Self-ignition temperature of the dust accumulations for sunflower and wood powders

Spontaneous combustion is a phenomenon that results from the heating of combustible organic powders by slow oxidation and which occurs through the air passage (created by an air depression) through the mass of dust. The oxidation phenomenon of combustible powders represents their reaction with atmospheric oxygen resulting in products of carbon dioxide, carbon oxide, water and other gases whose content depends on the temperature at which the oxidation takes place. The self-ignition of combustible dusts depends on their chemical composition, the properties of component substances, on the particle size and geometry of the material mass and, last but not least, on the temperature of the environment. Due to global worries of sustainability in construction engineering the trend is to use ecofriendly organic waste to various purposes as in construction materials. The challenge is that by using this kind of materials one should ensure the safety related to the process of such organic materials which are known to have combustible properties. The purpose of this work is to present the self-ignition behavior of combustible dusts such as sunflower and wood by means of drying tests under constant temperature conditions.

Diels–Alder Cycloaddition with CO, CO2, SO2, or N2 Extrusion: A Powerful Tool for Material Chemistry

Phenyl, naphthyl, polyarylphenyl, coronene, and other aromatic and polyaromatic moieties primarily influence the final materials’ properties. One of the synthetic tools used to implement (hetero)aromatic moieties into final structures is Diels–Alder cycloaddition (DAC), typically combined with Scholl dehydrocondensation. Substituted 2-pyranones, 1,1-dioxothiophenes, and, especially, 1,3-cyclopentadienones are valuable substrates for [4 + 2] cycloaddition, leading to multisubstituted derivatives of benzene, naphthalene, and other aromatics. Cycloadditions of dienes can be carried out with extrusion of carbon dioxide, carbon oxide, or sulphur dioxide. When pyranones, dioxothiophenes, or cyclopentadienones and DA cycloaddition are aided with acetylenes including masked ones, conjugated or isolated diynes, or polyynes and arynes, aromatic systems are obtained. This review covers the development and the current state of knowledge regarding thermal DA cycloaddition of dienes mentioned above and dienophiles leading to (hetero)aromatics via CO, CO2, or SO2 extrusion. Particular attention was paid to the role that introduced aromatic moieties play in designing molecular structures with expected properties. Undoubtedly, the DAC variants described in this review, combined with other modern synthetic tools, constitute a convenient and efficient way of obtaining functionalized nanomaterials, continually showing the potential to impact materials sciences and new technologies in the nearest future.

Comparative Analysis of the Complete Mitochondrion of Chlorophytum Comosum with 9 Other Species

Chlorophytum comosum belongs to genus Chlorophytum of family Asparagaceae that has more than 215 species. it is among 120 plant species assayed for phytoremediation of pollutants from indoor air. It has the ability to remove formaldehyde, nitrogen dioxide, carbon oxide, ozone, benzene, toluene, cigarette smoke and ammonia. It also is an important Chinese tradition medicine material. Aim to get more information about its mitochondrial genome, we sequenced the complete mitochondrial genome of C. comosum. The length of mitochondrial genome was 950316 bp with 36 protein coding genes, 5 rRNAs and 21 tRNAs. Although it has the biggest mitochondrial genome, the total PCGs content were the second least. C. comosum had the most repeats sequence and it may effect the size of mitochondrial genome, but base the result we found that the quantity of repeats sequence could not have the positive correlation with the mitochondrial size. Compared with other 9 species , we found in the mitochondrial genome of C. comosum, there were at least one PCGs suffered from the positive selection after divergence. Finally, the result of phylogenetic showed that C. comosum did not have colesd relationship with other species.

Assessment of The Renewable Energy Offshore and Wind Energy Markets Affects During The COVID-19 Virus

The main aims of the current study are to determine during the COVID-19 epidemic effects on renewable and green energy and control the raising the cost of utilizing renewable energy to power for country energy plants using the Levelized Cost of Energy methods. Objective 1) The COVID-19 pandemic can be provided through green financial policies such as coal pricing, transferable green certificates, and loans for renewable energy markets. Objective 2) examined the cost of offshore wind power in china before and after the COVID-19 outbreak, using data from 100 offshore wind power projects constructed between 2000 and 2020. Based on results, wind power's fixed average cost of electricity fell from 0.98 Chinese yuan in 2000 to 0.79 Chinese RMB in March 2019, and subsequently to 0.75 Chinese RMB in 2020, a 13.99 percent increase. Other results average electricity generation price down to 0.79 RMB, 0.99 RMB, and 0.79 RMB and average carbon oxide emissions was 50 RMB/ton increase. The green fiscal policies will be required during the COVID-19 epidemic to promote offshore wind energy generation investment.

Reactivity Model as a Tool to Compare the Combustion Process in Aviation Turbine Engines Powered by Synthetic Fuels

The paper aims to verify the thesis that the reactivity model, developed in earlier research, can be used to compare the fuels combustion processes in turbine engines, which is important for predicting the behavior of different alternative fuels in combustion process. Synthetic blending components from alcohol to jet and hydroprocessed esters and fatty acids technologies and their blends with conventional jet fuel were used in tests. The undertaken laboratory tests reveal the differences between the properties of the tested fuels. Bench tests were carried out on a test rig with a miniature turbojet engine, according to authorial methodology. For each blend, on selected points of rotational speed the carbon oxide concentration in the exhaust gases was recorded. The obtained results allowed the formulation of empirical power functions describing relations between carbon oxide concentration and fuel mass flow rate. Based on general assumptions, the reactivity model was adopted to compare the combustion processes of the different fuels in turbine engines. The directions of further research on the development of the proposed model were indicated.

Identification of Priority Air Pollutants in Confined Spaces

Introduction: Owing to the rapid development of digital technologies, most people nowadays are working indoors while using no machinery or equipment and being unexposed to volatile industrial chemicals. Yet, people staying inside for too long often complain of poor indoor air quality and microclimate. Our objective was to study air pollutants in a simulation experiment with continuous human occupancy inside unventilated confined spaces. Materials and methods: Up-to-date sensitive analytical techniques, such as photoionization, laser nephelometry, gas-phase chemiluminescence, spectrophotometry, high-performance liquid chromatography with diode array detection (HPLCDAD) and gas chromatography–mass spectrometry (GC-MS), were used to determine indoor air pollutants. Results: We compared changes in airborne concentrations of nitrogen oxides, prop-2-enenitrile, acetaldehyde, benzene, but-2-enal, airborne particulate matter (PM2,5 and PM10), methylbenzene, 2-methylbuta-1,3-diene, formaldehyde, prop-2-en-1-al, carbon oxide and dioxide following 1.5, 3.0, and 4.5 hours of stay of volunteers in a 15.9 m2 room (4.0 m2 per person; a 2.55 m ceiling height) against background levels. The established human occupancy-related priority pollutants included acetaldehyde, formaldehyde, prop-2-en-1-al, and carbon dioxide. Laboratory testing showed the presence of 83 volatile and semivolatile organic chemicals in the unventilated room, among which aromatic hydrocarbons, esters and aldehydes prevailed. Conclusion: Our findings could be useful for designing ventilation systems in confined spaces and optimizing the workbreak schedule during the working hours.