A logic fault tree of mine spontaneous combustion of sulphide ores was built by the fault tree analysis (FTA) based on a lot of mechanism investigation of sulphide ore spontaneous combustion in more than ten mines an...A logic fault tree of mine spontaneous combustion of sulphide ores was built by the fault tree analysis (FTA) based on a lot of mechanism investigation of sulphide ore spontaneous combustion in more than ten mines and review of a great amount of relevant展开更多
in order to achieve a more efficient way to accurately detect the position of the fire source of spontaneous combustion underground mine, a simple fire source locating method, based on infrared scanning system which c...in order to achieve a more efficient way to accurately detect the position of the fire source of spontaneous combustion underground mine, a simple fire source locating method, based on infrared scanning system which can determine the point where the highest temperature on the surface of igniting ores occurs, was proposed. First, the differential equations that describe heat flow in ore body were presented and the relationship between the surface temperature distribution and the depth and intensity of inner fire source was established with a relatively simple heat transfer model. With the solution of equation, the expression of the relationship between the surface temperature distribution and the inner fire source was deduced and the mathematical-physical model of heat transfer process was set up. Then, with the model, visualization of fire source on the basis of MATLAB simulation platform was realized. The results show that： 1） within 10 m, when the detecting depth is less than 2 m, the temperature perturbation on ores surface can change rapidly, and then slowly; after 4 m, in contrast, it changes very little, and is even close to zero at 10 m; 2） When it is close to self-ignition duration and the detective depths are 2, 5 and 10 m, respectively, the maximum temperature differences are correspondingly 0.5, 0.04 and 0.005 ℃ in the scope of 1 m×1 m; under the same condition, the maximum temperature differences are 1.391, 0.136 and 0.018 ℃, respectively, in the scope of 2 m×2 m. Therefore, this system can be used to measure the temperature differences on the surface of ore body and determine the highest temperature point directly. Also, it is possible to determine the depth of fire source and its intensity by locating method of fire source indirectly.展开更多
The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory d...The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as "K". The ratio of each index gas and value of "K", and the ratio of combination index gases and value of "K", were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C_2H_4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C_2H_6)/Φ(C_2H_2) and Φ(C_2H_6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.展开更多
To explore a new evaluation method for spontaneous combustion tendency of different areas in sulfide ore heap, ore samples from a pyrite mine in China were taken as experimental materials, and the temperature variatio...To explore a new evaluation method for spontaneous combustion tendency of different areas in sulfide ore heap, ore samples from a pyrite mine in China were taken as experimental materials, and the temperature variations of the measuring points of simulated ore heap were measured. Combined with wavelet transform and nonlinear parameters extraction, a new method for spontaneous combustion tendency of different areas in sulfide ore heap based on nonlinear parameters was proposed and its reliability was verified by field test. The results indicate that temperature field evolution of the simulated ore heap presents significant spatial difference during self-heating process. Area with the maximum increasing extent of temperature in sulfide ore heap changes notably with the proceeding of self-heating reaction. Self-heating of sulfide ore heap is a chaotic evolution process, which means that it is feasible to evaluate spontaneous combustion tendency of different areas by nonlinear analysis method. There is a relatively strong correlation between the maximum Lyapunov exponent and spontaneous combustion tendency with the correlation coefficient of 0.9792. Furthermore, the sort of the maximum Lyapunov exponent is consistent with that of spontaneous combustion tendency. Therefore, spontaneous combustion tendency of different areas in sulfide ore heap can be evaluated by means of the maximum Lyapunov exponent method.展开更多
To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous comb...To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 ℃, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages： incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0 ~C/min, 2.0 ~C/min and 4.2 ~C/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.展开更多
Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rat...Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rates of 5,10,15 and 20 °C/min in air flow from ambient temperature to 800 °C were studied by simultaneous thermal analysis and the TG/DSC curves before and after the pre-oxidation were compared.By the peak temperature of DTG curves,the whole reaction process for each sample was divided into different stages,and the apparent activation energies were calculated by the Ozawa-Flynn-Wall method.The results show that the reaction process of each sample after pre-oxidation is more complex,with quicker reaction rates,fewer heat production quantities,and higher or lower ignition-points.The apparent activation energies decrease from 364.017-474.228 kJ/mol to 244.523- 333.161 kJ/mol.Therefore,sulfide ores are more susceptible to spontaneous combustion after the pre-oxidation.展开更多
Objective BACKGROUND Spontaneous closure of direct traumatic carotid cavernous fistulas (TCCFs) is rare. A few cases have been reported in literature to be related to diagnostic cerebral angiography and orbital venogr...Objective BACKGROUND Spontaneous closure of direct traumatic carotid cavernous fistulas (TCCFs) is rare. A few cases have been reported in literature to be related to diagnostic cerebral angiography and orbital venography. Several mechanisms have been postulated, including irritation of the vessels from contrast media, compression of the carotid artery and reduced blood pressure from general anesthesia. In our own series of about 400 patients at Ramathibodi Hospital, the incidence is approximately 1.75%.CASE PRESENTATION We present a case, which spontaneous closure occurred during attempted endovascular embolization. A 45-year-old woman with left TCCF was referred to our hospital for endovascular treatment. Cerebral angiogram revealed a small-hole fistula at the posterosuperior wall of C2-3 segment of the LICA. Transarterial balloon failed due to the small size of the fistula and acute retroangulation of the balloon attached microcatheter. Transarterial GDC coil placement into the first venous pouch was then attempted for two times, but was unsuccessful. During repositioning of the microcatheter for a third attempt, spontaneous closure of the fistula was observed and confirmed by control angiogram. CONCLUSION Spontaneous closure of direct traumatic carotid cavernous fistulas may occur during endovascular procedures, which can be caused by dissection of the venous pouch by the microcatheter or coils during manipulation, irritation of the vascular walls from the contrast media and decreased blood pressure from general anesthesia.展开更多
OBJECTIVE To explore the underlying mechanisms involved in the effect of sesamin on aortic NO bioactivity in spontaneously hypertensive rat(SHR).METHODS Sesamin was orally administered for consecutive 8 weeks in SHR.S...OBJECTIVE To explore the underlying mechanisms involved in the effect of sesamin on aortic NO bioactivity in spontaneously hypertensive rat(SHR).METHODS Sesamin was orally administered for consecutive 8 weeks in SHR.Systolic blood pressure(SBP)was measured using the tail-cuff method.The aortas were isolated and in vitro vascular reactivity studies were performed.Superoxide anion production in carotid arteries was assessed by dihydroethidium fluorescence staining.The protein expression of endothelial nitric oxide synthase(eNOS),phosphorylated eNOS(P-eNOS),dihydrofolate reductase(DHFR),nicotinamide adenine dinucleotide phosphate(NADPH)oxidase subunit p47 phox and copper,zinc-superoxide dismutase(Cu/Zn-SOD)in aortas was detected by Western blotting.The dimeric form of eNOS in aortas was determined by low-temperature SDS-PAGE.Aortic level of nitrotyrosine and activities of antioxidant enzymes,namely,total SOD(T-SOD),glutathione peroxidase(GPx)and catalase were also detected.RESULTS In SHR,sesamin treatment reduced SBP,improved vascular relaxation induced by acetylcholine and enhanced aortic NO bioactivity.Sesamin treatment enhanced NO biosynthesis in SHR aortas was due to upregulated P-eNOS and suppressed eNOS uncoupling,and the latter effect might be attributed to decreased nitrotyrosine and upregulated DHFR.Sesamin also reducd the NO oxidative inactivation and decreased the superoxide anion production through downregulation of p47 phox and amelioration of eNOS uncoupling.In addition,sesamin treatment did not alter the levels of GPx and catalase activity but obviously reduced the compensatory elevated T-SOD activity and Cu/Zn-SOD protein expression.CONCLUSION Chronic treatment with sesamin could reduce hypertension and improve endothelial dysfunction through enhancement of NO bioactivity in SHRs aortas.展开更多
Aim To study the activity and mechanism of inhibition of myocardial hypertrophy of total flavonoids of Cydonia oblonga Mill. in spontaneously hypertensive rats. Methods Total flavonoids of COM （COMF） were sepa- rate...Aim To study the activity and mechanism of inhibition of myocardial hypertrophy of total flavonoids of Cydonia oblonga Mill. in spontaneously hypertensive rats. Methods Total flavonoids of COM （COMF） were sepa- rated and purified by the optimal process. SHtl were divided into 6 groups： SHR control group （SHR） , captopril group （SHR ＋ CAP, 25 μg · g^-1）, Eucommia ulmoides Oliver group （SHR ＋ EUO, 30 μg · g^-1）, low （SHR ＋ COMF-L, 40 μg · g^-1） ,middle （SHR ＋ COMF-M, 80 μg· g^-1） and high dose （SHR ＋ COMF-H, 160 μg · g^-1） of COMF groups. Wistar-Kyoto （WKY） rats （n= 8 ） were given distilled water as control The drugs were given by intragastric administration for 16 weeks. The histological and pathological examination of the heart were performed and organic damage were valued. The levels of Ang II and ALD in blood and heart were evaluated. The mRNA and protein expression of ACE, ACE2 and AT~ was determined by RT-PCR and Western blot to evaluate the effect of COMF on RAAS. Results Compared with SHR control group, HW, HW/BW, LVM and LVM/BW de- creased in SHR ＋ COMF-M and SHR ＋ COMF-H groups; Cadiomyocyte hypertrophy was inhibited in COMF groups; The concentration of Ang 11 and ALD in heart and blood decreased; ACE and AT1 mRNA and protein ex- pression in heart tissue decreased while ACE2 mRNA expression increased （P 〈 0.01 or P 〈 0.05） , Conclusion Total flavonoids of Cydonia oblonga Mill. showed the effect of inhibition of myocardial hypertrophy in spontaneously hypertensive rats and the mechanism was related to. inhibit the activity of Renin-angiotensin-aldosterone system.展开更多
OBJECTIVE To investigate the inhibitory effect and mechanism of sodium ferulate(SF)on myocardial hypertrophy in spontaneously hypertensive(SHR).METHODS Forty 14-week-old SHR male rats were randomly divided into model ...OBJECTIVE To investigate the inhibitory effect and mechanism of sodium ferulate(SF)on myocardial hypertrophy in spontaneously hypertensive(SHR).METHODS Forty 14-week-old SHR male rats were randomly divided into model group(SHR,receive distilled water)and SF treatment groups(SF 20,40 and 80 mg·kg^-1 per day,respectively).Age-matched male Wistar-Kyoto(WKY)rats gavaged with distilled water served as controls.After 12 weeks of treatment,the effects of SF on cardiac hypertrophy were evaluated using echocardiographic measurement,pathological analysis and the expression of atrial natriuretic peptide(ANP),myosin heavy chainβ(β-MHC)-a gene related to myocardial hypertrophy.In order to explore the mechanism of SF on myocardial hypertrophy,the calcium-sensing receptor(CaSR),calcineurin(CaN),nuclear factor of activated T cell 3(NFAT3),phosphorylation NFAT3(p-NFAT3),zinc finger transcription factor(GATA4),phosphorylation GATA4(p-GATA4),protein kinase Cβ(PKC-β),Raf-1,extracellular regulated protein kinase 1/2(ERK 1/2),phosphorylation ERK1/2(p-ERK 1/2)and mitogen-activated protein kinase phosphatase-1(MKP-1)were detected.RESULTS The myocardial hypertrophy parameters,myocardial cell cross section area,left ventricular wall thickness and expression of ANP and β-MHC,CaSR,CaN,NFAT3,p-GATA4,PKC-β,Raf-1,and p-ERK 1/2 were significantly increased,while the left ventricular cavity was significantly smaller,expression of p-NFAT3 and MKP-1 were significantly decreased,meanwhile,the ultra⁃structure of cardiomyocytes was significantly damaged in 26-week-old SHR rats.Notably,SF significantly ameliorated myocardial hyper⁃trophy in 26-week-old SHR rats;suppressed the overexpression of ANP,β-MHC,CaSR,CaN,NFAT3,p-GATA4,PKC-β,Raf-1,and p-ERK 1/2 and increased the expression of p-NFAT3 and MKP-1.CONCLUSION SF can inhibit cardiac hypertrophy in SHR rats,and the mechanism may be related to the inhibition of CaSR mediated signaling pathway.展开更多
According to spontaneous combustion propensity,the longwall gob is divided into three zones,including heat dissipation zone,self-heating zone and the choking zone.Only in the self-heating zone can temperature of coal ...According to spontaneous combustion propensity,the longwall gob is divided into three zones,including heat dissipation zone,self-heating zone and the choking zone.Only in the self-heating zone can temperature of coal rise due to oxidation.Studying the distribution of the "Three Zones" in gob is important for predicting and preventing spontaneous combustion in coalmine.In normal mining operations,temperature of coal is roughly constant.The process of mass transfer in the gob is considered to be steady.Based on mass conservation,gas species conservation,darcy's law,Ficks law of diffusion and coal oxidation 1-grade reaction rule,governing equation for air leakage intensity and species concentration are deduced.With critical value of coal spontaneous combustion and the size of longwall workface as basic dimension,a dimensionless steady coupled model of air flow diffusion and chemical reaction in loose coal of Fully Mechanized Top-Coal Caving Mining Workface(FMTCCMW) is setup.By solving the model numerically,regulation of three zones' distribution and spontaneous combustion in the gob can be obtained.The results can be easily popularized to prediction of spontaneous combustion in other coalmines' longwall gob.展开更多
Coal mine fires,which can cause heavy casualties,environmental damages and a waste of coal resources,have become a worldwide problem.Aiming at overcoming the drawbacks,such as a low analysis efficiency,poor stability ...Coal mine fires,which can cause heavy casualties,environmental damages and a waste of coal resources,have become a worldwide problem.Aiming at overcoming the drawbacks,such as a low analysis efficiency,poor stability and large monitoring error,of the existing underground coal fire monitoring technology,a novel monitoring system based on non-dispersive infrared(NDIR)spectroscopy is developed.In this study,first,the measurement principle of NDIR sensor,the gas concentration calculation and its temperature compensation algorithms were expounded.Next,taking CO and CH_(4) as examples,the liner correlation coefficients of absorbance and the temperature correction factors of the two indicator gases were calculated,and then the errors of concentration measurement for CO,CO_(2),CH_(4) and C_(2)H_(4) were further analyzed.The results disclose that the designed NDIR sensors can satisfy the requirements of industrial standards for monitoring the indicator gases for coal fire hazards.For the established NDIR-based monitoring system,the NDIRbased spectrum analyzer and its auxiliary equipment boast intrinsically safe and explosion-proof performances and can achieve real-time and in-situ detection of indicator gases when installed close to the coal fire risk area underground.Furthermore,a field application of the NDIR-based monitoring system in a coal mine shows that the NDIR-based spectrum analyzer has a permissible difference from the chromatography in measuring the concentrations of various indicator gases.Besides,the advantages of high accuracy,quick analysis and excellent security of the NDIR-based monitoring system have promoted its application in many coal mines.展开更多
Significant changes in spontaneous potential and exciting currents are observed during water and grout injection in a simulated porous media. Obvious correlations between the seepage flow field and the electric field ...Significant changes in spontaneous potential and exciting currents are observed during water and grout injection in a simulated porous media. Obvious correlations between the seepage flow field and the electric field in the porous media are identified.In this work, a detailed experimental study of geoelectric field variation occurring in water migration was reported by analyzing water and grout injection processes in a simulated porous media. The spontaneous potential varies linearly with the thickness of unsaturated porous media. Very interestingly, the spontaneous potential generated in the second grout injection exhibits some"memory" of previous grouting paths. The decreases in spontaneous potential observed during grout injection is very probably due to that the spontaneous potential variations are primarily caused by electro-filtration potential, as indicated by the far larger viscosity of grout compared to that of water. The geoelectric response can be utilized to effectively identify the grouting paths in water-bearing rocks.展开更多
Aim To study the anti-hypertensive effect of total flavonoids of Cydonia oblonga Mill. in spontaneously hypertensive rats, then preliminarily investigate the mechanism of action based on anti-inflammatory function. Me...Aim To study the anti-hypertensive effect of total flavonoids of Cydonia oblonga Mill. in spontaneously hypertensive rats, then preliminarily investigate the mechanism of action based on anti-inflammatory function. Methods Total flavonoids of COM （COMF） were separated and purified by the optimal process, SHR were divid- ed into 6 groups as SHR control group （SHR）, captopril group （CAP, 25mg· kg^-1 · d^-1）, Eucommia ulmoides Oliver group （EUO, 30 mg · kg^-1· d^-1）, low （COMF-L, 40 mg · kg^-1· d^-1）, middle （COMF-M, 80 mg · kg^-1 · d^-1） and high dose （COMF-H, 160 mg · kg^-1· d ^-1） of COMF groups. 8 Wistar-Kyoto （WKY） rats were given distilled water instead as control. The drugs were given by intragastric administration for 16 weeks, then the levels of IL-1β, IL-6, IL-10, TNF-α and CRP in serum were tested. Results Compared with WKY group, the levels of IL-I~, IL-6, TNF-α and CRP were increased and IL-10 was decreased; Compared with SHR group, the levels of IL-1β, IL-6, TNF-α and CRP were decreased in COMF groups （P 〈0.01 or P 〈0.05） , while IL-10 was increased a little but without any significant difference （P 〈 0.05 ）. Conclusion Total flavonoids of Cydonia ob- longa Mill. showed the anti-hypertensive activity in spontaneously hypertensive rats and the mechanism was related to the function of anti-inflammatory.展开更多
In order to utilize the spontaneous accumulation of heat (SAH) reasonably and obtain the high quality sinter with low energy consumption, a lower fuel consumption modeling based on raw materials of a certain steel wor...In order to utilize the spontaneous accumulation of heat (SAH) reasonably and obtain the high quality sinter with low energy consumption, a lower fuel consumption modeling based on raw materials of a certain steel works was built. An air-flow segregation feeding (ASF) experimental equipment was designed to simulate strand feeding process and calculate the lower fuel consumption quantity. Compared with baseline test, the ASF experimental equipment was adopted. The results of sinter pot tests show that the solid fuel consumption is lower than that in baseline test, which is decreased by 5.8%. Meanwhile, other sinter indexes, such as pan yeild, tumbler strength and strand productivity are improved. The mineralogical examination indicates that the mineral compositions and micostructures are improved in sinter.展开更多
Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.Howe...Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.展开更多
Liver tumours are among the most commonmalignancies worldwide. The international incidenceof the disease is about l million cases per year (male:femalc, 4: 1 ). These include primary and secondarytumours. Cancer is kn...Liver tumours are among the most commonmalignancies worldwide. The international incidenceof the disease is about l million cases per year (male:femalc, 4: 1 ). These include primary and secondarytumours. Cancer is known to be a genetic disease thatinvolves the alteration of activity of the products of atleast 2 genes, due to mutation (s) and/or otherfactors, e. g., the presence of viral oncoproteins. Thegenes most affected are the tumour suppressor展开更多
The quantum entangled photon-pair source,as an essential component of optical quantum systems,holds great potential for applications such as quantum teleportation,quan-tum computing,and quantum imaging.The current wor...The quantum entangled photon-pair source,as an essential component of optical quantum systems,holds great potential for applications such as quantum teleportation,quan-tum computing,and quantum imaging.The current workhorse technique for preparing photon pairs involves performing spon-taneous parametric down conversion(SPDC)in bulk nonlinear crystals.However,the current power consumption and cost of preparing entangled photon-pair sources are relatively high,pos-ing challenges to their integration and scalability.In this paper,we propose a low-power system model for the quantum entan-gled photon-pair source based on SPDC theory and phase matching technology.This model allows us to analyze the per-formance of each module and the influence of component cha-racteristics on the overall system.In our experimental setup,we utilize a 5 mW laser diode and a typical type-II barium metabo-rate(BBO)crystal to prepare an entangled photon-pair source.The experimental results are in excellent agreement with the model,indicating a significant step towards achieving the goal of low-power and low-cost entangled photon-pair sources.This achievement not only contributes to the practical application of quantum entanglement lighting,but also paves the way for the widespread adoption of optical quantum systems in the future.展开更多
The spontaneous burning has been lasting for thousands of years in the coal fields in the north of China. It spreads from the west (Tianshan coal field) to the east (Huolinhe coal field). Its E-W extension is up to 37...The spontaneous burning has been lasting for thousands of years in the coal fields in the north of China. It spreads from the west (Tianshan coal field) to the east (Huolinhe coal field). Its E-W extension is up to 3750km, concentrating in N35°toN45°, its vertical depth up to 260m, and the surface temprature locally up to 270℃. Annually, it burns out 0, 250-300 million tones of coal, causing economic loss equivalent to 2-3 billion R.M.B. Yuan.It destroies coal resources and causes hazards in coal mines. In order to locate the extent and the direction in coal burning areas, the remote sensing technique has heen used and has produced an obvious benefit.展开更多
文摘A logic fault tree of mine spontaneous combustion of sulphide ores was built by the fault tree analysis (FTA) based on a lot of mechanism investigation of sulphide ore spontaneous combustion in more than ten mines and review of a great amount of relevant
基金Project(2006BAK04B03) supported by the National Basic Research Program of ChinaProject(CX2009B053) supported by Innovation Foundation for Postgraduate Students of Hunan Province,ChinaProject(2009ybfz08) supported by the Doctoral Dissertation of Central South University,China
文摘in order to achieve a more efficient way to accurately detect the position of the fire source of spontaneous combustion underground mine, a simple fire source locating method, based on infrared scanning system which can determine the point where the highest temperature on the surface of igniting ores occurs, was proposed. First, the differential equations that describe heat flow in ore body were presented and the relationship between the surface temperature distribution and the depth and intensity of inner fire source was established with a relatively simple heat transfer model. With the solution of equation, the expression of the relationship between the surface temperature distribution and the inner fire source was deduced and the mathematical-physical model of heat transfer process was set up. Then, with the model, visualization of fire source on the basis of MATLAB simulation platform was realized. The results show that： 1） within 10 m, when the detecting depth is less than 2 m, the temperature perturbation on ores surface can change rapidly, and then slowly; after 4 m, in contrast, it changes very little, and is even close to zero at 10 m; 2） When it is close to self-ignition duration and the detective depths are 2, 5 and 10 m, respectively, the maximum temperature differences are correspondingly 0.5, 0.04 and 0.005 ℃ in the scope of 1 m×1 m; under the same condition, the maximum temperature differences are 1.391, 0.136 and 0.018 ℃, respectively, in the scope of 2 m×2 m. Therefore, this system can be used to measure the temperature differences on the surface of ore body and determine the highest temperature point directly. Also, it is possible to determine the depth of fire source and its intensity by locating method of fire source indirectly.
基金Projects(51274099,51474106)supported by the National Natural Science Foundation of China
文摘The coal of Anyuan Mine has the characteristic of easy spontaneous combustion. Conventional method is difficult to predict it. Coal samples from this mine were tested in laboratory. The data obtained from laboratory determination were initialized for the value which was defined as "K". The ratio of each index gas and value of "K", and the ratio of combination index gases and value of "K", were analyzed simultaneously. The research results show that for this coal mine, if there is carbon monoxide in the gas sample, the phenomenon of oxidation and temperature rising for coal exists in this mine; if there is C_2H_4 in the gas sample, the temperature of coal perhaps exceeds 130 °C. If the coal temperature is between 35 °C and 130 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(CO)/K mainly; if the temperature of coal is between 130 °C and 300 °C, prediction and forecast for coal spontaneous combustion depend on the value of Φ(C_2H_6)/Φ(C_2H_2) and Φ(C_2H_6)/K. The research results provide experimental basis for the prediction of coal spontaneous combustion in Anyuan coal mine, and have better guidance on safe production of this coal mine.
基金Projects(51304238,51534008)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China
文摘To explore a new evaluation method for spontaneous combustion tendency of different areas in sulfide ore heap, ore samples from a pyrite mine in China were taken as experimental materials, and the temperature variations of the measuring points of simulated ore heap were measured. Combined with wavelet transform and nonlinear parameters extraction, a new method for spontaneous combustion tendency of different areas in sulfide ore heap based on nonlinear parameters was proposed and its reliability was verified by field test. The results indicate that temperature field evolution of the simulated ore heap presents significant spatial difference during self-heating process. Area with the maximum increasing extent of temperature in sulfide ore heap changes notably with the proceeding of self-heating reaction. Self-heating of sulfide ore heap is a chaotic evolution process, which means that it is feasible to evaluate spontaneous combustion tendency of different areas by nonlinear analysis method. There is a relatively strong correlation between the maximum Lyapunov exponent and spontaneous combustion tendency with the correlation coefficient of 0.9792. Furthermore, the sort of the maximum Lyapunov exponent is consistent with that of spontaneous combustion tendency. Therefore, spontaneous combustion tendency of different areas in sulfide ore heap can be evaluated by means of the maximum Lyapunov exponent method.
基金Projects(51304238,51534008)supported by the National Natural Science Foundation of ChinaProject(2015CX005)supported by Innovation Driven Plan of Central South University,China
文摘To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 ℃, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages： incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0 ~C/min, 2.0 ~C/min and 4.2 ~C/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.
基金Project(51304051)supported by the National Natural Science Foundation of ChinaProject(2012J05088)supported by the Natural Science Foundation of Fujian Province,China+1 种基金Project(022409)supported by School Talent Award of Fuzhou University,ChinaProject(2013-XQ-18)supported by Science&Technology Development Foundation of Fuzhou University,China
文摘Three representative sulfide ore samples were collected from typical metal mines,and their corresponding pre-oxidized products were obtained under nature environment.The thermal behaviors of each sample at heating rates of 5,10,15 and 20 °C/min in air flow from ambient temperature to 800 °C were studied by simultaneous thermal analysis and the TG/DSC curves before and after the pre-oxidation were compared.By the peak temperature of DTG curves,the whole reaction process for each sample was divided into different stages,and the apparent activation energies were calculated by the Ozawa-Flynn-Wall method.The results show that the reaction process of each sample after pre-oxidation is more complex,with quicker reaction rates,fewer heat production quantities,and higher or lower ignition-points.The apparent activation energies decrease from 364.017-474.228 kJ/mol to 244.523- 333.161 kJ/mol.Therefore,sulfide ores are more susceptible to spontaneous combustion after the pre-oxidation.
文摘Objective BACKGROUND Spontaneous closure of direct traumatic carotid cavernous fistulas (TCCFs) is rare. A few cases have been reported in literature to be related to diagnostic cerebral angiography and orbital venography. Several mechanisms have been postulated, including irritation of the vessels from contrast media, compression of the carotid artery and reduced blood pressure from general anesthesia. In our own series of about 400 patients at Ramathibodi Hospital, the incidence is approximately 1.75%.CASE PRESENTATION We present a case, which spontaneous closure occurred during attempted endovascular embolization. A 45-year-old woman with left TCCF was referred to our hospital for endovascular treatment. Cerebral angiogram revealed a small-hole fistula at the posterosuperior wall of C2-3 segment of the LICA. Transarterial balloon failed due to the small size of the fistula and acute retroangulation of the balloon attached microcatheter. Transarterial GDC coil placement into the first venous pouch was then attempted for two times, but was unsuccessful. During repositioning of the microcatheter for a third attempt, spontaneous closure of the fistula was observed and confirmed by control angiogram. CONCLUSION Spontaneous closure of direct traumatic carotid cavernous fistulas may occur during endovascular procedures, which can be caused by dissection of the venous pouch by the microcatheter or coils during manipulation, irritation of the vascular walls from the contrast media and decreased blood pressure from general anesthesia.
基金The project supported by the Natural Science Foundation of Anhui Provincial(1308085QH145)
文摘OBJECTIVE To explore the underlying mechanisms involved in the effect of sesamin on aortic NO bioactivity in spontaneously hypertensive rat(SHR).METHODS Sesamin was orally administered for consecutive 8 weeks in SHR.Systolic blood pressure(SBP)was measured using the tail-cuff method.The aortas were isolated and in vitro vascular reactivity studies were performed.Superoxide anion production in carotid arteries was assessed by dihydroethidium fluorescence staining.The protein expression of endothelial nitric oxide synthase(eNOS),phosphorylated eNOS(P-eNOS),dihydrofolate reductase(DHFR),nicotinamide adenine dinucleotide phosphate(NADPH)oxidase subunit p47 phox and copper,zinc-superoxide dismutase(Cu/Zn-SOD)in aortas was detected by Western blotting.The dimeric form of eNOS in aortas was determined by low-temperature SDS-PAGE.Aortic level of nitrotyrosine and activities of antioxidant enzymes,namely,total SOD(T-SOD),glutathione peroxidase(GPx)and catalase were also detected.RESULTS In SHR,sesamin treatment reduced SBP,improved vascular relaxation induced by acetylcholine and enhanced aortic NO bioactivity.Sesamin treatment enhanced NO biosynthesis in SHR aortas was due to upregulated P-eNOS and suppressed eNOS uncoupling,and the latter effect might be attributed to decreased nitrotyrosine and upregulated DHFR.Sesamin also reducd the NO oxidative inactivation and decreased the superoxide anion production through downregulation of p47 phox and amelioration of eNOS uncoupling.In addition,sesamin treatment did not alter the levels of GPx and catalase activity but obviously reduced the compensatory elevated T-SOD activity and Cu/Zn-SOD protein expression.CONCLUSION Chronic treatment with sesamin could reduce hypertension and improve endothelial dysfunction through enhancement of NO bioactivity in SHRs aortas.
文摘Aim To study the activity and mechanism of inhibition of myocardial hypertrophy of total flavonoids of Cydonia oblonga Mill. in spontaneously hypertensive rats. Methods Total flavonoids of COM （COMF） were sepa- rated and purified by the optimal process. SHtl were divided into 6 groups： SHR control group （SHR） , captopril group （SHR ＋ CAP, 25 μg · g^-1）, Eucommia ulmoides Oliver group （SHR ＋ EUO, 30 μg · g^-1）, low （SHR ＋ COMF-L, 40 μg · g^-1） ,middle （SHR ＋ COMF-M, 80 μg· g^-1） and high dose （SHR ＋ COMF-H, 160 μg · g^-1） of COMF groups. Wistar-Kyoto （WKY） rats （n= 8 ） were given distilled water as control The drugs were given by intragastric administration for 16 weeks. The histological and pathological examination of the heart were performed and organic damage were valued. The levels of Ang II and ALD in blood and heart were evaluated. The mRNA and protein expression of ACE, ACE2 and AT~ was determined by RT-PCR and Western blot to evaluate the effect of COMF on RAAS. Results Compared with SHR control group, HW, HW/BW, LVM and LVM/BW de- creased in SHR ＋ COMF-M and SHR ＋ COMF-H groups; Cadiomyocyte hypertrophy was inhibited in COMF groups; The concentration of Ang 11 and ALD in heart and blood decreased; ACE and AT1 mRNA and protein ex- pression in heart tissue decreased while ACE2 mRNA expression increased （P 〈 0.01 or P 〈 0.05） , Conclusion Total flavonoids of Cydonia oblonga Mill. showed the effect of inhibition of myocardial hypertrophy in spontaneously hypertensive rats and the mechanism was related to. inhibit the activity of Renin-angiotensin-aldosterone system.
基金National Natural Science Foundation of China(81860732)Scientific and Technological Projects for Social Development in Guizhou Province of China([2011]3036)the State Key Laboratory of Cardiovascular Disease(2017kf-03)
文摘OBJECTIVE To investigate the inhibitory effect and mechanism of sodium ferulate(SF)on myocardial hypertrophy in spontaneously hypertensive(SHR).METHODS Forty 14-week-old SHR male rats were randomly divided into model group(SHR,receive distilled water)and SF treatment groups(SF 20,40 and 80 mg·kg^-1 per day,respectively).Age-matched male Wistar-Kyoto(WKY)rats gavaged with distilled water served as controls.After 12 weeks of treatment,the effects of SF on cardiac hypertrophy were evaluated using echocardiographic measurement,pathological analysis and the expression of atrial natriuretic peptide(ANP),myosin heavy chainβ(β-MHC)-a gene related to myocardial hypertrophy.In order to explore the mechanism of SF on myocardial hypertrophy,the calcium-sensing receptor(CaSR),calcineurin(CaN),nuclear factor of activated T cell 3(NFAT3),phosphorylation NFAT3(p-NFAT3),zinc finger transcription factor(GATA4),phosphorylation GATA4(p-GATA4),protein kinase Cβ(PKC-β),Raf-1,extracellular regulated protein kinase 1/2(ERK 1/2),phosphorylation ERK1/2(p-ERK 1/2)and mitogen-activated protein kinase phosphatase-1(MKP-1)were detected.RESULTS The myocardial hypertrophy parameters,myocardial cell cross section area,left ventricular wall thickness and expression of ANP and β-MHC,CaSR,CaN,NFAT3,p-GATA4,PKC-β,Raf-1,and p-ERK 1/2 were significantly increased,while the left ventricular cavity was significantly smaller,expression of p-NFAT3 and MKP-1 were significantly decreased,meanwhile,the ultra⁃structure of cardiomyocytes was significantly damaged in 26-week-old SHR rats.Notably,SF significantly ameliorated myocardial hyper⁃trophy in 26-week-old SHR rats;suppressed the overexpression of ANP,β-MHC,CaSR,CaN,NFAT3,p-GATA4,PKC-β,Raf-1,and p-ERK 1/2 and increased the expression of p-NFAT3 and MKP-1.CONCLUSION SF can inhibit cardiac hypertrophy in SHR rats,and the mechanism may be related to the inhibition of CaSR mediated signaling pathway.
基金Supported by the National Natural Science Foundatin of China(10972178)
文摘According to spontaneous combustion propensity,the longwall gob is divided into three zones,including heat dissipation zone,self-heating zone and the choking zone.Only in the self-heating zone can temperature of coal rise due to oxidation.Studying the distribution of the "Three Zones" in gob is important for predicting and preventing spontaneous combustion in coalmine.In normal mining operations,temperature of coal is roughly constant.The process of mass transfer in the gob is considered to be steady.Based on mass conservation,gas species conservation,darcy's law,Ficks law of diffusion and coal oxidation 1-grade reaction rule,governing equation for air leakage intensity and species concentration are deduced.With critical value of coal spontaneous combustion and the size of longwall workface as basic dimension,a dimensionless steady coupled model of air flow diffusion and chemical reaction in loose coal of Fully Mechanized Top-Coal Caving Mining Workface(FMTCCMW) is setup.By solving the model numerically,regulation of three zones' distribution and spontaneous combustion in the gob can be obtained.The results can be easily popularized to prediction of spontaneous combustion in other coalmines' longwall gob.
基金Project(2021MD703848) supported by the China Postdoctoral Science FoundationProjects(52174229, 52174230)supported by the National Natural Science Foundation of China+1 种基金Project(2021-KF-23-04) supported by the Natural Science Foundation of Liaoning Province,ChinaProject(2020CXNL10) supported by the Fundamental Research Funds for the Central Universities,China。
文摘Coal mine fires,which can cause heavy casualties,environmental damages and a waste of coal resources,have become a worldwide problem.Aiming at overcoming the drawbacks,such as a low analysis efficiency,poor stability and large monitoring error,of the existing underground coal fire monitoring technology,a novel monitoring system based on non-dispersive infrared(NDIR)spectroscopy is developed.In this study,first,the measurement principle of NDIR sensor,the gas concentration calculation and its temperature compensation algorithms were expounded.Next,taking CO and CH_(4) as examples,the liner correlation coefficients of absorbance and the temperature correction factors of the two indicator gases were calculated,and then the errors of concentration measurement for CO,CO_(2),CH_(4) and C_(2)H_(4) were further analyzed.The results disclose that the designed NDIR sensors can satisfy the requirements of industrial standards for monitoring the indicator gases for coal fire hazards.For the established NDIR-based monitoring system,the NDIRbased spectrum analyzer and its auxiliary equipment boast intrinsically safe and explosion-proof performances and can achieve real-time and in-situ detection of indicator gases when installed close to the coal fire risk area underground.Furthermore,a field application of the NDIR-based monitoring system in a coal mine shows that the NDIR-based spectrum analyzer has a permissible difference from the chromatography in measuring the concentrations of various indicator gases.Besides,the advantages of high accuracy,quick analysis and excellent security of the NDIR-based monitoring system have promoted its application in many coal mines.
基金Project(2013CB036003)supported by the National Basic Research,Program of ChinaProject(2010QNA54)Fundamental Research Funds for the Central Universities,ChinaProject supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions,China
文摘Significant changes in spontaneous potential and exciting currents are observed during water and grout injection in a simulated porous media. Obvious correlations between the seepage flow field and the electric field in the porous media are identified.In this work, a detailed experimental study of geoelectric field variation occurring in water migration was reported by analyzing water and grout injection processes in a simulated porous media. The spontaneous potential varies linearly with the thickness of unsaturated porous media. Very interestingly, the spontaneous potential generated in the second grout injection exhibits some"memory" of previous grouting paths. The decreases in spontaneous potential observed during grout injection is very probably due to that the spontaneous potential variations are primarily caused by electro-filtration potential, as indicated by the far larger viscosity of grout compared to that of water. The geoelectric response can be utilized to effectively identify the grouting paths in water-bearing rocks.
文摘Aim To study the anti-hypertensive effect of total flavonoids of Cydonia oblonga Mill. in spontaneously hypertensive rats, then preliminarily investigate the mechanism of action based on anti-inflammatory function. Methods Total flavonoids of COM （COMF） were separated and purified by the optimal process, SHR were divid- ed into 6 groups as SHR control group （SHR）, captopril group （CAP, 25mg· kg^-1 · d^-1）, Eucommia ulmoides Oliver group （EUO, 30 mg · kg^-1· d^-1）, low （COMF-L, 40 mg · kg^-1· d^-1）, middle （COMF-M, 80 mg · kg^-1 · d^-1） and high dose （COMF-H, 160 mg · kg^-1· d ^-1） of COMF groups. 8 Wistar-Kyoto （WKY） rats were given distilled water instead as control. The drugs were given by intragastric administration for 16 weeks, then the levels of IL-1β, IL-6, IL-10, TNF-α and CRP in serum were tested. Results Compared with WKY group, the levels of IL-I~, IL-6, TNF-α and CRP were increased and IL-10 was decreased; Compared with SHR group, the levels of IL-1β, IL-6, TNF-α and CRP were decreased in COMF groups （P 〈0.01 or P 〈0.05） , while IL-10 was increased a little but without any significant difference （P 〈 0.05 ）. Conclusion Total flavonoids of Cydonia ob- longa Mill. showed the anti-hypertensive activity in spontaneously hypertensive rats and the mechanism was related to the function of anti-inflammatory.
基金Project(NECT-04-0748) supported by New Century Excellent Talents Program of China
文摘In order to utilize the spontaneous accumulation of heat (SAH) reasonably and obtain the high quality sinter with low energy consumption, a lower fuel consumption modeling based on raw materials of a certain steel works was built. An air-flow segregation feeding (ASF) experimental equipment was designed to simulate strand feeding process and calculate the lower fuel consumption quantity. Compared with baseline test, the ASF experimental equipment was adopted. The results of sinter pot tests show that the solid fuel consumption is lower than that in baseline test, which is decreased by 5.8%. Meanwhile, other sinter indexes, such as pan yeild, tumbler strength and strand productivity are improved. The mineralogical examination indicates that the mineral compositions and micostructures are improved in sinter.
文摘Formamidinium lead bromide(FAPbBr_(3))nanocrystals(NCs)have been considered to be a good optoelectronic material due to their pure green emission,excellent stability and superior carrier transport characteristics.However,two-photon pumped amplified spontaneous emission(ASE)and the corresponding nonlinear optical properties of FAPbBr_(3) NCs are scarcely revealed.Herein,we synthesized colloidal FAPbBr_(3) NCs with different sizes by changing the molar ratio of FABr/PbBr_(2) in the precursor solution,using ligand assisted precipitation(LARP)technology at room temperature.Photoluminescence(PL)and time resolved photoluminescence(TRPL)spectroscopy were measured to characterize their ASE properties.And their nonlinear optical properties were studied through the Zscan technique and the two-photon excited fluorescence method.The stimulated emission properties including oneand two-photon pumped ASE have been realized from FAPbBr_(3) NCs.With large two-photon absorption coefficient(0.27 cm/GW)and high non-linear absorption cross-section(7.52×10^(5) GM),ASE with threshold as low as 9.8μJ/cm^(2) and 487μJ/cm^(2) have been obtained from colloidal FAPbBr_(3) NCs using one-and two-photon excitations.These results indicate that as a new possible green-emitting frequency-upconversion material with low thresholds,FAPbBr_(3) NCs hold great potential in the development of high-performance two-photon pump lasers.
文摘Liver tumours are among the most commonmalignancies worldwide. The international incidenceof the disease is about l million cases per year (male:femalc, 4: 1 ). These include primary and secondarytumours. Cancer is known to be a genetic disease thatinvolves the alteration of activity of the products of atleast 2 genes, due to mutation (s) and/or otherfactors, e. g., the presence of viral oncoproteins. Thegenes most affected are the tumour suppressor
文摘The quantum entangled photon-pair source,as an essential component of optical quantum systems,holds great potential for applications such as quantum teleportation,quan-tum computing,and quantum imaging.The current workhorse technique for preparing photon pairs involves performing spon-taneous parametric down conversion(SPDC)in bulk nonlinear crystals.However,the current power consumption and cost of preparing entangled photon-pair sources are relatively high,pos-ing challenges to their integration and scalability.In this paper,we propose a low-power system model for the quantum entan-gled photon-pair source based on SPDC theory and phase matching technology.This model allows us to analyze the per-formance of each module and the influence of component cha-racteristics on the overall system.In our experimental setup,we utilize a 5 mW laser diode and a typical type-II barium metabo-rate(BBO)crystal to prepare an entangled photon-pair source.The experimental results are in excellent agreement with the model,indicating a significant step towards achieving the goal of low-power and low-cost entangled photon-pair sources.This achievement not only contributes to the practical application of quantum entanglement lighting,but also paves the way for the widespread adoption of optical quantum systems in the future.
文摘The spontaneous burning has been lasting for thousands of years in the coal fields in the north of China. It spreads from the west (Tianshan coal field) to the east (Huolinhe coal field). Its E-W extension is up to 3750km, concentrating in N35°toN45°, its vertical depth up to 260m, and the surface temprature locally up to 270℃. Annually, it burns out 0, 250-300 million tones of coal, causing economic loss equivalent to 2-3 billion R.M.B. Yuan.It destroies coal resources and causes hazards in coal mines. In order to locate the extent and the direction in coal burning areas, the remote sensing technique has heen used and has produced an obvious benefit.
