Study on Coal Seam Damage Caused by Liquid Nitrogen Under Different Ground Temperature Conditions

2021 ◽  
Vol 144 (7) ◽  
Author(s):  
Zekai Wang ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
Shanjie Su ◽  
Menglin Du
Keyword(s):  
Coal Seam ◽  
Liquid Nitrogen ◽  
Wave Velocity ◽  
Coal Sample ◽  
Initial Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
Nitrogen Treatment ◽  
Scanning Electron

Abstract The thermal stress caused by the ultra-low temperature of liquid nitrogen (LN2) can seriously affect the porosity of the coalbed. In this paper, the effects of various temperature differences on the LN2 damage were studied by changing the initial temperature, so as to explore the effect of LN2 on coal seam with different buried depth. The X-ray diffraction (XRD), scanning electron microscope (SEM), wave velocity, acoustic emission (AE), and uniaxial compression experiments were used in the experiments. The experimental results show that LN2 causes a lot of damage to coal and the LN2 effect increase at first and then decrease with the increase of the initial temperature. When the initial temperature is 293 K, before and after liquid nitrogen treatment, the wave velocity damage of the coal sample reaches 0.2207 and the compressive strength decreases by 27.92%. These two values are 0.3697 and 47.37% at the initial temperature of 323 K, and 0.2727 and 28.27% at the initial temperature of 353 K. This is because if the temperature exceeds 353 K, it will cause a 3.17% drop in water content, thus reducing the damage caused by LN2, resulting in the overall effect slightly lower than that at 323 K.

The Effects of Ternary Elemental Additions on the Structure and Magnetic Properties of Nanocrystalline Feco Powders

2002 ◽  
Vol 753 ◽  
Author(s):  
I. Baker ◽  
R. G. Quiller ◽  
M. Robson ◽  
D. Wu
Keyword(s):  
Magnetic Properties ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Grain Sizes ◽  
Before And After ◽  
Diffraction Peaks ◽  
Computer Controlled ◽  
Steel Balls ◽  
Scanning Electron

ABSTRACTPowders of near-equiatomic Fe and Co were mechanically milled with additions of Zr, C, Ni, Cu and/or B for 60 hr using stainless steel balls in a Svegari attritor operated at 1300 r.p.m. under argon. The milled powders were examined before and after annealing at 600 °C. The morphologies and sizes of the powders were examined using a scanning electron microscope. The grain sizes were characterized from the widths of X-ray diffraction peaks obtained using a computer-controlled x-ray diffractometer and the lattice parameters were determined. The resulting magnetic properties were measured using a vibrating sample magnetometer.

scholarly journals Effect of H2O Activity on Zeolite Formation

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4780
Author(s):  
Claudia Belviso ◽  
Francesco Cavalcante
Keyword(s):  
Liquid Nitrogen ◽  
Sodium Aluminate ◽  
Drying Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lta Zeolite ◽  
Zeolite Formation ◽  
Silica Alumina ◽  
Over Time ◽  
Scanning Electron

In an effort to understand the effects of H2O activity on zeolite formation, we have synthesized LTA zeolite using a combination of freezing processes and varying drying temperatures. Sodium aluminate and sodium silicate were used to form LTA zeolite, according to the IZA (International Zeolite Association) protocol. The synthesis steps were modified by adding the precursor frozen process by a rapid liquid nitrogen (−196 °C) treatment or slow conventional freezer treatment (−20 °C). The samples were subsequently sonicated and then dried at 80 °C or 40 °C. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were performed on the samples immediately after the drying process as well as after 2 weeks and 1 month of aging the solid products. The results indicated that LTA zeolite does not form. The silica-alumina precursor after both freezing processes and after being dried at 80 °C showed the presence of sodalite displaying stable behavior over time. Both sets of samples dried at 40 °C and did not show the presence of zeolite immediately after the drying process. However, after 2 weeks, the liquid nitrogen–frozen precursor was characterized by the presence of EMT whereas zeolites never formed in the −20 °C samples. These results suggest that freezing processes differently control the H2O activity during the drying and aging processes in the solid state. Thus, although the precursor chemical composition is the same, the type of zeolite formed is different.

The Effect of Regeneration Conditions on the Properties of CeO2 Desulfurization Sorbent in SO2 Atmosphere

2017 ◽  
Vol 896 ◽  
pp. 155-161
Author(s):  
Lei Yang ◽  
Shang Guan Ju ◽  
Hui Qing Wang ◽  
Jia An ◽  
Jun Ming Yu ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Elemental Sulfur ◽  
Fixed Bed ◽  
Fixed Bed Reactor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
Regeneration Condition ◽  
Main Components ◽  
Scanning Electron

CeO2 desulfurization sorbent was prepared by calcination of Ce(NO3)3 ● 6H2O and the effect of regeneration conditions on its properties in SO2 atmosphere was investigated in a fixed bed reactor. The regeneration conversion and the yield of elemental sulfur for CeO2 desulfurization sorbent were tested and calculated. And the composition and the morphology of CeO2 desulfurization sorbent before and after regeneration were obtained by X-ray diffraction and scanning electron microscope. It was found that the main components of the regeneration products of Ce2O desulfurization sorbent were solid CeO2 and gaseous elemental S in SO2 atmosphere. The optimum regeneration condition of CeO2 desulfurization sorbent is that the regeneration temperature of 750 °C and the SO2 concentration of 4.25 %, under which the CeO2 desulfurization sorbent shows the higher regeneration conversion of 96 % and the yield of elemental sulfur of 68.95 wt. %.

Study on Spheroidization of Niobium Powders by RF Plasma Processing

2013 ◽  
Vol 442 ◽  
pp. 22-26
Author(s):  
Jian Jun Wang ◽  
Jun Jie Hao ◽  
Zhi Meng Guo
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Feeding Rate ◽  
Plasma Processing ◽  
Argon Plasma ◽  
Rf Plasma ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
Scanning Electron

Spherical niobium powders were synthesized by (RF) argon plasma with irregular niobium powders in this paper. The objective of the present work was to investigate how the feeding rate influence the spheroidization efficiency. The phase composition, morphology and particle size distribution of the powders before and after spheroidization were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser micron sizer (LMS). The results show that niobium powders after plasma processing have good dispersity and smooth surfaces, and their spheroidization ratio is almost 100%. The apparent density and flowability of the powder with the spheroidization efficiency 100% is 4.35 g/cm3 and 12.51 s/(50g), respectively. With the increasing of the feeding rate, the spheroidization ratio of niobium powders drops gradually.

scholarly journals The Comparative PDT Experiment of the Inactivation of HL60 on Modified TiO2Nanoparticles

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Kaiqi Lu ◽  
Qiyun He ◽  
Li Chen ◽  
Baoquan Ai ◽  
Jianwen Xiong
Keyword(s):  
Electron Microscope ◽  
Leukemia Cells ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Ultrasonic Methods ◽  
Photocatalytic Inactivation ◽  
Before And After ◽  
Inactivation Effect ◽  
Scanning Electron

Four samples of modified titanium dioxide (TiO2), Fe/TiO2(2 wt%), Fe/TiO2(5 wt%), and 5-ALA/TiO2, were experimented in photodynamic therapy (PDT) on leukemia cells HL60, performing promising photocatalytic inactivation effect. Fe/TiO2and 5-ALA/TiO2were synthesized in methods of precipitation and ultrasonic methods, respectively. X-ray diffraction spectra and UV-Vis spectra were studied for the samples’ crystalline phase and redshift of absorption peak. Further, FTIR spectra and Raman spectra were obtained to examine the combination of 5-aminolevulinic (5-ALA) and TiO2nanoparticles. The toxicity of these four kinds of nanoparticles was studied through darkroom experiments. And based on the concentration which caused the same toxic effect (90%) on HL60, PDT experiments of TiO2, Fe/TiO2(2%), Fe/TiO2(5%), and ALA/TiO2were done, resulting in the fact that the photokilling efficiency was 69.7%, 71.6%, 72%, and 80.6%, respectively. Scanning electron microscope (SEM) images of the samples were also taken to study the morphology of HL60 cells before and after PDT, resulting in the fact the activation of the modified TiO2from PDT was the main cause of cell apoptosis.

scholarly journals Chitosan Grafted Adsorbents for Diclofenac Pharmaceutical Compound Removal from Single-Component Aqueous Solutions and Mixtures

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 497 ◽  
Author(s):  
Areti Tzereme ◽  
Evi Christodoulou ◽  
George Kyzas ◽  
Margaritis Kostoglou ◽  
Dimitrios Bikiaris ◽  
...  
Keyword(s):  
Succinic Anhydride ◽  
Pharmaceutical Compounds ◽  
Aqueous Mixtures ◽  
X Ray Diffraction ◽  
Amino Groups ◽  
X Ray ◽  
Aconitic Acid ◽  
Optimum Ph ◽  
Before And After ◽  
Scanning Electron

The main purpose of this study was to investigate the synthesis of some cross-linked carboxyl-grafted chitosan derivatives to be used as selective adsorbents for diclofenac (DCF) pharmaceutical compounds from aqueous mixtures. Four different materials were synthesized using succinic anhydride (CsSUC), maleic anhydride (CsMAL), itaconic acid (CsITA), and trans-aconitic acid (CsTACON) as grafting agents. After synthesis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were performed before and after DCF adsorption. In addition, a complete adsorption evaluation was carried out for all materials studying some important parameters. The optimum pH was 4; the amino groups of DCF can be protonated at pH = 4 (–NH+), so this groups can easily attract the clear negatively carboxyl moieties (–COO−) of the chitosan adsorbents. The Qm for CsTACON was higher than those of the other materials, at all temperatures studied. By altering the temperature from 25 to 35 °C, an increase (16%) of Qm (from 84.56 to 98.34 mg g−1) was noted, while similar behavior was revealed after a further increase of temperature from 35 to 45 °C, improving by 5% (from 98.34 to 102.75 mg g−1). All isotherms were fitted to Langmuir, Freundlich, and Langmuir-Freundlich (L-F) models). In addition, a kinetic model was proposed taking into account not only the interactions but also the diffusivity of the molecule (DCF) into the polymeric network. The behavior of the prepared chitosan materials in simultaneously removing other compounds (synergetic or antagonistic) was also evaluated by experiments performed in mixtures. DCF presented the highest removal from the mixture in the order: CsTACON (92.8%) > CsITA (89.5%) > CsSUC (80.9%) > CsMAL (66.2%) compared to other pharmaceutical compounds (salicylic acid, ibuprofen and ketoprofen). Desorption was achieved by using different eluants (either water or organic). The highest desorption ability was found for acetone (100% for CsTACON, CsSUC, CsMAL and 77% for CsITA) for all materials.

Electrospun CuO Nanofibre Assemblies for H2S Sensing

2018 ◽  
Vol 233 (1) ◽  
pp. 105-116
Author(s):  
Christoph Seitz ◽  
Sebastian Werner ◽  
Roland Marschall ◽  
Bernd M. Smarsly
Keyword(s):  
Electron Microscopy ◽  
Linear Sweep Voltammetry ◽  
X Ray Diffraction ◽  
Linear Sweep ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After ◽  
Volumetric Stress ◽  
Scanning Electron

Abstract Copper oxide (CuO) nanofibres are utilised to sense the toxic and abrasive gas hydrogen sulfide (H2S) in the ppm (parts per million) range. The detection by CuO is based on a significant increase in the conductance upon the formation of CuS, and is thereby selective and sensitive towards H2S. Nanofibres outperform thin films of CuO by compensating the volumetric stress which occurs during sensing. Here, sensors are presented exhibiting up to 600 cycles of sensing and regeneration. To get further insights into the degradation of the fibres upon the reaction with H2S the sensors were analysed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), resistance and linear sweep voltammetry (LSV) measurements before and after cycling. SEM and TEM revealed a drastic change in morphology of the CuO fibres resulting in an undefined aggregate of nanoparticles after 600 cycles. Resistance and LSV measurements showed that the contacting and the measurement process itself are crucial factors for optimising long-term use of CuO-based H2S sensors.

scholarly journals Study of Calcium/Lead Apatite Structure Type for Stabilising Heavy Metals

2000 ◽  
Vol 658 ◽  
Author(s):  
Z.L. Dong ◽  
B. Wei ◽  
T.J. White
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Structure Type ◽  
X Ray Diffraction ◽  
Etch Pits ◽  
X Ray ◽  
Transmission Electron ◽  
Before And After ◽  
Calcium Lead ◽  
Scanning Electron

ABSTRACT(CaxPb10−x)(VO4)6F2 apatites were synthesised and their microstructures were studied using powder X-ray diffraction, scanning electron microscopy and transmission electron microscopy before and after leach testing. X-ray diffraction showed that the apatites were hexagonal with a ≍ 10Å and c ≍ 7Å. During the leach test, Pb was released into the solution more slowly than Ca, which is desirable as the immobilisation of Pb is of importance. The experimental results also showed that V was almost undetectable in the leaching test solutions. In the (Ca7Pb3)(VO4)6F2 pellet, Ca and Pb distributions were not homogenous from one grain to another. Microstructural evidence from scanning electron microscopy revealed that the dissolution via development of etch pits began at grain boundaries and inside grains, and progressed faster in Ca rich regions. These results suggest that apatites of high Pb to Ca ratio are more durable.

Improvement of the Crystalline Quality of β-Ga2O3 Films by High-Temperature Annealing

2012 ◽  
Vol 725 ◽  
pp. 273-276
Author(s):  
Motoki Takahara ◽  
Suguru Funasaki ◽  
Jyun Kudou ◽  
Isao Tsunoda ◽  
Kenichiro Takakura ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
Crystalline Quality ◽  
High Temperature Annealing ◽  
X Ray Diffraction ◽  
X Ray ◽  
Before And After ◽  
Si Doped ◽  
Scanning Electron

For the purpose of improving the crystalline quality of undoped and Si doped β-Ga2O3 films, high temperature annealing at 900°C was performed. The crystalline quality of the films investigated using scanning electron microscopy and X-ray diffraction. Also the conductivity of the films is compared before and after the annealing. After the 900°C annealing, the XRD peaks intensity corresponding to β-Ga2O3 is increased. This result indicates that the crystalline quality improves by the high temperature annealing.

Preparation and Characteristics of Highly Expandable Graphite Intercalation Compounds by Two-Step Chemical Intercalation

2016 ◽  
Vol 703 ◽  
pp. 278-283
Author(s):  
Xiao Xia Li ◽  
Ji Jin Zhao ◽  
De Yue Ma
Keyword(s):  
Interlayer Spacing ◽  
Intercalation Compounds ◽  
Expandable Graphite ◽  
X Ray Diffraction ◽  
Graphite Intercalation Compounds ◽  
X Ray ◽  
Graphite Intercalation ◽  
Before And After ◽  
One Step ◽  
Scanning Electron

Graphite intercalation compounds (GIC) are the most common precursors for expanded graphites which are promising materials for many applications. A series of GICs with different expanding volumes (EV) were prepared by a two-step chemical intercalation way. Effects of the input of oxidant and intercalating agent on the EV of GICs were discussed. The microstructures and morphologies of graphites before and after intercalation were analylized by X-ray diffraction and scanning electron microscope, respectively. The results show that the GIC with an EV of 600 ml⋅g-1 may be prepared under temperal conditions by a two-step intercalation way. The interlayer spacing of the pre-GIC formeded by one-step intercalation is a bit larger than that of natural graphites, while the interlayer spacing of the GIC obtained by two-step intercalation becomes much larger than that of the pre-GIC because of secondery intercalation. When the d-spacing (d002) value of the GIC rises from 0.3590 nm up to 0.3711nm, its EV increases from 267 up to 600 ml⋅g-1 due to the decomposition and release of much more intercalated substances during a thermal shock.

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