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The α-hemolysin (αHL) nanopore is capable of analyzing DNA duplex and DNA aptamer as they can be electrophoretically driven into the vestibule from the cis entrance. The current study describes the competitive interaction induced by Pb that changes the secondary structure of DNA duplex in asymmetrical electrolyte solution. DNA duplex formed by the partial complementary DNA and DNA aptamer sequence produced unzipping blockages with the dwell unzipping time lasting 2.84 ± 0.7 ms. By cation-DNA interaction with Pb, the DNA duplex will unwind and then form Pb-stabilized-DNA aptamer, which will be captured and unfolded in vestibule. The pore conductance were reduced to 54 % and 94 % with mean dwell unfolding times of 165 ± 12 ms. The competitive behavior between Pb and single-strand DNA was further utilized to detect Pb in solution with a detection limit of 0.5 nM. This nanopore platform also provides a powerful tool for studying the cation-DNA interactions in DNA aptamer conformational changes. Thus, the results drawn from these studies provide insights into the applications of α-hemolysin nanopore as a molecular sieve to different DNA secondary structure in future application of nanopore analysis. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

air-fuel equivalence ratio and timescales of kinetic reaction and oxygen transport were used to analyze the combustion of underground coal fires at different temperature stages. At high temperature stage, due to the fast rate of kinetic reaction, oxygen concentration transported from galleries or cracks was lower than that required by theoretical kinetic reaction. Thus the oxygen consumption rate of coal combustion was controlled by oxygen transport rate and the coal fires were incomplete combustion because of lean oxygen concentration. According to the Single-Particle Reaction- Diffusion model proposed by Krishnaswamy, a formula to estimate oxygen consumption rate of underground coal fires with lean oxygen concentration and incomplete combustion at high temperature was developed. A numerical case study was conducted to analyze and examine the proposed formula. The investigated results show that the proposed formula can effectively estimate oxygen consumption rale controlled by oxygen transport at high temperature. [ABSTRACT FROM AUTHOR]

By thermogravimetry (TG) experiments, evolution behaviors and properties of thermal oxidation processes at low temperature (< 230.0 °C) of a bituminous coal with five moisture contents were investigated. A novel Acceleration Temperature Point Method (ATPM), defined as the transition point from low-temperature oxidation to rapid self-sustained heating-up period, was proposed to determine the role of moisture content in accelerating such process. Results show that segments of water evaporation and gas desorption dominate in stage 1 (65.0–150.0 °C), while segments of generation of coal-oxygen complex and structure oxidation dominate in stage 2 (150.0–275.0 °C). In the moisture range of 9.16–12.06%, the promoted effect of physical desorption capacity becomes weak with increasing moisture content. This is owing to five aspects: the equilibrium of vapor pressure and wetting capability of physically bound water, the change of mass and heat transfer between gas phase (water vapor)-condensed phase (bulk coal particle), the diffusing effect of gaseous water, the heat from dissolving and swelling of gaseous water into bulk coal pores, and the heat of pyrolysis derived from coal particles. Taking Acceleration Temperature Point (ATP) as a barometer to evaluate the spontaneous combustion susceptibility, the critical moisture content of Gengcun bituminous coal is 9.16%. [ABSTRACT FROM AUTHOR]

To analyze the oxidation kinetics reason that self-ignition tendency of coal with different metamorphic degree are different, based on the basic assumptions of coal adiabatic self-heating process, a oxidation kinetics analysis on the reaction characteristics of the process was made combined with the Arrhenius equation, then this paper studied four feature parameters: adiabatic process apparent activation energy (Ec), the critical temperature ( Tc) and the average heating rates each stages of the adiabatic process, (Rhm,Rjs), finally, the relationship between each characteristic parameter and coal metamorphic level was made by numerical fitting. It is show that the oxidation kinetics characteristics are characterized by the four parameters (Ec, Tc, Rhm and Rjs) in the difficulty degree of coal self-ignition reaction (Ec),the difficulty degree of control ( Tc) and the heating speed (Rhm and Rjs) ;with the increase of coal metamorphic grade, Ec has a logarithmic relation with it, Tc has a linear relation, however, Rhm and Rjs have a negative exponent relation. The difference of self-ignition tendency of coal with different metamorphic degree is studied on oxidation kinetics, and it is of great significance to self-ignition control. [ABSTRACT FROM AUTHOR]

• Sound waves travel mainly through voids in the loose coal. • Influence of humidity on acoustic coal temperature measurement can not be ignored. • Acoustic temperature measurement technology can be applied to loose coal. Spontaneous coal bunker combustion disasters not only cause a waste of resources, but also cause huge economic losses and heavy casualties. The existing coal spontaneous combustion detection technology has obvious limitations, and there is an urgent need for new coal spontaneous combustion high temperature point detection technology. This paper constructs a model for measuring the temperature of loose coal using acoustic wave method that takes humidity into account. By measuring the mechanical properties of coal, it is found that when sound waves propagate in loose coal, they mainly propagate through the air in the gaps of loose coal. By analyzing the relationship between sound speed and temperature in free atmospheric pressure, a loose coal acoustic temperature measurement model considering humidity was constructed, and a correction factor was introduced to modify the temperature measurement model. Using the frequency sweep signal as the sound source signal, the temperatures of loose coal with three different degrees of metamorphism were measured. The results show that the temperature measurement of loose coal considering gas environment relative humidity is more accurate. The measured long flame coal temperature is closest to the real temperature, with a maximum absolute error of 1.68 °C and a maximum relative error of 5.44 %. Error analysis shows that the temperature measurement error is mainly caused by changes in the gas composition of the voids in the loose coal, the functional relationship between the characteristic factor and temperature, and errors in sound wave flight time measurement. This study can provide certain theoretical support for the acoustic method to measure the temperature of high temperature points in coal bunkers, and provide a new temperature detection method for coal fire disaster prevention and control. [ABSTRACT FROM AUTHOR]

• Combining the FAHP and BN for evaluating domino effect is proposed. • Four main influencing factors on escalation risk are contained in FAHP. • Three level of the risk of propagation are divided. • The method for assessing explosion of mixture in the domino effect is provided. • The value of CPT in BN is replaced by the results updated by FAHP. Domino effects in process facilities can lead to catastrophic consequences. Many previous models devoted to assessing domino effects, but the influence of the combination of heat radiation, overpressure and fragment on the escalation is not considered. In addition, although the quantity of dangerous substances stored in the affected unit has a non-negligible effect on the propagation of domino effects, their inclusion in the modeling of domino effects has hardly been taken into account. To address these challenges, in this work, using the Fuzzy Analytic Hierarchy Process (FAHP), the escalation of domino effects under multiple physical factors is assessed, while considering other factors in varying degrees such as meteorological, mitigation measures and the affected units. Finally, the conditional probability table (CPT) in Bayesian networks (BNs) is updated by the FAHP. The application of the methodology has been demonstrated using an illustrative case study; the comparison of the results with that of previous study illustrates the efficacy and practicality of the development methodology. This work will be beneficial for land-use planning. [ABSTRACT FROM AUTHOR]

• Variation in sound absorption is studied based on the structural properties of coal. • Sound waves mainly propagate along the voids in loose coal. • Loose coal belongs to the high absorption medium of sound waves. • The obtained peak frequency provides basis for the selection of the acoustic signal. With the advantages of high applicability and reliability, the acoustic detection method has been widely used in the field of temperature measurement, positioning, and flaw detection. To apply acoustic temperature measurement techniques to the detection of high temperature points of loose coal spontaneous combustion, the basic acoustic properties of loose coal need to be clarified. Four bituminous coals with different degrees of metamorphosis were selected for the study. The stacking structural characteristics of loose coal were studied by industrial computerized tomography. The sound absorption coefficient of loose coal was tested based on the sound absorption test system. The results revealed that with the increase of particle size, the voids of loose coal gradually became larger and the connectivity became better. The distribution characteristics of voids in loose coal were intrinsic to the variation in sound absorption coefficients. The sound absorption coefficient was more influenced by the particle size and stack thickness than by the degree of deterioration. Except for the particle size of less than 0.9 mm and the stacked thickness of 2 cm coal samples, the absorption coefficients of the coal samples increased gradually with decreasing particle size at the same acoustic frequency, and the peak absorption coefficients gradually shifted towards lower frequencies with increasing thickness. The peak frequency range of the absorption coefficient was calculated to provide a basis for the selection of the frequency band of the acoustic temperature measurement signal for loose coal. [ABSTRACT FROM AUTHOR]