To predict the occurrence of the collapse disaster in toppling perilous rock under the action of bidirectional earthquakes,the dynamic stability and fuzzy reliability calculation method of toppling perilous rock under...To predict the occurrence of the collapse disaster in toppling perilous rock under the action of bidirectional earthquakes,the dynamic stability and fuzzy reliability calculation method of toppling perilous rock under the action of bidirectional earthquakes is proposed.First,the mass viscoelasticity model is used to simulate two main control surfaces of toppling perilous rock,the seismic dynamic response model and motion equation of toppling perilous rock are established based on the D'Alembert principle,and the Newmark-β method is used to solve the dynamic motion equation.Then,the instability event of toppling perilous rock is considered a fuzzy event,the membership function expression of the stability coefficient of toppling perilous rock is determined based on the fuzzy failure criterion,the calculation equations of the toppling perilous rock dynamic stability coefficient and fuzzy reliability are established,and the fuzzy reliability evaluation method based on the probability distribution of reliability is proposed.Finally,the influence of different superposition modes of seismic excitation on the fuzzy reliability of toppling perilous rock is analyzed.The calculation results of toppling perilous rock in the engineering case show that the fuzzy reliability calculated after considering the fuzzy failure criterion is reduced by 10.73% to 25.66% compared with the classical reliability.Considering the bidirectional seismic excitation,the fuzzy reliability of toppling perilous rock is reduced by 5.46% to 14.89%.Compared with using the acceleration peak time encounter mode to superpose the seismic excitation,the fuzzy reliability of toppling perilous rock is reduced by 3.4% when the maximum action effect time encounter mode is adopted.展开更多
Hitherto, perilous rock is the weakest topic in disasters studies. Specially, damage of control fissure under loads is one key technique in study of develop mechanism of perilous rock. Damage division of end area of c...Hitherto, perilous rock is the weakest topic in disasters studies. Specially, damage of control fissure under loads is one key technique in study of develop mechanism of perilous rock. Damage division of end area of control fissure was defined by authors, then calculation methods of timed-Poisson＇s ratio and timed-Young＇s modulus were established in damage mechanics theory. Further, the authors set up damage constitutive equation of control fissure, which founds important basis to numerical simulation for control fissure to develop.展开更多
Rupture and safety of perilous rock are dominated by control fissure behind perilous rock block. Based on model-Ⅰ and model-Ⅱ stress strength factors of control fissure under acting of weight of perilous rock, water...Rupture and safety of perilous rock are dominated by control fissure behind perilous rock block. Based on model-Ⅰ and model-Ⅱ stress strength factors of control fissure under acting of weight of perilous rock, water pressure in control fissure and earth- quake forces, method to calculate critical linking length of control fissure is established. Take water pressure in control fissure as a variable periodic load, and abide by P-M criterion, when control fissure is filled with water, establish the method to calculate fatigue fracture life of control fissure in critical status by contributing value of stress strength factor stemming from water pressure of control fissure in Paris＇s fatigue equation. Further, parameters （C and m） of sandstone with quartz and feldspar in the area of the Three Gorges Reservoir of China are obtained by fatigue fracture testing.展开更多
The bioconversion of the hydrophobic and volatile limonene to perillic acid, a potential anticancer agent, by the yeast Yarrowia lipolytica was studied in two steps. Firstly, experimental design was used for process o...The bioconversion of the hydrophobic and volatile limonene to perillic acid, a potential anticancer agent, by the yeast Yarrowia lipolytica was studied in two steps. Firstly, experimental design was used for process optimization using high-purity limonene as substrate and secondly orange essential oil containing 89.1% limonene was used as substrate under the previously optimized conditions. Limonene concentration and pH were identified by fractional factorial design as significant factors and were optimized by central composite design. Under optimized process conditions (0.16% (v/v) limonene;pH 6.9), the 24 h biotransformation process resulted in the accumulation of 0.368 g·L-1 of perillic acid corresponding to a molar yield of 23.1%. A subsequent substrate addition under the same reaction conditions doubled perillic acid concentration to 0.793 g·L-1 and a molar yield of 24.2%. The use of orange essential oil under the optimized reaction conditions increased both perillic acid accumulation and yield to 0.872 g·L-1 and 29.7%, respectively. The robustness of Y. lipolytica allowed the efficient biotransformation of a crude by-product of the citrus industry into a valuable fine chemical.展开更多
Perillic acid can be obtained from microbial oxidation of the exocyclic methyl group of limonene. Due to the pharmacological potential of such a metabolite, the biotransformation processes leading to its synthesis hav...Perillic acid can be obtained from microbial oxidation of the exocyclic methyl group of limonene. Due to the pharmacological potential of such a metabolite, the biotransformation processes leading to its synthesis have been approached in recent studies. A robust analytical method is needed to assess the performance of such studies. An analytical method was developed and validated to determine perillic acid in the supernatants of a yeast-induced bioconversion of limonene, involving gas chromatography (GC) and an acid-induced precipitation during the sample preparation. GC analysis was performed using a column with polyethylene glycol as stationary phase (HP-Innowax) which resulted in higher loads and better peak shape. The sample preparation involved the supernatant initial filtration and precipitation with 0.6 M HCl followed by centrifugation and dissolution in ethyl acetate. GC analysis conditions were oven from 50°C to 250°C at 20°C·min-1, and then held 5 min (total runtime 15 min). Injector was set at 280°C, and detector at 300°C. Helium was the carrier gas at 1 ml·min-1. Injections of 1.0 μl were at the split ratio 25:1. The method was validated: Linearity with R2 of 0.9992, Accuracy of 98.3% in the range 190 - 950 μg·ml-1;Limit of detection of 10.4 μg·ml-1;Repeatability of 2.1% RSD. Thus, a complete methodology to determine perillic acid in a bioconversion supernatant was developed and validated. This overall approach may be useful for bioconversions of monoterpenes by other microorganisms that metabolize limonene.展开更多
The giant perilous rock at Wangxia (named Wangxia perilous rock) is representative in Three Gorges of the Yangtze River, China, has threatened badly the navigation of the Yangtze River channel for a long period. The g...The giant perilous rock at Wangxia (named Wangxia perilous rock) is representative in Three Gorges of the Yangtze River, China, has threatened badly the navigation of the Yangtze River channel for a long period. The giant perilous rock is composed of siliceous limestone and argillaceous limestone, and includes two elements marking by W1 and W2, respectively. The W1 is an isolated pillar while the W2 is in clintheriform. The linking segment of dominant fissure in the W2 is composed by moniliform solution funnels at its back, and the locked segment of the dominant fissure at the base of the W2 is composed by two parts. For the locked part of the dominant fissure of the W2, the upper segment shows the same lithology with the perilous rock and it can be simplified as an elastic medium, for the lower segment composed by argillaceous shale and mudstone can be simplified as a strain-softening medium. Introducing the water-softened function, the constitutive curves with two kinds of medium materials for the locked segment in the dominant fissure of the W2 have been proposed. Based on energy principle, the cusp catastrophe model for perilous rock rupture is built and formulas for the transient elastic and impulsive acceleration and the elastic-impulsive velocity of perilous rock catastrophe rupture have been established. By the calculation, the elastic-impulsive acceleration for the catastrophe rupture of the W2 is 531.4 m/s2, while the average elastic-impulsive velocity is 2.608 m/s. Further, it is deduced that the elastic-impulsive velocity at the base of the W2 is about 5.2 m/s. For the transient ruture of the W2, there is a greater speed difference between the top and the base of the W2, which impels the giant perilous rock to be retroverted sliding rupture, coinciding with the fact. Undoubtedly, studies in this paper must play an important role to analyze the catastrophe rupture mechanism of giant perilous rocks at both banks in Three Gorges of the Yangtze River, China.展开更多
In modern times,whenever China, the giant that had been abused and humil-iated by the West for more than a century, awoke and barely started to stand up,the clamor of the“Yellow Peril”rose in the West. Invariably su...In modern times,whenever China, the giant that had been abused and humil-iated by the West for more than a century, awoke and barely started to stand up,the clamor of the“Yellow Peril”rose in the West. Invariably such nonsense wastime and again refuted by the righteous voice.展开更多
Frenzied cries of“China threat”have once again cropped up in the West,withsome people in the US media shouting the loudest at a time when we are on thedawn of a new century.These gentlemen fly in the face of histori...Frenzied cries of“China threat”have once again cropped up in the West,withsome people in the US media shouting the loudest at a time when we are on thedawn of a new century.These gentlemen fly in the face of historical truth and al-lege that a resurgent China is posing a threat to its Asian neighbors and US.展开更多
In recent years,the rapid advancement of AI has led to its widespread integration into academic research.The technology is transforming traditional methodologies and optimizing key processes--from data analysis and li...In recent years,the rapid advancement of AI has led to its widespread integration into academic research.The technology is transforming traditional methodologies and optimizing key processes--from data analysis and literature reviews to the generation of research hypotheses.展开更多
In this essay, I take the recent publication of several texts examining the historical and contemporary phenomena of Sinophobia, Orientalism, and Sinologism as an opening for theorizing underlying and related issues i...In this essay, I take the recent publication of several texts examining the historical and contemporary phenomena of Sinophobia, Orientalism, and Sinologism as an opening for theorizing underlying and related issues including pervasive anti-China biases in Western journalism and China＇s position therein. In addition to illustrating how the concepts of Orientalism arise from Western historical and epistemological foundations, I theorize what I call a ＂new yellow journalism＂ that has grown in tandem with ＂China＇s rise＂ and the threat this indicates to many Western observers, and how this threat and others like it have been met in the age of ＂new imperialism.＂ I compare this new phenomenon with its historical antecedents, ＂yellow journalism＂ and America＇s emergence as a imperialism power with the Spanish-American War （1898）, and note several key insights offered by recent critical analyses of that period, which together suggest a confluence of different players, including policymakers, new media business models, and what I describe as a type of public ＂corporatism＂ in which citizens, particularly Americans, function effectively as shareholders in maintaining hegemonic if not imperialist power.展开更多
one of the things that drives me I nuts about China is parking on ’ footpaths. I nearly got knocked down recently on what will be my last visit to the historic old Maizidian Street. Here the local government
The seven-year run-up to the Olympics has seen China’s white-hot economy chug along with an annual growth rate of more than 10 percent. But the global economic race is more of a marathon than a sprint. Several former...The seven-year run-up to the Olympics has seen China’s white-hot economy chug along with an annual growth rate of more than 10 percent. But the global economic race is more of a marathon than a sprint. Several former Olympic host countries, including Japan and Australia, suffered economic slumps to varying degrees after the euphoria. Now eyes are turning to China to see if the Games will have a similar impact after they end. Will a post-Olympic slowdown play out here, or could it even prompt another economic take-off in the country? China Development Observation, a business monthly, interviewed Chen Jian, Executive Director of the Beijing Olympic Economy Research Association; Li Yining, a renowned economist; and Zhuang Jian, a senior economist at the Asian Development Bank China Resident Mission, for some answers.展开更多
基金financially supported by the National Key Research and Development Program of China(Nos.2021YFB2600604 and 2021YFB2600600)the General Program of Natural Science Foundation of Chongqing(No.cstc2020jcyj-msxm X0218)the Research and Innovation Program for Graduate Students in Chongqing Jiaotong University(No.2022S0021)。
文摘To predict the occurrence of the collapse disaster in toppling perilous rock under the action of bidirectional earthquakes,the dynamic stability and fuzzy reliability calculation method of toppling perilous rock under the action of bidirectional earthquakes is proposed.First,the mass viscoelasticity model is used to simulate two main control surfaces of toppling perilous rock,the seismic dynamic response model and motion equation of toppling perilous rock are established based on the D'Alembert principle,and the Newmark-β method is used to solve the dynamic motion equation.Then,the instability event of toppling perilous rock is considered a fuzzy event,the membership function expression of the stability coefficient of toppling perilous rock is determined based on the fuzzy failure criterion,the calculation equations of the toppling perilous rock dynamic stability coefficient and fuzzy reliability are established,and the fuzzy reliability evaluation method based on the probability distribution of reliability is proposed.Finally,the influence of different superposition modes of seismic excitation on the fuzzy reliability of toppling perilous rock is analyzed.The calculation results of toppling perilous rock in the engineering case show that the fuzzy reliability calculated after considering the fuzzy failure criterion is reduced by 10.73% to 25.66% compared with the classical reliability.Considering the bidirectional seismic excitation,the fuzzy reliability of toppling perilous rock is reduced by 5.46% to 14.89%.Compared with using the acceleration peak time encounter mode to superpose the seismic excitation,the fuzzy reliability of toppling perilous rock is reduced by 3.4% when the maximum action effect time encounter mode is adopted.
基金Project supported by the Natural Science Foundation of Chongqing (No.2005BA7008)the Fund of Key Laboratory of the Ministry of Education of China (No.200310)
文摘Hitherto, perilous rock is the weakest topic in disasters studies. Specially, damage of control fissure under loads is one key technique in study of develop mechanism of perilous rock. Damage division of end area of control fissure was defined by authors, then calculation methods of timed-Poisson＇s ratio and timed-Young＇s modulus were established in damage mechanics theory. Further, the authors set up damage constitutive equation of control fissure, which founds important basis to numerical simulation for control fissure to develop.
基金Project supported by the National Natural Science Foundation of China (No.50678182)the Chunhui International Fundation of China (No.Z2005155002)
文摘Rupture and safety of perilous rock are dominated by control fissure behind perilous rock block. Based on model-Ⅰ and model-Ⅱ stress strength factors of control fissure under acting of weight of perilous rock, water pressure in control fissure and earth- quake forces, method to calculate critical linking length of control fissure is established. Take water pressure in control fissure as a variable periodic load, and abide by P-M criterion, when control fissure is filled with water, establish the method to calculate fatigue fracture life of control fissure in critical status by contributing value of stress strength factor stemming from water pressure of control fissure in Paris＇s fatigue equation. Further, parameters （C and m） of sandstone with quartz and feldspar in the area of the Three Gorges Reservoir of China are obtained by fatigue fracture testing.
文摘The bioconversion of the hydrophobic and volatile limonene to perillic acid, a potential anticancer agent, by the yeast Yarrowia lipolytica was studied in two steps. Firstly, experimental design was used for process optimization using high-purity limonene as substrate and secondly orange essential oil containing 89.1% limonene was used as substrate under the previously optimized conditions. Limonene concentration and pH were identified by fractional factorial design as significant factors and were optimized by central composite design. Under optimized process conditions (0.16% (v/v) limonene;pH 6.9), the 24 h biotransformation process resulted in the accumulation of 0.368 g·L-1 of perillic acid corresponding to a molar yield of 23.1%. A subsequent substrate addition under the same reaction conditions doubled perillic acid concentration to 0.793 g·L-1 and a molar yield of 24.2%. The use of orange essential oil under the optimized reaction conditions increased both perillic acid accumulation and yield to 0.872 g·L-1 and 29.7%, respectively. The robustness of Y. lipolytica allowed the efficient biotransformation of a crude by-product of the citrus industry into a valuable fine chemical.
文摘Perillic acid can be obtained from microbial oxidation of the exocyclic methyl group of limonene. Due to the pharmacological potential of such a metabolite, the biotransformation processes leading to its synthesis have been approached in recent studies. A robust analytical method is needed to assess the performance of such studies. An analytical method was developed and validated to determine perillic acid in the supernatants of a yeast-induced bioconversion of limonene, involving gas chromatography (GC) and an acid-induced precipitation during the sample preparation. GC analysis was performed using a column with polyethylene glycol as stationary phase (HP-Innowax) which resulted in higher loads and better peak shape. The sample preparation involved the supernatant initial filtration and precipitation with 0.6 M HCl followed by centrifugation and dissolution in ethyl acetate. GC analysis conditions were oven from 50°C to 250°C at 20°C·min-1, and then held 5 min (total runtime 15 min). Injector was set at 280°C, and detector at 300°C. Helium was the carrier gas at 1 ml·min-1. Injections of 1.0 μl were at the split ratio 25:1. The method was validated: Linearity with R2 of 0.9992, Accuracy of 98.3% in the range 190 - 950 μg·ml-1;Limit of detection of 10.4 μg·ml-1;Repeatability of 2.1% RSD. Thus, a complete methodology to determine perillic acid in a bioconversion supernatant was developed and validated. This overall approach may be useful for bioconversions of monoterpenes by other microorganisms that metabolize limonene.
文摘The giant perilous rock at Wangxia (named Wangxia perilous rock) is representative in Three Gorges of the Yangtze River, China, has threatened badly the navigation of the Yangtze River channel for a long period. The giant perilous rock is composed of siliceous limestone and argillaceous limestone, and includes two elements marking by W1 and W2, respectively. The W1 is an isolated pillar while the W2 is in clintheriform. The linking segment of dominant fissure in the W2 is composed by moniliform solution funnels at its back, and the locked segment of the dominant fissure at the base of the W2 is composed by two parts. For the locked part of the dominant fissure of the W2, the upper segment shows the same lithology with the perilous rock and it can be simplified as an elastic medium, for the lower segment composed by argillaceous shale and mudstone can be simplified as a strain-softening medium. Introducing the water-softened function, the constitutive curves with two kinds of medium materials for the locked segment in the dominant fissure of the W2 have been proposed. Based on energy principle, the cusp catastrophe model for perilous rock rupture is built and formulas for the transient elastic and impulsive acceleration and the elastic-impulsive velocity of perilous rock catastrophe rupture have been established. By the calculation, the elastic-impulsive acceleration for the catastrophe rupture of the W2 is 531.4 m/s2, while the average elastic-impulsive velocity is 2.608 m/s. Further, it is deduced that the elastic-impulsive velocity at the base of the W2 is about 5.2 m/s. For the transient ruture of the W2, there is a greater speed difference between the top and the base of the W2, which impels the giant perilous rock to be retroverted sliding rupture, coinciding with the fact. Undoubtedly, studies in this paper must play an important role to analyze the catastrophe rupture mechanism of giant perilous rocks at both banks in Three Gorges of the Yangtze River, China.
文摘In modern times,whenever China, the giant that had been abused and humil-iated by the West for more than a century, awoke and barely started to stand up,the clamor of the“Yellow Peril”rose in the West. Invariably such nonsense wastime and again refuted by the righteous voice.
文摘Frenzied cries of“China threat”have once again cropped up in the West,withsome people in the US media shouting the loudest at a time when we are on thedawn of a new century.These gentlemen fly in the face of historical truth and al-lege that a resurgent China is posing a threat to its Asian neighbors and US.
文摘In recent years,the rapid advancement of AI has led to its widespread integration into academic research.The technology is transforming traditional methodologies and optimizing key processes--from data analysis and literature reviews to the generation of research hypotheses.
文摘In this essay, I take the recent publication of several texts examining the historical and contemporary phenomena of Sinophobia, Orientalism, and Sinologism as an opening for theorizing underlying and related issues including pervasive anti-China biases in Western journalism and China＇s position therein. In addition to illustrating how the concepts of Orientalism arise from Western historical and epistemological foundations, I theorize what I call a ＂new yellow journalism＂ that has grown in tandem with ＂China＇s rise＂ and the threat this indicates to many Western observers, and how this threat and others like it have been met in the age of ＂new imperialism.＂ I compare this new phenomenon with its historical antecedents, ＂yellow journalism＂ and America＇s emergence as a imperialism power with the Spanish-American War （1898）, and note several key insights offered by recent critical analyses of that period, which together suggest a confluence of different players, including policymakers, new media business models, and what I describe as a type of public ＂corporatism＂ in which citizens, particularly Americans, function effectively as shareholders in maintaining hegemonic if not imperialist power.
文摘one of the things that drives me I nuts about China is parking on ’ footpaths. I nearly got knocked down recently on what will be my last visit to the historic old Maizidian Street. Here the local government
文摘The seven-year run-up to the Olympics has seen China’s white-hot economy chug along with an annual growth rate of more than 10 percent. But the global economic race is more of a marathon than a sprint. Several former Olympic host countries, including Japan and Australia, suffered economic slumps to varying degrees after the euphoria. Now eyes are turning to China to see if the Games will have a similar impact after they end. Will a post-Olympic slowdown play out here, or could it even prompt another economic take-off in the country? China Development Observation, a business monthly, interviewed Chen Jian, Executive Director of the Beijing Olympic Economy Research Association; Li Yining, a renowned economist; and Zhuang Jian, a senior economist at the Asian Development Bank China Resident Mission, for some answers.
