Traumatic brain injury is a severe health problem leading to autophagy and apoptosis in the brain.3,6-Dibromo-beta-fluoro-N-(3-methoxyphenyl)-9H-carbazole-9-propanamine(P7C3-A20)can be neuroprotective in various disea...Traumatic brain injury is a severe health problem leading to autophagy and apoptosis in the brain.3,6-Dibromo-beta-fluoro-N-(3-methoxyphenyl)-9H-carbazole-9-propanamine(P7C3-A20)can be neuroprotective in various diseases,including ischemic stroke and neurodegenerative diseases.However,whether P7C3-A20 has a therapeutic effect on traumatic brain injury and its possible molecular mechanisms are unclear.Therefore,in the present study,we investigated the therapeutic effects of P7C3-A20 on traumatic brain injury and explored the putative underlying molecular mechanisms.We established a traumatic brain injury rat model using a modified weight drop method.P7C3-A20 or vehicle was injected intraperitoneally after traumatic brain injury.Severe neurological deficits were found in rats after traumatic brain injury,with deterioration in balance,walking function,and learning memory.Furthermore,hematoxylin and eosin staining showed significant neuronal cell damage,while terminal deoxynucleotidyl transferase mediated dUTP nick end labeling staining indicated a high rate of apoptosis.The presence of autolysosomes was observed using transmission electron microscope.P7C3-A20 treatment reversed these pathological features.Western blotting showed that P7C3-A20 treatment reduced microtubule-associated protein 1 light chain 3-Ⅱ(LC3-Ⅱ)autophagy protein,apoptosis-related proteins(namely,Bcl-2/adenovirus E1B 19-kDa-interacting protein 3[BNIP3],and Bcl-2 associated x protein[Bax]),and elevated ubiquitin-binding protein p62(p62)autophagy protein expression.Thus,P7C3-A20 can treat traumatic brain injury in rats by inhibiting excessive autophagy and apoptosis.展开更多
Background:Although overnight fasting is recommended prior to endoscopic retrograde cholangiopancreatography(ERCP),the benefits and safety of high-carbohydrate fluid diet(CFD)intake 2 h before ERCP remain unclear.This...Background:Although overnight fasting is recommended prior to endoscopic retrograde cholangiopancreatography(ERCP),the benefits and safety of high-carbohydrate fluid diet(CFD)intake 2 h before ERCP remain unclear.This study aimed to analyze whether high-CFD intake 2 h before ERCP can be safe and accelerate patients’recovery.Methods:This prospective,multicenter,randomized controlled trial involved 15 tertiary ERCP centers.A total of 1330 patients were randomized into CFD group(n=665)and fasting group(n=665).The CFD group received 400 mL of maltodextrin orally 2 h before ERCP,while the control group abstained from food/water overnight(>6 h)before ERCP.All ERCP procedures were performed using deep sedation with intravenous propofol.The investigators were blinded but not the patients.The primary outcomes included postoperative fatigue and abdominal pain score,and the secondary outcomes included complications and changes in metabolic indicators.The outcomes were analyzed according to a modified intention-to-treat principle.Results:The post-ERCP fatigue scores were significantly lower at 4 h(4.1±2.6 vs.4.8±2.8,t=4.23,P<0.001)and 20 h(2.4±2.1 vs.3.4±2.4,t=7.94,P<0.001)in the CFD group,with least-squares mean differences of 0.48(95%confidence interval[CI]:0.26-0.71,P<0.001)and 0.76(95%CI:0.57-0.95,P<0.001),respectively.The 4-h pain scores(2.1±1.7 vs.2.2±1.7,t=2.60,P=0.009,with a least-squares mean difference of 0.21[95%CI:0.05-0.37])and positive urine ketone levels(7.7%[39/509]vs.15.4%[82/533],χ^(2)=15.13,P<0.001)were lower in the CFD group.The CFD group had significantly less cholangitis(2.1%[13/634]vs.4.0%[26/658],χ^(2)=3.99,P=0.046)but not pancreatitis(5.5%[35/634]vs.6.5%[43/658],χ^(2)=0.59,P=0.444).Subgroup analysis revealed that CFD reduced the incidence of complications in patients with native papilla(odds ratio[OR]:0.61,95%CI:0.39-0.95,P=0.028)in the multivariable models.Conclusion:Ingesting 400 mL of CFD 2 h before ERCP is safe,with a reduction in post-ERCP fatigue,abdominal pain,and cholangitis during recovery.Trail Registration:ClinicalTrials.gov,No.NCT03075280.展开更多
The space-air-ground integrated networks (SAGIN) has emerged as a critical paradigm to address the growing demands for global connectivity and enhanced communication services. This paper gives a thorough review of the...The space-air-ground integrated networks (SAGIN) has emerged as a critical paradigm to address the growing demands for global connectivity and enhanced communication services. This paper gives a thorough review of the strategies and methodologies for resource allocation within SAGIN, focusing on the challenges and solutions within its complex structure. With the advent of technologies such as 6G, the dynamics of resource optimization have become increasingly complex, necessitating innovative approaches for efficient management. We examine the application of mathematical optimization, game theory, artificial intelligence (AI), and dynamic optimization techniques in SAGIN,offering insights into their effectiveness in ensuring optimal resource distribution, minimizing delays, and maximizing network throughput and stability. The survey highlights the significant advances in AI-based methods,particularly deep learning and reinforcement learning, in tackling the inherent challenges of SAGIN resource allocation. Through a critical review of existing literature, this paper categorizes various resource allocation strategies, identifies current research gaps, and discusses potential future directions. Our findings highlight the crucial role of integrated and intelligent resource allocation mechanisms in realizing the full potential of SAGIN for next-generation communication networks.展开更多
Background:Pancreatic solid pseudopapillary neoplasms(SPNs)are low-grade malignant tumors of the pancreas.Organ-pre-serving surgery is being increasingly performed for these tumors,although there is little evidence to...Background:Pancreatic solid pseudopapillary neoplasms(SPNs)are low-grade malignant tumors of the pancreas.Organ-pre-serving surgery is being increasingly performed for these tumors,although there is little evidence to support its use.This retro-spective multicenter study aimed to determine the clinicopathologic characteristics of pancreatic SPNs in Central and Western China and to determine the efficacy of organ-preserving surgery.Methods:The clinicopathologic,treatment and follow-up data of 227 pancreatic SPN patients treated between July 2003 and December 2016 at 5 tertiary care centers were retrospectively reviewed.Results:Among the 227 patients(38 males,189 females;mean age 33.30±12.70 years),only 72(31.7%)had symptoms.The mean tumor size was 55.08±29.56 mm.Adjacent organ/lymphovascular invasion was present in 16(7.1%)patients and distant metastasis in 3(1.3%)patients;no patient had spread to distant lymph nodes.Surgery included organ-preserving surgery in 108(47.6%)patients,classic surgery in 115(50.7%)patients,and palliative surgery in 4(1.8%)patients.Tumor recurrence was seen in 8(3.6%)patients.Cox regression analysis showed positive surgical margin(P<.01)and metastasis(P=.03)to be independent predictors of recurrence.Tumor characteristics were comparable between patients receiving organ-preserving surgery and classic surgery.The risk of recurrence was also similar in both groups(P=.72).Conclusions:Organ-preserving surgery appears to be an effective procedure for the treatment of pancreatic SPNs.Resection surgery should aim for negative surgical margins.展开更多
The Doushantuo negative carbon isotope excursion(DOUNCE) is the largest known marine inorganic carbon isotope anomaly. The origin of this pronounced negative excursion is still an enigmatic issue that attracts geologi...The Doushantuo negative carbon isotope excursion(DOUNCE) is the largest known marine inorganic carbon isotope anomaly. The origin of this pronounced negative excursion is still an enigmatic issue that attracts geologists. Time constraints on the excursion are the critical information that would provide insight into its genesis. In previous decades, the timing of its termination has been constrained by the widely cited zircon U-Pb age of 550.5 ± 0.8 Ma for the tuff at the top of the Miaohe Member at the Jiuqunao section in the Yangtze Gorges area, South China. However, results of recent studies indicate that the reliability of this time constraint needs to be re-evaluated. Here, a geochronological study was carried out using two K-bentonites from Fanglong in South China. A K-bentonite in the lower Dengying Formation yielded a U-Pb age of 557 ± 3 Ma, while a K-bentonite in the basal Liuchapo Formation yielded an age of 550 ± 3 Ma. Based on regional correlations between the Ediacaran successions in South China,the age(557 ± 3 Ma) for the K-bentonite in the lower Dengying Formation may serve as a second critical timing constraint for the ending of the DOUNCE. Combined with available estimates of the DOUNCE duration, our new data indicate that the DOUNCE has a maximum onset age ～570 Ma.展开更多
To acquire efficient photocatalysts,it is necessary to make effective use of visible light/Near Infrared(NIR)light,which takes up a large percentage of sunlight.Integrating upconversion materials with visible light ac...To acquire efficient photocatalysts,it is necessary to make effective use of visible light/Near Infrared(NIR)light,which takes up a large percentage of sunlight.Integrating upconversion materials with visible light active photocatalysts has attracted much attention in this regard.The interface contact between upcon-version material and photocatalyst has potential influence on the properties and thus the performance of the system.In this work,NaYF_(4):Yb,Er/CdS composites of the upconversion material NaYF_(4):Yb,Er nanorods and CdS nanoparticles were synthesized by ion adsorption/precipitation process and were then annealed in an argon atmosphere at different temperatures to modulate the microstructures.The annealing pro-cess endows the crystal transformation of cubic CdS with low crystallinity to hexagonal CdS with high crystallinity and,importantly,good interface contact between NaYF_(4):Yb,Er and CdS.Consequently,the hy-drogen evolution activity greatly increases from 171 to 2539μmol h^(−1) g^(−1) under the light irradiation ofλ>400 nm,and from 0 to 19μmol h^(−1) g^(−1) under the light irradiation ofλ>600 nm.This work might provide a useful reference for the rational design of promising photocatalyst involving upconversion ma-terials.展开更多
Reactions between basal 〈a60〉 dislocations and {1012} coherent twin boundaries(CTBs) in a Mg alloy were studied with atomic resolution. Individual dislocation-CTB reactions produced steps with residual dislocations ...Reactions between basal 〈a60〉 dislocations and {1012} coherent twin boundaries(CTBs) in a Mg alloy were studied with atomic resolution. Individual dislocation-CTB reactions produced steps with residual dislocations and multiple t winnin g dislocations(TDs) gliding away, consequently resulting in TB migration. Reactions between {1012} CTBs and low-angle grain boundaries composed of basal 〈a60〉 dislocations created either basal-prismatic/prismatic-basal interfaces or asymmetric tilt grain boundaries, depending on whether TDs gliding away or not. Not only the emission of TDs by dislocation-TB reactions may drive TB migration, but also the resultant steps or facets along TBs can act as TD sources to facilitate TB migration. Our results indicate that roughness or severe loss of local coherency induced by dislocation-TB reactions does not intrinsically impede TB migration in Mg alloys. Dislocation-TB reactions may provide another feasible strategy to improve the ductility of Mg alloys, in addition to other techniques like grain refinement and texture modification.展开更多
Magnesium(Mg^2+))ion plays important roles in biomineralization of bone,teeth and calcium carbonate skeletons.Herein,chicken eggshells mainly comprising of Mg-calcite nanocrystals(Mg/(Mg+Ca)2.0 mol.%)were used to fabr...Magnesium(Mg^2+))ion plays important roles in biomineralization of bone,teeth and calcium carbonate skeletons.Herein,chicken eggshells mainly comprising of Mg-calcite nanocrystals(Mg/(Mg+Ca)2.0 mol.%)were used to fabricate biphasic calcium phosphate(BCP),a mixture of hydroxyapatite(HA)and p-tricalcium phosphate(p-TCP)nanocrystals,through hydrothermal reactions at 200℃for 24 h.Our results indicated thatβ-TCP nanocrystals formed through the ion-exchange reactions of Mg-calcite,while HA nanocrystals were mainly produced by dissolution-reprecipitation reactions on the surfaces of eggshell samples in the hydrothermal system.Mg substitution in calcite resulted in formation ofβ-TCP nanocrystals instead of HA crystals through ion-exchange reactions.BCP samples with different compositions(28.6-77.8 wt.%β-TCP)were produced by controlling particle sizes of eggshells for hydrothermal reactions.The larger particles lead to the larger proportion ofβ-TCP in the BCP composition.Therefore,Mg substitution and particle size had synergetic effects on the hydrothermal synthesis of BCP using chicken eggshells through balance of ion-exchange and dissolution-reprecipitation reactions.Cell culture results showed that the BCP products were non-cytotoxic to MC3 T3-E1 cells,which may be used for bone substitute materials in future.展开更多
A new phase MgYZn4 in Mg-Zn-Y alloy was studied using aberration-corrected scanning-transmission electron microscopy and first-principles calculations. Nanometer-sized MgYZn4 precipitates were formed through ordered s...A new phase MgYZn4 in Mg-Zn-Y alloy was studied using aberration-corrected scanning-transmission electron microscopy and first-principles calculations. Nanometer-sized MgYZn4 precipitates were formed through ordered substitutions of Y with 50% Mg atoms in MgZn2. MgYZn4 has an orthorhombic structure with a space group of Pmnn, and lattice parameters a =5.2965∧, b =9.4886∧, and c =8.5966 ∧. Importantly, both size and structure of MgYZn4 are stable at 625 K for 5 h, showing higher thermostability than MgZn2, which should be important for applications at elevated temperatures. The enhanced thermostability of MgYZn4 is attributed to the lower formation energy and bonding enhancement due to Y substitution.展开更多
To battle with economic challenges during the COVID-19 pandemic,the US government implemented various measures to mitigate economic loss.From issuance of stimulus checks to reopening businesses,consumers had to consta...To battle with economic challenges during the COVID-19 pandemic,the US government implemented various measures to mitigate economic loss.From issuance of stimulus checks to reopening businesses,consumers had to constantly alter their behavior in response to government policies.Using anonymized card transactions and mobile device-based location tracking data,we analyze the factors that contribute to these behavior changes,focusing on stimulus check issuance and state-wide reopening.Our finding suggests that stimulus payment has a significant immediate effect of boosting spending,but it typically does not reverse a downward trend.State-wide reopening had a small effect on spending.Foot traffic increased gradually after stimulus check issuance,but only increased slightly after reopening,which also coincided or preceded several policy changes and confounding events(e.g.,protests)in the US.We also find differences in the reaction to these policies in different regions in the US.Our results may be used to inform future economic recovery policies and their potential consumer response.展开更多
We have investigated the low cycle fatigue(LCF)properties and the extent of strengthening in a dense additively manufactured stainless steel containing different volume fractions of cell structures but having all othe...We have investigated the low cycle fatigue(LCF)properties and the extent of strengthening in a dense additively manufactured stainless steel containing different volume fractions of cell structures but having all other microstructure characteristics the same.The samples were produced by laser powder bed fusion(L-PBF),and the concentration of cell structures was varied systematically by varying the annealing treatments.Load-controlled fatigue experiments performed on samples with a high fraction of cell structures reveal an up to 23 times increase in fatigue life compared to an essentially cell-free sample of the same grain configuration.Multiscale electron microscopy characterizations reveal that the cell structures serve as the soft barriers to the dislocation propagation and the partials are the main carrier for cyclic loading.The cell structures,stabilized by the segregated atoms and misorientation between the adjacent cells,are retained during the entire plastic deformation,hence,can continuously interact with dislocations,promote the formation of nanotwins,and provide massive 3D network obstacles to the dislocation motion.The compositional micro-segregation caused by the cellular solidification features serves as another nonnegligible strengthening mechanism to dislocation motion.Specifically,the cell structures with a high density of dislocation debris also appear to act as dislocation nucleation sites,very much like coherent twin boundaries.This work indicates the potential of additive manufacturing to design energy absorbent alloys with high performance by tailoring the microstructure through the printing process.展开更多
Microstructural evolution during severe plastic deformation and mixing of Mg95.8Zn3.6Gd0.6 and Mg97Cu1Y2(at%)alloys upon friction stir welding was studied.A laminated onion-ring structure composed of alternative distr...Microstructural evolution during severe plastic deformation and mixing of Mg95.8Zn3.6Gd0.6 and Mg97Cu1Y2(at%)alloys upon friction stir welding was studied.A laminated onion-ring structure composed of alternative distribution of layers with signifi cantly refi ned microstructures from diff erent alloys was formed in the stirred zone.Coarse quasicrystals were broken up and dispersed with most of them being transformed into cubic W-phase particles,and thick 18R long-period stacking ordered plates were fractured and transformed into fi ne 14H-LPSO lamellae in the stirred zone(SZ)experiencing complex material flow under high strain rate.Fine W-phase particles and 14H-LPSO lamellae formed during dissimilar friction stir welding(FSW)usually have no specifi c orientation relationship with surrounding Mg matrix.Chemical measurements demonstrated occurrence of interdiff usion between dissimilar layers in the SZ.Phase transformation was observed for some particles of quasicrystals and long-period stacking ordered(LPSO)in regions slightly outside the SZ.An ultimate tensile strength of~415 MPa and an elongation to failure of~27.8%,both exceeding those of base materials,were obtained in the SZ,due to microstructural refi nement and formation of a laminated structure.展开更多
Metal foams with hierarchically porous structures are highly desirable in energy applications as active materials or their host substrates.However,conventional preparation methods usually have a quite limited flexibil...Metal foams with hierarchically porous structures are highly desirable in energy applications as active materials or their host substrates.However,conventional preparation methods usually have a quite limited flexibility of adjusting pore size of metal foams.Herein,an alternative new method based on gaseous thermal oxidation-nitridation-denitridation processes was developed to prepare metal(copper and nickel)foams with adjustable pore size by controlling the thermal nitridation temperature.Moreover,this environment-friendly method is independent of the shape of starting pure metal substrates and can be repeatedly applied to the metal substrates to create hierarchical porous structures containing different size pores.As a demonstration of the advantages of the resultant foams with abundant pores by this method,compared with its starting material(commercial Ni foam with the pore size of several millimeters),the resultant hierarchical porous Ni foam gives the remarkably enhanced performance of electrochemical water splitting as HER/OER electrodes and electrochemical energy storage as the host substrate of capacitive material MnO2.The metal foams with adjustable pore size prepared by the developed method will find a wide range of important applications in energy storage and conversion areas.展开更多
基金supported by National Natural Science Foundation of China,No.32102745(to XL).
文摘Traumatic brain injury is a severe health problem leading to autophagy and apoptosis in the brain.3,6-Dibromo-beta-fluoro-N-(3-methoxyphenyl)-9H-carbazole-9-propanamine(P7C3-A20)can be neuroprotective in various diseases,including ischemic stroke and neurodegenerative diseases.However,whether P7C3-A20 has a therapeutic effect on traumatic brain injury and its possible molecular mechanisms are unclear.Therefore,in the present study,we investigated the therapeutic effects of P7C3-A20 on traumatic brain injury and explored the putative underlying molecular mechanisms.We established a traumatic brain injury rat model using a modified weight drop method.P7C3-A20 or vehicle was injected intraperitoneally after traumatic brain injury.Severe neurological deficits were found in rats after traumatic brain injury,with deterioration in balance,walking function,and learning memory.Furthermore,hematoxylin and eosin staining showed significant neuronal cell damage,while terminal deoxynucleotidyl transferase mediated dUTP nick end labeling staining indicated a high rate of apoptosis.The presence of autolysosomes was observed using transmission electron microscope.P7C3-A20 treatment reversed these pathological features.Western blotting showed that P7C3-A20 treatment reduced microtubule-associated protein 1 light chain 3-Ⅱ(LC3-Ⅱ)autophagy protein,apoptosis-related proteins(namely,Bcl-2/adenovirus E1B 19-kDa-interacting protein 3[BNIP3],and Bcl-2 associated x protein[Bax]),and elevated ubiquitin-binding protein p62(p62)autophagy protein expression.Thus,P7C3-A20 can treat traumatic brain injury in rats by inhibiting excessive autophagy and apoptosis.
文摘Background:Although overnight fasting is recommended prior to endoscopic retrograde cholangiopancreatography(ERCP),the benefits and safety of high-carbohydrate fluid diet(CFD)intake 2 h before ERCP remain unclear.This study aimed to analyze whether high-CFD intake 2 h before ERCP can be safe and accelerate patients’recovery.Methods:This prospective,multicenter,randomized controlled trial involved 15 tertiary ERCP centers.A total of 1330 patients were randomized into CFD group(n=665)and fasting group(n=665).The CFD group received 400 mL of maltodextrin orally 2 h before ERCP,while the control group abstained from food/water overnight(>6 h)before ERCP.All ERCP procedures were performed using deep sedation with intravenous propofol.The investigators were blinded but not the patients.The primary outcomes included postoperative fatigue and abdominal pain score,and the secondary outcomes included complications and changes in metabolic indicators.The outcomes were analyzed according to a modified intention-to-treat principle.Results:The post-ERCP fatigue scores were significantly lower at 4 h(4.1±2.6 vs.4.8±2.8,t=4.23,P<0.001)and 20 h(2.4±2.1 vs.3.4±2.4,t=7.94,P<0.001)in the CFD group,with least-squares mean differences of 0.48(95%confidence interval[CI]:0.26-0.71,P<0.001)and 0.76(95%CI:0.57-0.95,P<0.001),respectively.The 4-h pain scores(2.1±1.7 vs.2.2±1.7,t=2.60,P=0.009,with a least-squares mean difference of 0.21[95%CI:0.05-0.37])and positive urine ketone levels(7.7%[39/509]vs.15.4%[82/533],χ^(2)=15.13,P<0.001)were lower in the CFD group.The CFD group had significantly less cholangitis(2.1%[13/634]vs.4.0%[26/658],χ^(2)=3.99,P=0.046)but not pancreatitis(5.5%[35/634]vs.6.5%[43/658],χ^(2)=0.59,P=0.444).Subgroup analysis revealed that CFD reduced the incidence of complications in patients with native papilla(odds ratio[OR]:0.61,95%CI:0.39-0.95,P=0.028)in the multivariable models.Conclusion:Ingesting 400 mL of CFD 2 h before ERCP is safe,with a reduction in post-ERCP fatigue,abdominal pain,and cholangitis during recovery.Trail Registration:ClinicalTrials.gov,No.NCT03075280.
基金supported in part by the National Key Research and Development Program of China(2022YFB3608600)National Natural Science Foundation of China(62134006,62204193,62374122 and 62127812)+2 种基金China Postdoctoral Science Foundation(2021TQ0256)Key research and development program of Anhui Province(2023a05020006)Key R&D Plan of Shandong Province(2022CXGC020306).
基金supported by the Key Area Research and Development Program of Guangdong Province under Grant 2020B0101110003in part by Dongguan Science and Technology Special Commissioner Foundation under Grant 20231800500222.
文摘The space-air-ground integrated networks (SAGIN) has emerged as a critical paradigm to address the growing demands for global connectivity and enhanced communication services. This paper gives a thorough review of the strategies and methodologies for resource allocation within SAGIN, focusing on the challenges and solutions within its complex structure. With the advent of technologies such as 6G, the dynamics of resource optimization have become increasingly complex, necessitating innovative approaches for efficient management. We examine the application of mathematical optimization, game theory, artificial intelligence (AI), and dynamic optimization techniques in SAGIN,offering insights into their effectiveness in ensuring optimal resource distribution, minimizing delays, and maximizing network throughput and stability. The survey highlights the significant advances in AI-based methods,particularly deep learning and reinforcement learning, in tackling the inherent challenges of SAGIN resource allocation. Through a critical review of existing literature, this paper categorizes various resource allocation strategies, identifies current research gaps, and discusses potential future directions. Our findings highlight the crucial role of integrated and intelligent resource allocation mechanisms in realizing the full potential of SAGIN for next-generation communication networks.
基金This work was supported by the National Natural Science Foundation of China(grant number 81472309).
文摘Background:Pancreatic solid pseudopapillary neoplasms(SPNs)are low-grade malignant tumors of the pancreas.Organ-pre-serving surgery is being increasingly performed for these tumors,although there is little evidence to support its use.This retro-spective multicenter study aimed to determine the clinicopathologic characteristics of pancreatic SPNs in Central and Western China and to determine the efficacy of organ-preserving surgery.Methods:The clinicopathologic,treatment and follow-up data of 227 pancreatic SPN patients treated between July 2003 and December 2016 at 5 tertiary care centers were retrospectively reviewed.Results:Among the 227 patients(38 males,189 females;mean age 33.30±12.70 years),only 72(31.7%)had symptoms.The mean tumor size was 55.08±29.56 mm.Adjacent organ/lymphovascular invasion was present in 16(7.1%)patients and distant metastasis in 3(1.3%)patients;no patient had spread to distant lymph nodes.Surgery included organ-preserving surgery in 108(47.6%)patients,classic surgery in 115(50.7%)patients,and palliative surgery in 4(1.8%)patients.Tumor recurrence was seen in 8(3.6%)patients.Cox regression analysis showed positive surgical margin(P<.01)and metastasis(P=.03)to be independent predictors of recurrence.Tumor characteristics were comparable between patients receiving organ-preserving surgery and classic surgery.The risk of recurrence was also similar in both groups(P=.72).Conclusions:Organ-preserving surgery appears to be an effective procedure for the treatment of pancreatic SPNs.Resection surgery should aim for negative surgical margins.
基金supported by the National Natural Science Foundation of China (41462001, 41072054)the Project of National Key Research and Development Program of China (2016YFC0502601)
文摘The Doushantuo negative carbon isotope excursion(DOUNCE) is the largest known marine inorganic carbon isotope anomaly. The origin of this pronounced negative excursion is still an enigmatic issue that attracts geologists. Time constraints on the excursion are the critical information that would provide insight into its genesis. In previous decades, the timing of its termination has been constrained by the widely cited zircon U-Pb age of 550.5 ± 0.8 Ma for the tuff at the top of the Miaohe Member at the Jiuqunao section in the Yangtze Gorges area, South China. However, results of recent studies indicate that the reliability of this time constraint needs to be re-evaluated. Here, a geochronological study was carried out using two K-bentonites from Fanglong in South China. A K-bentonite in the lower Dengying Formation yielded a U-Pb age of 557 ± 3 Ma, while a K-bentonite in the basal Liuchapo Formation yielded an age of 550 ± 3 Ma. Based on regional correlations between the Ediacaran successions in South China,the age(557 ± 3 Ma) for the K-bentonite in the lower Dengying Formation may serve as a second critical timing constraint for the ending of the DOUNCE. Combined with available estimates of the DOUNCE duration, our new data indicate that the DOUNCE has a maximum onset age ～570 Ma.
基金supported by the National Natural Science Foundation of China (Nos. 51825204 and 52072379)。
文摘To acquire efficient photocatalysts,it is necessary to make effective use of visible light/Near Infrared(NIR)light,which takes up a large percentage of sunlight.Integrating upconversion materials with visible light active photocatalysts has attracted much attention in this regard.The interface contact between upcon-version material and photocatalyst has potential influence on the properties and thus the performance of the system.In this work,NaYF_(4):Yb,Er/CdS composites of the upconversion material NaYF_(4):Yb,Er nanorods and CdS nanoparticles were synthesized by ion adsorption/precipitation process and were then annealed in an argon atmosphere at different temperatures to modulate the microstructures.The annealing pro-cess endows the crystal transformation of cubic CdS with low crystallinity to hexagonal CdS with high crystallinity and,importantly,good interface contact between NaYF_(4):Yb,Er and CdS.Consequently,the hy-drogen evolution activity greatly increases from 171 to 2539μmol h^(−1) g^(−1) under the light irradiation ofλ>400 nm,and from 0 to 19μmol h^(−1) g^(−1) under the light irradiation ofλ>600 nm.This work might provide a useful reference for the rational design of promising photocatalyst involving upconversion ma-terials.
基金supported by the National Natural Science Foundation of China [51971225, 51771202, 51771201]Key Research Program of Frontier Sciences, CAS [QYZDY-SSW-JSC027]。
文摘Reactions between basal 〈a60〉 dislocations and {1012} coherent twin boundaries(CTBs) in a Mg alloy were studied with atomic resolution. Individual dislocation-CTB reactions produced steps with residual dislocations and multiple t winnin g dislocations(TDs) gliding away, consequently resulting in TB migration. Reactions between {1012} CTBs and low-angle grain boundaries composed of basal 〈a60〉 dislocations created either basal-prismatic/prismatic-basal interfaces or asymmetric tilt grain boundaries, depending on whether TDs gliding away or not. Not only the emission of TDs by dislocation-TB reactions may drive TB migration, but also the resultant steps or facets along TBs can act as TD sources to facilitate TB migration. Our results indicate that roughness or severe loss of local coherency induced by dislocation-TB reactions does not intrinsically impede TB migration in Mg alloys. Dislocation-TB reactions may provide another feasible strategy to improve the ductility of Mg alloys, in addition to other techniques like grain refinement and texture modification.
基金supported by the National Key Research and Development Program of China from Ministry of Science and Technology(2016YFC1100502)Key Research Program of Frontier Sciences(QYZDJ-SSW-JSC031)from Chinese Academy of Sciences(CAS)+1 种基金Key Research and Development Program of Liaoning Province(2017105005)Shenyang Key R&D and Technology Transfer Program(Z17-7-023)。
文摘Magnesium(Mg^2+))ion plays important roles in biomineralization of bone,teeth and calcium carbonate skeletons.Herein,chicken eggshells mainly comprising of Mg-calcite nanocrystals(Mg/(Mg+Ca)2.0 mol.%)were used to fabricate biphasic calcium phosphate(BCP),a mixture of hydroxyapatite(HA)and p-tricalcium phosphate(p-TCP)nanocrystals,through hydrothermal reactions at 200℃for 24 h.Our results indicated thatβ-TCP nanocrystals formed through the ion-exchange reactions of Mg-calcite,while HA nanocrystals were mainly produced by dissolution-reprecipitation reactions on the surfaces of eggshell samples in the hydrothermal system.Mg substitution in calcite resulted in formation ofβ-TCP nanocrystals instead of HA crystals through ion-exchange reactions.BCP samples with different compositions(28.6-77.8 wt.%β-TCP)were produced by controlling particle sizes of eggshells for hydrothermal reactions.The larger particles lead to the larger proportion ofβ-TCP in the BCP composition.Therefore,Mg substitution and particle size had synergetic effects on the hydrothermal synthesis of BCP using chicken eggshells through balance of ion-exchange and dissolution-reprecipitation reactions.Cell culture results showed that the BCP products were non-cytotoxic to MC3 T3-E1 cells,which may be used for bone substitute materials in future.
基金supported by the National Natural Science Foundation of China (Nos.51390473, 51371178, 51771202)the Key Research Program of Frontier Sciences, CAS (No. QYZDY-SSWJSC027)
文摘A new phase MgYZn4 in Mg-Zn-Y alloy was studied using aberration-corrected scanning-transmission electron microscopy and first-principles calculations. Nanometer-sized MgYZn4 precipitates were formed through ordered substitutions of Y with 50% Mg atoms in MgZn2. MgYZn4 has an orthorhombic structure with a space group of Pmnn, and lattice parameters a =5.2965∧, b =9.4886∧, and c =8.5966 ∧. Importantly, both size and structure of MgYZn4 are stable at 625 K for 5 h, showing higher thermostability than MgZn2, which should be important for applications at elevated temperatures. The enhanced thermostability of MgYZn4 is attributed to the lower formation energy and bonding enhancement due to Y substitution.
文摘To battle with economic challenges during the COVID-19 pandemic,the US government implemented various measures to mitigate economic loss.From issuance of stimulus checks to reopening businesses,consumers had to constantly alter their behavior in response to government policies.Using anonymized card transactions and mobile device-based location tracking data,we analyze the factors that contribute to these behavior changes,focusing on stimulus check issuance and state-wide reopening.Our finding suggests that stimulus payment has a significant immediate effect of boosting spending,but it typically does not reverse a downward trend.State-wide reopening had a small effect on spending.Foot traffic increased gradually after stimulus check issuance,but only increased slightly after reopening,which also coincided or preceded several policy changes and confounding events(e.g.,protests)in the US.We also find differences in the reaction to these policies in different regions in the US.Our results may be used to inform future economic recovery policies and their potential consumer response.
基金financially supported by the Swedish Governmental Agency for Innovation Systems(Vinnova grant No.2016–05175)the Center for Additive Manufacturingmetal(CAM2)+2 种基金financially supported in part by a research grant from Science Foundation Ireland(SFI)under Grant No.16/RC/3872cofounded under the European Regional Development Fund and by the I-Form industry partnersfinancial support(Grant No.X210141TL210)。
文摘We have investigated the low cycle fatigue(LCF)properties and the extent of strengthening in a dense additively manufactured stainless steel containing different volume fractions of cell structures but having all other microstructure characteristics the same.The samples were produced by laser powder bed fusion(L-PBF),and the concentration of cell structures was varied systematically by varying the annealing treatments.Load-controlled fatigue experiments performed on samples with a high fraction of cell structures reveal an up to 23 times increase in fatigue life compared to an essentially cell-free sample of the same grain configuration.Multiscale electron microscopy characterizations reveal that the cell structures serve as the soft barriers to the dislocation propagation and the partials are the main carrier for cyclic loading.The cell structures,stabilized by the segregated atoms and misorientation between the adjacent cells,are retained during the entire plastic deformation,hence,can continuously interact with dislocations,promote the formation of nanotwins,and provide massive 3D network obstacles to the dislocation motion.The compositional micro-segregation caused by the cellular solidification features serves as another nonnegligible strengthening mechanism to dislocation motion.Specifically,the cell structures with a high density of dislocation debris also appear to act as dislocation nucleation sites,very much like coherent twin boundaries.This work indicates the potential of additive manufacturing to design energy absorbent alloys with high performance by tailoring the microstructure through the printing process.
基金financially supported by the National Nature Science Foundation of China(Nos.51771202,51971225,U1760201)the Key Research Program of Frontier Science,Chinese Academy of Sciences(No.QYZDY-SSW-JSC207)。
文摘Microstructural evolution during severe plastic deformation and mixing of Mg95.8Zn3.6Gd0.6 and Mg97Cu1Y2(at%)alloys upon friction stir welding was studied.A laminated onion-ring structure composed of alternative distribution of layers with signifi cantly refi ned microstructures from diff erent alloys was formed in the stirred zone.Coarse quasicrystals were broken up and dispersed with most of them being transformed into cubic W-phase particles,and thick 18R long-period stacking ordered plates were fractured and transformed into fi ne 14H-LPSO lamellae in the stirred zone(SZ)experiencing complex material flow under high strain rate.Fine W-phase particles and 14H-LPSO lamellae formed during dissimilar friction stir welding(FSW)usually have no specifi c orientation relationship with surrounding Mg matrix.Chemical measurements demonstrated occurrence of interdiff usion between dissimilar layers in the SZ.Phase transformation was observed for some particles of quasicrystals and long-period stacking ordered(LPSO)in regions slightly outside the SZ.An ultimate tensile strength of~415 MPa and an elongation to failure of~27.8%,both exceeding those of base materials,were obtained in the SZ,due to microstructural refi nement and formation of a laminated structure.
基金the National Natural Science Foundation of China(51825204)the Key Research Program of Frontier Sciences CAS(QYZDB-SSW-JSC039)。
文摘Metal foams with hierarchically porous structures are highly desirable in energy applications as active materials or their host substrates.However,conventional preparation methods usually have a quite limited flexibility of adjusting pore size of metal foams.Herein,an alternative new method based on gaseous thermal oxidation-nitridation-denitridation processes was developed to prepare metal(copper and nickel)foams with adjustable pore size by controlling the thermal nitridation temperature.Moreover,this environment-friendly method is independent of the shape of starting pure metal substrates and can be repeatedly applied to the metal substrates to create hierarchical porous structures containing different size pores.As a demonstration of the advantages of the resultant foams with abundant pores by this method,compared with its starting material(commercial Ni foam with the pore size of several millimeters),the resultant hierarchical porous Ni foam gives the remarkably enhanced performance of electrochemical water splitting as HER/OER electrodes and electrochemical energy storage as the host substrate of capacitive material MnO2.The metal foams with adjustable pore size prepared by the developed method will find a wide range of important applications in energy storage and conversion areas.
