Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening ...Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.展开更多
BACKGROUND At present,the existing internal medicine drug treatment can alleviate the high glucose toxicity of patients to a certain extent,to explore the efficacy of laparoscopic jejunoileal side to side anastomosis ...BACKGROUND At present,the existing internal medicine drug treatment can alleviate the high glucose toxicity of patients to a certain extent,to explore the efficacy of laparoscopic jejunoileal side to side anastomosis in the treatment of type 2 diabetes,the report is as follows.AIM To investigate the effect of jejunoileal side-to-side anastomosis on metabolic parameters in patients with type 2 diabetes mellitus(T2DM).METHODS We retrospectively analyzed the clinical data of 78 patients with T2DM who were treated via jejunoileal lateral anastomosis.Metabolic indicators were collected preoperatively,as well as at 3 and 6 months postoperative.The metabolic indicators analyzed included body mass index(BMI),systolic blood pressure(SBP),diastolic blood pressure(DBP),fasting blood glucose(FBG),2-hour blood glucose(PBG),glycated hemoglobin(HbA1c),fasting C-peptide,2-hour C-peptide(PCP),fasting insulin(Fins),2-hour insulin(Pins),insulin resistance index(HOMA-IR),βCellular function index(HOMA-β),alanine aminotransferase,aspartate aminotransferase,serum total cholesterol(TC),low-density lipoprotein cholesterol(L DL-C),triglycerides(TG),high-density lipoprotein,and uric acid(UA)levels.RESULTS SBP,DBP,PBG,HbA1c,LDL-C,and TG were all significantly lower 3 months postoperative vs preoperative values;body weight,BMI,SBP,DBP,FBG,PBG,HbA1c,TC,TG,UA,and HOMA-IR values were all significantly lower 6 months postoperative vs at 3 months;and PCP,Fins,Pins,and HOMA-βwere all significantly higher 6 months postoperative vs at 3 months(all P<0.05).CONCLUSION Side-to-side anastomosis of the jejunum and ileum can effectively treat T2DM and improve the metabolic index levels associated with it.展开更多
由于储层埋藏深、造斜点深,塔河油田深水平井定向段和水平段钻进过程中摩阻和扭矩较大,容易造成起下钻困难、易托压等井下复杂事故,而目前普遍采用的聚磺混油钻井液由于后期处理困难,易对环境造成危害。针对这一问题,以自主研发的环保...由于储层埋藏深、造斜点深,塔河油田深水平井定向段和水平段钻进过程中摩阻和扭矩较大,容易造成起下钻困难、易托压等井下复杂事故,而目前普遍采用的聚磺混油钻井液由于后期处理困难,易对环境造成危害。针对这一问题,以自主研发的环保高性能润滑剂SMLUB-E为主要处理剂形成了不混油低摩阻SMO-FREE钻井液体系。室内评价结果表明,SMO-FREE钻井液抗温可达160℃,且润滑性能优异,极压润滑系数为0.095,优于聚磺混油钻井液。SMO-FREE体系在TP154XCH井成功进行了现场应用。钻井过程中钻井液性能稳定,钻进时未出现托压现象,起下钻顺畅,摩阻较低,完钻时摩阻仅为40 k N,展现了SMO-FREE钻井液体系优异的润滑效果。展开更多
Photocatalytic hydrogen peroxide(H_(2)O_(2))production offers a sustainable route to convert water and oxygen into H_(2)O_(2)using solar energy.However,achieving long-term stability in photocatalysts remains a critica...Photocatalytic hydrogen peroxide(H_(2)O_(2))production offers a sustainable route to convert water and oxygen into H_(2)O_(2)using solar energy.However,achieving long-term stability in photocatalysts remains a critical challenge due to mismatched kinetics between oxygen reduction(ORR)and water oxidation(WOR),which leads to hole accumulation and oxidative degradation.Here,we report a redox-mediated strategy to address this bottleneck by designing a hydroquinone-embedded covalent organic framework(Tz-QH-COF)that enables reversible hole buffering and kinetic balance.The hydroquinone(QH)units act as dynamic hole reservoirs,capturing excess holes during ORR and converting to benzoquinone(Q),which is regenerated to QH via WOR,thereby preventing oxidative decomposition.This reversible QH/Q cycle,directly visualized through in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy,ensures unmatched stability,achieving continuous H_(2)O_(2) production for 528 h(22 d)with an accumulated yield of 18.6 mmol L^(–1)—the highest reported duration for organic photocatalysts.Density functional theory calculations reveal that the QH units exhibit a strong oxygen adsorption energy and favorable two-electron ORR/WOR pathways with low energy barriers.The synergy between experimental and theoretical insights elucidates a redox-mediated charge-balance mechanism,advancing the design of robust photocatalysts for solar-driven H_(2)O_(2) synthesis.展开更多
Filler-reinforced polymer composites demonstrate pervasive applications due to their strengthened performances,multi-degree tunability,and ease of manufacturing.In thermal management field,polymer composites reinforce...Filler-reinforced polymer composites demonstrate pervasive applications due to their strengthened performances,multi-degree tunability,and ease of manufacturing.In thermal management field,polymer composites reinforced with thermally conductive fillers are widely adopted as thermal interface materials(TIMs).However,the three dimensional(3D)-stacked heterogenous integration of electronic devices has posed the problem that high-density heat sources are spatially distributed in the package.This situation puts forward new requirements for TIMs,where efficient heat dissipation channels must be established according to the specific distribution of discrete heat sources.To address this challenge,a 3D printing-assisted streamline orientation(3D-PSO)method was proposed to fabricate composite thermal materials with 3D programmable microstructures and orientations of fillers,which combines the shape-design capability of 3D printing and oriented control ability of fluid.The mechanism of fluid-based filler orientation control along streamlines was revealed by mechanical analysis of fillers in matrix.Thanks to the designed heat dissipation channels,composites showed better thermal and mechanical properties in comparison to random composites.Specifically,the thermal conductivity of 3D mesh-shape polydimethylsiloxane/liquid metal(PDMS/LM)composite was5.8 times that of random PDMS/LM composite under filler loading of 34.8 vol%.The thermal conductivity enhancement efficiency of 3D mesh-shape PDMS/carbon fibers composite reached101.05%under filler loading of 5.2 vol%.In the heat dissipation application of 3D-stacked chips,the highest chip temperature with 3D-PSO composite was 42.14℃lower than that with random composites.This is mainly attributed to the locally aggregated and oriented fillers'microstructure in fluid channels,which contributes to thermal percolation phenomena.The3D-PSO method exhibits excellent programmable design capabilities to adopt versatile distributions of heat sources,paving a new way to solve the complicated heat dissipation issue in 3D-stacked chips integration application.展开更多
The travel-time corrections for the primary seismic phases of 72 stations in the Guangdong seismic network,relative to the 1D South China travel-time model,were determined using joint hypocentral determination(JHD)and...The travel-time corrections for the primary seismic phases of 72 stations in the Guangdong seismic network,relative to the 1D South China travel-time model,were determined using joint hypocentral determination(JHD)and statistical analysis methods.The travel-time corrections for the Pg phase of 72 stations range between-0.25 s and 0.14 s,while the corrections for the Sg phase range between 0.27 s and 0.35 s,and those for the Pn phase are between-0.86 s and 0.07 s.The spatial distribution of travel-time corrections for Pg,Sg,and Pn phases of 72 stations correlates well with the geological structure in this region.This indicates that the travel-time corrections for Pg and Sg phases are mainly caused by the discrepancy between the actual crustal velocity structure beneath the stations and the 1D South China travel-time model.These corrections empirically compensate for systematic travel-time errors arising from such discrepancies.The primary factor contributing to the travel-time corrections for the Pn phase is the Moho undulations or tilt.These corrections are intended to compensate for systematic errors in travel time caused by variations in the actual Moho.By integrating the obtained travel-time corrections into the HYPO-SAT location algorithm,test results showed an obvious improvement in location accuracy and origin time precision for explosion events.The variation of horizontal distance between repeating earthquake pairs has also improved,with 86%of the repeating earthquake pair spacing being more accurately estimated after correction.This suggests the crucial significance of travel-time correction in earthquake location,and the consideration of travel-time correction exerts a notable impact on enhancing earthquake location accuracy.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52071053,U1704253,and 52103334).
文摘Traditional stealth materials do not fulfill the requirements of high absorption for radar waves and low emissivity for infrared waves.Furthermore,they can be detected by various technologies,considerably threatening weapon safety.Therefore,a stealth material compatible with radar and infrared was designed based on the photonic bandgap characteristics of photonic crystals.The radar stealth lay-er(bottom layer)is a composite of carbonyl iron/silicon dioxide/epoxy resin,and the infrared stealth layer(top layer)is a 1D photonic crystal with alternately and periodically stacked germanium and silicon nitride.Through composition optimization and structural adjust-ment,the effective absorption bandwidth of the compatible stealth material with a reflection loss of less than-10 dB has reached 4.95 GHz.The average infrared emissivity of the proposed design is 0.1063,indicating good stealth performance.The theoretical analysis proves that photonic crystals with this structural design can produce infrared waves within the photonic bandgap,achieving high radar wave transmittance and low infrared emissivity.Infrared stealth is achieved without affecting the absorption performance of the radar stealth layer,and the conflict between radar and infrared stealth performance is resolved.This work aims to promote the application of photonic crystals in compatible stealth materials and the development of stealth technology and to provide a design and theoretical found-ation for related experiments and research.
文摘BACKGROUND At present,the existing internal medicine drug treatment can alleviate the high glucose toxicity of patients to a certain extent,to explore the efficacy of laparoscopic jejunoileal side to side anastomosis in the treatment of type 2 diabetes,the report is as follows.AIM To investigate the effect of jejunoileal side-to-side anastomosis on metabolic parameters in patients with type 2 diabetes mellitus(T2DM).METHODS We retrospectively analyzed the clinical data of 78 patients with T2DM who were treated via jejunoileal lateral anastomosis.Metabolic indicators were collected preoperatively,as well as at 3 and 6 months postoperative.The metabolic indicators analyzed included body mass index(BMI),systolic blood pressure(SBP),diastolic blood pressure(DBP),fasting blood glucose(FBG),2-hour blood glucose(PBG),glycated hemoglobin(HbA1c),fasting C-peptide,2-hour C-peptide(PCP),fasting insulin(Fins),2-hour insulin(Pins),insulin resistance index(HOMA-IR),βCellular function index(HOMA-β),alanine aminotransferase,aspartate aminotransferase,serum total cholesterol(TC),low-density lipoprotein cholesterol(L DL-C),triglycerides(TG),high-density lipoprotein,and uric acid(UA)levels.RESULTS SBP,DBP,PBG,HbA1c,LDL-C,and TG were all significantly lower 3 months postoperative vs preoperative values;body weight,BMI,SBP,DBP,FBG,PBG,HbA1c,TC,TG,UA,and HOMA-IR values were all significantly lower 6 months postoperative vs at 3 months;and PCP,Fins,Pins,and HOMA-βwere all significantly higher 6 months postoperative vs at 3 months(all P<0.05).CONCLUSION Side-to-side anastomosis of the jejunum and ileum can effectively treat T2DM and improve the metabolic index levels associated with it.
文摘由于储层埋藏深、造斜点深,塔河油田深水平井定向段和水平段钻进过程中摩阻和扭矩较大,容易造成起下钻困难、易托压等井下复杂事故,而目前普遍采用的聚磺混油钻井液由于后期处理困难,易对环境造成危害。针对这一问题,以自主研发的环保高性能润滑剂SMLUB-E为主要处理剂形成了不混油低摩阻SMO-FREE钻井液体系。室内评价结果表明,SMO-FREE钻井液抗温可达160℃,且润滑性能优异,极压润滑系数为0.095,优于聚磺混油钻井液。SMO-FREE体系在TP154XCH井成功进行了现场应用。钻井过程中钻井液性能稳定,钻进时未出现托压现象,起下钻顺畅,摩阻较低,完钻时摩阻仅为40 k N,展现了SMO-FREE钻井液体系优异的润滑效果。
文摘Photocatalytic hydrogen peroxide(H_(2)O_(2))production offers a sustainable route to convert water and oxygen into H_(2)O_(2)using solar energy.However,achieving long-term stability in photocatalysts remains a critical challenge due to mismatched kinetics between oxygen reduction(ORR)and water oxidation(WOR),which leads to hole accumulation and oxidative degradation.Here,we report a redox-mediated strategy to address this bottleneck by designing a hydroquinone-embedded covalent organic framework(Tz-QH-COF)that enables reversible hole buffering and kinetic balance.The hydroquinone(QH)units act as dynamic hole reservoirs,capturing excess holes during ORR and converting to benzoquinone(Q),which is regenerated to QH via WOR,thereby preventing oxidative decomposition.This reversible QH/Q cycle,directly visualized through in situ attenuated total reflection surface-enhanced infrared absorption spectroscopy,ensures unmatched stability,achieving continuous H_(2)O_(2) production for 528 h(22 d)with an accumulated yield of 18.6 mmol L^(–1)—the highest reported duration for organic photocatalysts.Density functional theory calculations reveal that the QH units exhibit a strong oxygen adsorption energy and favorable two-electron ORR/WOR pathways with low energy barriers.The synergy between experimental and theoretical insights elucidates a redox-mediated charge-balance mechanism,advancing the design of robust photocatalysts for solar-driven H_(2)O_(2) synthesis.
基金supported by the National Natural Science Foundation of China(Grant No.52106089)the National Key R&D Project from Ministry of Science and Technology of China(Grant No.2022YFA1203100)。
文摘Filler-reinforced polymer composites demonstrate pervasive applications due to their strengthened performances,multi-degree tunability,and ease of manufacturing.In thermal management field,polymer composites reinforced with thermally conductive fillers are widely adopted as thermal interface materials(TIMs).However,the three dimensional(3D)-stacked heterogenous integration of electronic devices has posed the problem that high-density heat sources are spatially distributed in the package.This situation puts forward new requirements for TIMs,where efficient heat dissipation channels must be established according to the specific distribution of discrete heat sources.To address this challenge,a 3D printing-assisted streamline orientation(3D-PSO)method was proposed to fabricate composite thermal materials with 3D programmable microstructures and orientations of fillers,which combines the shape-design capability of 3D printing and oriented control ability of fluid.The mechanism of fluid-based filler orientation control along streamlines was revealed by mechanical analysis of fillers in matrix.Thanks to the designed heat dissipation channels,composites showed better thermal and mechanical properties in comparison to random composites.Specifically,the thermal conductivity of 3D mesh-shape polydimethylsiloxane/liquid metal(PDMS/LM)composite was5.8 times that of random PDMS/LM composite under filler loading of 34.8 vol%.The thermal conductivity enhancement efficiency of 3D mesh-shape PDMS/carbon fibers composite reached101.05%under filler loading of 5.2 vol%.In the heat dissipation application of 3D-stacked chips,the highest chip temperature with 3D-PSO composite was 42.14℃lower than that with random composites.This is mainly attributed to the locally aggregated and oriented fillers'microstructure in fluid channels,which contributes to thermal percolation phenomena.The3D-PSO method exhibits excellent programmable design capabilities to adopt versatile distributions of heat sources,paving a new way to solve the complicated heat dissipation issue in 3D-stacked chips integration application.
基金supported by the National Key Research and Development Program of China(2023YFC3008605)the Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(311021002)the Seismological Research Foundation for Youths of Guangdong Earthquake Agency(Open Funding Project of Key Laboratory of Earthquake Monitoring and Disaster Mitigation Technology,China Earthquake Administration)(GDDZY202309)。
文摘The travel-time corrections for the primary seismic phases of 72 stations in the Guangdong seismic network,relative to the 1D South China travel-time model,were determined using joint hypocentral determination(JHD)and statistical analysis methods.The travel-time corrections for the Pg phase of 72 stations range between-0.25 s and 0.14 s,while the corrections for the Sg phase range between 0.27 s and 0.35 s,and those for the Pn phase are between-0.86 s and 0.07 s.The spatial distribution of travel-time corrections for Pg,Sg,and Pn phases of 72 stations correlates well with the geological structure in this region.This indicates that the travel-time corrections for Pg and Sg phases are mainly caused by the discrepancy between the actual crustal velocity structure beneath the stations and the 1D South China travel-time model.These corrections empirically compensate for systematic travel-time errors arising from such discrepancies.The primary factor contributing to the travel-time corrections for the Pn phase is the Moho undulations or tilt.These corrections are intended to compensate for systematic errors in travel time caused by variations in the actual Moho.By integrating the obtained travel-time corrections into the HYPO-SAT location algorithm,test results showed an obvious improvement in location accuracy and origin time precision for explosion events.The variation of horizontal distance between repeating earthquake pairs has also improved,with 86%of the repeating earthquake pair spacing being more accurately estimated after correction.This suggests the crucial significance of travel-time correction in earthquake location,and the consideration of travel-time correction exerts a notable impact on enhancing earthquake location accuracy.
