Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20</span><sup><span style="font-family:Verdana;">th</span></sup><span ...Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> century. The facts justifying the connection are given by Siberian Fan Reliefs and the Tunguska Cosmic Body. It is most natural to assume that we are dealing with the falling of numerous fragments of a collapsed comet. The more likely version is that the comet is captured by the Earth-Moon system and remains in Earth orbit for some time.展开更多
Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20<sup>th</sup> century. These reliefs consist of several tens (up to hundreds) of stripes that have ...Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20<sup>th</sup> century. These reliefs consist of several tens (up to hundreds) of stripes that have arisen as a result of the destruction of vegetation and the surface layer of the ground. Structures of stripes are extended, ranging in size from 6 km to ≥20 km, with a width of several kilometers. Every strip (scratch on the ground) is roughly estimated to be up to 50 m wide and ≥500 m long. The stripes start from one edge of the relief and stretch at inter-vals to the other, slightly diverging symmetrically from the central axis. It was determined that these reliefs are not associated with the movement of soil (avalanches, mudflows) or with the impact of air currents (hurricanes, storm, tornado). Geographically, these struc-tures of stripes are located within a circle with a radius of 770 km, described around the epicenter of the Tunguska catastrophe.展开更多
Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her...Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her children at their home near the Angola border.展开更多
To investigate the energy relief effect of real-time drilling in preventing rockburst in high-stress rock,a series of high-stress real-time drilling uniaxial compression tests were conducted on red sandstone specimens...To investigate the energy relief effect of real-time drilling in preventing rockburst in high-stress rock,a series of high-stress real-time drilling uniaxial compression tests were conducted on red sandstone specimens using the SG4500 drilling rig.Results showed that the mechanical behavior(i.e.peak strength and rockburst intensity)of the rock was weakened under high-stress real-time drilling and exhibited a downward trend as the drilling diameter increased.The real-time drilling energy dissipation index(ERD)was proposed to characterize the energy relief during high-stress real-time drilling.The ERD exhibited a linear increase with the real-time drilling diameter.Furthermore,the elastic strain energy of post-drilling rock showed a linear relationship with the square of stress across different stress levels,which also applied to the peak elastic strain energy and the square of peak stress.This findingreveals the intrinsic link between the weakening effect of peak elastic strain energy and peak strength due to high-stress real-time drilling,confirmingthe consistency between energy relief and pressure relief effects.By establishing relationships among rockburst proneness,peak elastic strain energy,and peak strength,it was demonstrated that high-stress real-time drilling reduces rockburst proneness through energy dissipation.Specifically,both peak elastic strain energy and rockburst proneness decreased with larger drill bit diameters,consistent with reductions in peak strength,rockburst intensity,and fractal dimensions of high-stress real-time drilled rock.These results validate the energy relief mechanism of real-time drilling in mitigating rockburst risks.展开更多
The weak and broken roof,explosive control and other problems seriously restrict the promotion of non coal pillar self-forming roadway technology.In order to solve such problems,a new method of non coal pillar self-fo...The weak and broken roof,explosive control and other problems seriously restrict the promotion of non coal pillar self-forming roadway technology.In order to solve such problems,a new method of non coal pillar self-forming roadway through non-blasting roof cutting and pressure relief was proposed in this study.A systematic research system of"theoretical analysis-physical experiment-engineering verification"was constructed with the 9103 working face of Longmenta Coal Mine as the research object.Firstly,the theoretical analysis was conducted to reveal the roof cutting mechanics mechanism of rock mass weakened by dense drilling,establish the design criteria for key drilling parameters,and obtain the key design parameters of dense drilling in the test working face.Secondly,the physical model test was conducted to make clear that the dense drilling method can directionally cut off the goaf roof along the set position,reducing the stress and deformation of the roadway surrounding rock.Finally,the field engineering tests were conducted,and monitoring results showed that the pressure relief effect of the dense drilling method was comparable to that of the directional blasting method,achieving non coal pillar self-forming roadway mining under non blasting conditions.展开更多
In-situ stress is a key parameter for underground mine design and rock stability analysis.The borehole overcoring technique is widely used for in-situ stress measurement,but the rheological recovery deformation of roc...In-situ stress is a key parameter for underground mine design and rock stability analysis.The borehole overcoring technique is widely used for in-situ stress measurement,but the rheological recovery deformation of rocks after stress relief introduces errors.To improve accuracy,this study proposes an in-situ stress solution theory that incorporates time-dependent stress relief effects.Triaxial stepwise loadingunloading rheological tests on granite and siltstone established quantitative relationships between instantaneous elastic recovery and viscoelastic recovery under different stress levels,confirming their impact on measurement accuracy.By integrating a dual-class elastic deformation recovery model,an improved in-situ stress solution theory was derived.Additionally,accounting for the nonlinear characteristics of rock masses,a determination method for time-dependent nonlinear mechanical parameters was proposed.Based on the CSIRO hollow inclusion strain cell,time-dependent strain correction equations and long-term confining pressure calibration equations were formulated.Finally,the proposed theory was successfully applied at one iron mine(736 m depth)in Xinjiang,China,and one coal mine(510 m depth)in Ningxia,China.Compared to classical theory,the calculated mean stress values showed accuracy improvements of 6.0%and 9.4%,respectively,validating the applicability and reliability of the proposed theory.展开更多
Giant wooden reliefsillustrate some 45 ancientChinese myths, reflectingthe wisdom of the Chinesenation in antiquity. Eachboard depicts a legendaryscene, enabling viewers tovisualise the nature of theChinese nation and...Giant wooden reliefsillustrate some 45 ancientChinese myths, reflectingthe wisdom of the Chinesenation in antiquity. Eachboard depicts a legendaryscene, enabling viewers tovisualise the nature of theChinese nation and thespirit of the ancient country.展开更多
As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has...As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has been widely utilized for ceramic-metal heterogeneous joints.However,the residual stress relief in these welding joints is complicated and necessary.Because metals and ceramics have different properties,especially their coefficients of thermal expansion.Welding joints exhibit large residual stresses during the cooling process.The relatively high residual stresses may significantly degrade the joint properties.For this issue,four alleviation routes were reviewed:optimization of process parameters,setting an intermediate layer,surface structure modulation and particle-reinforced composite solder.The states and distribution patterns of residual stress in ceramic-metal brazed joints were summarized,and the generation and detection of residual stress were introduced.Eventually,upcoming prospects and challenges of residual stress research on ceramic/metal heterostructures were pointed out.展开更多
After the earthquake struck Myanmar on March 28th,China NGO Network for International Exchanges(CNIE)immediately contacted the emergency management department for the registration process of non-governmental rescue fo...After the earthquake struck Myanmar on March 28th,China NGO Network for International Exchanges(CNIE)immediately contacted the emergency management department for the registration process of non-governmental rescue forces participating in earthquake relief work and guided its member organisations and partners to orderly participate in the disaster relief.展开更多
Rainfall-induced landslides are often highly destructive.Reviewing and analyzing the causes,processes,impacts,and deficiencies in emergency response is critical for improving disaster prevention and management.From th...Rainfall-induced landslides are often highly destructive.Reviewing and analyzing the causes,processes,impacts,and deficiencies in emergency response is critical for improving disaster prevention and management.From the night of July 21 to the morning of July 22,2024,the Kencho Shacha Gozdi Village in Gezei Gofa,Southern Nations,Nationalities,and Peoples'Region,Ethiopia,suffered heavy rainfall that triggered two landslides.By July25,this event had claimed at least 257 lives.This study presents a detailed characterization of the landslides using multi-source data.By analyzing the landslide disaster process,this study summarizes key lessons and provides suggestions for preventing rainfall-induced geological hazards.The results indicate that rainfall has the greatest impact on the occurrence of landslides,while lithology and human activities have promoted and strengthened the landslide disaster.Despite the active disaster response in the local area,many problems were still exposed in the emergency response work.This analysis offers valuable insights for mitigating rainfall-induced geological hazards and enhancing emergency response capabilities.展开更多
Purpose:The aim of this study was to summarize the evidence regarding whether pain reduction in individuals with chronic non-specific low back pain(CNSLBP)following conservative interventions is related to correspondi...Purpose:The aim of this study was to summarize the evidence regarding whether pain reduction in individuals with chronic non-specific low back pain(CNSLBP)following conservative interventions is related to corresponding improvements in balance control.Methods:Randomized controlled trials were identified from 5 databases(MEDLINE,Cochrane Library,Embase,Web of Science,and PsycINFO).Two reviewers independently screened and identified relevant studies that investigated the effects of non-surgical or non-pharmacological CNSLBP treatments on both pain intensity and balance control.Meta-regression analyses were performed to establish the associations between post-treatment changes in these 2 variables.Results:Thirty one studies involving 1280 participants with CNSLBP were included.Moderate-quality evidence suggested that pain reduction was associated with and explained 34%-45%of decreases in body sway,as measured by center-of-pressure(CoP)area and CoP velocity with eyes open.However,no significant association was observed between pain reduction and CoP area or velocity in anteroposterior/mediolateral directions.Similarly,there was no significant association between pain reduction and CoP distance or radius.Low-quality evidence indicated that pain relief explained a 15%improvement in one-leg stance with eyes open but not in the eyes-closed condition.Additionally,very low-quality evidence suggested that pain relief explained a 44%decrease in the static anteroposterior stability index with eyes closed but not in the eyes-open,mediolateral,or overall conditions.Furthermore,low-quality evidence indicated that reduced pain was associated with and accounted for 25%-43%of the improved composite and posteromedial scores of the star-excursion balance test,rather than the anterior and posterolateral scores.Conclusion:Depending on the type of balance assessment,pain relief following conservative interventions may slightly to moderately enhance balance control in individuals with CNSLBP.Clinicians should pay close attention to the balance control in patients with CNSLBP,particularly among older adults.展开更多
The formation of a pressure relief zone is crucial for rockbust prevention during drilling pressure relief.This study investi-gates the mechanical behavior of high-stress rock under real-time drilling conditions and e...The formation of a pressure relief zone is crucial for rockbust prevention during drilling pressure relief.This study investi-gates the mechanical behavior of high-stress rock under real-time drilling conditions and elucidates the mechanism behind the creation of the pressure relief zone.Utilizing the independently developed SG4500 drilling rig,we conducted a theoreti-cal analysis of the forces acting on the drill bit.The analysis showed that cutting depth is directly proportional to real-time drilling speed,while tangential and normal forces are influenced by drilling diameter.Uniaxial compression tests on red sandstone specimens under high-stress real-time drilling conditions examined the impacts of different drilling speeds(800,400,100 r/min)and diameters(6,8,10,12 mm)on rock mechanical behavior,rockburst characteristics,crack evolution,and peak elastic strain energy.The results indicate that decreasing drilling speed and increasing drilling diameter weaken rock mechanical behavior,including peak strength,Young's modulus,rockburst characteristics,and peak elastic strain energy.Crack evolution analysis reveals that smaller drilling diameters and higher drilling speeds promote the development of far-field cracks,while larger drilling diameters and lower drilling speeds lead to crack formation around the borehole,and significantly affecting rock failure mechanisms.Theoretical analysis further confirms the correlation between crack evolution and stress distribution surrounding the drilling.Under vertical stress,the cracks near the borehole formed during real-time drilling are mainly influenced by tangential compressive and tensile stresses.Overall,this study provides a new perspective on understanding the mechanisms of drilling pressure relief for rockburst prevention.展开更多
On the title photo you can see in the background the distinctive peak of the highest mountain of the Krkono?e Mountains,and the whole Czechia,Snězka 1603 m above sea level,which is unique not only in Central Europe w...On the title photo you can see in the background the distinctive peak of the highest mountain of the Krkono?e Mountains,and the whole Czechia,Snězka 1603 m above sea level,which is unique not only in Central Europe with its size,altitude,glacial and periglacial relief and arctic-alpine tundra.In the foreground of the photograph,an inconspicuous platform with several benches and concrete blocks can be seen.展开更多
In this work,the effect of ultrasonic vibration modes on the mechanical properties and relaxation of residual stress in 6061-T6 aluminum alloy was studied.A new ultrasonic vibration Johnson-Cook model was proposed,and...In this work,the effect of ultrasonic vibration modes on the mechanical properties and relaxation of residual stress in 6061-T6 aluminum alloy was studied.A new ultrasonic vibration Johnson-Cook model was proposed,and the relaxation and distribution of residual stress under ultrasonic vibration were predicted and analyzed using the finite element method(FEM).The mechanical properties of 6061-T6 aluminum alloy under different ultrasonic vibration modes were analyzed through experiments involving notched specimen tensile testing and scanning electron microscopy(SEM)analysis.The findings indicate that ultrasonic vibration treatment during deformation,unloading,and load-holding,as well as treatment with its natural ultrasonic frequency,can effectively release residual stress;however,treatment with its natural frequency has the highest rate of release up to 65.4%.Ultrasonic vibration treatment during deformation better inhibits fracture under the same conditions.The FEM results are in good agreement with the experimental results,and it can be used as a valid tool for predicting residual stress release under ultrasonic vibration.展开更多
Objective:Acute appendicitis,as a common clinical acute abdominal condition,has a significant impact on patient prognosis depending on the choice of treatment strategy.This study aims to systematically compare the cli...Objective:Acute appendicitis,as a common clinical acute abdominal condition,has a significant impact on patient prognosis depending on the choice of treatment strategy.This study aims to systematically compare the clinical efficacy and safety of surgical versus conservative treatment in patients with acute appendicitis.Methods:A total of 60 patients with acute appendicitis admitted to our hospital from August 2024 to July 2025 were selected as the study subjects and divided into a surgical group(n=30)and a conservative group(n=30)based on the treatment approach.The surgical group underwent abdominal incision appendectomy,while the conservative group received antibiotic therapy combined with symptomatic supportive treatment.Evaluation indicators included the treatment effective rate,symptom relief time,and complication incidence.Results:The treatment effective rate in the surgical group was 96.67%,significantly higher than that in the conservative group(76.67%)(p<0.05).In terms of symptom relief,the time to relief of abdominal pain(1.25±0.36 days)and fever(1.08±0.29 days)in the surgical group was significantly shorter than that in the conservative group(3.12±0.57 days and 2.89±0.61 days,respectively,p<0.001).The complication rates in the two groups were 10.00%and 13.33%,respectively(p>0.05).Conclusion:Surgical treatment for acute appendicitis demonstrates significant advantages in improving treatment efficacy and shortening the time to symptom relief,with a comparable risk of complications to conservative treatment.It is therefore worthy of clinical priority recommendation,particularly for patients without surgical contraindications.展开更多
文摘Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20</span><sup><span style="font-family:Verdana;">th</span></sup><span style="font-family:Verdana;"> century. The facts justifying the connection are given by Siberian Fan Reliefs and the Tunguska Cosmic Body. It is most natural to assume that we are dealing with the falling of numerous fragments of a collapsed comet. The more likely version is that the comet is captured by the Earth-Moon system and remains in Earth orbit for some time.
文摘Unusual reliefs on the Earth’s surface were found in aerial photographs of Eastern Siberia in the late 20<sup>th</sup> century. These reliefs consist of several tens (up to hundreds) of stripes that have arisen as a result of the destruction of vegetation and the surface layer of the ground. Structures of stripes are extended, ranging in size from 6 km to ≥20 km, with a width of several kilometers. Every strip (scratch on the ground) is roughly estimated to be up to 50 m wide and ≥500 m long. The stripes start from one edge of the relief and stretch at inter-vals to the other, slightly diverging symmetrically from the central axis. It was determined that these reliefs are not associated with the movement of soil (avalanches, mudflows) or with the impact of air currents (hurricanes, storm, tornado). Geographically, these struc-tures of stripes are located within a circle with a radius of 770 km, described around the epicenter of the Tunguska catastrophe.
文摘Chinese food aid nourishes over 188,000 Zambians In the arid terrain of Shang’ombo District,approximately 850 km west of Lusaka,Zambia’s capital,Charity Imbuwa received a Chinese food-aid pack and shared it with her children at their home near the Angola border.
基金supported by the National Natural Science Foundation of China(Grant No.42077244)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(Grant No.KYCX24_0434).
文摘To investigate the energy relief effect of real-time drilling in preventing rockburst in high-stress rock,a series of high-stress real-time drilling uniaxial compression tests were conducted on red sandstone specimens using the SG4500 drilling rig.Results showed that the mechanical behavior(i.e.peak strength and rockburst intensity)of the rock was weakened under high-stress real-time drilling and exhibited a downward trend as the drilling diameter increased.The real-time drilling energy dissipation index(ERD)was proposed to characterize the energy relief during high-stress real-time drilling.The ERD exhibited a linear increase with the real-time drilling diameter.Furthermore,the elastic strain energy of post-drilling rock showed a linear relationship with the square of stress across different stress levels,which also applied to the peak elastic strain energy and the square of peak stress.This findingreveals the intrinsic link between the weakening effect of peak elastic strain energy and peak strength due to high-stress real-time drilling,confirmingthe consistency between energy relief and pressure relief effects.By establishing relationships among rockburst proneness,peak elastic strain energy,and peak strength,it was demonstrated that high-stress real-time drilling reduces rockburst proneness through energy dissipation.Specifically,both peak elastic strain energy and rockburst proneness decreased with larger drill bit diameters,consistent with reductions in peak strength,rockburst intensity,and fractal dimensions of high-stress real-time drilled rock.These results validate the energy relief mechanism of real-time drilling in mitigating rockburst risks.
基金Project(2024YFC2909500)supported by the National Key Research and Development Program of ChinaProjects(42377148,52204164)supported by the National Natural Science Foundation of ChinaProject(2022XJSB03)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The weak and broken roof,explosive control and other problems seriously restrict the promotion of non coal pillar self-forming roadway technology.In order to solve such problems,a new method of non coal pillar self-forming roadway through non-blasting roof cutting and pressure relief was proposed in this study.A systematic research system of"theoretical analysis-physical experiment-engineering verification"was constructed with the 9103 working face of Longmenta Coal Mine as the research object.Firstly,the theoretical analysis was conducted to reveal the roof cutting mechanics mechanism of rock mass weakened by dense drilling,establish the design criteria for key drilling parameters,and obtain the key design parameters of dense drilling in the test working face.Secondly,the physical model test was conducted to make clear that the dense drilling method can directionally cut off the goaf roof along the set position,reducing the stress and deformation of the roadway surrounding rock.Finally,the field engineering tests were conducted,and monitoring results showed that the pressure relief effect of the dense drilling method was comparable to that of the directional blasting method,achieving non coal pillar self-forming roadway mining under non blasting conditions.
基金supported by the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2024ZD1700201)the National Natural Science Foundation of China(Nos.U2034206,51974014 and 51574014)+1 种基金the Guangdong Basic and Applied Basic Research Foundation(No.2024A1515011631)the National Key Research and Development Project of China(No.2022YFC3004601)。
文摘In-situ stress is a key parameter for underground mine design and rock stability analysis.The borehole overcoring technique is widely used for in-situ stress measurement,but the rheological recovery deformation of rocks after stress relief introduces errors.To improve accuracy,this study proposes an in-situ stress solution theory that incorporates time-dependent stress relief effects.Triaxial stepwise loadingunloading rheological tests on granite and siltstone established quantitative relationships between instantaneous elastic recovery and viscoelastic recovery under different stress levels,confirming their impact on measurement accuracy.By integrating a dual-class elastic deformation recovery model,an improved in-situ stress solution theory was derived.Additionally,accounting for the nonlinear characteristics of rock masses,a determination method for time-dependent nonlinear mechanical parameters was proposed.Based on the CSIRO hollow inclusion strain cell,time-dependent strain correction equations and long-term confining pressure calibration equations were formulated.Finally,the proposed theory was successfully applied at one iron mine(736 m depth)in Xinjiang,China,and one coal mine(510 m depth)in Ningxia,China.Compared to classical theory,the calculated mean stress values showed accuracy improvements of 6.0%and 9.4%,respectively,validating the applicability and reliability of the proposed theory.
文摘Giant wooden reliefsillustrate some 45 ancientChinese myths, reflectingthe wisdom of the Chinesenation in antiquity. Eachboard depicts a legendaryscene, enabling viewers tovisualise the nature of theChinese nation and thespirit of the ancient country.
基金National Program of Foreign Experts of China(G2023026003L)National Natural Science Foundation of China(52475347)+4 种基金Postdoctoral Fund(2023M740475)International Science and Technology Cooperation Project of Henan Province(242102521057)Frontier Exploration Projects of Longmen Laboratory(LMQYTSKT016)Central Plains Science and Technology Innovation Leading TalentsProvincial Science and Technology R&D Program Joint Fund Projects(235200810030)。
文摘As service conditions become more challenging and production complexity increases,there is an increasing demand for enhanced comprehensive performance of ceramic/metal heterostructures.At present,brazing technique has been widely utilized for ceramic-metal heterogeneous joints.However,the residual stress relief in these welding joints is complicated and necessary.Because metals and ceramics have different properties,especially their coefficients of thermal expansion.Welding joints exhibit large residual stresses during the cooling process.The relatively high residual stresses may significantly degrade the joint properties.For this issue,four alleviation routes were reviewed:optimization of process parameters,setting an intermediate layer,surface structure modulation and particle-reinforced composite solder.The states and distribution patterns of residual stress in ceramic-metal brazed joints were summarized,and the generation and detection of residual stress were introduced.Eventually,upcoming prospects and challenges of residual stress research on ceramic/metal heterostructures were pointed out.
文摘After the earthquake struck Myanmar on March 28th,China NGO Network for International Exchanges(CNIE)immediately contacted the emergency management department for the registration process of non-governmental rescue forces participating in earthquake relief work and guided its member organisations and partners to orderly participate in the disaster relief.
基金supported by the National Institute of Natural Hazards,Ministry of Emergency Management of China(2023-JBKY-57)the National Natural Science Foundation of China(42077259)。
文摘Rainfall-induced landslides are often highly destructive.Reviewing and analyzing the causes,processes,impacts,and deficiencies in emergency response is critical for improving disaster prevention and management.From the night of July 21 to the morning of July 22,2024,the Kencho Shacha Gozdi Village in Gezei Gofa,Southern Nations,Nationalities,and Peoples'Region,Ethiopia,suffered heavy rainfall that triggered two landslides.By July25,this event had claimed at least 257 lives.This study presents a detailed characterization of the landslides using multi-source data.By analyzing the landslide disaster process,this study summarizes key lessons and provides suggestions for preventing rainfall-induced geological hazards.The results indicate that rainfall has the greatest impact on the occurrence of landslides,while lithology and human activities have promoted and strengthened the landslide disaster.Despite the active disaster response in the local area,many problems were still exposed in the emergency response work.This analysis offers valuable insights for mitigating rainfall-induced geological hazards and enhancing emergency response capabilities.
基金supported by GP Batteries Industrial Safety Trust Fund(Funding number:R-ZDDR).
文摘Purpose:The aim of this study was to summarize the evidence regarding whether pain reduction in individuals with chronic non-specific low back pain(CNSLBP)following conservative interventions is related to corresponding improvements in balance control.Methods:Randomized controlled trials were identified from 5 databases(MEDLINE,Cochrane Library,Embase,Web of Science,and PsycINFO).Two reviewers independently screened and identified relevant studies that investigated the effects of non-surgical or non-pharmacological CNSLBP treatments on both pain intensity and balance control.Meta-regression analyses were performed to establish the associations between post-treatment changes in these 2 variables.Results:Thirty one studies involving 1280 participants with CNSLBP were included.Moderate-quality evidence suggested that pain reduction was associated with and explained 34%-45%of decreases in body sway,as measured by center-of-pressure(CoP)area and CoP velocity with eyes open.However,no significant association was observed between pain reduction and CoP area or velocity in anteroposterior/mediolateral directions.Similarly,there was no significant association between pain reduction and CoP distance or radius.Low-quality evidence indicated that pain relief explained a 15%improvement in one-leg stance with eyes open but not in the eyes-closed condition.Additionally,very low-quality evidence suggested that pain relief explained a 44%decrease in the static anteroposterior stability index with eyes closed but not in the eyes-open,mediolateral,or overall conditions.Furthermore,low-quality evidence indicated that reduced pain was associated with and accounted for 25%-43%of the improved composite and posteromedial scores of the star-excursion balance test,rather than the anterior and posterolateral scores.Conclusion:Depending on the type of balance assessment,pain relief following conservative interventions may slightly to moderately enhance balance control in individuals with CNSLBP.Clinicians should pay close attention to the balance control in patients with CNSLBP,particularly among older adults.
基金supported by the National Natural Science Foundation of China(42077244)the Open Research Fund of Guangdong Provincial Key Laboratory of Deep Earth Sciences and Geothermal Energy Exploitation and Utilization(2020-05)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX24_0434).
文摘The formation of a pressure relief zone is crucial for rockbust prevention during drilling pressure relief.This study investi-gates the mechanical behavior of high-stress rock under real-time drilling conditions and elucidates the mechanism behind the creation of the pressure relief zone.Utilizing the independently developed SG4500 drilling rig,we conducted a theoreti-cal analysis of the forces acting on the drill bit.The analysis showed that cutting depth is directly proportional to real-time drilling speed,while tangential and normal forces are influenced by drilling diameter.Uniaxial compression tests on red sandstone specimens under high-stress real-time drilling conditions examined the impacts of different drilling speeds(800,400,100 r/min)and diameters(6,8,10,12 mm)on rock mechanical behavior,rockburst characteristics,crack evolution,and peak elastic strain energy.The results indicate that decreasing drilling speed and increasing drilling diameter weaken rock mechanical behavior,including peak strength,Young's modulus,rockburst characteristics,and peak elastic strain energy.Crack evolution analysis reveals that smaller drilling diameters and higher drilling speeds promote the development of far-field cracks,while larger drilling diameters and lower drilling speeds lead to crack formation around the borehole,and significantly affecting rock failure mechanisms.Theoretical analysis further confirms the correlation between crack evolution and stress distribution surrounding the drilling.Under vertical stress,the cracks near the borehole formed during real-time drilling are mainly influenced by tangential compressive and tensile stresses.Overall,this study provides a new perspective on understanding the mechanisms of drilling pressure relief for rockburst prevention.
文摘On the title photo you can see in the background the distinctive peak of the highest mountain of the Krkono?e Mountains,and the whole Czechia,Snězka 1603 m above sea level,which is unique not only in Central Europe with its size,altitude,glacial and periglacial relief and arctic-alpine tundra.In the foreground of the photograph,an inconspicuous platform with several benches and concrete blocks can be seen.
基金Project(51775480)supported by the National Natural Science Foundation of ChinaProjects(E2018203143,E2022203050)supported by the Natural Science Foundation of Hebei Province,China。
文摘In this work,the effect of ultrasonic vibration modes on the mechanical properties and relaxation of residual stress in 6061-T6 aluminum alloy was studied.A new ultrasonic vibration Johnson-Cook model was proposed,and the relaxation and distribution of residual stress under ultrasonic vibration were predicted and analyzed using the finite element method(FEM).The mechanical properties of 6061-T6 aluminum alloy under different ultrasonic vibration modes were analyzed through experiments involving notched specimen tensile testing and scanning electron microscopy(SEM)analysis.The findings indicate that ultrasonic vibration treatment during deformation,unloading,and load-holding,as well as treatment with its natural ultrasonic frequency,can effectively release residual stress;however,treatment with its natural frequency has the highest rate of release up to 65.4%.Ultrasonic vibration treatment during deformation better inhibits fracture under the same conditions.The FEM results are in good agreement with the experimental results,and it can be used as a valid tool for predicting residual stress release under ultrasonic vibration.
文摘Objective:Acute appendicitis,as a common clinical acute abdominal condition,has a significant impact on patient prognosis depending on the choice of treatment strategy.This study aims to systematically compare the clinical efficacy and safety of surgical versus conservative treatment in patients with acute appendicitis.Methods:A total of 60 patients with acute appendicitis admitted to our hospital from August 2024 to July 2025 were selected as the study subjects and divided into a surgical group(n=30)and a conservative group(n=30)based on the treatment approach.The surgical group underwent abdominal incision appendectomy,while the conservative group received antibiotic therapy combined with symptomatic supportive treatment.Evaluation indicators included the treatment effective rate,symptom relief time,and complication incidence.Results:The treatment effective rate in the surgical group was 96.67%,significantly higher than that in the conservative group(76.67%)(p<0.05).In terms of symptom relief,the time to relief of abdominal pain(1.25±0.36 days)and fever(1.08±0.29 days)in the surgical group was significantly shorter than that in the conservative group(3.12±0.57 days and 2.89±0.61 days,respectively,p<0.001).The complication rates in the two groups were 10.00%and 13.33%,respectively(p>0.05).Conclusion:Surgical treatment for acute appendicitis demonstrates significant advantages in improving treatment efficacy and shortening the time to symptom relief,with a comparable risk of complications to conservative treatment.It is therefore worthy of clinical priority recommendation,particularly for patients without surgical contraindications.
