels. Despite its overwhelming advantages, CBM evaluation studies of Nigerian coals have received little or no attention. To bridge the gap in knowledge, we have for the first time in Jangwa-Shankodi and Lafia-Obi, described the potential of harnessing CBM for its gainful utilization in Nigeria using some coal deposits in its north-central region as a case study. The gas contents of the coals were determined empirically by taking account of their ultimate and proximate properties. Other coal parameters such as fuel ratio and vitrinite reflectance (Ro (%)) have also been computed and discussed. Proximate analyses of the studied coal samples show moisture contents that vary between 2.28 and 2.56%, whereas, volatile matter yield is placed in the range of 29.98–30.34%. Ash yield ranges from 7.83 to 8.64%. Fixed carbon content varies from 55.97 to 56.30%. Variation in fuel ratio shows a restricted range from 1.72 to 1.87. All the coal samples were found to be low in sulphur (< 1%) with H/C ratios that vary from 0.072 (LAF 2, 3 and 4) to 0.086 (JSK 3). Moreover, the coals were found to be of medium-volatile bituminous rank, with gas contents that range from 12.65 to 13.20 cc/g. In the current study, kerogen lies in the Type IV zone, which suggests the generation of methane gas by the studied coal samples. Also the estimated range of vitrinite reflectance (Ro) which varies between 1.073% and 1.086% indicates thermogenic gas expulsion in the coals. There is a noticeable increase in gas content with coal maturity and depth. These values are indicative of good quality coals that show antecedents for CBM production. However, considering that this work is a pilot study, we recommend that core drilling be employed in obtaining insitu measurements of the coal gas contents and thus, verify these empirical estimates. Also, detailed laboratory study on pore structure (and its distribution) and adsorption isotherm curve are recommended to better understand the coal reservoir properties and hence, consolidate the present study.

Modeling volatility in dynamic term structure models

We propose no-arbitrage term structure models with volatility factors that follow GARCH processes. The models’ tractability is similar to canonical affine term structure models, but they fit yield volatility much better, especially for long-maturity yields. This improvement does not come at the expense of a deterioration in yield fit. Because of the improved volatility fit, the model performs substantially better in pricing Treasury futures options. We conclude that the specification of the volatility factors is critical. Modeling volatility as a function of (lagged) squared innovations to factors improves on models where volatility is a linear function of the factors.

Comparison of acid and hydrothermal pretreatments of date waste for value creation

The production of date syrup yields a substantial amount of date press cake (DPC), fibrous and moisturising material with great potential for generating value through bioprocessing. However, the recalcitrant structure of DPC affects the yield of products in bioprocesses. To boost the accessibility of the structure as well as increase the soluble fraction of carbohydrates and facilitate further enzymatic hydrolysis, hydrothermal and dilute acid (0.5% (v/v) sulfuric acid) pretreatments as cost-effective and feasible methods were applied on DPC at relatively low temperatures (80, 100, 120 and 140 °C) and reaction times (60 and 90 min). The success in pretreatment was then evaluated by a post-enzymatic treatment using an enzyme cocktail of cellulases and hemicelluloses. Based on total accessible sugar with minimum produced inhibitors, an optimal operating condition was considered acid pretreatment at 120 °C for 90 min with a 55.02% increase in total sugar yield. To explore the potential use of pretreated DPC, an anaerobic digestion was conducted on untreated and acid-pretreated DPC at 120 °C for 90 min. The results showed that pretreatment increased the total bioproduct yield, including hydrogen, ethanol, and volatile fatty acid yields, by 59.75%. This demonstrates the significant impact of pretreatment on product yields in a bioprocess.

Geochemistry of Middle Jurassic Coals from the Dananhu Mine, Xinjiang: Emphasis on Sediment Source and Control Factors of Critical Metals

In recent years, coal-type critical metal deposits have become a research hotspot in coal geology. As a major coal-accumulating basin in the Xinjiang area, the Turpan-Hami Basin contains abundant coal resources and has the potential to become a large coal-type critical metal deposit. However, previous studies on the enrichment characteristics of critical metal elements in coal are few and need further research. Based on SEM-EDS, XRF, and ICP-MS experiments, this study investigates the coal petrology, mineralogy, and geochemistry of the No. 22 coal of the Xishanyao Formation from the Dananhu Coal Mine, Xinjiang, to identify the sediment source, depositional environment, and controlling factors of the critical metal elements of the No. 22 coal. The results showed that the Dananhu coals are characterized by a low ash yield, low total sulfur content, high volatile yield, and high inertinite proportions. Quartz, kaolinite, and illite are the main minerals in the coal. Compared with the world’s low-rank coals, Ni, Co, Mo, and Ta are slightly enriched, Li, Rb, Cs, Ba, Tl, Bi, and Ge are depleted, and the concentrations of other trace elements are comparable to the average values of the world’s low-rank coals. The REY of the Dannanhu coals exhibited high fractionation, with its enrichment patterns characterized by the H-type and M-H-type. Although most of the critical metals are not enriched in the Dannanhu coals, the Ga, Zr (Hf), and Nb (Ta) concentrations in the coal ash of the Dannanhu coals have reached the economic cut-off grade and have the potential to be a substitute for rare metal resources. The terrigenous detrital sources of the Dannanhu coals mainly come from the Paleozoic dacite, andesite, and a small amount of granite from the Harik Mountain and Eastern Bogda Mountain in the Turpan-Hami Basin. The Dannanhu coals are generally in a dry and hot depositional environment, with high salinity and weak reduction-oxidation. The low source input and weak reduction-oxidation environment have resulted in low concentrations of critical metal of the No. 22 coal from the Dananhu Coal Mine.

Pore Size Distribution and Fractal Characteristics of Deep Coal in the Daning-Jixian Block on the Eastern Margin of the Ordos Basin.

Important breakthroughs have recently been achieved in deep coalbed methane (CBM) exploration and development in regions such as the eastern margin of the Ordos Basin, China. Investigating the development characteristics of various-scale pores in deep coalbeds is of great significance for resource assessment and selection of favorable zones for CBM exploration. Herein, six deep coal samples were selected from the Shanxi and Taiyuan Formations in the Daning-Jixian block on the eastern margin of the Ordos Basin. Low-pressure CO2/N2 adsorption (LP-CO2/N2GA) and high-pressure mercury intrusion (HPMI) methods were employed to analyze pore volume, specific surface area, and pore size distribution, thereby evaluating the full-scale pore characteristics. Furthermore, the fractal dimension characteristics of deep coal rock pores were elucidated, revealing the influence of pore structure, burial depth, and coal composition. The results indicate that micropores in deep coal rocks have the highest volume and specific surface area proportions, while mesopores have the smallest volume proportion, and macropores make the least contribution to the total specific surface area. The V-S, Frenkel-Halsey-Hill, and Sierpinski models were suitable for calculating the fractal dimensions of micropores, mesopores, and macropores with LP-CO2GA, LP-N2GA, and HPMI experimental data, respectively. Other than the relatively smaller mesopore fractal dimension of samples 20-8 and 20-10, the micropore, mesopore, and macropore fractal dimensions successively increased in the other four samples. The comprehensive fractal dimension, which exhibited a decreasing trend with increasing pore volume and specific surface area, was negatively correlated with burial depth, mineral and moisture contents, and ash and volatile component yields, while it was positively correlated with vitrinite and fixed carbon contents.

Catalytic Fast Pyrolysis of Tar-Rich Coal with a Bauxite Residue for Upgrading High-Value Products: Product Distribution and Kinetic Analysis.

Fast pyrolysis technology can reduce the secondary reactions, improve the volatile product yield, and reduce the semicoke yield. Still, the high proportion of heavy tar components affects the development of fast pyrolysis industrialization. Therefore, this paper put forward a catalytic upgrading method of coal based on the solid waste bauxite residue (BR) as a catalyst. This study investigated the impact of varying particle sizes of pulverized coal and the addition of the BR catalyst on the product distribution and kinetics of coal fast pyrolysis. The results found that the tar yield was the highest at 600 °C when the particle size of pulverized coal was 75-150 μm, which was 19.44%. In the range of 550-650 °C, the relative content of benzene and toluene xylene (BTX) in liquid products increased with the temperature. With the increase of the proportion of the BR catalyst, the yield of semicoke in coal pyrolysis products increased, the yield of the gas phase also increased, and the yield of the liquid phase decreased.

Mint-Scented Species in Lamiaceae: An Abundant and Varied Reservoir of Phenolic and Volatile Compounds.

This investigation aimed to identify the most favorable cultivar based on plant metabolites for potential targeted cultivation in the pharmaceutical industry. The analysis revealed the presence of 19 individual phenolics and 80 individual volatiles across the cultivars, a breadth of data not previously explored to such an extent. Flavones emerged as the predominant phenolic group in all mint-scented cultivars, except for peppermint, where hydroxycinnamic acids dominated. Peppermint exhibited high concentrations of phenolic acids, particularly caffeic acid derivatives and rosmarinic acid, which are known for their anti-inflammatory and antioxidant properties. Luteolin-rich concentrations were found in several mint varieties, known for their antioxidative, antitumor, and cardio-protective properties. Swiss mint and spearmint stood out with elevated levels of flavanones, particularly eriocitrin, akin to citrus fruits. Monoterpene volatiles, including menthol, camphor, limonene, and carvone, were identified across all cultivars, with Swiss mint and spearmint exhibiting the highest amounts. The study underscores the potential for targeted cultivation to enhance volatile yields and reduce agricultural land use. Notably, chocolate mint demonstrated promise for volatile content, while apple mint excelled in phenolics, suggesting their potential for broader agricultural, pharmaceutical, and food industry production.

Information Spillovers and Sovereign Debt: Theory Meets the Eurozone Crisis

Abstract We develop a theory of information spillovers in sovereign bond markets in which investors can learn about default risk before trading in primary and secondary markets. If primary markets are structured as multi-unit discriminatory-price auctions, an endogenous winner’s curse leads to strategic complementarities in information acquisition. Shocks to default risk in one country may trigger crisis episodes with widespread information acquisition, sharp increases in the level and volatility of yields in risky countries, low and stable yields in safe countries, market segmentation, and arbitrage profits between primary and secondary markets. These predictions are consistent with the dynamics of auction informativeness during the Eurozone Sovereign Debt Crisis, which we measure using the reaction of secondary market yields to primary market yields.

Comparative assessment of essential oil composition and yield in Cinnamomum tamala leaves upon application of different drying practices

ABSTRACT Cinnamomum tamala or Indian bay leaf is a widely used spice in the Asian subcontinent. The aim of this study was to assess the contents and composition of essential oils and volatiles internal pool in C. tamala leaves obtained from different drying practices such as, sun drying, freeze drying, shade drying and simultaneous oven drying at 60°C and 40°C, when compared with market-available dry leaves. Out of five different practices tested, leaves when oven dried at 60°C performed best in terms of free-radical scavenging capacities, internal pool of volatile contents (257.25 ± 37.57 μg/g of dried leaf tissue) and yields of essential oils (0.25%). This was followed by freeze-dried leaves, which showed 0.2% essential oils yield. Among the natural drying, sun dried leaves exhibited high yield of essential oils (0.16%). Performance of shade dried leaves was shown to be lowest i.e. 0.11% essential oils yield but was comparable with the yield of market-available leaves.

Volatility Connectedness of MOVE Index and Bond Returns

Research Originality: To the best of our knowledge, this is the first study which measures the impact of the MOVE index on bond yield volatility by comparing its effect on both short-term and long-term. The paper contributes to the existing literature by providing a better understanding of the relationship between maturity and volatility spillover. Research Objectives: This study examines the dynamic volatility connectedness between 2 and 10-year bond yields and the MOVE Index. Furthermore, it is aimed at detecting the transmitter of volatility among variables. Research Methods: Using a data set from 2010 to 2022, the study utilizes a Time-Varying Parameter Vector Autoregression (TVP-VAR) model to analyse the dynamics and relationship between bond yields and the MOVE Index. Empirical Results: The study finds a significant volatility spillover between the MOVE Index and Türkiye's bond yields. Notably, the linkage between the MOVE Index and the 10-year bond rates is stronger than with the 2-year rates. Additionally, the MOVE Index emerges as the primary transmitter of volatility, impacting both bond yields. Implications: This study sheds light on the complexity and dynamics of volatility spread in Türkiye's bond market, providing essential insights for forecasting bond yields and shaping financial policies.JEL Classification: G17, C22, G12How to Cite:Baykut, E., Gökgöz, H. (2024). Volatility Connectedness of MOVE Index and Bond Returns. Etikonomi, 23(1), 27 – 46. https://doi.org/10.15408/etk.v23i1.36131.

Research on the Volatility of China's Stock Market Returns Based on GARCH Model-Taking CSI 300 Index as an Example

The volatility of yields reflects the degree of risk in the market, and at the same time the volatility of yields is viewed as a measure of information, and high volatility is generally accompanied by large market information shocks. Therefore, it is particularly important to study the volatility of China's stock market returns so as to find out where the problems lie. In this paper, the CSI 300 index is taken as the research object, and a total of 2,671 daily closing prices from 4 January 2013 to 29 December 2023 are taken as the sample, and the GARCH family model is used to analyse this sample data, so as to derive the volatility characteristics of the CSI 300 index and to make static forecasts.

Effect of heating rate on the secondary reaction in low-rank coals pyrolysis with the real-time evolution analysis of in-situ tar

Performing online evolution analysis of tar in actual pyrolysis process is a major challenge. In this work, the effects of heating rate (HR) on evolution curves of in-situ tar for low-rank coals pyrolysis were investigated in a novel laboratory bench. The escape law of volatiles was obtained, the influence of HR on secondary reactions was analyzed, the association between products and molecular structures was constructed, and pyrolysis mechanism was deduced. Aliphatic hydrocarbons (except dienes), phenols, and oxygenated compounds have only one peak, while dienes and aromatics have multiple peaks throughout the pyrolysis process. The first peak is attributed to coal primary pyrolysis. At increased HRs, the second peak for 1∼2ring aromatics is from the cracking of primary volatiles, and that for 3∼4ring aromatics from coal continued cracking. The proportion of phenols and oxygenated compounds decreases, aromatics increases, and aliphatic hydrocarbons varies for different coals. Generally, HR increases the yield of primary volatiles by enhancing coal primary pyrolysis, elevates the proportion of light aromatics by promoting secondary cracking and aromatization of primary volatiles, reduces char yield by inhibiting condensation reactions throughout the pyrolysis process. The similar macromolecular structures of different coals make the evolution curve versus HRs follow a common law.

IMPROVING THE QUALITY OF EKIBASTUZ COAL USING THE DRY ENRICHMENT METHOD

This paper discusses the possibility of improving the ekibastuz coal quality through the use of "dry enrichment" technology. The experiments and calculations carried out made it possible to determine the optimal scheme for enrichment of samples of thermal coals from the Ekibastuzsky open-pit mineof "Angrensor-Energo" LLP. Testing of technical characteristics, such as moisture content, ash content, volatile matter yield and calculation of energy characteristics of enriched samples of thermal coal was carried out in 3 stages in a coal chemistry laboratory. As a result, it was found that the energy content of the enriched fuel samples increased to 28.5% of the original. This significantly improved consumer properties by obtaining the maximum yield of high quality coal concentrate. Consequently, the developed scheme of enrichment allows to significantly reduce the consumption of electricity, reduce emissions into the atmosphere, reduce the harmful impact on the environment, and expand the markets for coal.

Quantifying the impact of interest rate volatility on Asian energy companies: A comparative study of fossil and renewable sectors

This study examines the impact of government bond yield volatility on companies in the fossil and renewable energy sectors in five Asian countries from 2015 to 2023. The analysis uses quantile-based methods to explore the spillover effects of yield volatility on companies with high and low debt levels in these sectors. The findings show that yield volatility tends to transmit shocks at lower quantiles and over shorter periods. The network connectedness is more critical at extreme upper and lower quantiles in the short term. The results also reveal significant differences in how yield volatility affects companies with high and low leverage levels, and these effects vary across the sample countries. Overall, this research provides valuable insights into the influence of yield volatility on financial decision-making in different contexts and industries. The study's results underscore the imperative for policymakers and stakeholders in the energy industry to give precedence to improving risk management methods.

The influence mechanism of ionic liquids on the ash melting and combustion characteristics of Zhundong high-alkali coal

ABSTRACT This study investigated the ash reduction and quality improvement effects of four types of ionic liquids on Zhundong high-alkali coal, focusing on the evolution laws of coal ash melting and combustion performance under the ionic liquid system, which provided a theoretical basis for the subsequent utilization of high-alkali coal. Ionic liquids can effectively reduce inorganic mineral content and volatile matter yield, increase fixed carbon and oxygen content in coal, and reduce hydrogen and sulfur content. The silicon-aluminum ratio of coal ash increased, and the content of low-melting minerals in coal ash decreased, while the content of refractory minerals increased, leading to an increase in the melting temperature of coal ash. Ionic liquids can inhibit the oxidation reaction of coal, which is beneficial for suppressing spontaneous combustion of coal and improving safety during storage and transportation.