scholarly journals Experimental Investigation on Influencing Factors of Rock Fragmentation Induced by Carbon Dioxide Phase Transition Fracturing

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Bo Gao ◽  
Youjiang Yang ◽  
Weilong Xue ◽  
Anhui Guo ◽  
Xuedong Luo
Keyword(s):  
Phase Transition ◽  
Carbon Dioxide ◽  
Growth Rate ◽  
Field Experiments ◽  
Sheet Thickness ◽  
Peak Stress ◽  
Rock Breaking ◽  
Rock Fragmentation ◽  
Powder Factor ◽  
Crater Volume

Carbon dioxide phase transition fracturing is a novel physical blasting technique, which is gradually used in mining and underground space engineering. The improvement of its rock breaking efficiency is the key concern in the application. In this paper, field experiments of CO2 phase transition fracturing were conducted. Based on the strain monitoring and fracturing crater volume measuring, the variation of CO2 filling amount and shear sheet thickness on rock fragmentation of CO2 phase transition fracturing was investigated. The experimental results indicated that the fracturing crater is shaped as an elliptical cone that is longer in the jet direction and shorter in the vertical jet direction. With the increase of the CO2 filling amount, the excavated crater volume gradually increases, but the growth rate gradually decreases. The powder factor is constant within a certain charge amount, and after exceeding this charge amount, the powder factor of CO2 increases significantly. As the shear sheet thickness increases, although the consultant peak stress gradually increases, its growth rate is still unchanged. The crater volume and its growth rate gradually increase in the same situation. Moreover, with the shear sheet thickness increase, the CO2 powder factor decreases continuously, and the decline rate remains unchanged.

scholarly journals Rock Breaking and Dynamic Response Characteristics of Carbon Dioxide Phase Transition Fracturing Considering the Gathering Energy Effect

Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1336 ◽  
Author(s):  
Shengtao Zhou ◽  
Nan Jiang ◽  
Xu He ◽  
Xuedong Luo
Keyword(s):  
Phase Transition ◽  
Carbon Dioxide ◽  
Dynamic Response ◽  
Rock Breaking ◽  
Energy Effect ◽  
Secondary Impact ◽  
Peak Point ◽  
Point Velocity ◽  
The Impact ◽  
Primary Impact

Carbon dioxide phase transition fracturing has been widely used in rock mass excavation under complex environments, and its special rock breaking process shows obvious gathering energy effect. In this paper, the gathering energy effect of this technology is considered and then the impact reduction coefficient is defined and determined. Eventually, a combined method of field tests and numerical simulations is used to study the crack propagation characteristics and spatiotemporal changes of dynamic response. The results show that the cracks grow more and more slowly as time goes by; the peak displacement and peak point velocity in the primary impact direction are both greater than those in the secondary impact direction. The peak point velocity in different directions decreases as the distance from borehole increases and it decays more and more slowly. With the increase of distance from the borehole, the peak effective stress in the primary impact direction constantly decreases. However, it increases first and then decreases in the secondary impact direction. The results mentioned above can provide effective guidance for later experimental research and engineering.

Comments on “Impacts of CO2-Induced Warming on Simulated Hurricane Intensity and Precipitation: Sensitivity to the Choice of Climate Model and Convective Scheme”

2005 ◽  
Vol 18 (23) ◽  
pp. 5179-5182 ◽  
Author(s):  
Patrick J. Michaels ◽  
Paul C. Knappenberger ◽  
Christopher Landsea
Keyword(s):  
Carbon Dioxide ◽  
Growth Rate ◽  
Tropical Cyclones ◽  
Real World ◽  
Climate Model ◽  
Mesoscale Model ◽  
Strong Relationship ◽  
Sea Surface ◽  
Hurricane Intensity ◽  
Convective Scheme

Abstract In a simulation of enhanced tropical cyclones in a warmer world, Knutson and Tuleya make several assumptions that are not borne out in the real world. They include an unrealistically large carbon dioxide growth rate, an overly strong relationship between sea surface temperature and hurricane intensity, and the use of a mesoscale model that has shown little to no useful skill in predicting current-day hurricane intensity. After accounting for these inaccuracies, a detectable increase in Atlantic hurricane intensity in response to growing atmospheric greenhouse gas levels during this century becomes unlikely.

scholarly journals Seed mass effects on germination and growth of diverse European Scots pine populations

1994 ◽  
Vol 24 (2) ◽  
pp. 306-320 ◽  
Author(s):  
P.B. Reich ◽  
J. Oleksyn ◽  
M.G. Tjoelker
Keyword(s):  
Growth Rate ◽  
Relative Growth Rate ◽  
Scots Pine ◽  
Field Experiments ◽  
Seed Mass ◽  
Growing Season ◽  
Turkish Population ◽  
Dry Mass ◽  
Relative Growth ◽  
Mass Effects

Seedlings of 24 European Scots pine (Pinussylvestris L.) populations were grown in controlled environment chambers under simulated photoperiodic conditions of 50 and 60°N latitude to evaluate the effect of seed mass on germination and seedling growth characteristics. Seeds of each population were classified into 1-mg mass classes, and the four classes per population with the highest frequencies were used. Photoperiod had minimal influence on seed mass effects. Overall, seed mass was positively related to the number of cotyledons and hypocotyl height. Populations differed significantly in seed mass effect on biomass. In northern populations (55–61°N), dry mass at the end of the first growing season was little affected by seed mass. However, dry mass in 9 of 15 central populations (54–48°N) and all southern (<45°N) populations correlated positively with seed mass. Relative growth rate was not related to seed mass within or across populations, and thus early growth is largely determined by seed mass. Relative growth rate also did not differ among populations, except for a geographically isolated Turkish population with the highest seed mass and lowest relative growth rate. After one growing season, height was positively correlated (r2 > 0.6) with seed mass in 15 populations. To check the duration of seed mass effects, height growth of 1- to 7-year-old field experiments established with the same seed lots were compared. Seed mass effects on height were strongest for 1-year-old seedlings and declined or disappeared by the age of 5–7 years among central and southern populations, but remained stable over that time in northern populations.

scholarly journals Quantitative Interaction Effects of Carbon Dioxide, Sodium Chloride, and Sodium Nitrite on Neurotoxin Gene Expression in Nonproteolytic Clostridium botulinum Type B

2004 ◽  
Vol 70 (5) ◽  
pp. 2928-2934 ◽  
Author(s):  
Maria Lövenklev ◽  
Ingrid Artin ◽  
Oskar Hagberg ◽  
Elisabeth Borch ◽  
Elisabet Holst ◽  
...  
Keyword(s):  
Gene Expression ◽  
Carbon Dioxide ◽  
Growth Rate ◽  
Sodium Chloride ◽  
Optical Density ◽  
Sodium Nitrite ◽  
Clostridium Botulinum ◽  
Lag Phase ◽  
Type B ◽  
Phase Duration

ABSTRACT The effects of carbon dioxide, sodium chloride, and sodium nitrite on type B botulinum neurotoxin (BoNT/B) gene (cntB) expression in nonproteolytic Clostridium botulinum were investigated in a tryptone-peptone-yeast extract (TPY) medium. Various concentrations of these selected food preservatives were studied by using a complete factorial design in order to quantitatively study interaction effects, as well as main effects, on the following responses: lag phase duration (LPD), growth rate, relative cntB expression, and extracellular BoNT/B production. Multiple linear regression was used to set up six statistical models to quantify and predict these responses. All combinations of NaCl and NaNO2 in the growth medium resulted in a prolonged lag phase duration and in a reduction in the specific growth rate. In contrast, the relative BoNT/B gene expression was unchanged, as determined by the cntB-specific quantitative reverse transcription-PCR method. This was confirmed when we measured the extracellular BoNT/B concentration by an enzyme-linked immunosorbent assay. CO2 was found to have a major effect on gene expression when the cntB mRNA levels were monitored in the mid-exponential, late exponential, and late stationary growth phases. The expression of cntB relative to the expression of the 16S rRNA gene was stimulated by an elevated CO2 concentration; the cntB mRNA level was fivefold greater in a 70% CO2 atmosphere than in a 10% CO2 atmosphere. These findings were also confirmed when we analyzed the extracellular BoNT/B concentration; we found that the concentrations were 27 ng · ml−1 · unit of optical density−1 in the 10% CO2 atmosphere and 126 ng · ml−1 · unit of optical density−1 in the 70% CO2 atmosphere.

scholarly journals Influence of the specific growth rate on formation of sterols in yeast Saccharomyces cerevisiae during fed-batch cultivation

2000 ◽  
Vol 18 (No. 3) ◽  
pp. 110-114
Author(s):  
J. Čermák ◽  
M. Rychtera ◽  
P. Nechvíle ◽  
J. Náhlík ◽  
K. Melzoch ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Control Strategy ◽  
Respiratory Quotient ◽  
Specific Growth ◽  
Carbon Dioxide Concentration ◽  
Sterol Fraction ◽  
Yeast Cells ◽  
Dry Biomass

Ergosterol is a major sterol in yeast cells. Intermediates of ergosterol biosynthesis or products of ergosterol biotransformation occur in cells too. Sterols mainly form components of cell membranes. Fluidity of membranes is affected by sterols. The amount of sterols in cells can be influenced above all by cultivation conditions and by the yeast genotype. Specific growth rate is an important factor which affects the amount of sterols present in yeast cells. We carried out a series of 24-hour cultivations to find out the impact of specific growth rate on sterol biosynthesis. Inflow of synthetic medium to the bioreactor was controlled by means of a profile of carbon dioxide concentration in the outlet gases. This profile was acquired by simulation according to a mathematical model of cultivation. Profile of carbon dioxide concentration corresponded to a precalculated profile of specific growth rate. Cultivation was divided into two phases with different growth rate values. A constant value of the specific growth rate was maintained in the 1st phase. The specific growth rate value decreased by controlling the inflow in the 2nd phase (beginning at 12th hour of cultivation). Other cultivations were carried out using so-called physiological control which consisted in determining the immediate physiological state (e.g., RQ) and the choice of control strategy according to the metabolic state. Selected control strategy ensures an immediate action (inflow of the medium). If the specific growth rate decreased in the 1st phase, the amount of total sterols in yeast dry biomass increased (to 2.7% in yeast dry biomass). But the purity of ergosterol decreased (amount of sterol contaminants increased up to 23.3% in the sterol fraction). If a constant value of respiratory quotient was maintained (at about 1.1), the amount of total sterols in yeast dry biomass and the purity of ergosterol were constant. If the value of respiratory quotient was changed in the growth and final phase of cultivation, the amount of total sterols in yeast dry biomass increased (to 2.83% in yeast dry biomass). However, the purity of ergosterol decreased (amount of sterol contaminants increased up to 21.2% in sterol fraction).

scholarly journals Dynamic simulation of the oscillation characteristics of supercritical carbon dioxide impacting jets

2018 ◽  
Vol 25 (1) ◽  
pp. 61-71 ◽  
Author(s):  
Xinwei Zhang ◽  
Yiyu Lu ◽  
Jiren Tang ◽  
Zhe Zhou ◽  
Qian Li
Keyword(s):  
Carbon Dioxide ◽  
Numerical Model ◽  
Supercritical Carbon Dioxide ◽  
Oscillation Frequency ◽  
High Speed ◽  
Rock Breaking ◽  
Target Distance ◽  
Inlet Pressure ◽  
Oscillation Characteristics ◽  
Supercritical Carbon

A numerical model was established to investigate the dynamic oscillation characteristics of supercritical carbon dioxide (sc-CO2) impacting jets. The jet hydrodynamics, heat transfer, and physical properties of sc-CO2 fluid were incorporated into the model. The coupling of multiple fields with large velocity and pressure gradients was achieved using a modified SIMPLE segmentation algorithm. Laboratory experiments validated the reliability of the numerical model by detecting dynamic changes in the pressure on the centerline of the sc-CO2 impacting jet. Analysis of the flow field showed single or double high-speed sc-CO2 mass structures for the sc-CO2 impacting jet, revealing the generation mechanism of the impacting oscillation frequency and the mechanism of improved rock-breaking efficiency by sc-CO2 jet. The oscillation frequency equation was obtained through a quantitative treatment of the velocity and motion area of the sc-CO2 mass. Finally, the equation and simulation results were used to analyze the influences of the target distance, inlet pressure and temperature on the sc-CO2 jet oscillation characteristics. The results showed that the oscillation frequency and amplitude first increased and then decreased with increases in the target distance. The oscillation frequency and amplitude both increased with increasing inlet pressure; the oscillation frequency increased slowly with increasing temperature.

scholarly journals Permeability Characteristic and Failure Behavior of Filled Cracked Rock in the Triaxial Seepage Experiment

2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Xinyu Liu ◽  
Zhende Zhu ◽  
Aihua Liu
Keyword(s):  
Growth Rate ◽  
Rock Mass ◽  
Failure Modes ◽  
Peak Stress ◽  
Confining Pressure ◽  
Strength Characteristics ◽  
Failure Behavior ◽  
Compression Tests ◽  
Secondary Cracks ◽  
Safety And Stability

Filling is commonly found in natural cracked rock mass. As the weakest part of the rock, the filling properties directly affect the rock deformation and strength, permeability, and so on and affect the safety and stability of the rock mass engineering. In this study, a single slit has been preset in sandstones and filled with different physical properties materials. Based on the laboratory triaxial seepage test, the permeability and strength characteristics of filled cracked sandstones are analyzed, and the failure modes are obtained. The main findings of this study are as follows: (1) The permeability coefficient peak value of the filled cracked rock appears before the stress peak. (2) At the same confining pressure growth rate, the peak stress growth rate of the filled cracked rock is generally higher than that of the intact rock and the strength growth rate of the cracked rock increases with the length of the fracture. The strength characteristics of the filling in the uniaxial compression tests and triaxial seepage tests are significantly affected by the hydraulic properties. (3) The strength and permeability coefficients of cracked rock filled with cement mortar are more sensitive to the change of confining pressure, while under the same condition, the ones of cracked rock filled with gypsum mortar are stable. (4) According to the failure mechanism, under the seepage stress, the secondary cracks can be divided into 3 types and the failure modes can be divided into 2 types.

Carbon dioxide induced structural phase transition in metal–organic frameworks CPO-27

CrystEngComm ◽  
2020 ◽  
Vol 22 (26) ◽  
pp. 4353-4358
Author(s):  
Breogán Pato-Doldán ◽  
Mali H. Rosnes ◽  
Dmitry Chernyshov ◽  
Pascal D. C. Dietzel
Keyword(s):  
Phase Transition ◽  
Carbon Dioxide ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Metal Organic Frameworks ◽  
Honeycomb Structure ◽  
Metal Organic

The framework of CO2 saturated CPO-27 is deformed below 110 K into a superstructure of the original honeycomb structure.

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