Fissured rocks are prevalent in geotechnical engineering and can significantlyimpact the stability of engineering structures.Microbial-induced carbonate precipitation(MICP)technology provides an ecofriendly solution f...Fissured rocks are prevalent in geotechnical engineering and can significantlyimpact the stability of engineering structures.Microbial-induced carbonate precipitation(MICP)technology provides an ecofriendly solution for repairing fissuredrocks.To optimize repair effectiveness,this study firstinvestigated the effects of environmental factors on bacterial growth,urease activity,and calcium carbonate yield.The optimal MICP scheme was determined to be a pH of 9,a temperature of 25℃,and a cementation solution concentration of 0.5 mol/L.Subsequently,the sandstone specimens with various fissureapertures were repaired using MICP with different bacterial concentrations.Dynamic tests were carried out on the repaired specimens using a split Hopkinson pressure bar system.The experimental results indicate that the dynamic strength of the MICP-repaired specimens positively correlates with strain rate,but decreases with increasing bacterial concentration and fissureaperture.These factors have little effect on the progressive failure behavior.Surface cracks were mainly compression-shear cracks in the repair area and tensile-shear cracks at the end of the specimen.Moreover,the crystal morphology observed by scanning electron microscope indicates that MICP primarily produces vaterite crystals,and lower bacterial concentrations favor the formation of more stable calcite crystals,thereby enhancing the cementitious properties.Furthermore,X-ray computed tomography demonstrates an uneven distribution of calcium carbonate within fissures,with higher fillingrates observed at the injection end and at the bottom of the fissures.Lower bacterial concentrations and smaller fissureapertures are conducive to more uniform distribution and increased fillingrate of calcium carbonate,with fissureaperture exerting a more dominant influence.展开更多
According to geological conditions of No. 3 and No. 4 coal seams （namely A3 and B4） of the Pan＇er coal mine and the parameters of panels 11223, 11224, and 11124 with fully-mechanical coal mining, we built 2D simila...According to geological conditions of No. 3 and No. 4 coal seams （namely A3 and B4） of the Pan＇er coal mine and the parameters of panels 11223, 11224, and 11124 with fully-mechanical coal mining, we built 2D similar material simulation and FLAC3D numerical simulation models to investigate the development of mining-induced stress and the extraction effect of pressure-relief gas with large height and upward mining. Based on a comprehensive analysis of experimental data and observations, we obtained the deformation and breakage characteristics of strata overlying the coal seam, the development patterns of the mining-induced stress and fracture, and the size of the stress-relief area. The stress-relief effect was investigated and analyzed in consideration with mining height and three thick hard strata. Because of the group of three hard thick strata located in the main roof and the residual stress of mined panel 11124, the deformation, breakage, mining-induced stress and fracture development, and the stress-relief coefficient were discontinuous and asymmetrical. The breakage angle of the overlying strata, and the compressive and expansive zones of coal deformation were mainly controlled by the number, thickness, and strength of the hard stratum. Compared with the value of breakage angle derived by the traditional empirical method, the experimental value was lower than the traditional results by 3°-4°below the hard thick strata group, and by 13°-19° above the hard thick strata group. The amount of gas extracted from floor drainage roadway of B4 over 17 months was variable and the amount of gas per month differed considerably, being much smaller when panel 11223 influenced the area of the three hard thick strata. Generally, the stress-relief zone of No. 4 coal seam was small under the influence of the hard thick strata located in the main roof, which played an important role in delaying the breakage time and increasing the breakage space. In this study we gained understanding of the stress-relief mechanism influenced by the hard thick roof. The research results and engineering practice show that the main roof of the multiple hard thick strata is a critical factor in the design of panel layout and roadways for integrated coal exploitation and gas extraction, provides a theoretical basis for safe and high-efficient mining of coal resources.展开更多
A numerical study on flow control of ship airwake during shipboard landing is carried out to address the effect of flow control devices on helicopter rotor airload. The in-house Reynolds Averaged Navier-Stokes(RANS) b...A numerical study on flow control of ship airwake during shipboard landing is carried out to address the effect of flow control devices on helicopter rotor airload. The in-house Reynolds Averaged Navier-Stokes(RANS) based solver Rotorcraft AeroDynamics and Aeroacoustics Solver(RADAS), with combination of momentum source approach is employed to conduct the helicopter shipboard landing simulation. The control effects of three aerodynamic modifications of ship superstructure, i.e. ramp, notch and flap, in different Wind-Over-Deck(WOD) conditions are discussed.From the steady simulation results, the effect of spatial variation of ship airwake on rotor airloads is concluded. The aerodynamic modifications reduce the strength of shedding vortex and increase rotor normal force through delaying and relieving flow separation, and therefore are beneficial to alleviate the limitation of control inputs. By contrast, the perturbation of unsteady ship airwake can cause the serious oscillation of rotor forces during shipboard landing. The unsteady simulations show that the turbulence intensity of ship airwake and oscillatory rotor airloading, represented by Root-Mean-Square(RMS) loading, can be remarkably reduced by the ramp and notch modifications, while the flap modification has adverse effect. It means that flow control devices have large potential benefits to alleviate the pilot's workload and improve the shipboard landing safety, but they should be well designed to avoid the introduction of more vortex, which leads to increase in disturbance of flow field.展开更多
Metal-organic frameworks(MOFs),a family of highly porous materials possessing huge surface areas and feasible chemical tunability,are emerging as critical functional materials to solve the growing challenges associate...Metal-organic frameworks(MOFs),a family of highly porous materials possessing huge surface areas and feasible chemical tunability,are emerging as critical functional materials to solve the growing challenges associated with energy-water systems,such as water scarcity issues.In this contribution,the roles of MOFs are highlighted in electrochemical-based water applications(i.e.,reactions,sensing,and separations),where MOF-based functional materials exhibit outstanding performances in detecting/removing pollutants,recovering resources,and harvesting energies from different water sources.Compared with the pristine MOFs,the efficiency and/or selectivity can be further enhanced via rational structural modulation of MOFs(e.g.,partial metal substitution)or integration of MOFs with other functional materials(e.g.,metal clusters and reduced graphene oxide).Several key factors/properties that affect the performances of MOF-based materials are also reviewed,including electronic structures,nanoconfined effects,stability,conductivity,and atomic structures.The advancement in the fundamental understanding of these key factors is expected to shed light on the functioning mechanisms of MOFs(e.g.,charge transfer pathways and vip-host interactions),which will subsequently accelerate the integration of precisely designed MOFs into electrochemical architectures to achieve highly effective water remediation with optimized selectivity and long-term stability.展开更多
AIM： To explore whether acute cellular DNA damage response is induced upon hepatitis B virus （HBV） infection and the effects of the HBV infection. METHODS： We incubated HL7702 hepatocytes with HBV-positive serum, ...AIM： To explore whether acute cellular DNA damage response is induced upon hepatitis B virus （HBV） infection and the effects of the HBV infection. METHODS： We incubated HL7702 hepatocytes with HBV-positive serum, mimicking a natural HBV infection process. We used immunoblotting to evaluate protein expression levels in HBV-infected cells or in non-infected cells; immunofluorescence to show ATR foci ands Chkl phosphorylation foci formation; flow cytometry to analyze the cell cycle and apoptosis; ultraviolet （UV） radiation and ionizing radiation （IR）-treated cells to mimic DNA damage; and Trypan blue staining to count the viable cells. RESULTS： We found that HBV infection induced an increased steady state of ATR protein and increased phosphorylation of multiple downstream targets including Chkl, p53 and H2AX. In contrast to ATR and its target, the phosphorylated form of ATM at Ser-1981 and its downstream substrate Chk2 phosphorylation at Thr-68 did not visibly increase upon infection. However, the level of Mre11 and p21 were reduced beginning at 0.5 h aEer HBV-positive serum addition. Also, HBV infection led to transient cell cycle arrest in the S and the G2 phases without accompanying increasedapoptosis. Research on cell survival changes upon radiation following HBV infection showed that survival of UV-treated host cells was greatly increased by HBV infection, owing to the reduced apoptosis. Meanwhile, survival of IR-treated host cells was reduced by HBV infection. CONCLUSION： HBV infection activates ATR DNA damage response to replication stress and abrogates the checkpoint signaling controlled by DNA damage response.展开更多
The Dongyang gold deposit is a newly discovered epithermal deposit in Fujian Province,Southeast China,along the Circum-Pacific metallogenic belt.Herewith,the authors present mineralogical,scanning electron microscope,...The Dongyang gold deposit is a newly discovered epithermal deposit in Fujian Province,Southeast China,along the Circum-Pacific metallogenic belt.Herewith,the authors present mineralogical,scanning electron microscope,and laser ablation inductively coupled clasma mass spectrometry analysis to reveal the relations between Au and Te,As,S,Fe,etc.,and discuss the gold precipitation process.The pyrites in this deposit are Fe-deficient,and are enriched in Te and As.The authors infer that As was mainly in form of As-complexes,and Te-Au-Ag inclusions/solid solution also exsits in the Py I.Along with the depletion of Te and As,they were less active chemically in the Py II,and Au may be incorporated into As-rich and Fe-deficient surface sites by chemisorption onto As-rich growth surfaces.Because of the incorporation of new fluid,Te and As became the most active chemically in the Py III,which was the main elements precipitation stage,and As dominantly substituted for S in the lattice of pyrite,due to the more reducing condition.The authors propose Au was in form of invisible gold,and the incorporation of gold can be considered as post-pyrite event,while the Au-bearing minerals were result of post incorporation of gold in arsenian pyrite.展开更多
Designing post-formed two-dimensional(2D)perovskite on the surface of three-dimensional(3D)perovskite with matched energy levels and high stability is crucial for improving the performance and stability of perovskite ...Designing post-formed two-dimensional(2D)perovskite on the surface of three-dimensional(3D)perovskite with matched energy levels and high stability is crucial for improving the performance and stability of perovskite solar cells(PSCs).Herein,a long alkyl chain dodecylammonium bromide(DABr)was applied to react with excessive lead iodide(PbI_(2))on the grain boundary of metal halide perovskite preferentially,forming DA_(2)PbI_(4)(n=1)to constitute a clear 2D/3D heterojunction.The existence of heterojunction increases the intensity of the built-in electric field of the device to enhance carrier separation and extraction,and the amino group of dodecylammonium cation passivates defects,which jointly contribute to the improvement of the power conversion efficiency(PCE)from 20.35 to 21.81%.The long alkyl chain endows the 2D perovskite with good hydrophobic properties,improving the humidity and thermal stability of the device.The unencapsulated device can maintain 64%of its initial efficiency after 1065 h storage in ambient air.展开更多
As an important precursor of hydroxyl radical(OH),nitrous acid(HONO)plays a significant role in atmospheric chemistry.Here,an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 A...As an important precursor of hydroxyl radical(OH),nitrous acid(HONO)plays a significant role in atmospheric chemistry.Here,an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April,2017 was performed.Two distinct peaks of HONO concentrations occurred during the observation.In contrast,the concentration of particulate matter in the first period(periodⅠ)was significantly higher than that in the second period(periodⅡ).Comparing to HONO sources in the two periods,we found that the direct vehicle emissionwas an essential source of the ambient HONO during both periods at night,especially in periodⅡ.The heterogeneous reaction of NO_(2)was the dominant source in periodⅠ,while the homogeneous reaction of NO with OH was more critical source at night in periodⅡ.In the daytime,the heterogeneous reaction of NO_(2)was a significant source andwas confirmed by the good correlation coefficients(R^(2))between the unknown sources(P_(unknown))with NO_(2),PM_(2.5),NO_(2)×PM_(2.5)in periodⅠ.Moreover,when solar radiation and OH radicals were considered to explore unknown sources in the daytime,the enhanced correlation of P_(unknown)with photolysis rate of NO_(2)and OH(J_(NO_(2))×OH)were 0.93 in periodⅠ,0.95 in periodⅡ.These excellent correlation coefficients suggested that the unknown sources released HONO highly related to the solar radiation and the variation of OH radicals.展开更多
The present work investigates the potential applications of nitrogen oxides(NO_(x)),particularly nitric oxide(NO)and nitrogen dioxide(NO_(2)),generated through discharge plasma in diverse sectors such as medicine,nitr...The present work investigates the potential applications of nitrogen oxides(NO_(x)),particularly nitric oxide(NO)and nitrogen dioxide(NO_(2)),generated through discharge plasma in diverse sectors such as medicine,nitrogen fixation,energy,and environmental protection.In this study,a rotating sliding arc discharge reactor was initially employed to produce high concentrations of gaseous NO_(x),followed by the utilization of a molybdenum wire redox reactor for NO_(2)-to-NO conversion.The outcomes reveal that the discharge states and generations of NO_(x) are affected by varying parameters,including the applied energies,frequencies and airflow states(1.3-2.6 m/s are the laminar flow,2.6-5.2 m/s are the transition state,5.2-6.5 m/s are the turbulent flow),and the concentrations of NO_(x) within the arc discharge are higher than that in the spark discharge.Moreover,the concentrations of NO,NO_(2) and NO_(x) gradually increased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) decreased with increasing the applied energy for one cycle from 14.8 mJ to 24.3 mJ.Meanwhile,the concentrations of NO,NO_(2) and NO_(x) gradually decreased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) first decreased and then increased with increasing the applied frequencies from 5.0 kHz to 9.0 kHz.Further,the concentrations of NO,NO_(2) and NO_(x) gradually decreased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) first increased and then decreased with increasing the air flow speeds from 1.3 m/s to 6.5 m/s.Lastly,the concentrations of NO increased and NO_(2) decreased with increasing temperature from 25℃ to 400℃ using molybdenum converted.These findings provide experimental support for the application of plasma in the fields of medicine,nitrogen fixation,energy and environmental protection.展开更多
Microbial-induced carbonate precipitation(MICP)technique has been adopted in geotechnical engineering widely.In this study,the effect of drying-wetting cycles on MICP-recycled shredded coconut coir(RSC)reinforced calc...Microbial-induced carbonate precipitation(MICP)technique has been adopted in geotechnical engineering widely.In this study,the effect of drying-wetting cycles on MICP-recycled shredded coconut coir(RSC)reinforced calcareous sand was studied,and the deterioration mechanism under drying-wetting cycles was revealed.Test results indicated that drying-wetting cycles exert an important influence on the durability of MICP-RSC reinforced specimens.With the increase of drying-wetting cycles N,the specimens demonstrated significant increase in mass loss rate and critical void ratio,decrease in maximum shear modulus,peak strength and toughness.Furthermore,an increase in the initial relative density reduced the deterioration of MICP-RSC reinforced specimens exposed to drying-wetting cycles.Higher initial relative density of the specimen correlates with an increased maximum shear modulus,peak stress and toughness,a decreased in permeability and critical void ratio.Microanalysis revealed that the generated calcium carbonate adhering to sand particles and RSC gradually dropped off with the increase of N,weakened cementation,and led to the deterioration of MICP-RSC reinforced specimens,which is consistent with the deterioration characteristics under drying-wetting cycles.展开更多
A close relationship exists between the pore network structure of microbial solidified soil and its macroscopic mechanical properties.The microbial solidified engineering residue and sand were scanned by computed tomo...A close relationship exists between the pore network structure of microbial solidified soil and its macroscopic mechanical properties.The microbial solidified engineering residue and sand were scanned by computed tomography(CT),and a three-dimensional model of the sample was established by digital image processing.A spatial pore network ball-stick model of the representative elementary volume(REV)was established,and the REV parameters of the sample were calculated.The pore radius,throat radius,pore coordination number,and throat length were normally distributed.The soil particle size was larger after solidification.The calcium carbonate content of the microbial solidified engineering residue’s consolidated layer decreased with the soil depth,the porosity increased,the pore and throat network developed,and the ultimate structure was relatively stable.The calcium carbonate content of the microbial solidified sand’s consolidated layer decreased and increased with the soil depth.The content reached the maximum,the hardness of the consolidated layer was the highest,and the development of the pore and throat network was optimum at a depth of 10–15 mm.展开更多
Accurately predicting the remaining useful life(RUL)of bearings in mining rotating equipment is vital for mining enterprises.This research aims to distinguish the features associated with the RUL of bearings and propo...Accurately predicting the remaining useful life(RUL)of bearings in mining rotating equipment is vital for mining enterprises.This research aims to distinguish the features associated with the RUL of bearings and propose a prediction model based on these selected features.This study proposes a hybrid predictive model to assess the RUL of rolling element bearings.The proposed model begins with the pre-processing of bearing vibration signals to reconstruct sixty time-domain features.The hybrid model selects relevant features from the sixty time-domain features of the vibration signal by adopting the RReliefF feature selection algorithm.Subsequently,the extreme learning machine(ELM)approach is applied to develop a predictive model of RUL based on the optimal features.The model is trained by optimizing its parameters via the grid search approach.The training datasets are adjusted to make them most suitable for the regression model using the cross-validation method.The proposed hybrid model is analyzed and validated using the vibration data taken from the public XJTU-SY rolling element-bearing database.The comparison is constructed with other traditional models.The experimental test results demonstrated that the proposed approach can predict the RUL of bearings with a reliable degree of accuracy.展开更多
Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with...Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson＇s ratio of the materials can be obtained by analyzing the load relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson＇s ratio are within a reasonable range.展开更多
BACKGROUND Rhinophyma,a late-stage subtype of rosacea,is characterized by excessive sebaceous glands and connective tissue proliferation.Patients may experience respiratory disturbances and psychological distress that...BACKGROUND Rhinophyma,a late-stage subtype of rosacea,is characterized by excessive sebaceous glands and connective tissue proliferation.Patients may experience respiratory disturbances and psychological distress that significantly affect their quality of life when excessive nasal hyperplasia obstructs the external nasal valves.Surgery is the treatment of choice for rhinophyma.However,excessive bleeding,scarring,pigmentation,and high recurrence rates frequently characterize current surgical methods.AIM To evaluate the clinical effectiveness and recurrence rates after treating severe rhinophyma with the five-blade scratcher.METHODS This study retrospectively analyzed the clinical records of 28 patients with severe rhinophyma rosacea.The Global Flushing Severity Score(GFSS),Clinician Erythema Assessment(CEA),Rhinophyma Severity Index(RHISI),Glasgow Benefit Inventory(GBI),and satisfaction scores were used to assess the recovery of patients at 6 months and 5 years,with the recurrence rate calculated at 5 years postoperatively.In addition,the levels of pro-inflammatory factors(TNF-α,IL-1β,and IL-6)in the serum of patients before and after surgery were detected by ELISA.RESULTS The GFSS,CEA,and RHISI scores at 6 months and 5 years postoperatively were significantly lower than those preoperatively(P<0.001 for both periods).Five-blade scratcher treatment greatly benefits patients as demonstrated by the GBI and patient satisfaction.A small number of patients(7/28,25%)reported recurrence after surgical treatment for rhinophyma in our department that was not more serious than before treatment.The expression of pro-inflammatory factors(TNF-α,IL-1β,and IL-6)in the patient's serum was significantly reduced after surgery of five-blade scratcher.CONCLUSION The five-blade scratcher treatment demonstrates notable advantages,including simplicity,safety,efficacy,and cost-effectiveness,coupled with reduced bleeding,minimized scarring,lower recurrence rates,reduced the level of pro-inflammatory factors and improved patient satisfaction.Consequently,this therapeutic modality exhibits a viable option for individuals afflicted with severe rhinophyma.展开更多
Firstly,this paper reviews and analyzes historic background of urban-rural integration of Chongqing,and the evolution and trend of urban and rural dual economic structure.On the basis of previous researches,it selects...Firstly,this paper reviews and analyzes historic background of urban-rural integration of Chongqing,and the evolution and trend of urban and rural dual economic structure.On the basis of previous researches,it selects factors and variables influencing urban and rural dual economic structure,and establishes an econometric model.By state space Kalman filtering method,it analyzes dynamic influence of factors upon urban-rural dual economic intensity.According to empirical conclusion,it puts forward corresponding policy recommendations for promoting integrated urban and rural economic development of Chongqing.展开更多
UPE (Ultraweak photon emission) is one kind of a common phenomenon in biological organisms. It contains a wealth of information of biological functions. In this paper, single photon counting system is used to measure ...UPE (Ultraweak photon emission) is one kind of a common phenomenon in biological organisms. It contains a wealth of information of biological functions. In this paper, single photon counting system is used to measure UPE of some anti- cancer herbal plants. For the plants, the changes of UPE under different water condition are stud-ied and the varying laws of ultraweak photon number with time are analysed. The results are higher fit double exponential decay law.展开更多
基金support from the National Key R&D Program of China(Grant No.2023YFC3081500)the National Natural Science Foundation of China(Grant Nos.52225904 and 52039007).
文摘Fissured rocks are prevalent in geotechnical engineering and can significantlyimpact the stability of engineering structures.Microbial-induced carbonate precipitation(MICP)technology provides an ecofriendly solution for repairing fissuredrocks.To optimize repair effectiveness,this study firstinvestigated the effects of environmental factors on bacterial growth,urease activity,and calcium carbonate yield.The optimal MICP scheme was determined to be a pH of 9,a temperature of 25℃,and a cementation solution concentration of 0.5 mol/L.Subsequently,the sandstone specimens with various fissureapertures were repaired using MICP with different bacterial concentrations.Dynamic tests were carried out on the repaired specimens using a split Hopkinson pressure bar system.The experimental results indicate that the dynamic strength of the MICP-repaired specimens positively correlates with strain rate,but decreases with increasing bacterial concentration and fissureaperture.These factors have little effect on the progressive failure behavior.Surface cracks were mainly compression-shear cracks in the repair area and tensile-shear cracks at the end of the specimen.Moreover,the crystal morphology observed by scanning electron microscope indicates that MICP primarily produces vaterite crystals,and lower bacterial concentrations favor the formation of more stable calcite crystals,thereby enhancing the cementitious properties.Furthermore,X-ray computed tomography demonstrates an uneven distribution of calcium carbonate within fissures,with higher fillingrates observed at the injection end and at the bottom of the fissures.Lower bacterial concentrations and smaller fissureapertures are conducive to more uniform distribution and increased fillingrate of calcium carbonate,with fissureaperture exerting a more dominant influence.
基金Acknowledgments This work is supported by the National Nature Science Foundation of China （51374011）.
文摘According to geological conditions of No. 3 and No. 4 coal seams （namely A3 and B4） of the Pan＇er coal mine and the parameters of panels 11223, 11224, and 11124 with fully-mechanical coal mining, we built 2D similar material simulation and FLAC3D numerical simulation models to investigate the development of mining-induced stress and the extraction effect of pressure-relief gas with large height and upward mining. Based on a comprehensive analysis of experimental data and observations, we obtained the deformation and breakage characteristics of strata overlying the coal seam, the development patterns of the mining-induced stress and fracture, and the size of the stress-relief area. The stress-relief effect was investigated and analyzed in consideration with mining height and three thick hard strata. Because of the group of three hard thick strata located in the main roof and the residual stress of mined panel 11124, the deformation, breakage, mining-induced stress and fracture development, and the stress-relief coefficient were discontinuous and asymmetrical. The breakage angle of the overlying strata, and the compressive and expansive zones of coal deformation were mainly controlled by the number, thickness, and strength of the hard stratum. Compared with the value of breakage angle derived by the traditional empirical method, the experimental value was lower than the traditional results by 3°-4°below the hard thick strata group, and by 13°-19° above the hard thick strata group. The amount of gas extracted from floor drainage roadway of B4 over 17 months was variable and the amount of gas per month differed considerably, being much smaller when panel 11223 influenced the area of the three hard thick strata. Generally, the stress-relief zone of No. 4 coal seam was small under the influence of the hard thick strata located in the main roof, which played an important role in delaying the breakage time and increasing the breakage space. In this study we gained understanding of the stress-relief mechanism influenced by the hard thick roof. The research results and engineering practice show that the main roof of the multiple hard thick strata is a critical factor in the design of panel layout and roadways for integrated coal exploitation and gas extraction, provides a theoretical basis for safe and high-efficient mining of coal resources.
基金supported by the Fundamental Research Funds for the Central Universities (No. NS2018007)
文摘A numerical study on flow control of ship airwake during shipboard landing is carried out to address the effect of flow control devices on helicopter rotor airload. The in-house Reynolds Averaged Navier-Stokes(RANS) based solver Rotorcraft AeroDynamics and Aeroacoustics Solver(RADAS), with combination of momentum source approach is employed to conduct the helicopter shipboard landing simulation. The control effects of three aerodynamic modifications of ship superstructure, i.e. ramp, notch and flap, in different Wind-Over-Deck(WOD) conditions are discussed.From the steady simulation results, the effect of spatial variation of ship airwake on rotor airloads is concluded. The aerodynamic modifications reduce the strength of shedding vortex and increase rotor normal force through delaying and relieving flow separation, and therefore are beneficial to alleviate the limitation of control inputs. By contrast, the perturbation of unsteady ship airwake can cause the serious oscillation of rotor forces during shipboard landing. The unsteady simulations show that the turbulence intensity of ship airwake and oscillatory rotor airloading, represented by Root-Mean-Square(RMS) loading, can be remarkably reduced by the ramp and notch modifications, while the flap modification has adverse effect. It means that flow control devices have large potential benefits to alleviate the pilot's workload and improve the shipboard landing safety, but they should be well designed to avoid the introduction of more vortex, which leads to increase in disturbance of flow field.
基金supported by the start-up package and COES Institutional Research Incentive Program at the Florida Institute of Technology.
文摘Metal-organic frameworks(MOFs),a family of highly porous materials possessing huge surface areas and feasible chemical tunability,are emerging as critical functional materials to solve the growing challenges associated with energy-water systems,such as water scarcity issues.In this contribution,the roles of MOFs are highlighted in electrochemical-based water applications(i.e.,reactions,sensing,and separations),where MOF-based functional materials exhibit outstanding performances in detecting/removing pollutants,recovering resources,and harvesting energies from different water sources.Compared with the pristine MOFs,the efficiency and/or selectivity can be further enhanced via rational structural modulation of MOFs(e.g.,partial metal substitution)or integration of MOFs with other functional materials(e.g.,metal clusters and reduced graphene oxide).Several key factors/properties that affect the performances of MOF-based materials are also reviewed,including electronic structures,nanoconfined effects,stability,conductivity,and atomic structures.The advancement in the fundamental understanding of these key factors is expected to shed light on the functioning mechanisms of MOFs(e.g.,charge transfer pathways and vip-host interactions),which will subsequently accelerate the integration of precisely designed MOFs into electrochemical architectures to achieve highly effective water remediation with optimized selectivity and long-term stability.
基金National Natural Science Foundation of China,No.30700413
文摘AIM： To explore whether acute cellular DNA damage response is induced upon hepatitis B virus （HBV） infection and the effects of the HBV infection. METHODS： We incubated HL7702 hepatocytes with HBV-positive serum, mimicking a natural HBV infection process. We used immunoblotting to evaluate protein expression levels in HBV-infected cells or in non-infected cells; immunofluorescence to show ATR foci ands Chkl phosphorylation foci formation; flow cytometry to analyze the cell cycle and apoptosis; ultraviolet （UV） radiation and ionizing radiation （IR）-treated cells to mimic DNA damage; and Trypan blue staining to count the viable cells. RESULTS： We found that HBV infection induced an increased steady state of ATR protein and increased phosphorylation of multiple downstream targets including Chkl, p53 and H2AX. In contrast to ATR and its target, the phosphorylated form of ATM at Ser-1981 and its downstream substrate Chk2 phosphorylation at Thr-68 did not visibly increase upon infection. However, the level of Mre11 and p21 were reduced beginning at 0.5 h aEer HBV-positive serum addition. Also, HBV infection led to transient cell cycle arrest in the S and the G2 phases without accompanying increasedapoptosis. Research on cell survival changes upon radiation following HBV infection showed that survival of UV-treated host cells was greatly increased by HBV infection, owing to the reduced apoptosis. Meanwhile, survival of IR-treated host cells was reduced by HBV infection. CONCLUSION： HBV infection activates ATR DNA damage response to replication stress and abrogates the checkpoint signaling controlled by DNA damage response.
基金This work was supported by National Natural Science Foundation of China(41872071)China Geological Survey Project(DD20190006).
文摘The Dongyang gold deposit is a newly discovered epithermal deposit in Fujian Province,Southeast China,along the Circum-Pacific metallogenic belt.Herewith,the authors present mineralogical,scanning electron microscope,and laser ablation inductively coupled clasma mass spectrometry analysis to reveal the relations between Au and Te,As,S,Fe,etc.,and discuss the gold precipitation process.The pyrites in this deposit are Fe-deficient,and are enriched in Te and As.The authors infer that As was mainly in form of As-complexes,and Te-Au-Ag inclusions/solid solution also exsits in the Py I.Along with the depletion of Te and As,they were less active chemically in the Py II,and Au may be incorporated into As-rich and Fe-deficient surface sites by chemisorption onto As-rich growth surfaces.Because of the incorporation of new fluid,Te and As became the most active chemically in the Py III,which was the main elements precipitation stage,and As dominantly substituted for S in the lattice of pyrite,due to the more reducing condition.The authors propose Au was in form of invisible gold,and the incorporation of gold can be considered as post-pyrite event,while the Au-bearing minerals were result of post incorporation of gold in arsenian pyrite.
基金the National Natural Science Foundation of China(Nos.52025028,52072254,51772197,51872191,52002258)the Natural Science Foundation of Jiangsu Province(No.BK20200877)the Key University Science Research Project of Jiangsu Province(No.21KJA430005)。
文摘Designing post-formed two-dimensional(2D)perovskite on the surface of three-dimensional(3D)perovskite with matched energy levels and high stability is crucial for improving the performance and stability of perovskite solar cells(PSCs).Herein,a long alkyl chain dodecylammonium bromide(DABr)was applied to react with excessive lead iodide(PbI_(2))on the grain boundary of metal halide perovskite preferentially,forming DA_(2)PbI_(4)(n=1)to constitute a clear 2D/3D heterojunction.The existence of heterojunction increases the intensity of the built-in electric field of the device to enhance carrier separation and extraction,and the amino group of dodecylammonium cation passivates defects,which jointly contribute to the improvement of the power conversion efficiency(PCE)from 20.35 to 21.81%.The long alkyl chain endows the 2D perovskite with good hydrophobic properties,improving the humidity and thermal stability of the device.The unencapsulated device can maintain 64%of its initial efficiency after 1065 h storage in ambient air.
基金supported by the National Natural Science Foundation of China(Nos.41830106,22006124)Beijing National Laboratory for Molecular Sciences(No.BNLMS-CXXM-202011)the Youth Innovation Promotion Association CAS(No.2017042)
文摘As an important precursor of hydroxyl radical(OH),nitrous acid(HONO)plays a significant role in atmospheric chemistry.Here,an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April,2017 was performed.Two distinct peaks of HONO concentrations occurred during the observation.In contrast,the concentration of particulate matter in the first period(periodⅠ)was significantly higher than that in the second period(periodⅡ).Comparing to HONO sources in the two periods,we found that the direct vehicle emissionwas an essential source of the ambient HONO during both periods at night,especially in periodⅡ.The heterogeneous reaction of NO_(2)was the dominant source in periodⅠ,while the homogeneous reaction of NO with OH was more critical source at night in periodⅡ.In the daytime,the heterogeneous reaction of NO_(2)was a significant source andwas confirmed by the good correlation coefficients(R^(2))between the unknown sources(P_(unknown))with NO_(2),PM_(2.5),NO_(2)×PM_(2.5)in periodⅠ.Moreover,when solar radiation and OH radicals were considered to explore unknown sources in the daytime,the enhanced correlation of P_(unknown)with photolysis rate of NO_(2)and OH(J_(NO_(2))×OH)were 0.93 in periodⅠ,0.95 in periodⅡ.These excellent correlation coefficients suggested that the unknown sources released HONO highly related to the solar radiation and the variation of OH radicals.
基金partially supported by National Natural Science Foundation of China(No.52477141)the Natural Science Foundation of the Jiangsu Province(No.BK20191162)+2 种基金Fundamental Research Funds for the Central Universities(No.B210203006)the Research Fund of Innovation and Entrepreneurship Education Reform for Chinese Universities(No.16CCJG01Z004)Changzhou Science and Technology Program(No.CJ20190046).
文摘The present work investigates the potential applications of nitrogen oxides(NO_(x)),particularly nitric oxide(NO)and nitrogen dioxide(NO_(2)),generated through discharge plasma in diverse sectors such as medicine,nitrogen fixation,energy,and environmental protection.In this study,a rotating sliding arc discharge reactor was initially employed to produce high concentrations of gaseous NO_(x),followed by the utilization of a molybdenum wire redox reactor for NO_(2)-to-NO conversion.The outcomes reveal that the discharge states and generations of NO_(x) are affected by varying parameters,including the applied energies,frequencies and airflow states(1.3-2.6 m/s are the laminar flow,2.6-5.2 m/s are the transition state,5.2-6.5 m/s are the turbulent flow),and the concentrations of NO_(x) within the arc discharge are higher than that in the spark discharge.Moreover,the concentrations of NO,NO_(2) and NO_(x) gradually increased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) decreased with increasing the applied energy for one cycle from 14.8 mJ to 24.3 mJ.Meanwhile,the concentrations of NO,NO_(2) and NO_(x) gradually decreased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) first decreased and then increased with increasing the applied frequencies from 5.0 kHz to 9.0 kHz.Further,the concentrations of NO,NO_(2) and NO_(x) gradually decreased,and the concentration ratios of NO/NO_(2) and NO_(x)/NO_(2) first increased and then decreased with increasing the air flow speeds from 1.3 m/s to 6.5 m/s.Lastly,the concentrations of NO increased and NO_(2) decreased with increasing temperature from 25℃ to 400℃ using molybdenum converted.These findings provide experimental support for the application of plasma in the fields of medicine,nitrogen fixation,energy and environmental protection.
基金support from the National Natural Science Foundations of China(No.52171282,41831280)Shandong Provincial Key Research and Development Plan,China(No.2021ZLGX04)supported by Taishan Scholars of Shandong Province,China(No.tsqn202306098).
文摘Microbial-induced carbonate precipitation(MICP)technique has been adopted in geotechnical engineering widely.In this study,the effect of drying-wetting cycles on MICP-recycled shredded coconut coir(RSC)reinforced calcareous sand was studied,and the deterioration mechanism under drying-wetting cycles was revealed.Test results indicated that drying-wetting cycles exert an important influence on the durability of MICP-RSC reinforced specimens.With the increase of drying-wetting cycles N,the specimens demonstrated significant increase in mass loss rate and critical void ratio,decrease in maximum shear modulus,peak strength and toughness.Furthermore,an increase in the initial relative density reduced the deterioration of MICP-RSC reinforced specimens exposed to drying-wetting cycles.Higher initial relative density of the specimen correlates with an increased maximum shear modulus,peak stress and toughness,a decreased in permeability and critical void ratio.Microanalysis revealed that the generated calcium carbonate adhering to sand particles and RSC gradually dropped off with the increase of N,weakened cementation,and led to the deterioration of MICP-RSC reinforced specimens,which is consistent with the deterioration characteristics under drying-wetting cycles.
基金supported by the National Natural Science Foundation of China(51580166).
文摘A close relationship exists between the pore network structure of microbial solidified soil and its macroscopic mechanical properties.The microbial solidified engineering residue and sand were scanned by computed tomography(CT),and a three-dimensional model of the sample was established by digital image processing.A spatial pore network ball-stick model of the representative elementary volume(REV)was established,and the REV parameters of the sample were calculated.The pore radius,throat radius,pore coordination number,and throat length were normally distributed.The soil particle size was larger after solidification.The calcium carbonate content of the microbial solidified engineering residue’s consolidated layer decreased with the soil depth,the porosity increased,the pore and throat network developed,and the ultimate structure was relatively stable.The calcium carbonate content of the microbial solidified sand’s consolidated layer decreased and increased with the soil depth.The content reached the maximum,the hardness of the consolidated layer was the highest,and the development of the pore and throat network was optimum at a depth of 10–15 mm.
基金supported by the Anhui Provincial Key Research and Development Project(202104a07020005)the University Synergy Innovation Program of Anhui Province(GXXT-2022-019)+1 种基金the Institute of Energy,Hefei Comprehensive National Science Center under Grant No.21KZS217Scientific Research Foundation for High-Level Talents of Anhui University of Science and Technology(13210024).
文摘Accurately predicting the remaining useful life(RUL)of bearings in mining rotating equipment is vital for mining enterprises.This research aims to distinguish the features associated with the RUL of bearings and propose a prediction model based on these selected features.This study proposes a hybrid predictive model to assess the RUL of rolling element bearings.The proposed model begins with the pre-processing of bearing vibration signals to reconstruct sixty time-domain features.The hybrid model selects relevant features from the sixty time-domain features of the vibration signal by adopting the RReliefF feature selection algorithm.Subsequently,the extreme learning machine(ELM)approach is applied to develop a predictive model of RUL based on the optimal features.The model is trained by optimizing its parameters via the grid search approach.The training datasets are adjusted to make them most suitable for the regression model using the cross-validation method.The proposed hybrid model is analyzed and validated using the vibration data taken from the public XJTU-SY rolling element-bearing database.The comparison is constructed with other traditional models.The experimental test results demonstrated that the proposed approach can predict the RUL of bearings with a reliable degree of accuracy.
基金supported by the National "111 Project" Foundation of China(B06024)the National Natural Science Foundation of China(11372243)+3 种基金"Zhi Gu" Innovation Program of Southern Chinathe Major InternationalJoint Research Program of China(11120101002)International Science and Technology Cooperation Program of China(2013DFG02930)partially supported by the Fundamental Research Funds for the Central Universities(NCET-12-0437)
文摘Indentation is a simple and nondestructive method to measure the mechanical properties of soft materials, such as hydrogels, elastomers and soft tissues. In this work, we have developed a micro-indentation system with high-precision to measure the mechanical properties of soft materials, where the shear modulus and Poisson＇s ratio of the materials can be obtained by analyzing the load relaxation curve. We have validated the accuracy and stability of the system by comparing the measured mechanical properties of a polyethylene glycol sample with that obtained from a commercial instrument. The mechanical properties of another typical polydimethylsiloxane sample submerged in heptane are measured by using conical and spherical indenters, respectively. The measured values of shear modulus and Poisson＇s ratio are within a reasonable range.
基金Shanghai Science and Technology Commission,No.21ZR1464000.
文摘BACKGROUND Rhinophyma,a late-stage subtype of rosacea,is characterized by excessive sebaceous glands and connective tissue proliferation.Patients may experience respiratory disturbances and psychological distress that significantly affect their quality of life when excessive nasal hyperplasia obstructs the external nasal valves.Surgery is the treatment of choice for rhinophyma.However,excessive bleeding,scarring,pigmentation,and high recurrence rates frequently characterize current surgical methods.AIM To evaluate the clinical effectiveness and recurrence rates after treating severe rhinophyma with the five-blade scratcher.METHODS This study retrospectively analyzed the clinical records of 28 patients with severe rhinophyma rosacea.The Global Flushing Severity Score(GFSS),Clinician Erythema Assessment(CEA),Rhinophyma Severity Index(RHISI),Glasgow Benefit Inventory(GBI),and satisfaction scores were used to assess the recovery of patients at 6 months and 5 years,with the recurrence rate calculated at 5 years postoperatively.In addition,the levels of pro-inflammatory factors(TNF-α,IL-1β,and IL-6)in the serum of patients before and after surgery were detected by ELISA.RESULTS The GFSS,CEA,and RHISI scores at 6 months and 5 years postoperatively were significantly lower than those preoperatively(P<0.001 for both periods).Five-blade scratcher treatment greatly benefits patients as demonstrated by the GBI and patient satisfaction.A small number of patients(7/28,25%)reported recurrence after surgical treatment for rhinophyma in our department that was not more serious than before treatment.The expression of pro-inflammatory factors(TNF-α,IL-1β,and IL-6)in the patient's serum was significantly reduced after surgery of five-blade scratcher.CONCLUSION The five-blade scratcher treatment demonstrates notable advantages,including simplicity,safety,efficacy,and cost-effectiveness,coupled with reduced bleeding,minimized scarring,lower recurrence rates,reduced the level of pro-inflammatory factors and improved patient satisfaction.Consequently,this therapeutic modality exhibits a viable option for individuals afflicted with severe rhinophyma.
基金Supported by Social Science Planning Project of Chongqing(2010YBJJ13)the Fundamental Research Funds for the Central Universities(XDJK2010C103)Ph.D Foundation Project of Southwest University(SWU1209303)
文摘Firstly,this paper reviews and analyzes historic background of urban-rural integration of Chongqing,and the evolution and trend of urban and rural dual economic structure.On the basis of previous researches,it selects factors and variables influencing urban and rural dual economic structure,and establishes an econometric model.By state space Kalman filtering method,it analyzes dynamic influence of factors upon urban-rural dual economic intensity.According to empirical conclusion,it puts forward corresponding policy recommendations for promoting integrated urban and rural economic development of Chongqing.
文摘UPE (Ultraweak photon emission) is one kind of a common phenomenon in biological organisms. It contains a wealth of information of biological functions. In this paper, single photon counting system is used to measure UPE of some anti- cancer herbal plants. For the plants, the changes of UPE under different water condition are stud-ied and the varying laws of ultraweak photon number with time are analysed. The results are higher fit double exponential decay law.
