Temperature Range Research Articles

Oscillation rheometry of curing process of epoxy binders modified with polyetherimide

Objectives. The aim of this study is to ascertain the influence of polyetherimide on the curing process of epoxy binders.Methods. The storage modulus and loss modulus of epoxyamine systems were measured as a function of curing time on the Anton Paar MCR 302 rheometer. The experiments were carried out at an oscillation frequency of 1 Hz, with an amplitude aligned with the linear viscoelasticity region, and across a range of temperatures (160, 170, and 180°C). The crossover point was determined when the components of the complex modulus of elasticity are equal according to the obtained dependencies.Results. The influence of polyetherimide on the curing process of epoxyamine binders was investigated at a thermoplastic content of 5 to 20 pts. wt at three temperatures. In a system modified with 20 pts. wt of polyetherimide, phase separation was observed during the curing process. In systems modified with 10 and 20 pts. wt of polyetherimide, the limiting value of the modulus of elasticity was observed to be higher at 170°C than at 180°C.Conclusions. The modification of epoxyamine binders with thermoplastic in an amount of 5–20 pts. wt has been observed to extend the time required to reach the crossover point. Furthermore, the curing process markedly slows down in the system comprising 10 pts. wt of thermoplastic content, in which it takes the longest time to reach the crossover point at all three experimental temperatures.

Highly dispersed chromium(III) molybdate powders obtained by solid phase synthesis

Objectives. To obtain highly dispersed powders of chromium(III) molybdate Cr2(MoO4)3 by solid phase synthesis and to study their porous structure.Methods. After stirring in water, a mixture of Cr2O3 and MoO3 oxide powders was dried in air and subjected to heat treatment in the temperature range of 600–800°C. After heat treatment, the products were identified by X-ray phase and sedimentation analysis. The specific surface area was measured using the Brunauer–Emmett–Teller static adsorption method. Porosity parameters were measured using the Barrett–Joyner–Halenda (BJH) method.Results. The Gibbs free energy ΔG of the reaction between chromium and molybdenum oxides was calculated and it was shown that the process is characterized by a significant negative value of ΔG. Concurrently, the Gibbs energy exhibits a relatively weak dependence on temperature. The highly dispersed chromium(III) molybdate powders with specific surface area of 15.3–29.7 m2·g−1 obtained in this way were pure according to X-ray diffraction analysis. A study of the volume, diameter, and pore size distribution was conducted through the utilization of nitrogen adsorption–desorption isotherms in accordance with the BJH model.Conclusions. It was demonstrated that Cr2(MoO4)3 powders possess a mesoporous structure and are distinguished by a bimodal pore system comprising small pores with a diameter of 2–3 nm and larger pores with a diameter ranging from 15 to 30 nm.

Upcycling polynorbornene derivatives into chemically recyclable multiblock linear and thermoset plastics.

Synthetic polymers have found widespread use with functional lifetimes from seconds to decades. However, the lack of end-of-life treatment for these plastics is causing a significant environmental and human health crisis due to their persistence and bioaccumulation. Upcycling post-consumer plastic waste to products with inherent recyclability is an attractive strategy to tackle this problem, as it can broaden the range of accessible materials and uncover unprecedented features while dealing with current plastic waste. Here, we demonstrate the upcycling of polynorbornene derivatives (pNBEs) including polydicyclopentadiene (pDCPD) thermosets through their transformation into distinct oligomeric buildings blocks which can be repolymerized into chemically recyclable pNBEs-like multiblock linear and crosslinked plastics. These materials exhibit a diverse set of mechanical properties, while integrate a high melting transition temperature with a broad range of glass transition temperature, controlled by the feed ratio of building blocks. After use, upcycled plastics could be effectively deconstructed back to the oligomers for recovery and repolymerization. Overall, this work establishes an approach that can be utilized to upcycle pNBEs and pDCPD into previously inaccessible multiblock thermoset and thermoplastics with full recyclability, and may be generalizable to a range of polymers to shift their end-of-life waste disposal toward sustainable recovery and reuse.

Climate change influences on the potential geographic distribution of the invasive Asian longhorned tick, Haemaphysalis longicornis

The Asian long-horned tick, Haemaphysalis longicornis Neumann, 1901, is the competent vector for severe fever with thrombocytopenia syndrome virus (SFTSV). Haemaphysalis longicornis originated mainly in eastern Asia and invaded many areas like Australia, New Zealand, and the Pacific islands, and was recently introduced to eastern parts of the USA. This species is characterized by high adaptability to a wide range of temperatures and can reproduce parthenogenically under stressful conditions. Migratory birds are important hosts of H. longicornis and are thought to be responsible for its unexpected invasion and introduction into new areas worldwide. This study predicted the historical (near current) global environmental suitability and the possible shifts in environmental suitability for H. longicornis under the ongoing climate change between 2021 and 2100. The results demonstrated that Europe is at potential of high environmental suitability for H. longicornis invasion although this species has not been recorded in any regions of Europe yet. Our model also anticipated the environmental suitability for H. longicornis in eastern parts of the USA, although the recently recorded occurrences there were not used in the model calibration. Climate change is thought to affect and increase the range of suitable environments for H. longicornis. The different maps introduced in this study may help improve understanding of the global environmental suitability for this invasive disease vector and predict the areas at high environmental suitability for possible invasion to prioritize the control programs and enhance quarantine procedures in these areas.

The influence of temperature and pressure on the self-diffusion characteristics and mechanical sensitivity of DNTF: a molecular dynamics study.

3,4-Bis(3-nitrofurazan-4-yl) furoxan (DNTF) is a typical low-melting-point, high-energy-density compound that can serve as a cast carrier explosive. Therefore, understanding the safety of DNTF under different casting processes is of great significance for its efficient application. This study employed molecular dynamics simulations to investigate the effects of temperature and pressure on the self-diffusion characteristics and mechanical sensitivity of DNTF. The analysis focused on the mean square displacement, self-diffusion coefficient, cohesive energy density, non-bonded energy, and critical bond length of DNTF under various temperatures (250 to 450K) and pressures (0.1 to 10MPa). The results indicate that the self-diffusion coefficient and mechanical sensitivity of DNTF are more sensitive to changes in temperature. As the temperature increases, the self-diffusion behavior of DNTF accelerates, making it more volatile. This effect is particularly notable within the temperature range of 350 to 400K, where the growth rate of the self-diffusion coefficient is significantly faster than in the 250 to 350K range. The trigger bond length (Lmax) gradually increases with rising temperature, accurately reflecting the objective trend that mechanical sensitivity increases with temperature. The results of this study provide a theoretical basis for the application of DNTF in high-energy materials, particularly in enhancing its safety. An 8 × 4 × 2 supercell model comprising 256 DNTF molecules was constructed in the Materials Studio 8.0 package. The DNTF supercell was geometrically relaxed using the conjugate gradient method. Subsequently, a 10-ps NPT molecular dynamics simulation was conducted on the supercell under conditions of 300K and 0.1MPa to relieve internal stresses, thereby obtaining DNTF crystals in the equilibrium state. NPT molecular dynamics simulations of the DNTF supercell were then carried out under the COMPASS force field at constant temperature. The temperatures were set to 250K, 300K, 350K, 400K, and 450K, and the pressures were set to 0.1MPa, 1MPa, 3MPa, 5MPa, and 10MPa. The total simulation time was 1000ps with a time step of 1fs. Every 1000 steps, information on mean square displacement, non-bonded energy, intermolecular forces, and critical bond length was recorded.

Effect of Drying Temperature on Sensory Quality, Flavor Components, and Bioactivity of Lichuan Black Tea Processed by Echa No. 10

Lichuan black tea (LBT) is a well-known congou black tea in China, but there is relatively little research on its processing technology. Echa No. 10 is the main tea tree variety for producing LBT. This study investigated the sensory quality, flavor components, and bioactivity of Echa No. 10 Lichuan black tea (LBT) at different drying temperatures (70, 80, 90, 100, 110, 120, and 130 °C). During 80–120 °C, increasing the drying temperature enabled a higher sweet aroma concentration and enhanced the sweetness in the taste, in contrast to reducing the floral, fruity, and sweet aromas, and increasing the bitterness and astringency, at >120 °C. Additionally, with an increasing drying temperature, the contents of tea polyphenols and total catechins significantly decreased, with the theaflavins decreasing first and then increasing, and the alcohols, aldehydes, esters, and hydrocarbons increasing first and then decreasing. Meanwhile, compounds (including linalool, (Z)-linalool oxide (furanoid), (E)-linalool oxide (furanoid), cis-β-Ocimene, and methyl salicylate) contribute more to the floral and fruity aromas at <110 °C. Furthermore, low-temperature drying favors the antioxidant and inhibitory effects of the α-amylase, α-glucosidase, and glucose absorption activity. Both the tea quality and bioactivity results revealed 80–110 °C as the optimal drying temperature range for LBT.

Muscle and Metabolic Genes Are Differentially Expressed During Thermal Acclimation by the Brook Trout Myotome.

Cold-water fishes, such as Brook trout (Salvelinus fontinalis), are being challenged by the consequences of climate change. The ability of these fish to acclimate to warmer environmental conditions is vital to their survival. Acclimation to warmer water may allow brook trout to reduce the metabolic costs of higher temperatures. Previous work has shown that brook trout display a significant thermal acclimation response in their myotomal muscle, with slower contractile properties observed in warm acclimated fish. In this study, gene expression was examined in hatchery brook trout acclimated to a range in temperatures (4, 10 or 20°C). Brook trout displayed variations in gene expression in their myotomal muscle in accordance with acclimation temperature. Genes important for muscle function, cellular metabolism, protein degradation, and stress response showed variation to both warm (20°C) and cold (4°C) acclimation. The warm acclimated fish also showed decreased expression of genes associated with aerobic metabolism and increased expression of genes for heat shock proteins, while the cold acclimated fish showed increased expression of genes associated with lipid metabolism and protein turnover. α-tubulin displayed a close association with thermal acclimation, increasing in expression with acclimation temperature. The patterns of muscle gene expression were the opposite of what was expected. Although warm acclimated fish have previously been shown to display slow muscle contractile properties, this study found that warm acclimation is associated with increased expression of genes for kinetically faster isoforms of important muscle proteins. Collectively, the results demonstrate a robust response to elevated temperature in the hatchery fish greater than 10,000 genes showing differential expression with temperature. These results provide a roadmap for the analysis of the acclimation response of native populations of brook trout encountering climate change.

Development of a Nb‐Based Semiconductor‐Superconductor Hybrid 2DEG Platform

AbstractSemiconductor‐superconductor hybrid materials are used as a platform to realize Andreev bound states, which hold great promise for quantum applications. These states require transparent interfaces between the semiconductor and superconductor, which are typically realized by in‐situ deposition of an Al superconducting layer. Here a hybrid material is presented, based on an InAs 2D electron gas (2DEG) combined with in‐situ deposited Nb and NbTi superconductors, which offer a larger operating range in temperature and magnetic field due to their larger superconducting gap. The inherent difficulty associated with the formation of an amorphous interface between III‐V semiconductors and Nb‐based superconductors is addressed by introducing a 7 nm Al interlayer. The Al interlayer provides an epitaxial connection between an in‐situ magnetron sputtered Nb or NbTi thin film and a shallow InAs 2DEG. This metal‐to‐metal epitaxy is achieved by optimization of the material stack and results in an induced superconducting gap of approximately 1 meV, determined from transport measurements of superconductor‐semiconductor Josephson junctions. This induced gap is approximately five times larger than the values reported for Al‐based hybrid materials and indicates the formation of highly‐transparent interfaces that are required in high‐quality hybrid material platforms.

Electrolyte Chemistry Towards Ultra‐High Voltage (4.7 V) And Ultra‐Wide Temperature (−30 to 70 °C) LiCoO2 Batteries

AbstractLiCoO2 batteries for 3 C electronics demand high charging voltage and wide operating temperature range, which are virtually impossible for existing electrolytes due to aggravated interfacial parasitic reactions and sluggish kinetics. Herein, we report an electrolyte design strategy based on a partially fluorinated ester solvent (i.e., DFEA) that achieves a balance between weak Li+‐solvent interactions, sufficient salt dissociation, high interfacial stability, and superior thermal stability to address the aforementioned challenges. The resulting high‐voltage wide‐temperature electrolyte (HWE) not only possesses low desolvation energy, fast Li+ transport, high oxidation stability, excellent thermal‐abuse tolerance and non‐flammability, but also enables the formation of both inorganic‐rich cathode electrolyte interphase (CEI) and solid electrolyte interphase (SEI). Owing to the above merits, this HWE endows the highly stable operation of LiCoO2 cathodes under an ultra‐high voltage of 4.7 V and Graphite || LiCoO2 batteries in an ultra‐wide temperature range of −30 to 70 °C. Meanwhile, a 1.7 Ah‐level 4.6 V Graphite || LiCoO2 pouch cell with a high energy density of 240 Wh kg−1 also delivers excellent cycling stability, representing a significant advancement in the design of electrolytes towards ultra‐high voltage and ultra‐wide temperature batteries.

Effect of Ni–Bi Alloying on the Microstructure and Self‐Lubricating Properties of CoCrNi‐Based Coatings Across a Wide Temperature Range

This study investigates the use of bismuth (Bi) as a lubricating additive in laser cladding Co‐based composite coatings, addressing the issue of Bi segregation and agglomeration through Ni–Bi alloying. The microstructure, mechanical properties, and tribological properties of composite coatings with varying Ni–Bi contents are systematically evaluated at temperatures between 30 and 800 °C. Analysis reveals that Ni and Bi elemental powders are successfully alloyed to form BiNi and Bi3Ni intermetallic compounds following vacuum sintering. Incorporation of Ni–Bi alloying powder significantly enhances the friction coefficient and wear rates of the composite coating across the temperature range. Adhesive wear and abrasive wear are identified as primary wear mechanisms. Notably, the formation of BiNi, multiple oxides, and Bi16CrO27 compounds on the surface of the 85:15 (at%) Bi:Ni composite coating at 600 °C created a self‐lubricating friction layer, synergistically reducing friction. Consequently, compared to Co‐based alloy coatings without Ni–Bi alloying, the composite coating exhibited a three‐fold reduction in friction coefficient and a two‐order‐of‐magnitude improvement in wear rate, demonstrating exceptional tribological properties.

Heterologous Expression and Characterization of Estercin A, a Class II Lanthipeptide Derived from Clostridium estertheticum CF016, with Antimicrobial Activity against Clinically Relevant Pathogens.

Recent genome mining work revealed that unexplored habitats exhibit great potential for discovering new nonribosomal peptides (NRPs) and ribosomally synthesized and post-translationally modified peptides (RiPPs). Lanthipeptides are a group of RiPPs exhibiting a variety of biological functions. They are characterized by the presence of the thioether-containing bis-amino acids lanthionine and/or methyllanthionine. In this study, we heterologously expressed and structurally characterized estercin A, an unprecedented class II lanthipeptide derived from Clostridium estertheticum CF016 in Escherichia coli. Comprising 27 amino acids, estercin A features three overlapping (methyl-)lanthionine rings, with a shorter C-terminal part compared to most reported class II lanthipeptides. Estercin A exhibited selective antimicrobial properties against methicillin-resistant Staphylococcus aureus, bowel infection-associated Clostridium perfringens and Clostridium tetani. The mode of action of estercin A was determined as binding to lipid II on the cell membrane. Estercin A exhibited stability across a range of pH values and temperatures and showed resistance to degradation by trypsin. Our findings highlight estercin A as a novel and stable antimicrobial peptide with significant potential in combating clinically relevant pathogens.

Computational Model of the Effective Thermal Conductivity of a Bundle of Round Steel Bars

During the heat treatment of round steel bars, a heated charge in the form of a cylindrically formed bundle is placed in a furnace. This type of charge is a porous granular medium in which a complex heat flow occurs during heating. The following heat transfer mechanisms occur simultaneously in this medium: conduction in bars, conduction within the gas, thermal radiation between the surfaces of the bars, and contact conduction across the joints between the adjacent bars. This complex heat transfer can be quantified in terms of effective thermal conductivity. This article presents the original model of the effective thermal conductivity of a bundle of round steel bars. This model is based on the thermo-electric analogy. Each heat transfer mechanism is assigned an appropriate thermal resistance. As a result of the calculations, the impact of the following parameters on the intensity of heat transfer in the bundle was examined: temperature, the thermal conductivity of the bars, the thermal conductivity of the gas, diameter, and emissivity of the bar, and bundle porosity. Calculations were performed for a temperature range of 25–800 °C, covering a wide spectrum of variables, including bar diameters, bundle porosity, and type of gas. The knowledge obtained thanks to the calculations performed will facilitate the optimization of heat treatment processes for the considered charge. The greatest scientific value of the presented research is the demonstration that, thanks to the developed computational model, it is possible to analyze a very complex heat transfer phenomenon using relatively simple mathematical relationships.

Low‐Dimensional Structure Modulation in Ag8SnSe6 for Enhanced Thermoelectric Performance

AbstractTernary liquid‐like thermoelectric materials have garnered significant attention due to their ultra‐low lattice thermal conductivity. Among these, Ag8SnSe6 stands out for its exceptionally low sound velocity and thermal conductivity. However, the inherent poor electrical conductivity and suboptimal thermoelectric properties of Ag8SnSe6 necessitate further improvement. Here, a novel approach is initiated to enhance the thermoelectric properties of Ag8SnSe6 by combining low‐dimensionalization with intrinsic doping. For the first time, this work successfully synthesizes single‐phase Ag8SnSe6 nanocrystals, ≈10 nm in size, with the correct phase and composition using a robust and reliable colloidal method. This approach represents a significant improvement over previous reports on this material. Reducing the crystal domains of Ag8SnSe6 to the nanoscale induces quantum confinement effects, increasing the density of states near the Fermi surface. It also introduces additional grain boundaries, which lower the lattice thermal conductivity and simplify structural design. Moreover, incorporating small amounts of Sn nanopowder into the Ag8SnSe6 nanocrystals before consolidation further enhances the thermoelectric performance. Sn acts as a donor dopant, increasing the electronic concentration while at the same time improving their mobility by reducing interface barriers, thus significantly improving the material transport properties. Additionally, the presence of Sn leads to the formation of point defects, dislocations, and secondary phases, which increase phonon scattering and further reduce the thermal conductivity. Through this synergistic optimization, the figure of merit shows a significant increase across a wide temperature range. Overall, a strategy is presented for the controlled preparation of Ag8SnSe6 nanocrystals, the decoupling of their electrical and thermal transport, and the practical application of this material to thermoelectric single‐leg modules.

Observation of Large Low-Field Magnetoresistance in Layered (NdNiO3)n:NdO Films at High Temperatures.

Large low-field magnetoresistance (LFMR, <1 T), related to the spin-disorder scattering or spin-polarized tunneling at boundaries of polycrystalline manganates, holds considerable promise for the development of low-power and ultrafast magnetic devices. However, achieving significant LFMRtypically necessitates extremely low temperatures due to diminishing spin polarization as temperature rises. To address this challenge, one strategy involves incorporating Ruddlesden-Popper structures (ABO3)n:AO, which are layered derivatives of perovskite structure capable of potentially inducing heightened magnetic fluctuations at higher temperatures. Here, a remarkable LFMR of up to 1.0×103% is obtained in the layered (NdNiO3)n:NdO films with a high and wide temperature range (190-240 K). This finding underlines that the layered (NdNiO3)n:NdO (n = 1) structure show a complex magnetic structure above TMI of perovskite NdNiO3, where small ferromagnetic domains are embedded in the antiferromagnetic domains, raising the tunneling barriers and magnetic fluctuations at high temperatures. Furthermore, applying a low magnetic field (<0.1 T) near TMI effectively mitigates the disruption of antiferromagnetic order structures at boundaries, then a higher temperature is required to break the inhibition of ferromagnetic to antiferromagnetic phase transition. The results contribute significantly to the advancement of magnetic devices capable of achieving substantial LFMR at room temperature.

The effect of heavy metals on the radiation shielding capabilities of borated polyethylene: A Geant4 study

Abstract Research has increasingly focused on polymers for medical applications due to their beneficial properties. Polyethylene, a common polymer, is extensively used as a neutron shield in radiation-related environments, particularly in hospitals. Recently, borated polyethylene—created by combining polyethylene with 5% boron by weight—has been employed in hospital doors due to its exceptional durability across a wide temperature range and its effective neutron shielding capabilities. Hospital doors must protect against radiation leakage that could endanger patients and staff while also being lightweight, resistant to moisture and chemicals, sound-absorbent, and flexible during manufacturing. Borated polyethylene meets all these criteria, leading many manufacturers to produce hospital doors from borated high-density polyethylene (BHDPE). In this study, the shielding effectiveness of borated polyethylene, enhanced with 5% of heavy metals such as iron, bismuth, and tungsten, was theoretically analyzed using Geant4 against photons and neutrons with energies ranging from 10 keV to 20 MeV. The results indicated that iron-borated high-density polyethylene (Fe-BHDPE) offers the best neutron shielding, followed by tungsten-borated high-density polyethylene (W-BHDPE) and bismuth-borated high-density polyethylene (Bi-HDPE). For photon shielding, Bi-HDPE performed the best. The choice of metal and its proportion in radiation protection doors should be tailored to the specific type of radiation present in the facility, considering potential interactions, surrounding conditions, scattering effects, and any secondary particles that may be produced.&amp;#xD;

Operational Flexibility Evaluation and Techno-Economic Analysis on Hot Primary Air Temperature Boosting by Reheated Steam in a Lignite-Fired Power Plant

Abstract Coal-fired power plants are commonly used as adjustable power sources to complement the fluctuating output of wind and solar energy. The investigation is required to determine the flexible peak-shaving capabilities of coal-fired boilers. A modified scheme for a lignite-fired power plant to further improve the primary air temperature using the outlet steam from the low-temperature reheater is studied while increasing the inlet flue gas temperature of the air preheater is considered the conventional scheme. Thermodynamic models of the power plant are constructed using ebsilon software. The operational characteristics of both schemes are compared under 30% turbine heat acceptance (THA)–100%THA conditions and the economic performance of the modified scheme is also evaluated. Results indicate that the modified scheme exhibits superior thermodynamic and economic performances compared to the conventional scheme. The disparity in power generation efficiency between the conventional and modified schemes reaches a maximum of 0.23 percentage points under 75%THA conditions. The net present value of the modified scheme amounts to 4.51 million dollars over the power plant lifespan of 30 years. The modified scheme allows the conventional denitrification catalyst to maintain an optimal temperature range even under 30%THA conditions, resulting in a power generation efficiency only 4.8 percentage points lower than that under 100%THA conditions, thus demonstrating remarkable operational flexibility. This study presents an efficient, cost-effective, and adaptable approach for lignite-fired power plants.

When a Small Amount of Comonomer Is Enough: Tailoring the Critical Solution Temperature of LCST-Type Thermoresponsive Random Copolymers by PEG Methyl Ether Methacrylate with 1100 g/mol Molecular Weight

Tuning the critical solution temperature (CST) of thermoresponsive polymers is essential to exploit their immense potential in various applications. In the present study, the effect of PEG-methyl ether methacrylate with a higher molecular weight of 1100 g/mol (mPEGMA1100) as a comonomer was investigated for its suitability for the CST adjustment of LCST-type polymers. Accordingly, a library of mPEGMA1100-based copolymers was established with varying compositions (XmPEGMA1100) using four main comonomers, namely di(ethylene glycol) ethyl ether acrylate, N-isopropyl acrylamide and methacrylamide, and mPEGMA300, with different CST values (cloud points, TCP, and clearing points, TCL, by turbidimetry). It was found that less than 20 mol% of the mPEGMA1100 in the copolymers is practically sufficient for tuning the CST in the entire measurable temperature range, i.e., up to 100 °C, regardless of the CST of the homopolymer of the main comonomer (CST0). Moreover, a predictive asymptotic model was developed based on the measured CST values, which strikingly revealed that the CSTs of mPEGMA1100-containing copolymers depend only on the two main parameters of these copolymers, XmPEGMA1100 and the CST of the homopolymer of the main comonomer (CST0), that is, CST = f(CST0, XmPEGMA1100). The revealed two-parameter relationship defines a surface in 3D plotting, and it is applicable to determine the CST of copolymers in advance for a given composition or to define the suitable composition for a required CST value. These unprecedented results on the dependence of CSTs on two major well-defined parameters enable to design a variety of novel macromolecular structures with tailored thermoresponsive properties.

Study on the Number and Spacing of Calibration Points for High-Precision NTC Thermistors Across the Ocean Temperature Range

Study on the Number and Spacing of Calibration Points for High-Precision NTC Thermistors Across the Ocean Temperature Range

Structural and Dynamic Heterogeneity of Deep Eutectic Solvents Composed of Choline Chloride and Ortho-Phenol Derivatives.

Structural, thermal, and dynamic properties of four deep eutectic solvents comprising choline chloride paired with ortho-phenolic derivative hydrogen-bond donors were probed using experiments and molecular simulations. The hydrogen-bond donors include phenol, catechol, o-chlorophenol, and o-cresol, in a 3:1 mixture with the hydrogen-bond acceptor choline chloride. Density, viscosity, and pulsed-field gradient NMR diffusivity measurements were conducted over a range of temperatures. Classical and ab initio molecular dynamics simulation results match experimental data reasonably well. The simulation results were then used to perform a more detailed analysis of the local structure and dynamics of these systems.

Experimental Study on Constructing a Classification and Early Warning Index System for Non-Stick Coal Spontaneous Combustion

ABSTRACT Focused on the complex underground environment and the difficulty in quantitative characterization of CSC indicator gases, the temperature-programmed experiments were conducted to explore the releasing rule of gaseous compounds during the low-temperature oxidation process of nonstick coal, taking into account coal particle size and mine ventilation volume. By combining the rate of increase in oxygen consumption, the critical temperature for the coal was determined to be 60–80°C, and the dry cracking temperature ranging from 110°C to 120°C. The experimental process revealed that both particle size and ventilation volume have a significant impact on gaseous compounds. Therefore, the coefficient of variation method, gray relational analysis, and weighted gray relational analysis were introduced to evaluate the gas indexes of each temperature range by particle size and air volume. It was found that at 30–50°C, the O2/CH4 ratio was the primary indicator; at 60–80°C, the CO/O2 was selected as the primary index; at 110–120°C, the CO/CO2 and O2/CH4 were selected the primary indicators; and at 130–180°C, the C2H6/CH4 was selected the primary indicator. And build a graded early warning system for coal spontaneous combustion. This study provides a reference for the construction of grading prediction indicators for nonstick coal.