Статті в журналах з теми "Strain burst"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Strain burst.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-50 статей у журналах для дослідження на тему "Strain burst".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте статті в журналах для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Li, H., A. H. W. Ngan, and M. G. Wang. "Continuous Strain Bursts in Crystalline and Amorphous Metals During Plastic Deformation by Nanoindentation." Journal of Materials Research 20, no. 11 (November 2005): 3072–81. http://dx.doi.org/10.1557/jmr.2005.0379.
Повний текст джерелаАнотація:
Using depth-sensing indentation with sub-nanometer displacement resolution, the plastic deformation of a range of materials, including a metallic glass, amorphous selenium, Ni3Al, pure Nb, Al, Cu, and Zn metals, and an Al-Mg alloy, has been investigated at room temperature. In amorphous selenium, even the sub-nanometer displacement resolution of the nanoindentation technique cannot reveal any strain burst during deformation at room temperature. In all other metals studied, what may appear to be smooth load-displacement curves at macroscopic scale during indentation deformation in fact turn out to consist of a continuous series of random bursts of the nanometer scale. The occurrence probability of the bursts is found to decrease at increasing burst size. In all of the crystalline metals and alloys studied, the size distribution of the strain bursts seems to follow an exponential law with a characteristic length scale. The absence of the self-organized critical behavior is likely a result of the small size of the strained volume in the nanoindentation situation, which gives rise to a constraint of a characteristic strain. In the metallic glass sample, due to the limited range of the burst sizes encountered, whether the deformation bursts follow an exponential or a power-law behavior corresponding to self-organized criticality is inconclusive. From a theoretical viewpoint based on the Shannon entropy, the exponential distribution is the most likely distribution at a given mean burst size, and this is thought to be the reason for its occurrence in different materials.
2
He, Manchao, Fuqiang Ren, and Cheng Cheng. "Mechanism of Strain Burst by Laboratory and Numerical Analysis." Shock and Vibration 2018 (October 23, 2018): 1–15. http://dx.doi.org/10.1155/2018/8940798.
Повний текст джерелаАнотація:
Strain burst is often considered to be a type of failure related to brittle rock material; therefore, many studies on strain burst focus on the brittleness of rock. However, the laboratory experiments show that strain burst can not only occur in hard brittle rock-like granite but also in the relatively ductile rock-like argillaceous sandstone. This result proves that behavior of rock material is not the only factor influencing the occurrence of strain burst. What must also be considered is the relative stiffness between the excavation wall/ore body and the surrounding rock mass. In order to further studying the mechanism of strain burst considering the whole system, the engineering geomechanial model and numerical model of strain burst due to excavation are built, respectively. In a series of numerical tests, the rock mass involving the excavation wall as well as roof and floor is biaxially loaded to the in situ stress state before one side of the excavation wall is unloaded abruptly to simulate the excavation in the field. With various system stiffness determined by the microproperties including the contact moduli of particles and parallel bond moduli in the models of roof and floor, the different failure characteristics are obtained. Based on the failure phenomenon, deformation, and released energy from the roof and floor, this study proves that the system stiffness is a key factor determining the violence of the failure, and strain burst is prone to happen when the system is soft. Two critical Young’s moduli ratios and stiffness ratios are identified to assess the violence of failure.
3
Yin, Yanchun, Xingxue Tang, Qinwei Ma, Zhenan Li, and Wei Zhang. "Simulation Research on Energy Evolution and Supply Law of Rock–Coal System under the Influence of Stiffness." Sustainability 15, no. 2 (January 10, 2023): 1335. http://dx.doi.org/10.3390/su15021335.
Повний текст джерелаАнотація:
The energy supply effect caused by the stiffness difference between roofs and sidewalls is an important factor that induces strain coal bursts. In order to quantitatively reveal the energy supply mechanism of strain coal bursts, this paper first establishes a coal burst energy model of the rock–coal system and proposes the calculation formula of coal burst kinetic energy considering supply energy and the stiffness ratio of rock to coal. Then the whole energy evolution law of the rock–coal system with different stiffness ratios is researched by using the numerical simulation method, and the whole process is divided into three stages. With the decrease in the stiffness ratio, the elastic strain energy of the coal changes little, while its kinetic energy is negatively correlated with the stiffness ratio in a power function. Meanwhile, the elastic strain energy and kinetic energy of the rock have power function relations with the stiffness ratio, too. When the rock–coal system is fractured, the kinetic energy of the coal comes from the release of elastic strain energy from the coal and the energy supplied from the rock. The energy supply rate is between 22% and 35% when the stiffness ratio changes from 3.0 to 0.5, and they show a linear relationship, while the supplied energy has a negative power function relationship with the stiffness ratio.
4
Lai, Y. H., H. M. Chen, C. J. Lee, J. C. Huang, and J. S. C. Jang. "Strain burst speeds in metallic glass micropillars." Intermetallics 18, no. 10 (October 2010): 1893–97. http://dx.doi.org/10.1016/j.intermet.2010.02.037.
Повний текст джерела
5
Tadmor, E. B., and D. Durban. "Plastic Deformation and Burst of Pressurized Multilayered Cylinders." Journal of Pressure Vessel Technology 117, no. 1 (February 1, 1995): 85–91. http://dx.doi.org/10.1115/1.2842096.
Повний текст джерелаАнотація:
A large strain analysis is presented for internally pressurized multilayered tubes, in generalized plane strain. Material behavior is modeled by an elastoplastic deformation theory with an orthotropic yield function, introduced by Hill, and arbitrary hardening. Elastic compressibility is neglected. An exact solution is given, in terms of quadratures, along with a general condition for burst. Simple yet useful relations are derived for thin-walled cylinders with the neglect of elastic strains. For rigid/nonlinear-hardening response, we obtain an expression for the onset of burst in terms of overall effective moduli. A few numerical examples are given and the possibility of locating an optimal two-layer configuration is discussed. It appears that optimization with respect to weight is attainable provided that appropriate materials are selected.
6
Matemilola, S. A., and W. J. Stronge. "Low-Speed Impact Damage in Filament-Wound CFRP Composite Pressure Vessels." Journal of Pressure Vessel Technology 119, no. 4 (November 1, 1997): 435–43. http://dx.doi.org/10.1115/1.2842327.
Повний текст джерелаАнотація:
Quasi-static and impact tests were conducted on filament-wound carbon fiber composite pressure vessels to study factors that affect burst pressure. Observed damage included fiber microbuckling, matrix cracking, and delamination. Fiber microbuckling of the outer surface layer near the impact point was the main factor that reduced the burst pressure of the vessels. This type of damage was visually detectable on the surface. For similar levels of missile kinetic energy, the impact damage to filament-wound composite pressure vessels depends on size and shape of the colliding body in the contact area. Burst pressure for a damaged vessel decreases with the ratio of axial length of damaged fibers 1, to vessel wall thickness h, up to a ratio 1/h = 3; beyond this length of damaged section the burst pressure was independent of length of damage. Strain measurements near the region of loading showed that damage related to fiber microbuckling is sensitive to strain rate. At locations where impact damage was predominately due to fiber microbuckling, the failure strain was about six times the strain for microbuckling during quasi-static loading.
7
Zhu, Hongbo, Weipu Xu, Zhiping Luo, and Hongxing Zheng. "Finite Element Analysis on the Temperature- Dependent Burst Behavior of Domed 316L Austenitic Stainless Steel Rupture Disc." Metals 10, no. 2 (February 8, 2020): 232. http://dx.doi.org/10.3390/met10020232.
Повний текст джерелаАнотація:
As a safety device, a rupture disc instantly bursts as a nonreclosing pressure relief component to minimize the explosion risk once the internal pressure of vessels or pipes exceeds a critical level. In this study, the influence of temperature on the ultimate burst pressure of domed rupture discs made of 316L austenitic stainless steel was experimentally investigated and assessed with finite element analysis. Experimental results showed that the ultimate burst pressure gradually reduced from 6.88 MPa to 5.24 MPa with increasing temperature from 300 K to 573 K, which are consistent with the predicted instability pressures acquired by nonlinear buckling analysis using ABAQUS software. Additionally, it was found that a gradual transition from opening ductile mode to cleavage mode happened with increasing temperature due to more cross slips occurring under serious plastic deformation. The equivalent stress, equivalent strain and strain hardening rates acquired by static analysis were effective at rationalizing the temperature-dependent fracture behavior of the domed rupture discs.
8
Zhong, Kun, Wusheng Zhao, Changkun Qin, and Weizhong Chen. "Experimental Study on the Mechanical Behavior and Failure Characteristics of Layered Coal at Medium Strain Rates." Energies 14, no. 20 (October 13, 2021): 6616. http://dx.doi.org/10.3390/en14206616.
Повний текст джерелаАнотація:
The study of the mechanical properties and failure behaviors for coal with different bedding structures at various medium strain rates is of great importance for revealing the mechanism of rock burst. In our study, we systematically analyze the uniaxial compressive strength (UCS), acoustic emission (AE) characteristics, failure pattern, and risk of rock burst on coal specimens with two bedding orientations under ranged in strain rates from 10−4 s−1 to 10−2 s−1. The results reflect that and the bedding direction and the strain rates significantly affect the UCS and failure modes of coal specimens. The UCS of coal specimens with loading directions perpendicular to bedding planes (horizontal bedding) increases logarithmically with increasing strain rate while the UCS increases first and then decreases of coal specimens with loading directions parallel to bedding planes (vertical bedding). The AE cumulative energy of the specimens with horizontal bedding is an order of magnitude higher than that of specimens with vertical bedding. However, it is independent of the strain rates. The energy release rates of these two types of bedded coal specimens increase in a power function as the strain rate increases. The coal specimens with horizontal bedding show violent failure followed by the ejection of fragments, indicating a high risk of rock burst. On the other hand, the coal specimens with vertical bedding exhibit a tensile splitting failure with a low risk of rock burst. Strain localization is a precursor of coal failure, and the concentration area of local principal strain is highly consistent with the initial damage area, and the area where the principal strain gradient is significantly increased corresponds to the fracture initiation area.
9
Zhong, Kun, Wusheng Zhao, Changkun Qin, and Weizhong Chen. "Experimental Study on the Mechanical Behavior and Failure Characteristics of Layered Coal at Medium Strain Rates." Energies 14, no. 20 (October 13, 2021): 6616. http://dx.doi.org/10.3390/en14206616.
Повний текст джерелаАнотація:
The study of the mechanical properties and failure behaviors for coal with different bedding structures at various medium strain rates is of great importance for revealing the mechanism of rock burst. In our study, we systematically analyze the uniaxial compressive strength (UCS), acoustic emission (AE) characteristics, failure pattern, and risk of rock burst on coal specimens with two bedding orientations under ranged in strain rates from 10−4 s−1 to 10−2 s−1. The results reflect that and the bedding direction and the strain rates significantly affect the UCS and failure modes of coal specimens. The UCS of coal specimens with loading directions perpendicular to bedding planes (horizontal bedding) increases logarithmically with increasing strain rate while the UCS increases first and then decreases of coal specimens with loading directions parallel to bedding planes (vertical bedding). The AE cumulative energy of the specimens with horizontal bedding is an order of magnitude higher than that of specimens with vertical bedding. However, it is independent of the strain rates. The energy release rates of these two types of bedded coal specimens increase in a power function as the strain rate increases. The coal specimens with horizontal bedding show violent failure followed by the ejection of fragments, indicating a high risk of rock burst. On the other hand, the coal specimens with vertical bedding exhibit a tensile splitting failure with a low risk of rock burst. Strain localization is a precursor of coal failure, and the concentration area of local principal strain is highly consistent with the initial damage area, and the area where the principal strain gradient is significantly increased corresponds to the fracture initiation area.
10
Eriksen, Rasmus Skytte, and Sandeep Krishna. "Defence versus growth in a hostile world: lessons from phage and bacteria." Royal Society Open Science 7, no. 9 (September 2020): 201118. http://dx.doi.org/10.1098/rsos.201118.
Повний текст джерелаАнотація:
Bacterial communities are often highly diverse with several closely related species (or strains) coexisting together. These bacteria compete for resources and the competitive exclusion principle predicts that all but the fastest-growing bacteria will go extinct. When exposed to phage, it is predicted that bacterial strains with restriction–modification (RM) systems can circumvent the competitive exclusion principle and reach diversity of the order of the phage burst size. We show that with a trade-off between bacterial growth rates and the strength of their RM systems, the diversity of such an ecosystem can further increase several fold beyond the burst size limit. Moreover, we find that the ratio of the growth rate of a bacterial strain to the imperfection of its RM system is an excellent predictor of (i) whether the strain will go extinct or not, and (ii) the biomass of the strain if it survives. In contrast, the growth rate alone is not a determinant of either of these properties. Our work provides a quantitative example of a model ecosystem where the fitness of a species is determined not by growth rate, but by a trade-off between growth and defence against predators.
11
Purkall, Donald, John G. Tew, and Harvey A. Schenkein. "Opsonization of Actinobacillus actinomycetemcomitans by Immunoglobulin G Antibody Reactive with Phosphorylcholine." Infection and Immunity 70, no. 11 (November 2002): 6485–88. http://dx.doi.org/10.1128/iai.70.11.6485-6488.2002.
Повний текст джерелаАнотація:
ABSTRACT We used two strains of Actinobacillus actinomycetemcomitans, one bearing phosphorylcholine (PC) (strain D045D-40) and one devoid of PC antigens (strain DB03A-42), as well as a nonencapsulated strain of Streptococcus pneumoniae (strain 39937), to examine the opsonic properties of physiological concentrations (⩽30 μg/ml) of purified human anti-PC immunoglobulin G (IgG). Anti-PC bound to both A. actinomycetemcomitans DO45D-40 and S. pneumoniae 39937 and induced superoxide anion production by polymorphonuclear neutrophils; induction of the oxidative burst was inhibited by antibodies to either CD16 or CD32. Thus, anti-PC IgG at concentrations present in most human sera promotes the opsonization of PC-expressing strains of A. actinomycetemcomitans in the absence of complement, implying that anti-PC may be a protective antibody against such strains of bacteria.
12
Kec, Jan, Ivo Černý, Jan Luštinec, Miloslav Poupa, Romana Pavelková, and Jiří Janovec. "Experimental Verification of Dents Effect on the Structural Integrity of Pipeline DN 300." Key Engineering Materials 774 (August 2018): 319–24. http://dx.doi.org/10.4028/www.scientific.net/kem.774.319.
Повний текст джерелаАнотація:
The stress-strain behaviour of two dents with different depth and shape during the fatigue pressure and burst pressure test is described. The internal inspection carried out on a high-pressure line DN 300 revealed the presence of two dents. Then, the part containing the dents was dug out, removed from operation and the pressure tests were carried out. The stress-strain behaviour was measured with help of nine strain gauges placed on the external pipe surface in the vicinity of dents. The fatigue pressure test simulated fluctuation of pressure, temperature and landslides during operation. During the fatigue pressure test, the profile changes of dents were observed; on the other hand, no fracture occurred. It followed the pressure burst test, the results of which enabled to determine the limit state, burst pressure and position of fracture.
13
Akdag, Selahattin, Murat Karakus, Giang D. Nguyen, and Abbas Taheri. "Strain burst vulnerability criterion based on energy-release rate." Engineering Fracture Mechanics 237 (October 2020): 107232. http://dx.doi.org/10.1016/j.engfracmech.2020.107232.
Повний текст джерела
14
Wang, Yang, Manchao He, Fuqiang Ren, Chun Zhu, and Lohrasb Faramarzi. "Source analysis of acoustic emissions during granite strain burst." Geomatics, Natural Hazards and Risk 10, no. 1 (January 1, 2019): 1542–62. http://dx.doi.org/10.1080/19475705.2019.1593888.
Повний текст джерела
15
Deng, Lin, Yan Lv, and Rong Gui Deng. "New Rock Burst Prediction Method." Advanced Materials Research 446-449 (January 2012): 762–66. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.762.
Повний текст джерелаАнотація:
This paper gives a new rock burst prediction method of potential index, according to the rock deformation and failure of the rock and the relationship between energy transfer, the characteristics of uniaxial compression stress-strain entire process curve. The new prediction method of rock burst of energy with existing method for forecasting index was compared and analyzed. Testing study was made on the typical rocks of rhyolite, from the deep deposit of Niba mountain tunnel, Combined with the actual phenomen of rock burst, the rock burst potential index is verified to be able to show fairly well the rock burst proneness. Finally, a criterion of rock burst proneness is put forward.
16
Hu, Jiang, and Jingang Li. "Effect of Loading Rates on Mechanical Characteristics and Rock Burst Tendency of Coal-Rock Combined Samples." Advances in Materials Science and Engineering 2022 (September 9, 2022): 1–10. http://dx.doi.org/10.1155/2022/8176721.
Повний текст джерелаАнотація:
According to the universal law of thermodynamics, the failure of any substance is closely related to its energy change. Understanding the strain energy and rock burst tendency of rock or coal under different loading rates is critical in many geological projects, such as mining, tunneling, and other underground engineering project. The mechanical and energy evolution characteristics of the coal-rock combined sample under different loading rates of uniaxial compression were numerically investigated. And, the rock burst tendency was also calculated by the Rock Burst Energy Index KE. The results show that with the increase of the loading rate, the total input energy, elastic strain energy, and dissipation energy all show an increasing trend. But the growth trend is different. And, under the five loading rates, the Rock Burst Energy Index KE of the coal-rock combined sample were all between 1.5 ≤ KE < 5. That is, they all have weak rock burst tendency. And the rock burst energy index increases first and then decreases with the increase of loading rates. This study provides references for propulsion speed of working face in the field mining practice.
17
Gu, Shitan, Zhimin Xiao, Bangyou Jiang, Ruifeng Huang, and Peng Shan. "Research of Rock Burst Risk Induced by Mining and Field Case in Anticlinal Control Area." Advances in Civil Engineering 2018 (October 22, 2018): 1–10. http://dx.doi.org/10.1155/2018/2632549.
Повний текст джерелаАнотація:
Stress concentration caused by tectonic stress and mining disturbance in coal mines induces a unique type of rock burst. No. 3201 working face controlled by an anticline structure in the Shandong mining area is used as the research background. The formation mechanism for anticlines is analyzed. Theoretical research shows that the bigger the tectonic couple is, the smaller the foundation stiffness, and the greater the bending degree and elastic strain energy of the coal will be. The distribution characteristics of abutment pressure and maximum principle stress in anticlinal control areas are analyzed using UDEC numerical software. The results show that rock bursts result from interactions between abutment pressure and residual tectonic stress. The “connection-overlay-separation” phenomenon of abutment pressure presents with working face advancement. Furthermore, the energy criterion for rock burst initiation is established based on the energy principle. Residual energy “E0−EC” and rock burst danger characteristics during mining are discussed. Based on the simulation results, microseismic monitoring data for No. 3201 working face are analyzed, and the law of microseismic energy is consistent with the variation law for the residual energy “E0−EC” at the peak of the simulated abutment pressure. The microseismic energy and frequency are higher during mining, increasing the risk of rock burst events. It can provide scientific basis for prevention and control of rock burst.
18
Saito, M., T. Mano, S. Iwase, K. Koga, H. Abe, and Y. Yamazaki. "Responses in muscle sympathetic activity to acute hypoxia in humans." Journal of Applied Physiology 65, no. 4 (October 1, 1988): 1548–52. http://dx.doi.org/10.1152/jappl.1988.65.4.1548.
Повний текст джерелаАнотація:
Responses in muscle sympathetic activity (MSA) to acute hypoxia were studied in 13 healthy male subjects under hypobaric hypoxic conditions at a simulated altitude of 4,000, 5,000, and 6,000 m. Efferent postganglionic MSA was recorded directly with a tungsten microelectrode inserted percutaneously into the tibial nerve. Heart rate (HR) and respiratory rate (RR) were counted respectively from the R wave of an electrocardiogram and from the respiratory tracing recorded by the strain-gauge method. The average values of the MSA burst rate and total activity of MSA (burst rate x mean burst amplitude) at 4,000, 5,000, and 6,000 m were 36.4 +/- 2.6, 39.1 +/- 3.1, and 40.2 +/- 4.2 (SE) bursts/min and 616 +/- 138, 794 +/- 190, and 764 +/- 227 arbitrary units, respectively. These values were significantly higher than the values of 27.1 +/- 2.9 bursts/min and 446 +/- 28 at sea level. HR increased significantly at altitudes, but RR did not show significant change. Under severe hypoxic conditions beyond 5,000 m, there were large interindividual differences in the MSA responsiveness to hypoxia. The results indicate that MSA is activated under hypoxia by stimulating the chemoreceptors. However, the central controlling mechanisms that would be affected by hypoxia may also influence the MSA responsiveness under severe hypoxia.
19
Lehmann, A. K., A. R. Gorringe, K. M. Reddin, K. West, I. Smith, and A. Halstensen. "Human Opsonins Induced during Meningococcal Disease Recognize Transferrin Binding Protein Complexes." Infection and Immunity 67, no. 12 (December 1, 1999): 6526–32. http://dx.doi.org/10.1128/iai.67.12.6526-6532.1999.
Повний текст джерелаАнотація:
ABSTRACT Patient serum opsonins against transferrin binding protein A+B (TbpA+B) complexes from two Neisseria meningitidis strains (K454 and B16B6, with 85- and 68-kDa TbpB, respectively) were quantified by a functional phagocytosis and oxidative burst assay. TbpA+B complexes adsorbed to fluorescent beads were opsonized with individual acute and convalescent sera from 40 patients infected by a variety of meningococcal strains. Flow cytometric quantitation of leukocyte phagocytosis products (PP) demonstrated that disease-induced serum opsonins recognized TbpA+B, and the highest anti-TbpA+B serum opsonic activities were found between admission to hospital and 6 weeks later. The PP values obtained with TbpA+B from strain B16B6 (PPB16B6) were higher than those obtained with TbpA+B from strain K454 (PPK454), with both acute and convalescent sera (P < 0.0001), and correlated positively with higher immunoglobulin G enzyme-linked immunosorbent assay titers against TbpA+B from strain B16B6 than from strain K454 (P < 0.001). In spite of considerable variations between individuals, significant correlations were found between the PPB16B6 and PPK454 values, and the PP values did not depend on the variability of the TbpB proteins of the disease-causing strains. Simultaneously measured oxidative burst activity correlated closely with the PP values. We conclude that highly cross-reactive anti-TbpA+B serum opsonins are produced during meningococcal disease. The anti-TbpA+B opsonic activities were not affected by the variability of the TbpB proteins of the disease-causing strains, which further adds to the evidence for the vaccine potential of meningococcal TbpA+B complexes.
20
Liu, Xuewei, Quansheng Liu, Bin Liu, and Yongshui Kang. "A Modified Bursting Energy Index for Evaluating Coal Burst Proneness and Its Application in Ordos Coalfield, China." Energies 13, no. 7 (April 5, 2020): 1729. http://dx.doi.org/10.3390/en13071729.
Повний текст джерелаАнотація:
Coal burst is a type of dynamic geological hazard in coal mine. In this study, a modified bursting energy index, which is defined as the ratio of elastic strain energy at the peak strength to the released strain energy density at the post-peak stage, was proposed to evaluate the coal burst proneness. The calculation method for this index was also introduced. Two coal mines (PJ and TJH coal mines) located in Ordos coalfield were used to verify the validity of the proposed method. The tests results indicate that modified bursting energy index increases linearly with increasing uniaxial compressive strength. The parameter A, which is used to fit relation between total input and elastic strain energy density, has a significant effect on the modified bursting energy index. A large value of parameter A means more elastic strain energy before the peak strength while a small value indicates most of input energy was dissipated. Finally, the coal burst proneness of these two coal mines was evaluated with the modified index. The results of modified index are consistent with that of laboratory tests, and more reasonable than that from original bursting energy index because it removed the dissipated strain energy from the total input strain energy density.
21
Doi, Shoichi, Ikuo Taniguchi, Masahiro Yasukawa, Yuriko Kakihana, and Mitsuru Higa. "Effect of Alkali Treatment on the Mechanical Properties of Anion-Exchange Membranes with a Poly(vinyl Chloride) Backing and Binder." Membranes 10, no. 11 (November 16, 2020): 344. http://dx.doi.org/10.3390/membranes10110344.
Повний текст джерелаАнотація:
An alkali treatment under various operating conditions is conducted on a commercial anion-exchange membrane containing poly(vinyl chloride) (PVC) as a backing and binder to study the effect of the treatment on the mechanical properties by both Müllen burst and tensile tests. Contrary to our expectations, the Müllen burst pressure and tensile strain at break improved significantly after the alkali treatment in comparison to the pristine membrane and then decreased as the treatment period progressed. A good correlation is observed between the area below the stress–strain curve and burst pressure. To understand the obtained results, the PVC degradates are recovered by Soxhlet extraction and characterized via nuclear magnetic resonance and gel permeation chromatography. It is discovered that the PVC main chains degraded in the alkali solution. We propose a composite model to explain the burst pressure improvement mechanism by the change in the chemical structure of the PVC binder.
22
Guo, Hongjun, Ming Ji, Dapeng Liu, Mengxi Liu, and Weisheng Zhao. "The Influence of Fracture Strain Energy on the Burst Tendency of Coal Seams and Field Application." Advances in Civil Engineering 2021 (April 14, 2021): 1–10. http://dx.doi.org/10.1155/2021/6632328.
Повний текст джерелаАнотація:
Coal is typically considered a special engineering rock mass because of its low strength, high internal fracture development, good permeability, and random distribution of microparticles and fractures. The results of cyclic loading and unloading tests indicate that the strain energy during the coal deformation process can be divided into three parts: plastic strain energy; fracture strain energy; and base-material strain energy. The energy composition ratio differs depending on coal strength. Lower proportions of fracture strain energy are associated with higher elastic energy indexes, and there is a negative correlation between fracture strain energy and other coal burst tendency indexes. The results were applied on the 4206 isolated island working face of coal mine A in Yan’an, Shanxi, China, yielding good benefits. The findings presented here provide a theoretical basis for understanding the principle of coal seam bursting and guidance for reducing burst risks.
23
Zhou, Nan, Hengfeng Liu, Jixiong Zhang, and Hao Yan. "Study on Rock Burst Event Disaster and Prevention Mechanisms of Hard Roof." Advances in Civil Engineering 2019 (April 1, 2019): 1–14. http://dx.doi.org/10.1155/2019/6910139.
Повний текст джерелаАнотація:
Coal mining under hard roofs is jeopardized by rock burst-induced hazards. In this paper, mechanisms of hard roof rock burst events and key techniques for their prevention are analyzed from the standpoint of energy evolution within geological conditions typical of the hard roofs found in Chinese coal mines. Equations used to calculate the total strain energy densities of the coal-rock mass and hard roof working face are derived. Moreover, several failure-causing energy evolution rules are analyzed under various conditions. Various rock roof and coal mass thicknesses and strengths are considered, and a method of preventing hard roof rock burst events is proposed. The results obtained show that rock burst events can be facilitated by high stress concentrations, significant accumulation of strain energy in the coal-rock mass, and rapid energy release during roof breakage. The above conditions are subdivided into two classes: energy accumulation and energy release. The total strain energies of the coal mass and working faces in the roof are positively correlated with the roof thickness, roof strength, and coal mass strength. The coal mass strength primarily influences the overall accumulation of energy in the working face, and it also has the largest effect on the total energy release (i.e., the earthquake magnitude).
24
Lu, Lu, Jinfeng Chen, Sofia M. C. Robb, Yutaka Okumoto, Jason E. Stajich, and Susan R. Wessler. "Tracking the genome-wide outcomes of a transposable element burst over decades of amplification." Proceedings of the National Academy of Sciences 114, no. 49 (November 20, 2017): E10550—E10559. http://dx.doi.org/10.1073/pnas.1716459114.
Повний текст джерелаАнотація:
To understand the success strategies of transposable elements (TEs) that attain high copy numbers, we analyzed two pairs of rice (Oryza sativa) strains, EG4/HEG4 and A119/A123, undergoing decades of rapid amplification (bursts) of the class 2 autonomous Ping element and the nonautonomous miniature inverted repeat transposable element (MITE) mPing. Comparative analyses of whole-genome sequences of the two strain pairs validated that each pair has been maintained for decades as inbreds since divergence from their respective last common ancestor. Strains EG4 and HEG4 differ by fewer than 160 SNPs and a total of 264 new mPing insertions. Similarly, strains A119 and A123 exhibited about half as many SNPs (277) as new mPing insertions (518). Examination of all other potentially active TEs in these genomes revealed only a single new insertion out of ∼40,000 loci surveyed. The virtual absence of any new TE insertions in these strains outside the mPing bursts demonstrates that the Ping/mPing family gradually attains high copy numbers by maintaining activity and evading host detection for dozens of generations. Evasion is possible because host recognition of mPing sequences appears to have no impact on initiation or maintenance of the burst. Ping is actively transcribed, and both Ping and mPing can transpose despite methylation of terminal sequences. This finding suggests that an important feature of MITE success is that host recognition does not lead to the silencing of the source of transposase.
25
Bi, Zuoqing, Han Liang, and Qianjia Hui. "Identification of Initial Crack and Fracture Development Monitoring under Uniaxial Compression of Coal with High Bump Proneness." Geofluids 2021 (December 21, 2021): 1–8. http://dx.doi.org/10.1155/2021/6561152.
Повний текст джерелаАнотація:
The rock burst proneness of coal is closely related to the coal mass structure. Therefore, the initial crack distribution of high burst proneness coal, its fracture development, and failure process under loading conditions are of great significance for the prediction of rock burst. In this study, high burst proneness coal is used to prepare experiment samples. The surface cracks of the samples are identified and recorded. The internal crack of the sample is detected by nuclear magnetic resonance (NMR) technology to determine the crack ratio of each sample. Then, 3D-CAD technology is used to restore the initial crack of the samples. Uniaxial compression test is carried out, and AE properties are recorded in the test. The stress-strain curve, the distribution of the fractural points within the sample at different stress states, and the relationship between ring count and stress are obtained. Results show that the stress-strain curves of high burst proneness coal are almost linear, to which the stress-ring count curves are similar. The distributions of fractural points in different bearing states show that the fracture points emerge in the later load stage and finally penetrate to form macrofracture, resulting in sample failure. This study reveals the initial crack distribution of coal with high burst proneness and the fracture development under bearing conditions, which provides a theoretical basis for the prediction technology of rock burst and technical support for the research of coal structure.
26
ZHU, S., X. GAO, and J. NIE. "Strain burst in creep of Mg–1Ca–0.5Zn–0.6Zr alloy." Materials Science and Engineering A 384, no. 1-2 (October 25, 2004): 270–74. http://dx.doi.org/10.1016/s0921-5093(04)00828-7.
Повний текст джерела
27
Fakhimi, Ali, Omid Hosseini, and Roosevelt Theodore. "Physical and numerical study of strain burst of mine pillars." Computers and Geotechnics 74 (April 2016): 36–44. http://dx.doi.org/10.1016/j.compgeo.2015.12.018.
Повний текст джерела
28
Feng, G., and A. H. W. Ngan. "Creep and strain burst in indium and aluminium during nanoindentation." Scripta Materialia 45, no. 8 (October 2001): 971–76. http://dx.doi.org/10.1016/s1359-6462(01)01120-4.
Повний текст джерела
29
Nimaga, O. G., G. J. Cheng, H. W. Yen, and M. X. Huang. "Large strain burst induced by martensitic transformation in austenitic micropillars." Scripta Materialia 137 (August 2017): 64–68. http://dx.doi.org/10.1016/j.scriptamat.2017.05.018.
Повний текст джерела
30
Wang, M. G., and A. H. W. Ngan. "Indentation strain burst phenomenon induced by grain boundaries in niobium." Journal of Materials Research 19, no. 8 (August 2004): 2478–86. http://dx.doi.org/10.1557/jmr.2004.0316.
Повний текст джерелаАнотація:
Using depth-sensing indentation, a pop-in phenomenon induced by grain boundaries, namely, a sudden indenter displacement jump when indented near a grain boundary segment, was observed in polycrystalline niobium. This grain-boundary type of pop-in occurs at a larger force than the initial elasto-plastic pop-in, which is observed with and without a grain boundary nearby. The experimental results show that this pop-in effect has a close relationship with the misorientation across the grain boundary. The occurrence of this pop-in phenomenon is rationalized in terms of slip transmission across the grain boundary.
31
Xu, Zhao-Yong, Run-Hai Yang, Bin Wang, Jin-Ming Zhao, Yu-Feng Yao, Pei-Zhong Hua, and Shi-Rong Mei. "Burst strain disturbance — A new test study on fracture precursor." Acta Seismologica Sinica 11, no. 6 (November 1998): 737–44. http://dx.doi.org/10.1007/s11589-998-0009-7.
Повний текст джерела
32
Terada, Lance S., Kristine A. Johansen, Sogol Nowbar, Adriana I. Vasil, and Michael L. Vasil. "Pseudomonas aeruginosa Hemolytic Phospholipase C Suppresses Neutrophil Respiratory Burst Activity." Infection and Immunity 67, no. 5 (May 1, 1999): 2371–76. http://dx.doi.org/10.1128/iai.67.5.2371-2376.1999.
Повний текст джерелаАнотація:
ABSTRACT Pseudomonas aeruginosa is a persistent pathogen in the airways of patients with cystic fibrosis or bronchiectasis from other causes and appears to have evolved strategies to survive the inflammatory response of the host. We hypothesized that the secreted hemolytic phospholipase C (PLC) of P. aeruginosa (PlcHR) would decrease neutrophil respiratory burst activity. We found that while intact wild-type P. aeruginosa cells stimulated moderate respiratory burst activity from human neutrophils, an isogenic mutant pseudomonas (ΔHR strain) containing a targeted deletion of the plcHR operon induced a much more robust oxidative burst from neutrophils. In contrast, a second pseudomonas mutant (ΔN) containing a disruption in the gene encoding the nonhemolytic PLC (PlcN) was not different from the wild type in stimulating neutrophil O2 ·−production. Readdition of purified PlcHR to the ΔHR strain suppressed neutrophil O2 ·−production to levels stimulated by wild-type bacteria. Interestingly, purified PlcHR decreased phorbol myristate acetate (PMA)- but not formyl methionyl-leucyl-proline (fMLP)-induced respiratory burst activity, suggesting interference by PlcHR with a protein kinase C (PKC)-specific signaling pathway. Accordingly, the PKC inhibitor bisindolylmaleimide inhibited the oxidative burst induced by either PMA or intact pseudomonas, but not by fMLP, whereas the p38 kinase inhibitor SB-203580 fully inhibited the respiratory burst induced by fMLP or the PlcHR-replete wild-type bacteria, but not PMA or the PlcHR-deficient ΔHR bacterial mutant. We conclude that expression of PlcHR by P. aeruginosa suppresses bacterium-induced neutrophil respiratory burst by interfering with a PKC-dependent, non-p38 kinase-dependent pathway.
33
Golder, Francis J., Andrea G. Zabka, Ryan W. Bavis, Tracy Baker-Herman, David D. Fuller, and Gordon S. Mitchell. "Differences in time-dependent hypoxic phrenic responses among inbred rat strains." Journal of Applied Physiology 98, no. 3 (March 2005): 838–44. http://dx.doi.org/10.1152/japplphysiol.00984.2004.
Повний текст джерелаАнотація:
Hypoxic ventilatory responses differ between rodent strains, suggesting a genetic contribution to interindividual variability. However, hypoxic ventilatory responses consist of multiple time-dependent mechanisms that can be observed in different respiratory motor outputs. We hypothesized that strain differences would exist in discrete time-dependent mechanisms of the hypoxic response and, furthermore, that there may be differences between hypoglossal and phrenic nerve responses to hypoxia. Hypoglossal and phrenic nerve responses were assessed during and after a 5-min hypoxic episode in anesthetized, vagotomized, and ventilated rats from four inbred strains: Brown Norway (BN), Fischer 344 (FS), Lewis (LW), and Piebald-viral-Glaxo (PVG). During baseline, burst frequency was higher in PVG than LW rats ( P < 0.05), phrenic burst amplitude was higher in PVG vs. other strains ( P < 0.05), and hypoglossal burst amplitude was higher in PVG and BN vs. FS and LW ( P < 0.05). During hypoxia, burst frequency did not change in BN or LW rats, but it increased in PVG and FS rats. The phrenic amplitude response was smallest in PVG vs. other strains ( P < 0.05), and the hypoglossal response was similar among strains. Short-term potentiation posthypoxia was slowest in FS and fastest in LW rats ( P < 0.05). Posthypoxia frequency decline was absent in PVG, but it was observed in all other strains. Augmented breaths were observed during hypoxia in FS rats only. Thus genetic differences exist in the time domains of the hypoxic response, and these are differentially expressed in hypoglossal and phrenic nerves. Furthermore, genetic diversity observed in hypoxic ventilatory responses in unanesthetized rats may arise from multiple neural mechanisms.
34
Ding, Ke, Lianguo Wang, Mei Yu, Wenmiao Wang, and Bo Ren. "Study on Microseismic Monitoring, Early Warning, and Comprehensive Prevention of a Rock Burst under Complex Conditions." Shock and Vibration 2020 (September 19, 2020): 1–12. http://dx.doi.org/10.1155/2020/8863771.
Повний текст джерелаАнотація:
Rock bursts in coal mines are usually unpredictable. In view of this problem, the energy–frequency relationship and spatial distribution characteristics of microseismic events during the mining of 5305 working face in Xinhe Coal Mine under complex geological conditions were analyzed in this study. Besides, the law and precursors of rock burst occurrence in this working face were discussed. The following research results were obtained. Before the rock burst occurred in 5305 working face, the energy and frequency of microseismic events vary in the following order: “peak-drop-rise-rock burst.” The analysis on spatial characteristics of microseismic events suggests that microseismic events were mainly concentrated at the boundary between the roof and the coal seam or at the hard roof near the coal seam within 0–160 m in front of the working face, and most of the events lay on the goaf side. Moreover, the energy and frequency of microseismic events both decrease in the above region before the rock burst occurred. This “microseismic event absence” phenomenon can be regarded as one of the precursors of rock burst occurrence. In addition, a multilevel antiburst scheme was proposed for the complex conditions: (1) to adopt large-diameter boreholes pressure relief technology and key layer high-level pressure relief technology for adjusting the stress distribution in the surrounding rock of crossheading in front of the working face and dissipating elastic strain energy; (2) to determine the advance speed to be 1.5 m/d for reducing the mining disturbance; (3) to adopt full-section reinforced support of the roadway for enhancing the antiburst capacity of surrounding rock. After the implementation of this scheme, the energy and frequency of microseismic events monitored on-site changed gently, and 5305 working face was safely recovered to the stop line position. The scheme boasts a remarkable rock burst prevention and control effect.
35
Yang, Zeng-Qiang, Chang Liu, and Hui-Wu Jin. "Study on Pressure Relief Zone Formed Inside Roadway Rib by Rotary Cutting with Pressurized Water Jet for Preventing Rock Burst." Advances in Civil Engineering 2022 (May 23, 2022): 1–19. http://dx.doi.org/10.1155/2022/9647029.
Повний текст джерелаАнотація:
Based on the engineering geological conditions of mining area 2502 in Yanbei coal mine as a background, the comprehensive index method is used to evaluate the rock burst risk of mining area 2502, and the burst tendency of coal seam 5# under natural and water-saturated conditions is also tested in laboratory. Then the pressurized water jet technology is proposed as an effective and feasible method to prevent rock burst. By means of theoretical analysis, the coal-rock mass system has three strain-stress states under the influence of static load, and it has another strain-stress state under the influence of static and dynamic combined load; meanwhile, the greater the horizontal tectonic stress caused by fold structure is, the more prone to instability and failure and induce rock burst coal mass composed of countless cell cubes is; when a pressure relief zone is formed inside the roadway rib by using pressurized water jet technology, the initial single peak stress curve will change to a final bimodal stress curve inside the roadway rib. A “strong-weak-strong” prevention structure can be formed inside the roadway rib and this prevention structure can well prevent the occurrence of rock burst. By means of numerical simulation analysis, the optimal diameter, length, and interval of rotary cutting sections are identified as 400 mm, 3.0 m, and 15.0 m, respectively. By means of on-site industrial application analysis, all these monitoring results verify that when the pressurized water jet is used to conduct rotary cutting of roadway rib, a large-scale pressure relief zone will be formed in the coal mass inside the roadway rib, and it can achieve the purpose of preventing rock burst in the roadway rib. The research results can effectively provide theoretical foundation and a new guidance for preventing rock burst with similar engineering geological conditions.
36
Wo, P. C., L. Zuo, and A. H. W. Ngan. "Time-dependent incipient plasticity in Ni3Al as observed in nanoindentation." Journal of Materials Research 20, no. 2 (February 2005): 489–95. http://dx.doi.org/10.1557/jmr.2005.0056.
Повний текст джерелаАнотація:
The time-dependent characteristics of incipient plasticity in Ni3Al during nanoindentation in the subcritical load regime were investigated statistically. The waiting time for incipient plasticity to occur at constant load was found to follow a Poisson-like distribution, with the peak shifting toward zero holding time as the load increased and eventually becoming an exponential distribution when the load was close to a critical value. The observed distribution of the strain burst waiting time at loads smaller than the critical value was inconsistent with the picture in which dislocations nucleated homogeneously out of the perfect crystal. The kinetics for the occurrence of strain burst in this case is thought to be governed by the accumulative growth of nucleation precursors.
37
Zhang, Xu, Xiangcheng Zhang, Fulin Shang, and Qian Li. "Second-order work and strain burst in single-crystalline micropillar plasticity." International Journal of Plasticity 77 (February 2016): 192–213. http://dx.doi.org/10.1016/j.ijplas.2015.08.007.
Повний текст джерела
38
Wang, Peng, Fengxian Liu, Yinan Cui, Zhanli Liu, Shaoxing Qu, and Zhuo Zhuang. "Interpreting strain burst in micropillar compression through instability of loading system." International Journal of Plasticity 107 (August 2018): 150–63. http://dx.doi.org/10.1016/j.ijplas.2018.04.002.
Повний текст джерела
39
Wang, Li, ZhongLiang Lu, and Qian Gao. "A numerical study of rock burst development and strain energy release." International Journal of Mining Science and Technology 22, no. 5 (September 2012): 675–80. http://dx.doi.org/10.1016/j.ijmst.2012.08.014.
Повний текст джерела
40
Ideguchi, Yamato, Yuta Oshikoshi, Masashi Ryo, Shogo Motoki, Takashi Kuwano, Takafumi Tezuka, and Setsuyuki Aoki. "Posttranslationally caused bioluminescence burst of the Escherichia coli luciferase reporter strain." Archives of Microbiology 198, no. 1 (October 27, 2015): 35–41. http://dx.doi.org/10.1007/s00203-015-1165-5.
Повний текст джерела
41
Bai, Jinzheng, Linming Dou, Xuwei Li, Jinrong Cao, Kangkang Wang, Yanjiang Chai, and Jiliang Kan. "Mechanism of Coal Burst Triggered by Disturbing Mining-Induced Stress: An Experimental Investigation." Applied Sciences 12, no. 21 (October 30, 2022): 10993. http://dx.doi.org/10.3390/app122110993.
Повний текст джерелаАнотація:
The true triaxial test can accurately simulate the dynamic and static load superposition environment of deep mining and then reproduce the spatial and temporal evolution process of coal-rock dynamic disasters. This study used a self-developed true triaxial coal-rock dynamic behavior test system to investigate the dynamic failure characteristics and mechanism of coal bursts under different mining-induced stress disturbances. The results show that the perturbation duration of the coal samples under quasi-static load decreases with the increase of the disturbance rate, and the perturbation stress level increases first and then decreases. The coal samples can accumulate higher strain energy and show progressive and dynamic failure. The perturbation duration and stress peak of the coal sample under the cycle load decreased with the increase of the cycle amplitude and frequency, and the coal sample first spalled off on the free surface. The damage then developed internally until the coal burst. The perturbation duration and stress peak of coal samples decrease with the increase of transient stress and the perturbation stress levels. The dynamic failure process of coal samples is straightforward, and the strength of coal burst is violent and is more difficult to predict. The conclusions obtained help to deepen the understanding of the triggering mechanism of coal bursts.
42
Saboori, Mehdi, Henri Champliaud, Javad Ghoulipor, Augustin Gakwaya, Jean Savoie, and Priti Wanjara. "Study of True Stress-Strain Curve after Necking for Application in Ductile Fracture Criteria in Tube Hydroforming of Aerospace Material." Key Engineering Materials 504-506 (February 2012): 95–100. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.95.
Повний текст джерелаАнотація:
Tube hydroforming (THF) is an advanced metal forming process that is used widely in automotive industry, but the application of the THF process in aerospace field is comparatively new with many challenges due to high strength and limited formability of aerospace materials. The success of THF process largely depends on many factors, such as mechanical properties of the material, loading path during the process, tool geometry and friction condition. Due to complexity of this process, finite element modeling (FEM) can largely reduce the production cost. One of the important input in FEM is the material behavior during hydroforming process. The true stress-strain curve before necking can be easily determined, using either tensile testing or bulge testing, but for an accurate failure prediction in a large deformation, such as hydroforming, the study of true stress-strain curve after necking is important because it improves the quality of the analysis due to utilizing a real extended stress-strain curve. Hence, the objective of this research was to establish a methodology to determine the true stress-strain curve after necking in order to predict burst pressure in the THF of aerospace materials. Uniaxial tensile tests were performed on standard tensile samples (ASME E8M-04) to determine the true stress-strain before and after necking, using an analytical method presented in this study. To validate the approach, burst pressure in the THF process was predicted using the extended stress-strain curve in conjunction with Brozzo's decoupled fracture model. The approach was evaluated using data obtained from the free expansion (tube bulging) tests performed on stainless steel 321 tubes with 2 inches diameter and two different thicknesses, 0.9 mm and 1.2 mm. The comparison of the predicted and measured burst pressures was promising, indicating that the approach has the potential to be extended to predict formability limits in THF of complex shapes.
43
Zhang, Li Ming, and Zai Quan Wang. "Study on Rock Unloading Failure and its Effects on Rock Burst." Applied Mechanics and Materials 71-78 (July 2011): 1455–58. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.1455.
Повний текст джерелаАнотація:
The mechanical parameters and failure characteristics were obtained based on the results of triaxial unloading tests of limestone. Results show that: The evolution of volumetric strain is determined by lateral strain under unloading condition. Failure modes of rock can be classified into three types. Deformation modulus decreases and Poisson ratio increases in the process of unloading. Mohr-Coulomb criterion can not describe rock unloading failure strength property. Rock burst occur during tunnel excavation are closely related to the rock unloading failure characteristic.
44
Gong, Shuang, Zhen Wang, Lei Zhou, and Wen Wang. "Influence of Cyclic Impact Loading and Axial Stress on Dynamic Mechanical Properties of Burst-Prone Coal." Shock and Vibration 2021 (January 13, 2021): 1–10. http://dx.doi.org/10.1155/2021/6649308.
Повний текст джерелаАнотація:
High in-situ stress and frequent dynamic disturbances caused by the mining process in deep coal mines can easily induce dynamic disasters such as coal burst. We conducted laboratory experiments to assess the effects of the axial stress loading and dynamic cyclic impact loading on the dynamic mechanical properties of burst-prone coals by using a modified split Hopkinson pressure bar (SHPB). Comparisons were made using two types of burst-prone and burst-resistant coal samples. The mineral components, organic macerals, and dynamic mechanical features of both burst-prone and burst-resistant coal samples were comparatively analyzed based on the obtained X-ray diffraction (XRD), optical microscope observations, and dynamic compressive stress-strain curves, respectively. The results of the microstructure analysis indicated a larger difference between the minimum and maximum reflectances of vitrinite for burst-prone coal. Compared to the burst-resistant coal samples, the burst-prone coals contained less corpocollinite and fusinite. While applying a high axial static load combined with cyclic impact load, the coal samples showed the characteristics of fatigue damage. The results also demonstrated that preaxial stress affected the burst resistance of coal samples. The greater the preaxial stress was, the less the coal samples could withstand the dynamic cyclic impact load. In comparison to the burst-resistant coal sample, the burst-prone coal sample showed a larger dynamic compressive strength and a lower deformation. They were also more positively capable of the propagation and activation of the coal burst. We believe that the results of the study are conducive to further understanding of the distribution of microcomponents of burst-prone coals. The results are also beneficial for realizing the dynamic mechanical characteristics of burst-prone coals under the impact of cyclic dynamic load.
45
Sibelius, Ulf, Eva-Cathrin Schulz, Frank Rose, Katja Hattar, Thomas Jacobs, Siegfried Weiss, Trinad Chakraborty, Werner Seeger, and Friedrich Grimminger. "Role of Listeria monocytogenes Exotoxins Listeriolysin and Phosphatidylinositol-Specific Phospholipase C in Activation of Human Neutrophils." Infection and Immunity 67, no. 3 (March 1, 1999): 1125–30. http://dx.doi.org/10.1128/iai.67.3.1125-1130.1999.
Повний текст джерелаАнотація:
ABSTRACT Polymorphonuclear leukocytes (PMN) are essential for resolution of infections with Listeria monocytogenes. The present study investigated the role of the listerial exotoxins listeriolysin (LLO) and phosphatidylinositol-specific phospholipase C (PlcA) in human neutrophil activation. Different Listeria strains, mutated in individual virulence genes, as well as purified LLO were used. Coincubation of human neutrophils with wild-type L. monocytogenes provoked PMN activation, occurring independently of phagocytosis events, with concomitant elastase secretion, leukotriene generation, platelet-activating factor (PAF) synthesis, respiratory burst, and enhanced phosphoinositide hydrolysis. Degranulation and leukotriene formation were noted to be solely dependent on LLO expression, as these features were absent when the LLO-defective mutant EGD− and the avirulent strain L. innocua were used. These effects were fully reproduced by a recombinant L. innocuastrain expressing LLO (INN+) and by the purified LLO molecule. LLO secretion was also required for PAF synthesis. However, wild-typeL. monocytogenes was more potent in eliciting PAF formation than mutants expressing LLO, suggesting the involvement of additional virulence factors. This was even more obvious for phosphoinositide hydrolysis and respiratory burst: these events were provoked not only by INN+ but also by the LLO-defective mutant EGD− and by a recombinantL. innocua strain producing listerial PlcA. We conclude that human neutrophils react to extracellularly provided listerial exotoxins by rapid cell activation. Listeriolysin is centrally involved in triggering degranulation and lipid mediator generation, and further virulence factors such as PlcA apparently contribute to trigger neutrophil phosphoinositide hydrolysis and respiratory burst. In this way, listerial exotoxins may influence the host defense against infections with L. monocytogenes.
46
Michel, L., A. Vadean, and R. Benoit. "Tire Burst Phenomenon and Rupture of a Typical Truck Tire Bead Design." Tire Science and Technology 39, no. 4 (December 1, 2011): 270–83. http://dx.doi.org/10.2346/1.3672044.
Повний текст джерелаАнотація:
Abstract Even though relatively rare, the tire failures are very dangerous. An example of tire failure is over-pressurization that usually occurs during inflation of the tire, when the latter is inflated well beyond the pressure recommended by the tire manufacturer. When inflating tires, personnel assigned to vehicle repair and maintenance are likely to suffer severe injuries if several safety rules are ignored. Experimental data on tire burst is somewhat rare in the open literature. In order to determine the strength limits of a typical truck tire and describe the mechanism of the tire burst phenomenon, a hydrostatic burst test was first conducted on an 11R22.5 tire. From this test, tire burst pressure was determined. Over pressurizing the tire results in a high tension in the steel wire beads. As the total strain this kind of steel can withstand is rather low, their fracture will be source of the general failure. Then, an x-ray inspection and microscopic analysis were performed on the tire beads in order to characterize their behavior and failure. Furthermore, a finite element analysis was also conducted using material properties from the available literature to determine the inflation pressure resulting in failure of a new tire. The model was able to well predict the tire burst pressure by identifying the pressure at which the maximal plastic strain of steel bead wires is reached. Finally, the various tests and finite element analysis allowed to understand why, where, when, and how a truck tire fails when over pressurized.
47
STOKES, DARRELL R., and ROBERT K. JOSEPHSON. "The Mechanical Power Output of a Crab Respiratory Muscle." Journal of Experimental Biology 140, no. 1 (November 1, 1988): 287–99. http://dx.doi.org/10.1242/jeb.140.1.287.
Повний текст джерелаАнотація:
The mechanical power output was measured from scaphognathite (SG = gill bailer) muscle L2B of the crab Carcinus maenas (L.). The work was determined from the area of the loop formed by plotting muscle length against force when the muscle was subjected to sinusoidal length change (strain) and phasic stimulation in the length cycle. The stimulation pattern (10 stimuli per burst, burst length = 20% of cycle length) mimicked that which has been recorded from muscle L2B in intact animals. Work output was measured at cycle frequencies ranging from 0.5 to 5 Hz. The work output at optimum strain and stimulus phase increased with increasing cycle frequency to a maximum at 2–3 Hz and declined thereafter. The maximum work per cycle was 2.7 J kg−1 (15 °C). The power output reached a maximum (8.8 W kg−1) at 4 Hz. Both optimum strain and optimum stimulus phase were relatively constant over the range of burst frequencies examined. Based on the fraction of the total SG musculature represented by muscle L2B (18%) and literature values for the oxygen consumption associated with ventilation in C. maenas and for the hydraulic power output from an SG, we estimate that at a beat frequency of 2 Hz the SG muscle is about 10% efficient in converting metabolic energy to muscle power, and about 19% efficient in converting muscle power to hydraulic power.
48
Zhu, Xian-Kui, and Brian N. Leis. "Theoretical and Numerical Predictions of Burst Pressure of Pipelines." Journal of Pressure Vessel Technology 129, no. 4 (February 22, 2007): 644–52. http://dx.doi.org/10.1115/1.2767352.
Повний текст джерелаАнотація:
To accurately characterize plastic yield behavior of metals in multiaxial stress states, a new yield theory, i.e., the average shear stress yield (ASSY) theory, is proposed in reference to the classical Tresca and von Mises yield theories for isotropic hardening materials. Based on the ASSY theory, a theoretical solution for predicting the burst pressure of pipelines is obtained as a function of pipe diameter, wall thickness, material hardening exponent, and ultimate tensile strength. This solution is then validated by experimental data for various pipeline steels. According to the ASSY yield theory, four failure criteria are developed for predicting the burst pressure of pipes by the use of commercial finite element softwares such as ABAQUS and ANSYS, where the von Mises yield theory and the associated flow rule are adopted as the classical metal plasticity model for isotropic hardening materials. These failure criteria include the von Mises equivalent stress criterion, the maximum principal stress criterion, the von Mises equivalent strain criterion, and the maximum tensile strain criterion. Applications demonstrate that the proposed failure criteria in conjunction with the ABAQUS or ANSYS numerical analysis can effectively predict the burst pressure of end-capped line pipes.
49
Zughaier, Susu M., Henry C. Ryley, and Simon K. Jackson. "A Melanin Pigment Purified from an Epidemic Strain of Burkholderia cepacia Attenuates Monocyte Respiratory Burst Activity by Scavenging Superoxide Anion." Infection and Immunity 67, no. 2 (February 1, 1999): 908–13. http://dx.doi.org/10.1128/iai.67.2.908-913.1999.
Повний текст джерелаАнотація:
ABSTRACT The acquisition of Burkholderia cepacia in some cystic fibrosis patients is associated with symptoms of acute pulmonary inflammation that may be life threatening. The ability of lipopolysaccharide (LPS) from B. cepacia to prime a monocyte cell line for enhanced superoxide anion generation was investigated and compared with the priming activities of LPSs fromPseudomonas aeruginosa, Stenotrophomonas maltophilia, and Escherichia coli. The human monocyte cell line MonoMac-6 (MM6) was primed overnight with different LPSs (100 ng/ml), and the respiratory burst was triggered by exposure to opsonized zymosan (125 μg/ml). Superoxide generation was detected by enhanced chemiluminescence with Lucigenin. B. cepacia LPS was found to prime MM6 cells to produce more superoxide anion thanP. aeruginosa or S. maltophilia LPS, and this priming response was CD14 dependent. In addition, the inhibition of respiratory burst responses in monocytes by a bacterial melanin-like pigment purified from an epidemic B. cepacia strain was investigated. The melanin-like pigment was isolated from tyrosine-enriched media on which B. cepacia had been grown and was purified by gel filtration, anion ion-exchange chromatography, and ethanol precipitation. The scavenging potential of the melanin-like pigment for superoxide anion radical (•O2 −) generated during the respiratory burst was confirmed with superoxide produced from a cell-free system with xanthine-xanthine oxidase and detected by electron paramagnetic resonance spectroscopy with the spin trap 5-diethoxyphosphoryl-5-methyl-1-pyrroline-n-oxide. The addition of melanin during the LPS priming stage had no effect on the subsequent triggering of the respiratory burst, but melanin inhibited•O2 − detection when added at the triggering stage of the respiratory burst. We conclude that melanin-producing B. cepacia may derive protection from the free-radical-scavenging properties of this pigment.
50
Yang, Jinhui, and Shaowei Hu. "Estimation of Burst Pressure of PVC Pipe Using Average Shear Stress Yield Criterion: Experimental and Numerical Studies." Applied Sciences 11, no. 21 (November 8, 2021): 10477. http://dx.doi.org/10.3390/app112110477.
Повний текст джерелаАнотація:
Polyvinyl chloride (PVC) pipes have been extensively applied in water supply network fields. Understanding the mechanical properties and burst pressure of PVC pipes is necessary because a large number of pipes rupture due to excessive internal water pressure. In this paper, a practical approach based on the average shear stress yield (ASSY) criterion was proposed to assess the PVC pipe burst pressure. In addition, the PVC uniaxial tensile tests and the pipe burst tests were carried out to determine the material characteristic parameters and burst pressure of the PVC pipe. Furthermore, a finite element analysis (FEA) of PVC burst pressure was also performed based on the tangent intersection (TI) method to validate the proposed method and experimental results. Moreover, the impact of material parameters and pipe size, such as the strain hardening exponent and standard dimension ratio (SDR) on bursting pressure, were investigated. The comparison with the proposed theoretical model and the experimental and FEA results shows that the burst pressure derived from ASSY was consistent with the experimental data, with a relative error ranging from −2.76% to 2.65%, which is more accurate compared to other yield criteria. The burst pressure obtained by the ASSY approach declined with the increase of the hardening exponent n and increased with the increase of SDR. Therefore, the burst pressure solution-based ASSY proposed in this paper is an adequately suitable and precise predictive tool for assessing the failure pressure of PVC pipes.