The immune-stromal cell interactions play a key role in health and diseases. In periodontitis, the most prevalent infectious disease in humans, immune cells accumulate in the oral mucosa and promote bone destruction b...The immune-stromal cell interactions play a key role in health and diseases. In periodontitis, the most prevalent infectious disease in humans, immune cells accumulate in the oral mucosa and promote bone destruction by inducing receptor activator of nuclear factor-κB ligand (RANKL) expression in osteogenic cells such as osteoblasts and periodontal ligament cells. However, the detailed mechanism underlying immune–bone cell interactions in periodontitis is not fully understood. Here, we performed single-cell RNAsequencing analysis on mouse periodontal lesions and showed that neutrophil–osteogenic cell crosstalk is involved in periodontitis-induced bone loss. The periodontal lesions displayed marked infiltration of neutrophils, and in silico analyses suggested that the neutrophils interacted with osteogenic cells through cytokine production. Among the cytokines expressed in the periodontal neutrophils, oncostatin M (OSM) potently induced RANKL expression in the primary osteoblasts, and deletion of the OSM receptor in osteogenic cells significantly ameliorated periodontitis-induced bone loss. Epigenomic data analyses identified the OSM-regulated RANKL enhancer region in osteogenic cells, and mice lacking this enhancer showed decreased periodontal bone loss while maintaining physiological bone metabolism. These findings shed light on the role of neutrophils in bone regulation during bacterial infection, highlighting the novel mechanism underlying osteoimmune crosstalk.展开更多
In this study, both an atmospheric model [Weather Research and Forecasting(WRF) model] and an atmosphere(WRF)–ocean(Princeton Ocean Model;POM) coupled model are used to simulate the tropical cyclone(TC) Kaemi(2006). ...In this study, both an atmospheric model [Weather Research and Forecasting(WRF) model] and an atmosphere(WRF)–ocean(Princeton Ocean Model;POM) coupled model are used to simulate the tropical cyclone(TC) Kaemi(2006). By comparing the simulation results of the models, effects of oceanic elements, especially the TC-induced sea surface temperature(SST) cooling, on the simulated TC size and destructiveness are identified and analyzed. The results show that there are no notable differences in the simulated TC track and its intensity between the uncoupled and coupled experiments;however, there are large differences in the TC size(i.e., the radius of gale-force wind)between the two experiments, and it is the TC-induced SST cooling that decreases the TC size. The SST cooling contributes to the decrease of air–sea moisture difference(ASMD) outside the TC eyewall, which subsequently leads to the decreases in surface enthalpy flux(SEF), radial sea-level pressure gradient, absolute vorticity advection, and wind speed outside the TC eyewall. As a result, the TC size and size-dependent TC destructive potential all decrease remarkably.展开更多
To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers i...To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers in the Junggar Basin,Xinjiang.By changing the confining pressure,we compared the mechanical properties,acoustic emission characteristics,and fractal features of the acoustic emission sequence for volcanic breccia with different bedding dip angles.The research results indicate that as the bedding dip angle increases,peak strength,internal friction angle,and cohesion exhibit a“U-shaped”variation pattern.The correlation dimension of the acoustic emission amplitude was calculated using the G-P algorithm,revealing that volcanic breccia exhibits fractal characteristics.Furthermore,a positive correlation between the correlation dimension and the bedding dip angle was observed.When the stress of the test specimen reaches 0.8σ_(c),there is a significant decrease in the fractal dimension,serving as a criterion for predicting the failure of the specimen.By analyzing the changes in fractal dimension at different stress levels,the slope of the fractal dimension△D<-0.5 can be used as a precursor to failure for test specimens with a bedding dip angle of 15°≤β≤45°.Similarly,when the bedding dip angle of the specimen is 0°≤β<15°or 45°<β≤90°,△D<0 can be considered as a precursor to specimen failure.This study provides theoretical references for understanding the failure patterns of volcanic rock.展开更多
The damage and failure law of rock mass with holes is of great significance to the stability control of roadways. This study investigates the mechanical properties and failure modes of porous rock masses under cyclic ...The damage and failure law of rock mass with holes is of great significance to the stability control of roadways. This study investigates the mechanical properties and failure modes of porous rock masses under cyclic loading, elucidates the acoustic emission (AE) characteristics and their spatial evolution, and establishes the interrelation among AE, stress, strain, time, and cumulative damage. The results reveal that the rock mass with holes and the intact rock mass show softening and hardening characteristics after cyclic loading. The plastic strain of the rock mass with holes is smaller than that of the intact rock mass, and the stress −strain curve shows hysteresis characteristics. Under uniaxial compression, the pore-bearing rock mass shows the characteristics of higher ringing count, AE energy, b-value peak, and more cumulative ringing count in the failure stage, while it shows lower characteristics under cyclic action. At the initial stage of loading, compared with the intact rock mass, the pore-containing rock mass shows the characteristics of a low b-value. The AE positioning and cumulative damage percentage are larger, and the AE positioning is denser around the hole. The specimen with holes is mainly shear failure, and the complete specimen is mainly tensile shear failure.展开更多
Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in c...Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in cold regions.In this study,the triaxial compression test are performed on mudstone in the weakly cemented soft rock strata in the mining area of western China,and the mechanical characteristics and failure mechanism of weakly cemented mudstone are systematically investigated under the combined action of freezing and loading.Furthermore,the quantitative relationship between the microstructural parameters and the macroscopic strength and deformation parameters is established based on fractal theory.Thus,the failure mechanism of frozen weakly cemented mudstone is revealed on both micro- and macro-scales.The results show that temperature and confining pressure significantly affects the elastic modulus and peak strength of weakly cemented mudstone.With decreasing temperature,the compressive strength increases,while the corresponding peak strain decreases gradually.On the deformation curve,the plastic deformation stage is shortened,and the brittle fracture feature at the post-peak stage is more prominent,and the elastic modulus correspondingly increases with decreasing temperature.Under low-temperature conditions,most of the weakly cemented mudstone undergoes microscopic shear failure along the main fracture surface.The micro-fracture morphology characteristics of weakly cemented mudstone under different temperatures are quantified via the fractal dimension,and an approximately exponential relationship can be obtained among the fractal dimension and the temperature,compressive strength and elastic modulus.展开更多
Airblasts,as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches,commonly result in catastrophic damages and are attracting more and more scientific attention.To quantitatively a...Airblasts,as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches,commonly result in catastrophic damages and are attracting more and more scientific attention.To quantitatively analyze the intensity of airblast initiated by landslides,the Wangjiayan landslide,occurred in the Wenchuan earthquake,is selected here with the landslide propagation and airblast evolution being studied using FLUENT by introducing the Voellmy rheological law.The results reveal that:(1)For the Wangjiayan landslide,its whole travelling duration is only 12 s with its maximum velocity reaching 36 m/s at t=10 s;(2)corresponding to the landslide propagation,the maximum velocity,28 m/s,of the airblast initiated by the landslide also appears at t=10 s with its maximum pressure reaching594.8 Pa,which is equivalent to violent storm;(3)under the attack of airblast,the load suffered by buildings in the airblast zone increases to 1300 Pa at t=9.4 s and sharply decreased to-7000 Pa as the rapid decrease of the velocity of the sliding mass at t=10 s,which is seriously unfavorable for buildings and might be the key reason for the destructive collapse of buildings in the airblast zone of the Wangjiayan landslide.展开更多
At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of...At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of He generation rate and the geochemical characteristics of the produced gas, both the similarities and differences between natural gas and He resources in the Bohai Bay, Ordos and the surrounding Songliao Basin are compared and analyzed, discussing the main controlling factors of helium resources in the three main petroliferous basins of the North China Craton. It is found that the three basins of Bohai Bay, Ordos and Songliao have similar characteristics of source rocks, reservoirs and cap rocks, that's why their methane resource characteristics are essentially the same. The calculated ~4He generation per cubic metamorphic crystalline basement in the three basins is roughly equivalent, which is consistent with the measured He resources, and it is believed that the ~4He of radiogenic from the crust is the main factor controlling the overall He accumulation in the three basins;there is almost no contribution of the mantle-derived CH_4, which suggests that the transport and uplift of mantle-derived ~3He carried by the present-day magmatic activities along the deep-large faults is not the main reason for the mantle-derived ~3He mixing in the basins. Combined with the results of regional volcanic and geophysical studies,it is concluded that under the background of the destruction of North China Craton, magma intrusion carried a large amount of mantle-derived material and formed basic volcanic rocks in the Bohai Bay Basin and Songliao Basin, which replenished mantle-derived ~3He for the interior of the basins, and that strong seismic activities in and around the basins also promoted the upward migration of mantle source ~3He. This study suggests that the tectonic zone with dense volcanic rocks in the Cenozoic era and a high incidence of historical strong earthquakes history may be a potential area for helium resource exploration.展开更多
AIM:To assess the clinical presentations and outcomes of idiopathic orbital inflammatory pseudotumor(IOIP)patients with orbital wall bone destruction(OWBD)and to propose an expanded classification system that includes...AIM:To assess the clinical presentations and outcomes of idiopathic orbital inflammatory pseudotumor(IOIP)patients with orbital wall bone destruction(OWBD)and to propose an expanded classification system that includes bone destruction.METHODS:The study retrospectively reviewed clinical presentations,imaging findings,treatment modalities,and outcomes of six patients diagnosed histopathologically with IOIP and OWBD at the Beijing Tongren Hospital,Capital Medical University between October 2018 and June 2021.RESULTS:Over two years,6(10%)of 60 IOIP patients at our hospital exhibited OWBD,but this may overrepresent severe cases.The cohort consisted of three men and three women,aged 17 to 60y(mean 35.5±16.1y).Presenting symptoms included proptosis,eyelid swelling,decreased visual acuity with pain,and palpable mass.Imaging revealed multiple anatomical structures involved with the medial wall being the most common site of bone destruction.Histopathological examination showed classic type in five patients and sclerosing type in one patient.All patients underwent surgical resection followed by methylprednisolone treatment.Follow-up(mean 30.3±3.1mo)indicated three patients had no recurrence,while others had varying degrees of symptom persistence or recurrence.CONCLUSION:IOIP with bone destruction is a rare but significant subtype that mimics malignancy,leading to potential diagnostic and therapeutic challenges.Our findings suggest that complete surgical resection combined with adjunctive glucocorticoid therapy can yield favorable outcomes.However,larger-scale studies are needed to further optimize therapeutic approaches.展开更多
NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse gas.Therefore,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse effect.Am...NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse gas.Therefore,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse effect.Among the technologies for NF_(3)abatement,the destructive sorption of NF_(3)over metal oxides sorbents is an effective way.Thus,the search for a highly reactive and utilized sorbent for NF_(3)destruction is in great demand.In this work,AlOOH supported on carbon-sphere(AlOOH/CS)as precursors were synthesized hydrothermally and heat-treated to prepare the Al_(2)O_(3)sorbents.The influence of AlOOH/CS hydrothermal temperatures on the reactivity of derived Al_(2)O_(3)sorbents for NF_(3)destruction was investigated,and it is shown that the Al2O3 from AlOOH/CS hydro-thermalized at 120℃is superior to others.Subsequently,the optimized Al_(2)O_(3)was covered by Mn(OH)x to prepare Mn/Al_(2)O_(3)sorbents via changing hydrothermal temperatures and Mn loadings.The results show that the Mn/Al_(2)O_(3)sorbents are more utilized than bare Al_(2)O_(3)in NF_(3)destructive sorption due to the promotional effect of Mn_(2)O_(3)as surface layer on the fluorination of Al_(2)O_(3)as substrate,especially the optimal 5%Mn/Al2O3(160℃)exhibits a utilization percentage as high as 90.4%,and remarkably exceeds all the sorbents reported so far.These findings are beneficial to develop more efficient sorbents for the destruction of NF_(3).展开更多
The treatments of malignant diseases nowadays are rapidly developing. One of the groups of novel therapies applies electromagnetic fields to destroy the malignant lesions. The thermal (heating) and nonthermal (polariz...The treatments of malignant diseases nowadays are rapidly developing. One of the groups of novel therapies applies electromagnetic fields to destroy the malignant lesions. The thermal (heating) and nonthermal (polarization, molecular excitations) processes are combined in novel methods. The non-ionizing energy absorption from the electric field may produce substantial heat, increasing the targeted lesion’s temperature and inducing hyperthermic effects. The modulated electro-hyperthermia (mEHT) uses thermal conditions to optimize and accelerate the chemical reactions induced by the nonthermal excitation of the electric field. The mEHT cooperates with the body’s homeostatic control and harmonizes the mutual efforts to destroy the malignancy. Our objective is to show in vivo proof of the combined complementary electromagnetic impact on various tumors produced by mEHT. Furthermore, we present evidence of the increasing efficacy of the complementary application of mEHT with conventional treatments.展开更多
To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concret...To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.展开更多
The power dissipation index(PDI),which is defined as the sum of the cube of tropical cyclone(TC)maximum wind speed during TC lifetime,is widely used to estimate the TC destructive potential.However,due to the lack of ...The power dissipation index(PDI),which is defined as the sum of the cube of tropical cyclone(TC)maximum wind speed during TC lifetime,is widely used to estimate the TC destructive potential.However,due to the lack of high-resolution observations,little attention has been paid to the contribution of TC size change to TC destructive potential in response to ocean warming.In this study,sensitivity experiments are performed by using the high-resolution Weather Research and Forecasting(WRF)model to investigate the responses of TC size and TC destructive potential to prescribed sea surface temperature(SST)increase under the present climate condition.The results show that TC size increases with the ocean warming.Possible reasons for TC size change are investigated with a focus on the outer air–sea moisture difference(ASMD).As SST increases,ASMD in the outer zone of the TC is larger than that in the inner zone,which increases the surface entropy flux(SEF)of the outer zone.This change in the radial distribution of SEF causes the increase of tangential wind in the outer zone,which further increases SEF,resulting in a positive feedback between outer-zone SEF and outer-zone tangential wind.This feedback leads to the increase of the radius of gale-force wind,leading to the expansion of TC size.Moreover,to estimate the contribution of TC size change to TC destructiveness,we calculate TC size-dependent destructive potential(PDS)as the storm size information is available in the model outputs,as well as PDI that does not consider the effect of TC size change.We find that PDS increases exponentially as SST increases from 1 to 4°C,while PDI increases linearly;hence the former is soon much greater than the latter.This suggests that the growth effect of TC size cannot be ignored in estimating destructiveness under ocean warming.展开更多
Large-scale tectonic magmatism and extensive gold mineralization have occurred in the eastern North China Craton(NCC)(Jiaodong and Liaodong peninsulas)since Mesozoic,which indicated that the region experienced decrato...Large-scale tectonic magmatism and extensive gold mineralization have occurred in the eastern North China Craton(NCC)(Jiaodong and Liaodong peninsulas)since Mesozoic,which indicated that the region experienced decratonization process.The genesis type of granites evolved from S-type to I-type and A-type during Late Jurassic to Early Cretaceous,and thus reflects the evolution of geodynamics in the Late Mesozoic,indicating the varied subduction process of the Paleo-Pacific Plate(PPP)and the craton destruction.The evolution of geochemical features shows that the mantle beneath the Jiaodong Peninsula evolved from EM-II in Jurassic to EM-I in Early Cretaceous,demonstrating that the mantle switched from enriched to depleted.The gold of decratonic gold deposits in Jiaodong Peninsula mainly comes from the lithospheric mantle domains metasomatized by fluids derived from the metamorphism and dehydration of the subducted slab in the mantle transition zone.The rapid decomposition of minerals leads to the concentrated release of ore-forming fluids,and this process leads to the explosive gold mineralization during the craton destruction.Extensive magmatic uplift and extensional structures,triggered by the craton destruction in Early Cretaceous formed the extensional tectonic system,providing space for the decratonic gold deposits in Jiaodong Peninsula.展开更多
Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes.Polyolefin elastomers(POE)are a typical example.Due to cost,only a ...Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes.Polyolefin elastomers(POE)are a typical example.Due to cost,only a few linear a-olefins(e.g.,1-butene,1-hexene,and 1-octene)are used as comonomers in solution polymerization in industry.However,a-olefin comonomers with other structures may have different effects on polymerization in comparison with common linear ones.Moreover,the properties of the corresponding materials may differ significantly.In this work,copolymers of ethylene with linear and endcyclized a-olefins are synthesized using a metallocene catalyst.The copolymerization of ethylene with linear a-olefins results in a higher turn-over frequency(TOF)and lower incorporation than copolymerization with end-cyclized a-olefins,which may indicate that end-cyclized a-olefins have a higher coordination probability and lower insertion rate.In this reaction,the comonomer is distributed randomly in the polymer chain and efficiently destroys crystallization.End-cyclized a-olefins exhibit a much stronger crystallization destructive capacity(CDC)in the copolymer than linear a-olefins,possibly because linear a-olefins act mainly in the radial direction of the main chain of the polymer,while end-cyclized a-olefins act mainly in the axial direction of the main chain.展开更多
In the present work,the turbulent mixing process of a polydisperse quartz particle flow with a plasma stream generated by a radio-frequency(RF)inductively coupled plasma torch was numerically studied.The thermobaric s...In the present work,the turbulent mixing process of a polydisperse quartz particle flow with a plasma stream generated by a radio-frequency(RF)inductively coupled plasma torch was numerically studied.The thermobaric stress in the quartz particles under dynamic heating in a heterogeneous plasma flow was determined by a two-stage approximation approach.The effect of the presence of vacuoles in natural quartz on the particle thermobaric destruction conditions was studied.It was found that the equivalent thermal and baric stresses in quartz particles may significantly increase in the presence of vacuoles within a small gas volume fraction.The influence of the regime and energetic working conditions of an RF inductively coupled plasma torch system on the particle thermobaric destruction conditions was examined,and a recommendation was given to promote the degree of thermobaric destruction of quartz particles,which is of substantial importance for improving the overall enrichment efficiency of quartz concentrates.展开更多
Objective:To investigate whether miR-483-5p regulates osteoclast generation by targeting Timp2.miR-483-5p can promote osteoclast differentiation and bone destruction.Methods:Target genes of miR-483-5p were predicted b...Objective:To investigate whether miR-483-5p regulates osteoclast generation by targeting Timp2.miR-483-5p can promote osteoclast differentiation and bone destruction.Methods:Target genes of miR-483-5p were predicted by miRNAs target gene prediction software TargetScan8.0,and wild type and mutant 3'UTR plasmids were constructed.Dual luciferase reporter genes were used to verify whether target genes had a targeted regulatory relationship with miR-483-5p.Western blotting was used to detect the corresponding changes in the expression level of target protein after adjusting the level of miR-483-5p in cells.Cells were transfected or infected with target gene siRNA or target protein lentivirus,and TRAP staining and q-PCR assays were performed.In addition,for osteoclast induction experiment,RAW264.7 cells were co-transfected with ago-miR-483-5p and target protein-overexpressed lentiviruses q-PCR and TRAP staining were performed respectively.Results:Bioinformatics software was used to predict the target gene of miR-483-5p,and the Timp2 gene was found to regulate osteoclasts,and the dual luciferase reporter detection system found that miR-483-5p could be associated with the 3-UTR of the predicted target gene Timp2 gene.There are complementary loci and targeted regulatory relationship between them.Subsequently,we upregulated miR-483-5p in RAW264.7 cells to reduce the expression of Timp2.Compared with the normal group,the number of osteoclasts and the expression of osteoclast-specific genes increased significantly after the induction of Timp2 in knockdown cells.After co-transfection of target gene and miR-483-5p into cells,the number of osteoclasts and the expression of specific genes decreased significantly compared with the normal group.Conclusion:Timp2 is a downstream target gene of miR-483-5p and is involved in and inhibits osteoclast generation.展开更多
In this study,the Radio Direction Finding method is proposed for the detection of electromagnetic signals,in the VLF band,to try to anticipate the occurrence of potentially destructive geophysical events.The experimen...In this study,the Radio Direction Finding method is proposed for the detection of electromagnetic signals,in the VLF band,to try to anticipate the occurrence of potentially destructive geophysical events.The experimentation concerns the interception of electromagnetic anomalies in Sierra Leone,in the five-day time window,associated with seismic events that could potentially generate tsunamis.The area of investigation is Sierra Leone,whose coastline is subjected to tidal wave hazards triggered by earthquakes generated in the Mid-Atlantic Ridge.Although Sierra Leone is not affected by recurrent earthquakes,there is nevertheless a low probability,estimated at 2 percent,of the occurrence of destructive earthquakes in the next 50 years.Also in estimates,the risk of rogue and potentially damaging waves is estimated to strike the Sierra Leone coast at least once in the next 10 years.The Radio Direction Finding experiment carried out continuously 24/7,has shown a close relationship between increased radio-anomalies,in the frequencies of 6,000 Hz,a time window between electromagnetic anomaly detection and the imminence of an earthquake,and higher frequency times for the risk of earthquake occurrence in the Mid-Atlantic Ridge.展开更多
In order to improve the destruction efficiency of dioxins and also for developing new dioxin control technology, the destruction mechanisms of 2,3,7,8-tetrachlorodihenzo-p-dioxin (2,3,7,8-TCDD) by O3 and NO3, were i...In order to improve the destruction efficiency of dioxins and also for developing new dioxin control technology, the destruction mechanisms of 2,3,7,8-tetrachlorodihenzo-p-dioxin (2,3,7,8-TCDD) by O3 and NO3, were investigated employing quantum chemical calculations. For involved reactions, the microcosmic reaction processes were analyzed and depicted in detail based on geometry optimizations made by the B3LYP/6-31G(d) method. At the same time, the reaction activation energies were also calculated at the MP2/6- 311G(d,p)//B3LYP/6-31G(d) level. Configuration analysis indicated that 2,3,7,8-TCDD could be destroyed by 03 and NO3 in two different ways. The destruction of 2,3,7,8-TCDD by 03 proceeded via the addition of 03 and the cleavage of C=C while the destruction of 2,3,7,8-TCDD by NO3 proceeded via the substitution of chlorine by NO3. Calculated results show that, the activation energy of the destruction reaction of 2,3,7,8-TCDD by NO3 (267.48 kJ/mol) is much larger than that of the destruction reaction of 2,3,7,8-TCDD by O3 (51.20 kJ/mol). This indicated that the destruction of 2,3,7,8-TCDD by 03 is much more efficient than that of 2,3,7,8-TCDD by NO3. The reason why the activation energy for the destruction reaction of 2,3,7,8-TCDD by NO3 is so large, is also discussed.展开更多
Unidirectional carbon/carbon(C/C) composites modified with in situ grown carbon nanofibers(CNFs) were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of...Unidirectional carbon/carbon(C/C) composites modified with in situ grown carbon nanofibers(CNFs) were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of the C/C composites was investigated by detailed analyses of destructive process. The results show that there is a sharp increase in the flexural load-displacement curve in the axial direction of the CNF-C/C composites, followed by a serrated yielding phenomenon similar to the plastic materials. The failure mode of the C/C composites modified with in situ grown CNFs is changed from the pull-out of single fiber to the breaking of fiber bundles. The existence of interfacial layer composed by middle-textured pyrocarbon, CNFs and high-textured pyrocarbon can block the crack propagation and change the propagation direction of the main crack, which leads to the higher flexural strength and modulus of C/C composites.展开更多
基金supported in part by the Japan Agency for Medical Research and Development (AMED) under grant number JP20ek0410073, JP23ek0410108, JP22ek0410100, AMEDCREST under grant number JP19gm1210008 and AMED-PRIME under grant number JP21gm6310029, the AMED Japan Initiative for World leading Vaccine Research and Development Centers (JP223fa627001)Japan Society for the Promotion of Science (JSPS): Scientific Research S (21H05046), Scientific Research B (21H03104, 22H03195, and 22H02844) and Challenging Research (20K21515 and 21K18254)+3 种基金the JST FOREST Program (JPMJFR2261, JPMJFR205Z)Y.A. was supported by a JSPS Research Fellowship for Young Scientists (23KJ1949)Japanese Society for Immunology (JSI)Kibou Scholarship for Doctoral Students in Immunology。
文摘The immune-stromal cell interactions play a key role in health and diseases. In periodontitis, the most prevalent infectious disease in humans, immune cells accumulate in the oral mucosa and promote bone destruction by inducing receptor activator of nuclear factor-κB ligand (RANKL) expression in osteogenic cells such as osteoblasts and periodontal ligament cells. However, the detailed mechanism underlying immune–bone cell interactions in periodontitis is not fully understood. Here, we performed single-cell RNAsequencing analysis on mouse periodontal lesions and showed that neutrophil–osteogenic cell crosstalk is involved in periodontitis-induced bone loss. The periodontal lesions displayed marked infiltration of neutrophils, and in silico analyses suggested that the neutrophils interacted with osteogenic cells through cytokine production. Among the cytokines expressed in the periodontal neutrophils, oncostatin M (OSM) potently induced RANKL expression in the primary osteoblasts, and deletion of the OSM receptor in osteogenic cells significantly ameliorated periodontitis-induced bone loss. Epigenomic data analyses identified the OSM-regulated RANKL enhancer region in osteogenic cells, and mice lacking this enhancer showed decreased periodontal bone loss while maintaining physiological bone metabolism. These findings shed light on the role of neutrophils in bone regulation during bacterial infection, highlighting the novel mechanism underlying osteoimmune crosstalk.
基金Supported by the National Natural Science Foundation of China(42075035 and 41675077)Natural Science Foundation of Jiangsu Province(BK20160768)。
文摘In this study, both an atmospheric model [Weather Research and Forecasting(WRF) model] and an atmosphere(WRF)–ocean(Princeton Ocean Model;POM) coupled model are used to simulate the tropical cyclone(TC) Kaemi(2006). By comparing the simulation results of the models, effects of oceanic elements, especially the TC-induced sea surface temperature(SST) cooling, on the simulated TC size and destructiveness are identified and analyzed. The results show that there are no notable differences in the simulated TC track and its intensity between the uncoupled and coupled experiments;however, there are large differences in the TC size(i.e., the radius of gale-force wind)between the two experiments, and it is the TC-induced SST cooling that decreases the TC size. The SST cooling contributes to the decrease of air–sea moisture difference(ASMD) outside the TC eyewall, which subsequently leads to the decreases in surface enthalpy flux(SEF), radial sea-level pressure gradient, absolute vorticity advection, and wind speed outside the TC eyewall. As a result, the TC size and size-dependent TC destructive potential all decrease remarkably.
基金funded by the National Natural Science Foundation of China(Grant Nos.52174096,42277174).
文摘To investigate the mechanical failure characteristics of volcanic breccia with different bedding dip angles in deep layers,triaxial compression experiments were conducted on specimens taken from volcanic rock layers in the Junggar Basin,Xinjiang.By changing the confining pressure,we compared the mechanical properties,acoustic emission characteristics,and fractal features of the acoustic emission sequence for volcanic breccia with different bedding dip angles.The research results indicate that as the bedding dip angle increases,peak strength,internal friction angle,and cohesion exhibit a“U-shaped”variation pattern.The correlation dimension of the acoustic emission amplitude was calculated using the G-P algorithm,revealing that volcanic breccia exhibits fractal characteristics.Furthermore,a positive correlation between the correlation dimension and the bedding dip angle was observed.When the stress of the test specimen reaches 0.8σ_(c),there is a significant decrease in the fractal dimension,serving as a criterion for predicting the failure of the specimen.By analyzing the changes in fractal dimension at different stress levels,the slope of the fractal dimension△D<-0.5 can be used as a precursor to failure for test specimens with a bedding dip angle of 15°≤β≤45°.Similarly,when the bedding dip angle of the specimen is 0°≤β<15°or 45°<β≤90°,△D<0 can be considered as a precursor to specimen failure.This study provides theoretical references for understanding the failure patterns of volcanic rock.
基金Projects(U22A20165, 52004289) supported by the National Natural Science Foundation of ChinaProjects(2022XJNY01, BBJ2024001) supported by the Fundamental Research Funds for the Central Universities,China。
文摘The damage and failure law of rock mass with holes is of great significance to the stability control of roadways. This study investigates the mechanical properties and failure modes of porous rock masses under cyclic loading, elucidates the acoustic emission (AE) characteristics and their spatial evolution, and establishes the interrelation among AE, stress, strain, time, and cumulative damage. The results reveal that the rock mass with holes and the intact rock mass show softening and hardening characteristics after cyclic loading. The plastic strain of the rock mass with holes is smaller than that of the intact rock mass, and the stress −strain curve shows hysteresis characteristics. Under uniaxial compression, the pore-bearing rock mass shows the characteristics of higher ringing count, AE energy, b-value peak, and more cumulative ringing count in the failure stage, while it shows lower characteristics under cyclic action. At the initial stage of loading, compared with the intact rock mass, the pore-containing rock mass shows the characteristics of a low b-value. The AE positioning and cumulative damage percentage are larger, and the AE positioning is denser around the hole. The specimen with holes is mainly shear failure, and the complete specimen is mainly tensile shear failure.
基金funding support from Natural Science Foundation of Shandong Province(Grant No.ZR2021QE187).
文摘Understanding the mechanical properties and multiscale failure mechanism of frozen soft rock is an important prerequisite for the construction safety of tunnels,artificially frozen ground and other infrastructure in cold regions.In this study,the triaxial compression test are performed on mudstone in the weakly cemented soft rock strata in the mining area of western China,and the mechanical characteristics and failure mechanism of weakly cemented mudstone are systematically investigated under the combined action of freezing and loading.Furthermore,the quantitative relationship between the microstructural parameters and the macroscopic strength and deformation parameters is established based on fractal theory.Thus,the failure mechanism of frozen weakly cemented mudstone is revealed on both micro- and macro-scales.The results show that temperature and confining pressure significantly affects the elastic modulus and peak strength of weakly cemented mudstone.With decreasing temperature,the compressive strength increases,while the corresponding peak strain decreases gradually.On the deformation curve,the plastic deformation stage is shortened,and the brittle fracture feature at the post-peak stage is more prominent,and the elastic modulus correspondingly increases with decreasing temperature.Under low-temperature conditions,most of the weakly cemented mudstone undergoes microscopic shear failure along the main fracture surface.The micro-fracture morphology characteristics of weakly cemented mudstone under different temperatures are quantified via the fractal dimension,and an approximately exponential relationship can be obtained among the fractal dimension and the temperature,compressive strength and elastic modulus.
基金supported by the National Natural Science Foundation of China(42322702,42177131)。
文摘Airblasts,as one common phenomenon accompanied by rapid movements of landslides or rock/snow avalanches,commonly result in catastrophic damages and are attracting more and more scientific attention.To quantitatively analyze the intensity of airblast initiated by landslides,the Wangjiayan landslide,occurred in the Wenchuan earthquake,is selected here with the landslide propagation and airblast evolution being studied using FLUENT by introducing the Voellmy rheological law.The results reveal that:(1)For the Wangjiayan landslide,its whole travelling duration is only 12 s with its maximum velocity reaching 36 m/s at t=10 s;(2)corresponding to the landslide propagation,the maximum velocity,28 m/s,of the airblast initiated by the landslide also appears at t=10 s with its maximum pressure reaching594.8 Pa,which is equivalent to violent storm;(3)under the attack of airblast,the load suffered by buildings in the airblast zone increases to 1300 Pa at t=9.4 s and sharply decreased to-7000 Pa as the rapid decrease of the velocity of the sliding mass at t=10 s,which is seriously unfavorable for buildings and might be the key reason for the destructive collapse of buildings in the airblast zone of the Wangjiayan landslide.
基金The Natural gas formation rules and key technologies for exploration in the western exploration area KT2022A02the Science and Technology Fundamental Resources Investigation Program under contract No. 2023FY101500+2 种基金the National Key Research and Development Program of China under contract No. 2023YFC3012005the Central Public-interest Scientific Institution Basal Researchunder contract No. CEAIEF20230505。
文摘At present, the main controlling factors of helium accumulation is one of the key scientific problems restricting the exploration and development of helium reservoir. In this paper, based on the calculation results of He generation rate and the geochemical characteristics of the produced gas, both the similarities and differences between natural gas and He resources in the Bohai Bay, Ordos and the surrounding Songliao Basin are compared and analyzed, discussing the main controlling factors of helium resources in the three main petroliferous basins of the North China Craton. It is found that the three basins of Bohai Bay, Ordos and Songliao have similar characteristics of source rocks, reservoirs and cap rocks, that's why their methane resource characteristics are essentially the same. The calculated ~4He generation per cubic metamorphic crystalline basement in the three basins is roughly equivalent, which is consistent with the measured He resources, and it is believed that the ~4He of radiogenic from the crust is the main factor controlling the overall He accumulation in the three basins;there is almost no contribution of the mantle-derived CH_4, which suggests that the transport and uplift of mantle-derived ~3He carried by the present-day magmatic activities along the deep-large faults is not the main reason for the mantle-derived ~3He mixing in the basins. Combined with the results of regional volcanic and geophysical studies,it is concluded that under the background of the destruction of North China Craton, magma intrusion carried a large amount of mantle-derived material and formed basic volcanic rocks in the Bohai Bay Basin and Songliao Basin, which replenished mantle-derived ~3He for the interior of the basins, and that strong seismic activities in and around the basins also promoted the upward migration of mantle source ~3He. This study suggests that the tectonic zone with dense volcanic rocks in the Cenozoic era and a high incidence of historical strong earthquakes history may be a potential area for helium resource exploration.
基金Supported by Beijing Natural Science Foundation(No.7222025)Beijing Science and Technology Rising Star Program Cross-cooperation(No.20220484218).
文摘AIM:To assess the clinical presentations and outcomes of idiopathic orbital inflammatory pseudotumor(IOIP)patients with orbital wall bone destruction(OWBD)and to propose an expanded classification system that includes bone destruction.METHODS:The study retrospectively reviewed clinical presentations,imaging findings,treatment modalities,and outcomes of six patients diagnosed histopathologically with IOIP and OWBD at the Beijing Tongren Hospital,Capital Medical University between October 2018 and June 2021.RESULTS:Over two years,6(10%)of 60 IOIP patients at our hospital exhibited OWBD,but this may overrepresent severe cases.The cohort consisted of three men and three women,aged 17 to 60y(mean 35.5±16.1y).Presenting symptoms included proptosis,eyelid swelling,decreased visual acuity with pain,and palpable mass.Imaging revealed multiple anatomical structures involved with the medial wall being the most common site of bone destruction.Histopathological examination showed classic type in five patients and sclerosing type in one patient.All patients underwent surgical resection followed by methylprednisolone treatment.Follow-up(mean 30.3±3.1mo)indicated three patients had no recurrence,while others had varying degrees of symptom persistence or recurrence.CONCLUSION:IOIP with bone destruction is a rare but significant subtype that mimics malignancy,leading to potential diagnostic and therapeutic challenges.Our findings suggest that complete surgical resection combined with adjunctive glucocorticoid therapy can yield favorable outcomes.However,larger-scale studies are needed to further optimize therapeutic approaches.
基金The financial support from the Natural Science Foundation of Shandong Province (ZR2020KB003)
文摘NF_(3)is commonly used as an etching and cleaning gas in semiconductor industry,however it is a strongly greenhouse gas.Therefore,the destruction of disposal NF_(3)is an urgent task to migrate the greenhouse effect.Among the technologies for NF_(3)abatement,the destructive sorption of NF_(3)over metal oxides sorbents is an effective way.Thus,the search for a highly reactive and utilized sorbent for NF_(3)destruction is in great demand.In this work,AlOOH supported on carbon-sphere(AlOOH/CS)as precursors were synthesized hydrothermally and heat-treated to prepare the Al_(2)O_(3)sorbents.The influence of AlOOH/CS hydrothermal temperatures on the reactivity of derived Al_(2)O_(3)sorbents for NF_(3)destruction was investigated,and it is shown that the Al2O3 from AlOOH/CS hydro-thermalized at 120℃is superior to others.Subsequently,the optimized Al_(2)O_(3)was covered by Mn(OH)x to prepare Mn/Al_(2)O_(3)sorbents via changing hydrothermal temperatures and Mn loadings.The results show that the Mn/Al_(2)O_(3)sorbents are more utilized than bare Al_(2)O_(3)in NF_(3)destructive sorption due to the promotional effect of Mn_(2)O_(3)as surface layer on the fluorination of Al_(2)O_(3)as substrate,especially the optimal 5%Mn/Al2O3(160℃)exhibits a utilization percentage as high as 90.4%,and remarkably exceeds all the sorbents reported so far.These findings are beneficial to develop more efficient sorbents for the destruction of NF_(3).
文摘The treatments of malignant diseases nowadays are rapidly developing. One of the groups of novel therapies applies electromagnetic fields to destroy the malignant lesions. The thermal (heating) and nonthermal (polarization, molecular excitations) processes are combined in novel methods. The non-ionizing energy absorption from the electric field may produce substantial heat, increasing the targeted lesion’s temperature and inducing hyperthermic effects. The modulated electro-hyperthermia (mEHT) uses thermal conditions to optimize and accelerate the chemical reactions induced by the nonthermal excitation of the electric field. The mEHT cooperates with the body’s homeostatic control and harmonizes the mutual efforts to destroy the malignancy. Our objective is to show in vivo proof of the combined complementary electromagnetic impact on various tumors produced by mEHT. Furthermore, we present evidence of the increasing efficacy of the complementary application of mEHT with conventional treatments.
文摘To investigate the evolution of load-bearing characteristics of pre-stressed beams throughout their service life and to provide a basis for accurately assessing the actual working state of damaged pre-stressed concrete T-beams,destructive tests were conducted on full-scale pre-stressed concrete beams.Based on the measurement and ana-lysis of beam deflection,strain,and crack development under various loading levels during the research tests,combined with the verification coefficient indicators specified in the codes,the verification coefficients of bridges at different stages of damage can be examined.The results indicate that the T-beams experience complete,incom-plete linear,and non-linear stages during the destructive test process.In the complete linear elastic stage,both the deflection and bottom strain verification coefficients comply with the specifications,indicating a good structural load-bearing capacity no longer adheres to the code’s requirements.In the non-linear stage,both coefficients exhi-bit a sharp increase,resulting in a further decrease in the structure’s load-bearing capacity.According to the pro-visions of the current code,the beam can be in the incomplete linear stage when both values fall within the code’s specified range.The strain verification coefficient sourced from the compression zone at the bottom of theflange is not recommended for assessing the bridge’s load-bearing capacity.
基金Supported by the National Key Research and Development Program of China(2018YFC1505803)National Natural Science Foundation of China(41605072)+1 种基金Natural Science Foundation of Jiangsu Province(BK20160768)Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions.
文摘The power dissipation index(PDI),which is defined as the sum of the cube of tropical cyclone(TC)maximum wind speed during TC lifetime,is widely used to estimate the TC destructive potential.However,due to the lack of high-resolution observations,little attention has been paid to the contribution of TC size change to TC destructive potential in response to ocean warming.In this study,sensitivity experiments are performed by using the high-resolution Weather Research and Forecasting(WRF)model to investigate the responses of TC size and TC destructive potential to prescribed sea surface temperature(SST)increase under the present climate condition.The results show that TC size increases with the ocean warming.Possible reasons for TC size change are investigated with a focus on the outer air–sea moisture difference(ASMD).As SST increases,ASMD in the outer zone of the TC is larger than that in the inner zone,which increases the surface entropy flux(SEF)of the outer zone.This change in the radial distribution of SEF causes the increase of tangential wind in the outer zone,which further increases SEF,resulting in a positive feedback between outer-zone SEF and outer-zone tangential wind.This feedback leads to the increase of the radius of gale-force wind,leading to the expansion of TC size.Moreover,to estimate the contribution of TC size change to TC destructiveness,we calculate TC size-dependent destructive potential(PDS)as the storm size information is available in the model outputs,as well as PDI that does not consider the effect of TC size change.We find that PDS increases exponentially as SST increases from 1 to 4°C,while PDI increases linearly;hence the former is soon much greater than the latter.This suggests that the growth effect of TC size cannot be ignored in estimating destructiveness under ocean warming.
基金Supported by projects of the Youth Science and Technology Innovation Fund of Shandong Provincial No.6 Exploration Institute of Geology and Mineral Resources(No.LY-QK-202203)National Natural Science Foundation of China-Shandong Joint Fund(No.U2006201).
文摘Large-scale tectonic magmatism and extensive gold mineralization have occurred in the eastern North China Craton(NCC)(Jiaodong and Liaodong peninsulas)since Mesozoic,which indicated that the region experienced decratonization process.The genesis type of granites evolved from S-type to I-type and A-type during Late Jurassic to Early Cretaceous,and thus reflects the evolution of geodynamics in the Late Mesozoic,indicating the varied subduction process of the Paleo-Pacific Plate(PPP)and the craton destruction.The evolution of geochemical features shows that the mantle beneath the Jiaodong Peninsula evolved from EM-II in Jurassic to EM-I in Early Cretaceous,demonstrating that the mantle switched from enriched to depleted.The gold of decratonic gold deposits in Jiaodong Peninsula mainly comes from the lithospheric mantle domains metasomatized by fluids derived from the metamorphism and dehydration of the subducted slab in the mantle transition zone.The rapid decomposition of minerals leads to the concentrated release of ore-forming fluids,and this process leads to the explosive gold mineralization during the craton destruction.Extensive magmatic uplift and extensional structures,triggered by the craton destruction in Early Cretaceous formed the extensional tectonic system,providing space for the decratonic gold deposits in Jiaodong Peninsula.
文摘Olefin solution polymerization can be used to obtain high-performance polyolefin materials that cannot be obtained via other polymerization processes.Polyolefin elastomers(POE)are a typical example.Due to cost,only a few linear a-olefins(e.g.,1-butene,1-hexene,and 1-octene)are used as comonomers in solution polymerization in industry.However,a-olefin comonomers with other structures may have different effects on polymerization in comparison with common linear ones.Moreover,the properties of the corresponding materials may differ significantly.In this work,copolymers of ethylene with linear and endcyclized a-olefins are synthesized using a metallocene catalyst.The copolymerization of ethylene with linear a-olefins results in a higher turn-over frequency(TOF)and lower incorporation than copolymerization with end-cyclized a-olefins,which may indicate that end-cyclized a-olefins have a higher coordination probability and lower insertion rate.In this reaction,the comonomer is distributed randomly in the polymer chain and efficiently destroys crystallization.End-cyclized a-olefins exhibit a much stronger crystallization destructive capacity(CDC)in the copolymer than linear a-olefins,possibly because linear a-olefins act mainly in the radial direction of the main chain of the polymer,while end-cyclized a-olefins act mainly in the axial direction of the main chain.
基金supported by National Natural Science Foundation of China(Nos.52202460,52177128)National Key R&D Program of China(Nos.2020YFC2201100,2021YFC2202804)+2 种基金China Postdoctoral Science Foundation(Nos.2021M690392,2021TQ0036)Science Foundation for Youth Scholars of the Beijing Institute of TechnologyAdvanced Space Propulsion Laboratory of BICE and the Beijing Engineering Research Centre of Efficient and Green Aerospace Propulsion Technology(No.LabASP-2021-04)。
文摘In the present work,the turbulent mixing process of a polydisperse quartz particle flow with a plasma stream generated by a radio-frequency(RF)inductively coupled plasma torch was numerically studied.The thermobaric stress in the quartz particles under dynamic heating in a heterogeneous plasma flow was determined by a two-stage approximation approach.The effect of the presence of vacuoles in natural quartz on the particle thermobaric destruction conditions was studied.It was found that the equivalent thermal and baric stresses in quartz particles may significantly increase in the presence of vacuoles within a small gas volume fraction.The influence of the regime and energetic working conditions of an RF inductively coupled plasma torch system on the particle thermobaric destruction conditions was examined,and a recommendation was given to promote the degree of thermobaric destruction of quartz particles,which is of substantial importance for improving the overall enrichment efficiency of quartz concentrates.
基金National Natural Science Foundation of China(No.81860645)Hainan Medical University Introduced Talents Research Start-Up Funds(No.2015)。
文摘Objective:To investigate whether miR-483-5p regulates osteoclast generation by targeting Timp2.miR-483-5p can promote osteoclast differentiation and bone destruction.Methods:Target genes of miR-483-5p were predicted by miRNAs target gene prediction software TargetScan8.0,and wild type and mutant 3'UTR plasmids were constructed.Dual luciferase reporter genes were used to verify whether target genes had a targeted regulatory relationship with miR-483-5p.Western blotting was used to detect the corresponding changes in the expression level of target protein after adjusting the level of miR-483-5p in cells.Cells were transfected or infected with target gene siRNA or target protein lentivirus,and TRAP staining and q-PCR assays were performed.In addition,for osteoclast induction experiment,RAW264.7 cells were co-transfected with ago-miR-483-5p and target protein-overexpressed lentiviruses q-PCR and TRAP staining were performed respectively.Results:Bioinformatics software was used to predict the target gene of miR-483-5p,and the Timp2 gene was found to regulate osteoclasts,and the dual luciferase reporter detection system found that miR-483-5p could be associated with the 3-UTR of the predicted target gene Timp2 gene.There are complementary loci and targeted regulatory relationship between them.Subsequently,we upregulated miR-483-5p in RAW264.7 cells to reduce the expression of Timp2.Compared with the normal group,the number of osteoclasts and the expression of osteoclast-specific genes increased significantly after the induction of Timp2 in knockdown cells.After co-transfection of target gene and miR-483-5p into cells,the number of osteoclasts and the expression of specific genes decreased significantly compared with the normal group.Conclusion:Timp2 is a downstream target gene of miR-483-5p and is involved in and inhibits osteoclast generation.
文摘In this study,the Radio Direction Finding method is proposed for the detection of electromagnetic signals,in the VLF band,to try to anticipate the occurrence of potentially destructive geophysical events.The experimentation concerns the interception of electromagnetic anomalies in Sierra Leone,in the five-day time window,associated with seismic events that could potentially generate tsunamis.The area of investigation is Sierra Leone,whose coastline is subjected to tidal wave hazards triggered by earthquakes generated in the Mid-Atlantic Ridge.Although Sierra Leone is not affected by recurrent earthquakes,there is nevertheless a low probability,estimated at 2 percent,of the occurrence of destructive earthquakes in the next 50 years.Also in estimates,the risk of rogue and potentially damaging waves is estimated to strike the Sierra Leone coast at least once in the next 10 years.The Radio Direction Finding experiment carried out continuously 24/7,has shown a close relationship between increased radio-anomalies,in the frequencies of 6,000 Hz,a time window between electromagnetic anomaly detection and the imminence of an earthquake,and higher frequency times for the risk of earthquake occurrence in the Mid-Atlantic Ridge.
文摘In order to improve the destruction efficiency of dioxins and also for developing new dioxin control technology, the destruction mechanisms of 2,3,7,8-tetrachlorodihenzo-p-dioxin (2,3,7,8-TCDD) by O3 and NO3, were investigated employing quantum chemical calculations. For involved reactions, the microcosmic reaction processes were analyzed and depicted in detail based on geometry optimizations made by the B3LYP/6-31G(d) method. At the same time, the reaction activation energies were also calculated at the MP2/6- 311G(d,p)//B3LYP/6-31G(d) level. Configuration analysis indicated that 2,3,7,8-TCDD could be destroyed by 03 and NO3 in two different ways. The destruction of 2,3,7,8-TCDD by 03 proceeded via the addition of 03 and the cleavage of C=C while the destruction of 2,3,7,8-TCDD by NO3 proceeded via the substitution of chlorine by NO3. Calculated results show that, the activation energy of the destruction reaction of 2,3,7,8-TCDD by NO3 (267.48 kJ/mol) is much larger than that of the destruction reaction of 2,3,7,8-TCDD by O3 (51.20 kJ/mol). This indicated that the destruction of 2,3,7,8-TCDD by 03 is much more efficient than that of 2,3,7,8-TCDD by NO3. The reason why the activation energy for the destruction reaction of 2,3,7,8-TCDD by NO3 is so large, is also discussed.
基金Project(2011CB605804)supported by the National Basic Research Program of ChinaProject(51165006)supported by the National Natural Science Foundation of China+1 种基金Project(BY2013015-32)supported by Cooperative Innovation Fund-Prospective Project of Jiangsu Province,ChinaProject(JUSRP1045)supported by the Fundamental Research Funds for the Central Universities,China
文摘Unidirectional carbon/carbon(C/C) composites modified with in situ grown carbon nanofibers(CNFs) were prepared by catalysis chemical vapor deposition. The effect of in situ grown CNFs on the flexural properties of the C/C composites was investigated by detailed analyses of destructive process. The results show that there is a sharp increase in the flexural load-displacement curve in the axial direction of the CNF-C/C composites, followed by a serrated yielding phenomenon similar to the plastic materials. The failure mode of the C/C composites modified with in situ grown CNFs is changed from the pull-out of single fiber to the breaking of fiber bundles. The existence of interfacial layer composed by middle-textured pyrocarbon, CNFs and high-textured pyrocarbon can block the crack propagation and change the propagation direction of the main crack, which leads to the higher flexural strength and modulus of C/C composites.