Accurate simulation of the cracking process caused by rust expansion of reinforced concrete(RC)structures plays an intuitive role in revealing the corrosion-induced failure mechanism.Considering the quasi-brittle frac...Accurate simulation of the cracking process caused by rust expansion of reinforced concrete(RC)structures plays an intuitive role in revealing the corrosion-induced failure mechanism.Considering the quasi-brittle fracture of concrete,the fracture phase field driven by the compressive-shear term is constructed and added to the traditional brittle fracture phase field model.The rationality of the proposed model is verified by a mixed fracture example under a shear displacement load.Then,the extended fracture phase model is applied to simulate the corrosion-induced cracking process of RC.The cracking patterns caused by non-uniform corrosion expansion are discussed for RC specimens with homogeneous macroscopically or heterogeneous with different polygonal aggregate distributions at the mesoscopic scale.Then,the effects of the protective layer on the crack propagation trajectory and cracking resistance are investigated,illustrating that the cracking angle and cracking resistance increase with the increase of the protective layer thickness,consistent with the experimental observation.Finally,the corrosion-induced cracking process of concrete specimens with large and small spacing rebars is simulated,and the interaction of multiple corrosion cracking is easily influenced by the reinforcement spacing,which increases with the decrease of the steel bar interval.These conclusions play an important role in the design of engineering anti-corrosion measures.The fracture phase field model can provide strong support for the life assessment of RC structures.展开更多
The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing effect.Accordingly,we designed and conducted indoor experiments related to ...The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing effect.Accordingly,we designed and conducted indoor experiments related to the changes in macro and microscopic characteristics after the interaction of acid with the shale of Wujiaping Formation,based on which the characteristic law of fracture volume modification after acid fracturing was studied using numerical simulation.The results demonstrate that the pores and fractures are enlarged and the structure is significantly loosened after the acid immersion.And a 15%concentration of hydrochloric acid can effectively dissolve shale.Furthermore,the degree of acid-etching reaction is highly variable because of the different carbonate content,which reveals the strong inhomogeneity of the shale system in the Wujiaping Group reservoir section.After the acid interacted with the shale rock samples,the triaxial compressive strength,elastic modulus,and Poisson’s ratio of shale decreased.Moreover,the evaluation of the effect after acid fracturing simulated by fracturing software revealed that the smaller the value of elastic modulus in shale-based reservoirs,the more favorable the fracture volume modification.This discovery not only provides a theoretical basis for the expansion and extension patterns of acid-fracturing in carbonaceous shale formations but also offers research methods and theoretical insights for the fundamental exploration of other deep-seated oil and gas resources.展开更多
Carbonate outcrops were taken from Ma 51 sub-member in the Lower Paleozoic in the Yan’an gas field to conduct true tri-axial hydraulic fracturing experiments with water, liquid CO_(2) and supercritical CO_(2). CT sca...Carbonate outcrops were taken from Ma 51 sub-member in the Lower Paleozoic in the Yan’an gas field to conduct true tri-axial hydraulic fracturing experiments with water, liquid CO_(2) and supercritical CO_(2). CT scan was applied to analyze initiation and propagation laws of hydraulic fractures in carbonate rocks. The experiments show that supercritical CO_(2) has low viscosity, strong diffusivity and large filtration during fracturing, which is more liable to increase pore pressure of rocks around wellbore and decrease breakdown pressure of carbonate rocks. However, it would cost much more volume of supercritical CO_(2) than water to fracture rocks since the former increases the wellbore pressure more slowly during fracturing. For carbonate rocks with few natural fractures, tensional fractures are generated by fracturing with water and liquid CO_(2), and these fractures propagate along the maximum horizontal principal stress direction;while fracturing with supercritical CO_(2) can form shear fractures, whose morphology is rarely influenced by horizontal stress difference. Besides, the angle between propagation direction of these shear fractures near the wellbore and the maximum horizontal principal stress is 45°, and the fractures would gradually turn to propagate along the maximum horizontal principal stress when they extend to a certain distance from the wellbore, leading to an increase of fracture tortuosity compared with the former. For carbonate rocks with well-developed natural fractures, fracturing with fresh water is conducive to connect natural fractures with low approaching angle and form stepped fractures with simple morphology. The key to forming complex fractures after fracturing carbonate rocks is to connect the natural fractures with high approaching angle. It is easier for liquid CO_(2) with low viscosity to realize such connection. Multi-directional fractures with relatively complex morphology would be formed after fracturing with liquid CO_(2).展开更多
BACKGROUND Intertrochanteric fracture (ITF) is a common type of injury, and nearly 30% of ITF patients die in the first 12 mo, especially the elderly with limited activity. Tranexamic acid (TXA) has been widely used i...BACKGROUND Intertrochanteric fracture (ITF) is a common type of injury, and nearly 30% of ITF patients die in the first 12 mo, especially the elderly with limited activity. Tranexamic acid (TXA) has been widely used in reducing traumatic and surgical bleeding, however, the paucity of studies regarding its use in orthopedic trauma surgery has limited its integration into this field, which may benefit most from TXA. The safety of TXA in this group has not achieved a consensus. AIM This meta-analysis was designed to investigate the efficacy and safety of TXA in elderly ITF patients undergoing surgery. METHODS Databases, including Medline and PubMed, were searched for randomized controlled trials (RCTs) that were published before October 2018 and that addressed the efficacy and safety of TXA in patients who underwent ITF surgery. The Consolidated Standards of Reporting Trials 2010 Statement Checklist was used to assess the methodological quality of each study. Trials without and with heterogeneity were compared by fixed-effects analysis and random-effects analysis, respectively. For each study, odds ratio (OR) and 95%CI and mean differences and 95%CI were calculated for dichotomous and continuous outcomes, respectively. The Power and Sample Size Program software was used to calculate power and sample size. Stability of the results was assessed via sensitivity analysis. RESULTS A total of 836 patients from eight RCTs were subjected to meta-analysis. TXA treatment compared with the control group significantly reduced postoperative blood loss (95%CI,-20.83 to -7.93 mL, P < 0.0001), hidden blood loss (95%CI,- 213.67 to -64.43 mL, P = 0.0003), and total blood loss (95%CI,-332.49 to -23.18 mL, P = 0.02) by weighted mean differences of -14.38,-139.05, and -177.83 mL, respectively. However, no significant difference was observed between groups for analysis of intraoperative blood loss. The meta-analysis also proved that the usage of TXA in ITFs may not significantly increase the incidence of deep venous thrombosis. Allogeneic blood transfusion data showed that significantly fewer patients in the TXA group (42%) required transfusion than the control group (95%CI, 0.36 to 0.69;P < 0.0001). CONCLUSION In ITF surgery, intravenous administration of TXA reduces the risk of hidden blood loss and the need for allogeneic transfusion, without increasing thrombotic risk.展开更多
<strong>Background:</strong> Zoledronic acid and teriparatide have been proved to be effective in improving bone metabolism and preventing fractures, but there is no clear clinical report on the efficacy o...<strong>Background:</strong> Zoledronic acid and teriparatide have been proved to be effective in improving bone metabolism and preventing fractures, but there is no clear clinical report on the efficacy of their combined application. <strong>Purpose:</strong> To discuss the clinical effect of zoledronic acid combined with teriparatide in perverting recurrent fracture of osteoporotic vertebral compressive fractures (OVCF) in the elderly after percutaneous kyphoplasty (PKP). <strong>Method:</strong> A randomized clinical trial was conducted at the First Affiliated Hospital of Hebei North University in China from September 2018 and September 2019. A total of 60 patients with OVCF were enrolled in the study (zoledronic acid: 20 cases;teriparatide: 20 cases;zoledronic acid + teriparatide: 20 cases). Observe and compare the changes of bone mineral density (BMD), pro-collagen type I N-terminal propeptide (PINP) and cross-linked C-terminal telopeptide of type I collagen (<em>β</em>-CTX) before surgery, 6 months and 1 year after surgery. At the same time, secondary fracture events and adverse reaction events were recorded during the follow-up period. <strong>Results:</strong> After normalized treatment, the bone metabolism indexes of PINP and <em>β</em>-CTX were improved and BMD was increased in three groups. <strong>Adverse Reactions:</strong> There was no statistical significance in the incidence of fever, gastrointestinal reactions and myalgia among the three groups (P > 0.05). The incidence of recurrent fractures in group A was higher than that in group C (P < 0.05), but there was no significant difference between group B and group C (P > 0.05). <strong>Conclusion:</strong> Zoledronic acid combined with teriparatide is superior to Zoledronic acid in preventing the risk of recurrent fracture after PKP for old patients with OVCF, but it has no significant advantage over teriparatide.展开更多
In the paper, a new kind of electrochemical sensor was used for measuring the permeation rate of atomic hydrogen (H permeation current I) through the sensor in 5% HCI solution containing ferric ion with different conc...In the paper, a new kind of electrochemical sensor was used for measuring the permeation rate of atomic hydrogen (H permeation current I) through the sensor in 5% HCI solution containing ferric ion with different concentrations. The susceptibility of brittle fracture and the fracture mechanism of UNS G10190 steel in the solution were studied by slow strain rate tensile technique (SSRT), scanning electron microscope (SEM) and cathodic and anodic polarization. The embrittlement of the steel in the solution was expressed as index of embrittlement (F%). The results showed that the fracture mechanism of the steel in 5%HCl aqueous solution containing ferric ion would be changed from hydrogen induced cracking (HIC) to anodic dissolution in nature with the increase of the concentration of ferric ion in the solution.展开更多
Objective: To discuss the effect of α-lipoic acid combined with nerve growth factor on bone metabolism, oxidative stress and nerve conduction function after femoral fracture surgery. Methods: A total of 110 patients ...Objective: To discuss the effect of α-lipoic acid combined with nerve growth factor on bone metabolism, oxidative stress and nerve conduction function after femoral fracture surgery. Methods: A total of 110 patients with femoral fracture who received surgical treatment in the hospital between January 2015 and January 2017 were collected and divided into the control group (n=55) and study group (n=55) by random number table. Control group received postoperative nerve growth factor therapy, and study group received postoperative α-lipoic acid combined with nerve growth factor therapy. The differences in the contents of bone metabolism and oxidative stress indexes as well as the levels of nerve conduction function indexes were compared between the two groups before and after treatment. Results: Before treatment, the differences in the contents of bone metabolism and oxidative stress indexes as well as the levels of nerve conduction function indexes were not statistically significant between the two groups. After treatment, serum bone metabolism indexes BGP and PⅠNP contents of study group were higher than those of control group while CTX-Ⅰ and TRAP contents were lower than those of control group;serum oxidative stress indexes TAC, CAT and SOD contents of study group were higher than those of control group while MDA content was lower than that of control group;limb nerve conduction velocity SCV and MCV levels of study group were higher than those of control group. Conclusion: α-lipoic acid combined with nerve growth factor therapy after femoral fracture surgery can effectively balance osteoblast/osteoclast activity, reduce oxidative stress and improve limb nerve conduction velocity.展开更多
Carbonate reservoirs generally achieved relatively low primary resource recovery rates.It is therefore often necessary to clean those reservoirs up and/or stimulate them post drilling and later in their production lif...Carbonate reservoirs generally achieved relatively low primary resource recovery rates.It is therefore often necessary to clean those reservoirs up and/or stimulate them post drilling and later in their production life.A common and basic carbonate reservoir cleanup technique to remove contaminating material from the wellbore is acidizing.The efficiency of acid treatments is determined by many factors,including:the type and quantity of the acid used;the number of repeated treatments performed,heterogeneity of the reservoir,water cut of the reservoir fluids,and presence of idle zones and interlayers.Post-treatment production performance of such reservoirs frequently does not meet design expectations.There is therefore much scope to improve acidizing technologies and treatment designs to make them more reliable and effective.This review considers acid treatment technologies applied to carbonate reservoirs at the laboratory scale and in field-scale applications.The range of acid treatment techniques commonly applied are compared.Differences between specific acid treatments,such as foamed acids,acid emulsions,gelled and thickened acid systems,targeted acid treatments,and acid hydraulic fracturing are described in terms of the positive and negative influences they have on carbonate oil production rates and recovery.Opportunities to improve acid treatment techniques are identified,particularly those involving the deployment of nanoparticles(NPs).Due consideration is also given to the potential environmental impacts associated with carbonate reservoir acid treatment.Recommendations are made regarding the future research required to overcome the remaining challenges pertaining to acid treatment applications.展开更多
基金the National Natural Science Foundation of China(Qing Zhang,Nos.11932006,U1934206,12172121)the Fundamental Research Funds for the Central Universities(Xin Gu,No.B210201031).
文摘Accurate simulation of the cracking process caused by rust expansion of reinforced concrete(RC)structures plays an intuitive role in revealing the corrosion-induced failure mechanism.Considering the quasi-brittle fracture of concrete,the fracture phase field driven by the compressive-shear term is constructed and added to the traditional brittle fracture phase field model.The rationality of the proposed model is verified by a mixed fracture example under a shear displacement load.Then,the extended fracture phase model is applied to simulate the corrosion-induced cracking process of RC.The cracking patterns caused by non-uniform corrosion expansion are discussed for RC specimens with homogeneous macroscopically or heterogeneous with different polygonal aggregate distributions at the mesoscopic scale.Then,the effects of the protective layer on the crack propagation trajectory and cracking resistance are investigated,illustrating that the cracking angle and cracking resistance increase with the increase of the protective layer thickness,consistent with the experimental observation.Finally,the corrosion-induced cracking process of concrete specimens with large and small spacing rebars is simulated,and the interaction of multiple corrosion cracking is easily influenced by the reinforcement spacing,which increases with the decrease of the steel bar interval.These conclusions play an important role in the design of engineering anti-corrosion measures.The fracture phase field model can provide strong support for the life assessment of RC structures.
基金This study is supported by a Scientific Research Project of Sinopec(Program No.P21087-2)the Open Fund of Key Laboratory of Marine Oil&Gas Reservoirs Production,Sinopec(Grant No.33550000-22-FW2099-0004).
文摘The microscopic characteristics and mechanical properties of rocks change after the action of acid on deep shale,which affects the fracturing effect.Accordingly,we designed and conducted indoor experiments related to the changes in macro and microscopic characteristics after the interaction of acid with the shale of Wujiaping Formation,based on which the characteristic law of fracture volume modification after acid fracturing was studied using numerical simulation.The results demonstrate that the pores and fractures are enlarged and the structure is significantly loosened after the acid immersion.And a 15%concentration of hydrochloric acid can effectively dissolve shale.Furthermore,the degree of acid-etching reaction is highly variable because of the different carbonate content,which reveals the strong inhomogeneity of the shale system in the Wujiaping Group reservoir section.After the acid interacted with the shale rock samples,the triaxial compressive strength,elastic modulus,and Poisson’s ratio of shale decreased.Moreover,the evaluation of the effect after acid fracturing simulated by fracturing software revealed that the smaller the value of elastic modulus in shale-based reservoirs,the more favorable the fracture volume modification.This discovery not only provides a theoretical basis for the expansion and extension patterns of acid-fracturing in carbonaceous shale formations but also offers research methods and theoretical insights for the fundamental exploration of other deep-seated oil and gas resources.
基金Supported by National Natural Science Foundation of China Project(51704249)The Open Fund Project of the State Key Laboratory Oil and Gas Reservoir Geology and Exploitation(PLN2020-1)。
文摘Carbonate outcrops were taken from Ma 51 sub-member in the Lower Paleozoic in the Yan’an gas field to conduct true tri-axial hydraulic fracturing experiments with water, liquid CO_(2) and supercritical CO_(2). CT scan was applied to analyze initiation and propagation laws of hydraulic fractures in carbonate rocks. The experiments show that supercritical CO_(2) has low viscosity, strong diffusivity and large filtration during fracturing, which is more liable to increase pore pressure of rocks around wellbore and decrease breakdown pressure of carbonate rocks. However, it would cost much more volume of supercritical CO_(2) than water to fracture rocks since the former increases the wellbore pressure more slowly during fracturing. For carbonate rocks with few natural fractures, tensional fractures are generated by fracturing with water and liquid CO_(2), and these fractures propagate along the maximum horizontal principal stress direction;while fracturing with supercritical CO_(2) can form shear fractures, whose morphology is rarely influenced by horizontal stress difference. Besides, the angle between propagation direction of these shear fractures near the wellbore and the maximum horizontal principal stress is 45°, and the fractures would gradually turn to propagate along the maximum horizontal principal stress when they extend to a certain distance from the wellbore, leading to an increase of fracture tortuosity compared with the former. For carbonate rocks with well-developed natural fractures, fracturing with fresh water is conducive to connect natural fractures with low approaching angle and form stepped fractures with simple morphology. The key to forming complex fractures after fracturing carbonate rocks is to connect the natural fractures with high approaching angle. It is easier for liquid CO_(2) with low viscosity to realize such connection. Multi-directional fractures with relatively complex morphology would be formed after fracturing with liquid CO_(2).
基金Supported by (in part) National Natural Science Foundation of China,No.81702179Major Scientific and Technological Project of Changzhou Municipal Commission of Health and Family Planning,No.ZD201809
文摘BACKGROUND Intertrochanteric fracture (ITF) is a common type of injury, and nearly 30% of ITF patients die in the first 12 mo, especially the elderly with limited activity. Tranexamic acid (TXA) has been widely used in reducing traumatic and surgical bleeding, however, the paucity of studies regarding its use in orthopedic trauma surgery has limited its integration into this field, which may benefit most from TXA. The safety of TXA in this group has not achieved a consensus. AIM This meta-analysis was designed to investigate the efficacy and safety of TXA in elderly ITF patients undergoing surgery. METHODS Databases, including Medline and PubMed, were searched for randomized controlled trials (RCTs) that were published before October 2018 and that addressed the efficacy and safety of TXA in patients who underwent ITF surgery. The Consolidated Standards of Reporting Trials 2010 Statement Checklist was used to assess the methodological quality of each study. Trials without and with heterogeneity were compared by fixed-effects analysis and random-effects analysis, respectively. For each study, odds ratio (OR) and 95%CI and mean differences and 95%CI were calculated for dichotomous and continuous outcomes, respectively. The Power and Sample Size Program software was used to calculate power and sample size. Stability of the results was assessed via sensitivity analysis. RESULTS A total of 836 patients from eight RCTs were subjected to meta-analysis. TXA treatment compared with the control group significantly reduced postoperative blood loss (95%CI,-20.83 to -7.93 mL, P < 0.0001), hidden blood loss (95%CI,- 213.67 to -64.43 mL, P = 0.0003), and total blood loss (95%CI,-332.49 to -23.18 mL, P = 0.02) by weighted mean differences of -14.38,-139.05, and -177.83 mL, respectively. However, no significant difference was observed between groups for analysis of intraoperative blood loss. The meta-analysis also proved that the usage of TXA in ITFs may not significantly increase the incidence of deep venous thrombosis. Allogeneic blood transfusion data showed that significantly fewer patients in the TXA group (42%) required transfusion than the control group (95%CI, 0.36 to 0.69;P < 0.0001). CONCLUSION In ITF surgery, intravenous administration of TXA reduces the risk of hidden blood loss and the need for allogeneic transfusion, without increasing thrombotic risk.
文摘<strong>Background:</strong> Zoledronic acid and teriparatide have been proved to be effective in improving bone metabolism and preventing fractures, but there is no clear clinical report on the efficacy of their combined application. <strong>Purpose:</strong> To discuss the clinical effect of zoledronic acid combined with teriparatide in perverting recurrent fracture of osteoporotic vertebral compressive fractures (OVCF) in the elderly after percutaneous kyphoplasty (PKP). <strong>Method:</strong> A randomized clinical trial was conducted at the First Affiliated Hospital of Hebei North University in China from September 2018 and September 2019. A total of 60 patients with OVCF were enrolled in the study (zoledronic acid: 20 cases;teriparatide: 20 cases;zoledronic acid + teriparatide: 20 cases). Observe and compare the changes of bone mineral density (BMD), pro-collagen type I N-terminal propeptide (PINP) and cross-linked C-terminal telopeptide of type I collagen (<em>β</em>-CTX) before surgery, 6 months and 1 year after surgery. At the same time, secondary fracture events and adverse reaction events were recorded during the follow-up period. <strong>Results:</strong> After normalized treatment, the bone metabolism indexes of PINP and <em>β</em>-CTX were improved and BMD was increased in three groups. <strong>Adverse Reactions:</strong> There was no statistical significance in the incidence of fever, gastrointestinal reactions and myalgia among the three groups (P > 0.05). The incidence of recurrent fractures in group A was higher than that in group C (P < 0.05), but there was no significant difference between group B and group C (P > 0.05). <strong>Conclusion:</strong> Zoledronic acid combined with teriparatide is superior to Zoledronic acid in preventing the risk of recurrent fracture after PKP for old patients with OVCF, but it has no significant advantage over teriparatide.
文摘In the paper, a new kind of electrochemical sensor was used for measuring the permeation rate of atomic hydrogen (H permeation current I) through the sensor in 5% HCI solution containing ferric ion with different concentrations. The susceptibility of brittle fracture and the fracture mechanism of UNS G10190 steel in the solution were studied by slow strain rate tensile technique (SSRT), scanning electron microscope (SEM) and cathodic and anodic polarization. The embrittlement of the steel in the solution was expressed as index of embrittlement (F%). The results showed that the fracture mechanism of the steel in 5%HCl aqueous solution containing ferric ion would be changed from hydrogen induced cracking (HIC) to anodic dissolution in nature with the increase of the concentration of ferric ion in the solution.
文摘Objective: To discuss the effect of α-lipoic acid combined with nerve growth factor on bone metabolism, oxidative stress and nerve conduction function after femoral fracture surgery. Methods: A total of 110 patients with femoral fracture who received surgical treatment in the hospital between January 2015 and January 2017 were collected and divided into the control group (n=55) and study group (n=55) by random number table. Control group received postoperative nerve growth factor therapy, and study group received postoperative α-lipoic acid combined with nerve growth factor therapy. The differences in the contents of bone metabolism and oxidative stress indexes as well as the levels of nerve conduction function indexes were compared between the two groups before and after treatment. Results: Before treatment, the differences in the contents of bone metabolism and oxidative stress indexes as well as the levels of nerve conduction function indexes were not statistically significant between the two groups. After treatment, serum bone metabolism indexes BGP and PⅠNP contents of study group were higher than those of control group while CTX-Ⅰ and TRAP contents were lower than those of control group;serum oxidative stress indexes TAC, CAT and SOD contents of study group were higher than those of control group while MDA content was lower than that of control group;limb nerve conduction velocity SCV and MCV levels of study group were higher than those of control group. Conclusion: α-lipoic acid combined with nerve growth factor therapy after femoral fracture surgery can effectively balance osteoblast/osteoclast activity, reduce oxidative stress and improve limb nerve conduction velocity.
基金supported by the Tomsk Polytechnic University development program.
文摘Carbonate reservoirs generally achieved relatively low primary resource recovery rates.It is therefore often necessary to clean those reservoirs up and/or stimulate them post drilling and later in their production life.A common and basic carbonate reservoir cleanup technique to remove contaminating material from the wellbore is acidizing.The efficiency of acid treatments is determined by many factors,including:the type and quantity of the acid used;the number of repeated treatments performed,heterogeneity of the reservoir,water cut of the reservoir fluids,and presence of idle zones and interlayers.Post-treatment production performance of such reservoirs frequently does not meet design expectations.There is therefore much scope to improve acidizing technologies and treatment designs to make them more reliable and effective.This review considers acid treatment technologies applied to carbonate reservoirs at the laboratory scale and in field-scale applications.The range of acid treatment techniques commonly applied are compared.Differences between specific acid treatments,such as foamed acids,acid emulsions,gelled and thickened acid systems,targeted acid treatments,and acid hydraulic fracturing are described in terms of the positive and negative influences they have on carbonate oil production rates and recovery.Opportunities to improve acid treatment techniques are identified,particularly those involving the deployment of nanoparticles(NPs).Due consideration is also given to the potential environmental impacts associated with carbonate reservoir acid treatment.Recommendations are made regarding the future research required to overcome the remaining challenges pertaining to acid treatment applications.
