The hot deformation behaviors of sulfur-containing gear steel 20MnCr5 containing three different contents of Nb and B(0,0.021%Nb,and 0.024%Nb-0.0022%B)were investigated.Hot compression and tenssion tests were carried ...The hot deformation behaviors of sulfur-containing gear steel 20MnCr5 containing three different contents of Nb and B(0,0.021%Nb,and 0.024%Nb-0.0022%B)were investigated.Hot compression and tenssion tests were carried out by Gleeble3800 at the austenite region from 850 to 1150℃and the adverse effects of Nb and B were analyzed by the fracture,microstructure and precipitate observations.Hot compression tests showed that the proportions of instable area in hot processing maps of 0.021%Nb and Nb-B steels were higher and the deformability of Nb free steel was better.The tensile deformation experiments showed that the reduction areas of Nb free,0.021%Nb and Nb-B steels were 92%-99%,84%-98%and 67%-97%,respectively.The addition of Nb or Nb and B inhibited the dynamic recrystallization during hot deformation,and consequently,more deformed grains were then formed in 0.021%Nb and Nb-B steels thus to obtain the microstructure with worse uniformity and then deteriorate the deformability.In addition,the interaction between inclusions and microalloyed elements was also significant.NbC particles of 0.021%Nb and Nb-B steels dynamically precipitated during deformation and precipitated together with MnS thus to worsen the deformability,resulting in the decrease of reduction area.展开更多
Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction m...Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction mechanism and phase evolution of the low-temperature selective chlorination process of Nd-Fe-B sludge are not clear.In this paper,we systematically investigated the lowtemperature selective chlorination process of Nd-Fe-B sludge with NH4Cl by combining thermokinetic theoretical calculations and experiments,and revealed its reaction mechanism.The phase evolution during chlorination was determined by X-ray diffraction(XRD),scanning electron microscopy(SEM)and ene rgy-dispersive X-ray spectroscopy(EDS)characterization as well as co mputational analysis of the phase stability diagram of the M-O-Cl system.To determine the optimum chlorination conditions,the effects of chlorinating agent dosage,reaction temperature and reaction time on the reaction were investigated.The results show that the rare earth components in Nd-Fe-B sludge are selectively chlorinated to RECl3and the formation of REOCl is avoided in the temperature range of 300-420℃,while the iron components are preferentially oxidized to Fe2O3.The selective chlorination reaction is consistent with the unreacted shrinking core model,and the rate-controlling step of the reaction is the internal diffusion process of NH4Cl through the transition layer of the reactant product to the surface of the Nd-Fe-B sludge.The complete chlorination of REEs is successfully achieved and 99.8%of REEs are selectively extracted into the leaching solution under optimal chlorination conditions(300℃,2.5 times of stoichiometric amount,4 h).展开更多
Objective:Huachansu injection(HCSI),a promising anti-cancer Chinese medicine injection,has been reported to have the potential for reducing the toxicity of chemotherapy and improving the quality of life for colorectal...Objective:Huachansu injection(HCSI),a promising anti-cancer Chinese medicine injection,has been reported to have the potential for reducing the toxicity of chemotherapy and improving the quality of life for colorectal cancer(CRC)patients.The objective of this study is to explore the synergistic and detoxifying effects of HCSI when used in combination with irinotecan(CPT-11).Methods:To investigate the effect of HCSI on anti-CRC efficacy and intestinal toxicity of CPT-11,we measured changes in the biological behavior of LoV o cells in vitro,and anti-tumor effects in LoV o cell xenograft nude mice models in vivo.Meanwhile,the effect of HCSI on intestinal toxicity and the uridine diphosphateglucuronosyltransferase 1A1(UGT1A1)expression was investigated in the CPT-11-induced colitis mouse model.Subsequently,we measured the effect of HCSI and its 13 constituent bufadienolides on the expression of UGT1A1 and organic anion transporting polypeptides 1B3(OATP1B3)in HepG 2 cells.Results:The combination index(CI)results showed that the combination of HCSI and CPT-11 exhibited a synergistic effect(CI<1),which significantly suppressing the LoV o cell migration,enhancing G2/M and S phase arrest,and inhibiting tumor growth in vivo.Additionally,the damage to intestinal tissues was attenuated by HCSI in CPT-11-induced colitis model,while the increased expression of UGT1A1 in HepG 2 cells and in mouse was observed.Conclusion:The co-therapy with HCSI alleviated the intestinal toxicity induced by CPT-11 and exerted an enhanced anti-CRC effect.The detoxifying mechanism may be related to the increased expression of UGT1A1 and OATP1B3 by HCSI and its bufadienolides components.The findings of this study may serve as a theoretical insights and strategies to improve CRC patient outcomes.展开更多
The in-depth exploration of the multi-dimensional disaster-causing mechanisms associated with battery thermal runaway facilitates the whole-process safety evaluation.However,the still insufficient understanding of the...The in-depth exploration of the multi-dimensional disaster-causing mechanisms associated with battery thermal runaway facilitates the whole-process safety evaluation.However,the still insufficient understanding of the thermal failure process and the limited dimensionality of the existing evaluation indexes subsequently lead to ineffective prevention and control and finally result in a high frequency of severe damage and unforeseen casualties.To address this issue,a general framework for evaluating the whole-process safety by integrating thermal and gas perspectives,involving dozens of multidimensional characteristic parameters obtained by experimental measurements and theoretical calculations,is proposed.Based on this framework,comparing the initial thermal hazards of lithium iron phosphate and nickel-cobalt-manganese lithium-ion batteries and quantifying the derived hazards of singlephase/multi-phase emissions considering battery venting gases and electrolyte solvent vapors,the significant hidden hazards of emissions dominated by reductive components that can lead to higher derived explosion and combustion risks within the external environment are identified,effectively updating the previous paradigm for evaluating cell-level thermal safety.For single-phase emissions with dominant reductive components,higher risks of low lower explosion limit and high laminar burning velocity are demonstrated;after considering typical solvent vapor types(dimethyl carbonate/ethyl methyl carbonate/diethyl carbonate)and specific mixing ratios,highly reductive multi-phase emissions still exhibit higher risks.The proposed framework reveals the underlying effect of the reductive gas-phase emissions in accelerating and aggravating system-level thermal hazards,providing important guidance and inspiration for the whole-process safety control based on gas-phase atmosphere regulation as well as for the overall safety evaluation of emerging battery material chemistries.展开更多
Styrene-butadiene-styrene(SBS)modified asphalt(SA)has long found effective applications in road construction materials.When combined with fillers,SBS-modified asphalt has demonstrated promising resistance to fatigue c...Styrene-butadiene-styrene(SBS)modified asphalt(SA)has long found effective applications in road construction materials.When combined with fillers,SBS-modified asphalt has demonstrated promising resistance to fatigue cracking caused by temperature fluctuations and aging.In this study,molybdenum disulfide(MoS_(2))and polyphosphoric acid(PPA)were ground in naphthenic oil(NO)and subjected to mechanical activation to create PPAmodified MoS_(2),referred to as OMS-PPA.By blending various ratios of OMS-PPA with SBS-modified asphalt,composite-modified asphalts were successfully developed to enhance their overall properties.To assess the mechanical characteristics and stability of these modified asphalts,various methods were employed,including penetration factor,flow activation energy,fluorescence microscopy,and dynamic shear rheology.Additionally,the short-term aging performance was evaluated using Fourier transform infrared(FTIR)spectroscopy and nanoindentation tests.The results revealed a 3.7%decrease in the penetration-temperature coefficient for SAOMS compared to SA,while 1-SA-OMS-PPA showed an even greater reduction of 7.1%.Furthermore,after short-term aging,carboxyl group generation in SA increased by 5.93%,while SA-OMS exhibited a smaller rise of 1.36%,and 1-SA-OMS-PPA saw an increase of just 0.93%.The study also highlighted significant improvements in the hardness of these materials.The hardness change ratio for SA-OMS decreased by 43.08%,while the ratio for 1-SA-OMS-PPA saw a notable reduction of 65.16% compared to unmodified SA.These findings suggest that OMS-PPA contributed to improvements in temperature sensitivity,particle dispersibility,and resistance to shortterm aging in asphalts.The results hold significant promise for the future development of advanced asphalt-based materials with potential high-value applications in flexible pavements for highways.展开更多
A new oxidative N-heterocyclic carbene(NHC)-catalyzed high-order[7+3]annulation reaction ofγ-indolyl phenols as 1,7-dinucleophiles andα,β-alkynals with the aid of Sc(OTf)_(3)is reported,enabling the highly regiosel...A new oxidative N-heterocyclic carbene(NHC)-catalyzed high-order[7+3]annulation reaction ofγ-indolyl phenols as 1,7-dinucleophiles andα,β-alkynals with the aid of Sc(OTf)_(3)is reported,enabling the highly regioselective access to unprecedented polyarene-fused ten-membered lactams bearing a bridged aryl-aryl-indole scaffold in moderate to good yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and complete regioselectivity,providing an organocatalytic modular synthetic strategy for creating medium-sized lactams.展开更多
Lightweight aluminum alloy conductor materials(Al-Mg-Si alloys)require not only high electrical conductivity to reduce electrical loss,but also high strength to withstand extreme weather conditions.To improve electric...Lightweight aluminum alloy conductor materials(Al-Mg-Si alloys)require not only high electrical conductivity to reduce electrical loss,but also high strength to withstand extreme weather conditions.To improve electrical conductivity and mechanical properties of Al-Mg-Si alloy simultaneously,the rare earth La was introduced to modify the Al-Mg-Si alloy.The effect of La addition on the microstructure,tensile properties and electrical conductivity of cast Al-Mg-Si alloy was investigated systematically.Results indicate that the appropriate La content is helpful to improve the strength and electrical conductivity of Al-Mg-Si alloys.When the addition of La is 0.2wt.%,theα-Al grains are refined apparently,Mg and Si solute atoms in the Al matrix are reduced by the formation of Mg_(2)Si phase;the distribution of Al_(11)La_(3)phases is uniform,and the morphology of AlFeSi phase transforms from continuous state to discontinuous state.The Al-Mg-Si-0.2La alloy exhibits the optimal tensile properties and electrical conductivity,with an ultimate tensile strength of 170 MPa,a yield strength of 88 MPa,an elongation of 18.9%,and an electrical conductivity of 44.0%IACS.These values represent improvements of 9.0%,15.8%,70.3%,and 17.3%,respectively,compared to the Al-Mg-Si alloy without La addition.However,excessive La deteriorates the properties of Al-Mg-Si-xLa alloys.展开更多
The degradation of Lithium-ion batteries(LIBs)during cycling is particularly exacerbated at low temperatures,which has a significant impact on the longevity of electric vehicles,energy storage systems,and consumer ele...The degradation of Lithium-ion batteries(LIBs)during cycling is particularly exacerbated at low temperatures,which has a significant impact on the longevity of electric vehicles,energy storage systems,and consumer electronics.A comprehensive understanding of the low-temperature aging mechanisms throughout the whole life cycle of LIBs is crucial.However,existing research is limited,which typically focuses on capacity degradation to 80%.To fill this gap,this paper conducts low-temperature cyclic aging tests at three different charging rates.The investigation employs differential voltage analysis,the distribution of relaxation times technique,and disassembly characterization to explore both thermodynamic degradation and kinetic degradation,alongside a correlation analysis of the factors influencing these degradation processes.The results reveal two distinct knee points in the capacity decline of LIBs during the whole life cycle,in contrast to prior studies identifying only one.Before the first knee point,the thickening of the SEI film dominates capacity loss,with higher charging rates accelerating the process.After the first knee point,the main degradation mechanisms shift to lithium plating and the fracture of the positive electrode active particles.These two aging factors become more pronounced with ongoing cycling,culminating in a second knee point in capacity decline.Notably,a novel finding demonstrates that after the second knee point,capacity degradation progresses faster at lower charging rates compared to medium rates.The reason is the fracture of graphite particles also becomes a critical contributor to the severe capacity degradation at lower charging rates.These insights will guide the designs of next-generation low-temperature LIBs and low-temperature battery management systems.展开更多
Background Clearance of coronary arterial thrombosis is necessary in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing urgent percutaneous coronary intervention (PCI). There is currentl...Background Clearance of coronary arterial thrombosis is necessary in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing urgent percutaneous coronary intervention (PCI). There is currently no highly-recommended method of thrombus removal during interventional procedures. We describe a new method for opening culprit vessels to treat STEMI: intracoronary arterial retrograde thrombolysis (ICART) with PCI. Methods & Results Eight patients underwent ICART. The guidewire was advanced to the distal coronary artery through the occlusion lesion. Then, we inserted a microcatheter into the distal end of the occluded coronary artery over the guidewire. Urokinase (5–10 wu) mixed with contrast agents was slowly injected into the occluded section of the coronary artery through the microcatheter. The intracoronary thrombus gradually dissolved in 3–17 min, and the effect of thrombolysis was visible in real time. Stents were then implanted according to the characteristics of the recanalized culprit lesion to achieve full revascularization. One patient experienced premature ventricular contraction during vascular revascularization, and no malignant arrhythmias were seen in any patient. No reflow or slow flow was not observed post PCI. Thrombolysis in myocardial infarction flow grade and myocardial blush grade post-primary PCI was 3 in all eight patients. No patients experienced bleeding or stroke. Conclusions ICART was accurate and effective for treating intracoronary thrombi in patients with STEMI in this preliminary study. ICART was an effective, feasible, and simple approach to the management of STEMI, and no intraprocedural complications occurred in any of the patients. ICART may be a breakthrough in the treatment of acute STEMI.展开更多
Aegilops variabilis(S^(v)S^(v)U^(v)U^(v))is a source of resistance to wheat stripe rust.The phKL locus in Chinese common wheat landrace Kaixian-Luohanmai(KL)can induce homoeologous wheat-alien chromosome pairing and r...Aegilops variabilis(S^(v)S^(v)U^(v)U^(v))is a source of resistance to wheat stripe rust.The phKL locus in Chinese common wheat landrace Kaixian-Luohanmai(KL)can induce homoeologous wheat-alien chromosome pairing and recombination.In this study,we confirmed that the whole 2S^(v)chromosome introgressed into wheat from Ae.variabilis accession AS116 conferred all-stage stripe rust resistance.The underlying gene(s),named YrAev,was mapped to the long arm 2S^(v)L using an F_(2)population.Two 2S^(v)-2B recombinants,derived from a cross of the 2S^(v)(2B)chromosome substitution line and KL,were confirmed to harbor the resistance locus.The physical region containing YrAev,determined from RNA-seq data,was 844.6-852.1 Mb on the chromosome arm 2S^(l)of the Ae.longissima(S^(v)genome donor species of Ae.variabilis)accession TL05 assembly v1.0.Differential gene expression analysis of post-inoculation with the Pst race has indicated two disease-resistance-related genes(annotated as mixed lineage kinase domain-like protein and nucleotide-binding leucine-rich repeat like protein,respectively)as promising candidates for YrAev.This study demonstrates the utility of the phKL gene system in alien gene localization and transfer.The resistant translocation line harboring YrAev can be exploited by wheat breeders as a novel source of resistance to stripe rust.展开更多
AIM:To assess the value of double-balloon enteroscopy(DBE) for the diagnosis of gastrointestinal mesenchymal tumors(GIMTs) in the small bowel and clarify their clinical and endoscopic characteristics.METHODS:A retrosp...AIM:To assess the value of double-balloon enteroscopy(DBE) for the diagnosis of gastrointestinal mesenchymal tumors(GIMTs) in the small bowel and clarify their clinical and endoscopic characteristics.METHODS:A retrospective review in a total of 783 patients who underwent a DBE procedure from January 2003 to December 2011 was conducted.Data from patients with pathologically confirmed GIMTs were analyzed at a single tertiary center with nine years' experience.The primary outcomes assessed included characteristics of patients with GIMTs,indications for DBE,overall diagnostic yield of GIMTs,endoscopic morphology,positive biopsy,comparison of diagnosis with capsule endoscopy,and subsequent interventional management.RESULTS:GIMTs were identified and analyzed in 77 patients.The mean age was 47.74 ± 14.14 years(range:20-77 years),with 63.6% being males.The majority of individuals presented with gastrointestinal bleeding,accounting for 81.8%,followed by abdominal pain,accounting for 10.4%.Small bowel pathologies were found in 71 patients,the detection rate was 92.2%.The diagnostic yield of DBE for GIMTs was 88.3%.DBE was superior to capsule endoscopy in the diagnosis of GIMTs(P = 0.006;McNemar's χ2 test).Gastrointestinal stromal tumor was the most frequent and leiomyoma was the second frequent GIMT.Single and focal lesions were typical of GIMTs,and masses with smooth or unsmooth surface were the most common in the small bowel.GIMTs were removed from all the patients surgically except one patient treated with endoscopic resection.CONCLUSION:DBE is a safe and valuable procedure for patients with suspected GIMTs,and it provides an accurate position for subsequent surgical intervention.展开更多
Objective To evaluate the clinical impact of whole body diffusion weighted imaging （WB-DWI） on diagnosis and staging of malignant lymphoma. Methods Thirty-one patients with suspected lymphadenopathy were enrolled. ...Objective To evaluate the clinical impact of whole body diffusion weighted imaging （WB-DWI） on diagnosis and staging of malignant lymphoma. Methods Thirty-one patients with suspected lymphadenopathy were enrolled. WB-DWI was performed by using short TI inversion recovery echo-planar imaging sequence with free breathing and built-in body coil. Axial T2- weighted imaging images of the same location were used as reference. The results of WB-DWI were compared with pathological results and other imaging modalities. The mean apparent diffusion coefficient （ADC） values of different kinds of lymph nodes were compared. Results WB-DWI was positive in all 18 cases with lymphoma, 5 cases with metastatic lymph nodes and 4 of 8 eases with benign lymphadenopathy. The mean ADC value of lymphomatous, metastatic and benign lymph nodes was （0.87 ± 0.17） × 10^3, （0.98± 0.09） × 10^3 and （1.20 ± 0.10） × 10^3 mm^2/s. There was significant difference in ADC value between benign lymph nodes and other two groups （P 〈 0.01）. The sensitivity, specificity and accuracy of WB-DWI in diagnosis of lymphoma were 100% （18/18）, 30.8% （4/13） and 71.0% （22/31）. When an ADC value of 1.08 × 10^-3 mm^2/s was used as the threshold value for differentiating malignant from benign lymph nodes, the best results were obtained with sensitivity of 87.8% and specificity of 91.3%. Sixteen of eighteen cases （88.9%） of lymphoma were accurately staged in accordance with clinical staging. Conclusions WB-DWI is a sensitive, but less specific technique for diagnosis of lymphoma. It is difficult to differentiate lymphnmatous from metastatic lymph nodes using WB-DWI. However, it is a valuable imaging modality for staging of patients with malignant lymphoma.展开更多
Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers al...Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers always suffer from high filler loading.Herein,we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles(Ni@NPC).These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities.Moreover,the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization,conduction loss,multiple reflection and scattering.Impressively,with an ultralow filler loading of 5 wt.%,the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as-72.4 dB and a broad absorption bandwidth of 5.0 GHz.This capability outperforms most current magnetic-dielectric hybrids counterparts.Furthermore,the MA capacity can be easily tuned with adjustments in thickness,content and type of magnetic material.Thus,this work opens up new avenues for the development of high-performance and lightweight MA materials.展开更多
Most reported electromagnetic wave absorption(EWA)materials show significant effective absorption in a certain frequency range,but their performances deteriorate dramatically as the frequency changes.As the range of w...Most reported electromagnetic wave absorption(EWA)materials show significant effective absorption in a certain frequency range,but their performances deteriorate dramatically as the frequency changes.As the range of working frequencies for electronic devices is gradually widening,it is of great interest to explore frequency-insensitive EWA materials that can achieve efficient absorption in every waveband by simply changing the absorption thickness.To this end,a multi-scale absorber(Fe/Fe_(3) C@NC)is rationally synthesized by chemical foaming and in-situ growth strategy.By controlling the growth of carbon nan-otubes,the Fe/Fe_(3) C@NC-2 exhibits a well-constructed 3D multi-scale architecture.Thanks to dipole po-larization,interface polarization and magnetic-dielectric energy conversion,the Fe/Fe_(3) C@NC-2 overcomes the frequency dispersion behavior and keeps a stable dielectric attenuation capability across the entire frequency range.Consequently,it delivers a superb full-band absorption of-50.1,-59.83,-55.87 and-51.91 dB in the S,C,X and Ku bands,respectively.The maximum radar cross-sectional reduction reaches 35.44 dB m^(-2) when the incidentθis 20°,testifying its impressive performance.Surprisingly,this EWA material also shows a remarkable resistance to oxidation and corrosion derived from the tightly coated carbon layers.This work provides new insight into the design of multi-band and stable EWA materials for practical application.展开更多
Thrombotic thrombocytopenic purpura(TTP) is a multisystem disorder that essentially can affect any organ in the human body. The hallmark of the pathogenesis in TTP is the large von Willebrand factor multimers on plate...Thrombotic thrombocytopenic purpura(TTP) is a multisystem disorder that essentially can affect any organ in the human body. The hallmark of the pathogenesis in TTP is the large von Willebrand factor multimers on plateletmediated micro-thrombi formation, leading to microvascular thrombosis.Autopsy studies showed that cardiac arrest and myocardial infarction are the most common immediate causes of death in these patients. Clinical manifestations of cardiac involvement in TTP vary dramatically, from asymptomatic elevation of cardiac biomarkers, to heart failure, MI and sudden cardiac death. There is limited knowledge about optimal cardiac evaluation and management in patients with TTP. The absence of typical cardiac symptoms,combined with complicated multi-organ involvement in TTP, may contribute to the under-utilization of cardiac evaluation and treatment. Prompt diagnosis and timely initiation of effective therapy could be critically important in selected cases. Based on our experience and this review of the literature, we developed several recommendations for focused cardiac evaluation for patients with acute TTP:(1) patients with suspected or confirmed TTP should be screened for the potential presence of cardiac involvement with detailed history and physical,electrocardiogram and cardiac enzymes;(2) clinical deterioration of TTP patients warrants immediate cardiac reevaluation;(3) TTP patients with clinical evidence of cardiac involvement should be monitored for telemetry, cardiac biomarkers and evaluated with transthoracic echocardiography. These patients require urgent targeted TTP treatment as well as cardiac-specific treatment. Aspirin therapy is indicated for all TTP patients. Since epicardial coronary artery involvement is rare, cardiac catheterization is usually not required, given the high risk for hemorrhage and kidney injury;(4) we recommend evidence-based medical therapy for ischemic symptoms and heart failure. TTP patients with evidence of cardiac involvement would also benefit from routine cardiology follow up during remission.展开更多
In this study,the low emission combustion technology of Rich-Quench-Lean(RQL)has been applied in Trapped-Vortex Combustor(TVC),and the combinative RQL-TVC shows a promising low emissions performance.By utilizing a que...In this study,the low emission combustion technology of Rich-Quench-Lean(RQL)has been applied in Trapped-Vortex Combustor(TVC),and the combinative RQL-TVC shows a promising low emissions performance.By utilizing a quench orifice plate combined with a bluffbody,a lab-scale RQL-TVC was designed.The flow fields of RQL-TVC were measured by 2-D PIV and predicted by 3-D numerical simulation.Flow structures,radial profiles of normalized mean axial velocity,turbulence intensity and mixing level of the quench zone were analyzed.Results reveal that the dual-vortex and the single-vortex flow patterns both exist in cavities and quench zone of RQL-TVC,and the turbulence intensity is strong in the quench zone with some reverse flows.The spiral vortex was discussed by 3-D streamlines and the detail flow structures of the quench zone were analyzed based on the numerical results.The mixing level of the quench zone was determined,and results show that the quench device enhances the mixing level compared with TVC.Combustion efficiency and emissions performance were investigated experimentally,and results demon-strate that RQL-TVC has relatively higher combustion efficiency and lower emission index of CO,UHC and NO_xthan the same size lab-scale TVC in present work.展开更多
In this study,a novel method termed hydrothermal carbonized deposition on chips(HTCDC)is proposed to prepare aluminum alloy-amorphous carbon(Al/APC)composites.The influences of glucose concentration in hydrothermally ...In this study,a novel method termed hydrothermal carbonized deposition on chips(HTCDC)is proposed to prepare aluminum alloy-amorphous carbon(Al/APC)composites.The influences of glucose concentration in hydrothermally reaction on the microstructure and wear resistance of the Al/APC composites were thoroughly studied.Amorphous carbon was deposited by HTCDC onto Al–20Si chips as a supporter.The Al/APC composites were prepared by hot extrusion from the chips.The results indicated that a uniform carbon film was successfully synthesized on the surface of the chips,improving the wear resistance of the Al/APC composites.With increasing concentration of glucose solution,the size and the number of delamination on the wear surface and the coefficient of friction decreased,and the wear rate decreased at first and then increased.In addition,the dehydration and carbonization processes in the hydrothermal reaction of glucose were analyzed.A schematic model of the wear surface of the Al/APC composites was established and the wear mechanisms were discussed.展开更多
The microstructure and mechanical properties of a traditional Ti-microalloyed weathering steel were analyzed,and the strength was improved by proposing an optimized Ti content.The yield strength and elongation of the ...The microstructure and mechanical properties of a traditional Ti-microalloyed weathering steel were analyzed,and the strength was improved by proposing an optimized Ti content.The yield strength and elongation of the steel were 640 MPa and 25.5%,respectively.The microstructure was ferrite and pearlite,and the average grain size was 5.4μm.The precipitates were mainly TiC with the size below 20 nm,and the average diameter was 18.2 nm.The yield strength of the newly proposed weathering steel with Ti content of 0.018%higher than that of the traditional steel reached up to 709 MPa,and the elongation was 23.5%.The ferrite grain was refined to 3.8μm,the fraction of TiC under 10 nm was obviously increased,and the average diameter of particles was 9.8 nm.The increase in Ti also promoted the recrystallization process,thus leading to the reduction in dislocation density.The yield strength of the newly proposed weathering steel was increased to higher than 700 MPa by adjusting the Ti content mainly resulting from three aspects:grain refinement,precipitation and dislocation strengthening.The contributed values were 45,64 and–40 MPa,respectively.展开更多
Though weighted voting matching is one of most successful image matching methods, each candidate correspondence receives voting score from all other candidates, which can not apparently distinguish correct matches and...Though weighted voting matching is one of most successful image matching methods, each candidate correspondence receives voting score from all other candidates, which can not apparently distinguish correct matches and incorrect matches using voting scores. In this paper, a new image matching method based on mutual k-nearest neighbor (k-nn) graph is proposed. Firstly, the mutual k-nn graph is constructed according to similarity between candidate correspondences.Then, each candidate only receives voting score from its mutual k nearest neighbors. Finally, based on voting scores, the matching correspondences are computed by a greedy ranking technique. Experimental results demonstrate the effectiveness of the proposed method.展开更多
Effective language strategies play an essential role in traditional teaching.However,the benefits of nonverbal behavior teaching strategy in the classroom have been underestimated.Facial expressions,gestures,and eye c...Effective language strategies play an essential role in traditional teaching.However,the benefits of nonverbal behavior teaching strategy in the classroom have been underestimated.Facial expressions,gestures,and eye contact are all instantaneous nonverbal behaviors that play a significant part in exchanging information in classroom.This study aims to examine how different nonverbal teaching strategies affect teaching and learning and discover what it is used for and how important they are in education.Finally,some suggestions for improving teachers’use of nonverbal behaviors from a teacher professional development perspective are presented.展开更多
基金The authors appreciate the financial support from Xining Special Steel Co.,Ltd.and student research training project of University of Science and Technology Beijing.
文摘The hot deformation behaviors of sulfur-containing gear steel 20MnCr5 containing three different contents of Nb and B(0,0.021%Nb,and 0.024%Nb-0.0022%B)were investigated.Hot compression and tenssion tests were carried out by Gleeble3800 at the austenite region from 850 to 1150℃and the adverse effects of Nb and B were analyzed by the fracture,microstructure and precipitate observations.Hot compression tests showed that the proportions of instable area in hot processing maps of 0.021%Nb and Nb-B steels were higher and the deformability of Nb free steel was better.The tensile deformation experiments showed that the reduction areas of Nb free,0.021%Nb and Nb-B steels were 92%-99%,84%-98%and 67%-97%,respectively.The addition of Nb or Nb and B inhibited the dynamic recrystallization during hot deformation,and consequently,more deformed grains were then formed in 0.021%Nb and Nb-B steels thus to obtain the microstructure with worse uniformity and then deteriorate the deformability.In addition,the interaction between inclusions and microalloyed elements was also significant.NbC particles of 0.021%Nb and Nb-B steels dynamically precipitated during deformation and precipitated together with MnS thus to worsen the deformability,resulting in the decrease of reduction area.
基金Project supported by the National Natural Science Foundation of China(52261037,52401251)Key Research Project of Jiangxi Province(20203ABC28W006)+2 种基金the Research Fund of Key Laboratory of Rare Earths,Chinese Academy of SciencesKey Laboratory of Ionic Rare Earth Re sources and Environment,Ministry of Natural Resources of the People's Republic of China(2022IRERE302)the Ganzhou Science and Technology Innovation Empowerment Youth"Jie bang Gua shuai"Project。
文摘Recovery of rare earth elements(REEs)from bulk Nd-Fe-B scrap by chlorination with NH_(4)Cl as a chlorinating agent has been reported to be an energy efficient and environmentally friendly method.However,the reaction mechanism and phase evolution of the low-temperature selective chlorination process of Nd-Fe-B sludge are not clear.In this paper,we systematically investigated the lowtemperature selective chlorination process of Nd-Fe-B sludge with NH4Cl by combining thermokinetic theoretical calculations and experiments,and revealed its reaction mechanism.The phase evolution during chlorination was determined by X-ray diffraction(XRD),scanning electron microscopy(SEM)and ene rgy-dispersive X-ray spectroscopy(EDS)characterization as well as co mputational analysis of the phase stability diagram of the M-O-Cl system.To determine the optimum chlorination conditions,the effects of chlorinating agent dosage,reaction temperature and reaction time on the reaction were investigated.The results show that the rare earth components in Nd-Fe-B sludge are selectively chlorinated to RECl3and the formation of REOCl is avoided in the temperature range of 300-420℃,while the iron components are preferentially oxidized to Fe2O3.The selective chlorination reaction is consistent with the unreacted shrinking core model,and the rate-controlling step of the reaction is the internal diffusion process of NH4Cl through the transition layer of the reactant product to the surface of the Nd-Fe-B sludge.The complete chlorination of REEs is successfully achieved and 99.8%of REEs are selectively extracted into the leaching solution under optimal chlorination conditions(300℃,2.5 times of stoichiometric amount,4 h).
基金the award from Pudong Commission of Science and Technology and Economy and Informatization(No.PKJ2019-Y04)Pudong New Area Health Commission Health Research Project(No.PW2021E-03)Traditional Chinese Medicine Inheritance and Scientific and Technological Innovation Project of Shanghai Municipal Health Commission(No.ZYCC2019017)for financial support of this study。
文摘Objective:Huachansu injection(HCSI),a promising anti-cancer Chinese medicine injection,has been reported to have the potential for reducing the toxicity of chemotherapy and improving the quality of life for colorectal cancer(CRC)patients.The objective of this study is to explore the synergistic and detoxifying effects of HCSI when used in combination with irinotecan(CPT-11).Methods:To investigate the effect of HCSI on anti-CRC efficacy and intestinal toxicity of CPT-11,we measured changes in the biological behavior of LoV o cells in vitro,and anti-tumor effects in LoV o cell xenograft nude mice models in vivo.Meanwhile,the effect of HCSI on intestinal toxicity and the uridine diphosphateglucuronosyltransferase 1A1(UGT1A1)expression was investigated in the CPT-11-induced colitis mouse model.Subsequently,we measured the effect of HCSI and its 13 constituent bufadienolides on the expression of UGT1A1 and organic anion transporting polypeptides 1B3(OATP1B3)in HepG 2 cells.Results:The combination index(CI)results showed that the combination of HCSI and CPT-11 exhibited a synergistic effect(CI<1),which significantly suppressing the LoV o cell migration,enhancing G2/M and S phase arrest,and inhibiting tumor growth in vivo.Additionally,the damage to intestinal tissues was attenuated by HCSI in CPT-11-induced colitis model,while the increased expression of UGT1A1 in HepG 2 cells and in mouse was observed.Conclusion:The co-therapy with HCSI alleviated the intestinal toxicity induced by CPT-11 and exerted an enhanced anti-CRC effect.The detoxifying mechanism may be related to the increased expression of UGT1A1 and OATP1B3 by HCSI and its bufadienolides components.The findings of this study may serve as a theoretical insights and strategies to improve CRC patient outcomes.
基金financially supported by the Shanghai Pilot Program for Basic Research and the National Natural Science Foundation of China(NSFC,Grant No.52307248)。
文摘The in-depth exploration of the multi-dimensional disaster-causing mechanisms associated with battery thermal runaway facilitates the whole-process safety evaluation.However,the still insufficient understanding of the thermal failure process and the limited dimensionality of the existing evaluation indexes subsequently lead to ineffective prevention and control and finally result in a high frequency of severe damage and unforeseen casualties.To address this issue,a general framework for evaluating the whole-process safety by integrating thermal and gas perspectives,involving dozens of multidimensional characteristic parameters obtained by experimental measurements and theoretical calculations,is proposed.Based on this framework,comparing the initial thermal hazards of lithium iron phosphate and nickel-cobalt-manganese lithium-ion batteries and quantifying the derived hazards of singlephase/multi-phase emissions considering battery venting gases and electrolyte solvent vapors,the significant hidden hazards of emissions dominated by reductive components that can lead to higher derived explosion and combustion risks within the external environment are identified,effectively updating the previous paradigm for evaluating cell-level thermal safety.For single-phase emissions with dominant reductive components,higher risks of low lower explosion limit and high laminar burning velocity are demonstrated;after considering typical solvent vapor types(dimethyl carbonate/ethyl methyl carbonate/diethyl carbonate)and specific mixing ratios,highly reductive multi-phase emissions still exhibit higher risks.The proposed framework reveals the underlying effect of the reductive gas-phase emissions in accelerating and aggravating system-level thermal hazards,providing important guidance and inspiration for the whole-process safety control based on gas-phase atmosphere regulation as well as for the overall safety evaluation of emerging battery material chemistries.
基金financially supported by the Key Research and Development Program of Hubei Province(Nos.2022BCA077 and 2022BCA082).
文摘Styrene-butadiene-styrene(SBS)modified asphalt(SA)has long found effective applications in road construction materials.When combined with fillers,SBS-modified asphalt has demonstrated promising resistance to fatigue cracking caused by temperature fluctuations and aging.In this study,molybdenum disulfide(MoS_(2))and polyphosphoric acid(PPA)were ground in naphthenic oil(NO)and subjected to mechanical activation to create PPAmodified MoS_(2),referred to as OMS-PPA.By blending various ratios of OMS-PPA with SBS-modified asphalt,composite-modified asphalts were successfully developed to enhance their overall properties.To assess the mechanical characteristics and stability of these modified asphalts,various methods were employed,including penetration factor,flow activation energy,fluorescence microscopy,and dynamic shear rheology.Additionally,the short-term aging performance was evaluated using Fourier transform infrared(FTIR)spectroscopy and nanoindentation tests.The results revealed a 3.7%decrease in the penetration-temperature coefficient for SAOMS compared to SA,while 1-SA-OMS-PPA showed an even greater reduction of 7.1%.Furthermore,after short-term aging,carboxyl group generation in SA increased by 5.93%,while SA-OMS exhibited a smaller rise of 1.36%,and 1-SA-OMS-PPA saw an increase of just 0.93%.The study also highlighted significant improvements in the hardness of these materials.The hardness change ratio for SA-OMS decreased by 43.08%,while the ratio for 1-SA-OMS-PPA saw a notable reduction of 65.16% compared to unmodified SA.These findings suggest that OMS-PPA contributed to improvements in temperature sensitivity,particle dispersibility,and resistance to shortterm aging in asphalts.The results hold significant promise for the future development of advanced asphalt-based materials with potential high-value applications in flexible pavements for highways.
基金National Natural Science Foundation of China(Nos.21971090 and 22271123)the NSF of Jiangsu Province(No.BK20230201)+1 种基金the Natural Science Foundation of Jiangsu Education Committee(No.22KJB150024)the Natural Science Foundation of Jiangsu Normal University(No.21XSRX010)。
文摘A new oxidative N-heterocyclic carbene(NHC)-catalyzed high-order[7+3]annulation reaction ofγ-indolyl phenols as 1,7-dinucleophiles andα,β-alkynals with the aid of Sc(OTf)_(3)is reported,enabling the highly regioselective access to unprecedented polyarene-fused ten-membered lactams bearing a bridged aryl-aryl-indole scaffold in moderate to good yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and complete regioselectivity,providing an organocatalytic modular synthetic strategy for creating medium-sized lactams.
基金supported by the National Natural Science Foundation of China(No.51704087)the Natural Science Foundation of Heilongjiang Province(No.LH2020E083).
文摘Lightweight aluminum alloy conductor materials(Al-Mg-Si alloys)require not only high electrical conductivity to reduce electrical loss,but also high strength to withstand extreme weather conditions.To improve electrical conductivity and mechanical properties of Al-Mg-Si alloy simultaneously,the rare earth La was introduced to modify the Al-Mg-Si alloy.The effect of La addition on the microstructure,tensile properties and electrical conductivity of cast Al-Mg-Si alloy was investigated systematically.Results indicate that the appropriate La content is helpful to improve the strength and electrical conductivity of Al-Mg-Si alloys.When the addition of La is 0.2wt.%,theα-Al grains are refined apparently,Mg and Si solute atoms in the Al matrix are reduced by the formation of Mg_(2)Si phase;the distribution of Al_(11)La_(3)phases is uniform,and the morphology of AlFeSi phase transforms from continuous state to discontinuous state.The Al-Mg-Si-0.2La alloy exhibits the optimal tensile properties and electrical conductivity,with an ultimate tensile strength of 170 MPa,a yield strength of 88 MPa,an elongation of 18.9%,and an electrical conductivity of 44.0%IACS.These values represent improvements of 9.0%,15.8%,70.3%,and 17.3%,respectively,compared to the Al-Mg-Si alloy without La addition.However,excessive La deteriorates the properties of Al-Mg-Si-xLa alloys.
基金financially supported by the National Natural Science Foundation of China(NSFC,Grant number U20A20310)the Program of Shanghai Academic/Technology Research Leader(Grant number 22XD1423800)。
文摘The degradation of Lithium-ion batteries(LIBs)during cycling is particularly exacerbated at low temperatures,which has a significant impact on the longevity of electric vehicles,energy storage systems,and consumer electronics.A comprehensive understanding of the low-temperature aging mechanisms throughout the whole life cycle of LIBs is crucial.However,existing research is limited,which typically focuses on capacity degradation to 80%.To fill this gap,this paper conducts low-temperature cyclic aging tests at three different charging rates.The investigation employs differential voltage analysis,the distribution of relaxation times technique,and disassembly characterization to explore both thermodynamic degradation and kinetic degradation,alongside a correlation analysis of the factors influencing these degradation processes.The results reveal two distinct knee points in the capacity decline of LIBs during the whole life cycle,in contrast to prior studies identifying only one.Before the first knee point,the thickening of the SEI film dominates capacity loss,with higher charging rates accelerating the process.After the first knee point,the main degradation mechanisms shift to lithium plating and the fracture of the positive electrode active particles.These two aging factors become more pronounced with ongoing cycling,culminating in a second knee point in capacity decline.Notably,a novel finding demonstrates that after the second knee point,capacity degradation progresses faster at lower charging rates compared to medium rates.The reason is the fracture of graphite particles also becomes a critical contributor to the severe capacity degradation at lower charging rates.These insights will guide the designs of next-generation low-temperature LIBs and low-temperature battery management systems.
基金supported by the Hainan Province’s Key Research and Development Project(ZDYF 2017096&ZDYF2018118)National Natural Science Foundation of China(NSFC:81500202)+2 种基金Beijing Lisheng Cardiovascular Health Foundation Pilot Fund Project(LHJJ201610620)Provincial Key Science and Technology Projects supporting projects in Sanya(2018PT48)Sanya Medical and Health Science and Technology Innovation Project(2017YW10)
文摘Background Clearance of coronary arterial thrombosis is necessary in patients with acute ST-segment elevation myocardial infarction (STEMI) undergoing urgent percutaneous coronary intervention (PCI). There is currently no highly-recommended method of thrombus removal during interventional procedures. We describe a new method for opening culprit vessels to treat STEMI: intracoronary arterial retrograde thrombolysis (ICART) with PCI. Methods & Results Eight patients underwent ICART. The guidewire was advanced to the distal coronary artery through the occlusion lesion. Then, we inserted a microcatheter into the distal end of the occluded coronary artery over the guidewire. Urokinase (5–10 wu) mixed with contrast agents was slowly injected into the occluded section of the coronary artery through the microcatheter. The intracoronary thrombus gradually dissolved in 3–17 min, and the effect of thrombolysis was visible in real time. Stents were then implanted according to the characteristics of the recanalized culprit lesion to achieve full revascularization. One patient experienced premature ventricular contraction during vascular revascularization, and no malignant arrhythmias were seen in any patient. No reflow or slow flow was not observed post PCI. Thrombolysis in myocardial infarction flow grade and myocardial blush grade post-primary PCI was 3 in all eight patients. No patients experienced bleeding or stroke. Conclusions ICART was accurate and effective for treating intracoronary thrombi in patients with STEMI in this preliminary study. ICART was an effective, feasible, and simple approach to the management of STEMI, and no intraprocedural complications occurred in any of the patients. ICART may be a breakthrough in the treatment of acute STEMI.
基金supported by the National Natural Science Foundation of China(32172020,31971884)the National Key Research and Development Program of China(2024YFD1201202,2024YFD1200402)+4 种基金the Sichuan Science and Technology Program(2022ZDZX0014,2023YFN0085)the Qinghai Provincial Key Laboratory of Crop Molecular Breeding(2023-1-1)the State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China(SKLKF202409)the Alliance of National and International Science Organizations for the Belt and Road Regions(ANSO-CR-KP-202205)the International Partnership Program of Chinese Academy of Sciences(077GJHZ2023028GC)。
文摘Aegilops variabilis(S^(v)S^(v)U^(v)U^(v))is a source of resistance to wheat stripe rust.The phKL locus in Chinese common wheat landrace Kaixian-Luohanmai(KL)can induce homoeologous wheat-alien chromosome pairing and recombination.In this study,we confirmed that the whole 2S^(v)chromosome introgressed into wheat from Ae.variabilis accession AS116 conferred all-stage stripe rust resistance.The underlying gene(s),named YrAev,was mapped to the long arm 2S^(v)L using an F_(2)population.Two 2S^(v)-2B recombinants,derived from a cross of the 2S^(v)(2B)chromosome substitution line and KL,were confirmed to harbor the resistance locus.The physical region containing YrAev,determined from RNA-seq data,was 844.6-852.1 Mb on the chromosome arm 2S^(l)of the Ae.longissima(S^(v)genome donor species of Ae.variabilis)accession TL05 assembly v1.0.Differential gene expression analysis of post-inoculation with the Pst race has indicated two disease-resistance-related genes(annotated as mixed lineage kinase domain-like protein and nucleotide-binding leucine-rich repeat like protein,respectively)as promising candidates for YrAev.This study demonstrates the utility of the phKL gene system in alien gene localization and transfer.The resistant translocation line harboring YrAev can be exploited by wheat breeders as a novel source of resistance to stripe rust.
文摘AIM:To assess the value of double-balloon enteroscopy(DBE) for the diagnosis of gastrointestinal mesenchymal tumors(GIMTs) in the small bowel and clarify their clinical and endoscopic characteristics.METHODS:A retrospective review in a total of 783 patients who underwent a DBE procedure from January 2003 to December 2011 was conducted.Data from patients with pathologically confirmed GIMTs were analyzed at a single tertiary center with nine years' experience.The primary outcomes assessed included characteristics of patients with GIMTs,indications for DBE,overall diagnostic yield of GIMTs,endoscopic morphology,positive biopsy,comparison of diagnosis with capsule endoscopy,and subsequent interventional management.RESULTS:GIMTs were identified and analyzed in 77 patients.The mean age was 47.74 ± 14.14 years(range:20-77 years),with 63.6% being males.The majority of individuals presented with gastrointestinal bleeding,accounting for 81.8%,followed by abdominal pain,accounting for 10.4%.Small bowel pathologies were found in 71 patients,the detection rate was 92.2%.The diagnostic yield of DBE for GIMTs was 88.3%.DBE was superior to capsule endoscopy in the diagnosis of GIMTs(P = 0.006;McNemar's χ2 test).Gastrointestinal stromal tumor was the most frequent and leiomyoma was the second frequent GIMT.Single and focal lesions were typical of GIMTs,and masses with smooth or unsmooth surface were the most common in the small bowel.GIMTs were removed from all the patients surgically except one patient treated with endoscopic resection.CONCLUSION:DBE is a safe and valuable procedure for patients with suspected GIMTs,and it provides an accurate position for subsequent surgical intervention.
文摘Objective To evaluate the clinical impact of whole body diffusion weighted imaging （WB-DWI） on diagnosis and staging of malignant lymphoma. Methods Thirty-one patients with suspected lymphadenopathy were enrolled. WB-DWI was performed by using short TI inversion recovery echo-planar imaging sequence with free breathing and built-in body coil. Axial T2- weighted imaging images of the same location were used as reference. The results of WB-DWI were compared with pathological results and other imaging modalities. The mean apparent diffusion coefficient （ADC） values of different kinds of lymph nodes were compared. Results WB-DWI was positive in all 18 cases with lymphoma, 5 cases with metastatic lymph nodes and 4 of 8 eases with benign lymphadenopathy. The mean ADC value of lymphomatous, metastatic and benign lymph nodes was （0.87 ± 0.17） × 10^3, （0.98± 0.09） × 10^3 and （1.20 ± 0.10） × 10^3 mm^2/s. There was significant difference in ADC value between benign lymph nodes and other two groups （P 〈 0.01）. The sensitivity, specificity and accuracy of WB-DWI in diagnosis of lymphoma were 100% （18/18）, 30.8% （4/13） and 71.0% （22/31）. When an ADC value of 1.08 × 10^-3 mm^2/s was used as the threshold value for differentiating malignant from benign lymph nodes, the best results were obtained with sensitivity of 87.8% and specificity of 91.3%. Sixteen of eighteen cases （88.9%） of lymphoma were accurately staged in accordance with clinical staging. Conclusions WB-DWI is a sensitive, but less specific technique for diagnosis of lymphoma. It is difficult to differentiate lymphnmatous from metastatic lymph nodes using WB-DWI. However, it is a valuable imaging modality for staging of patients with malignant lymphoma.
基金financially supported by the National Natural Science Foundation of China(Nos.21776308 and 21908245)the Science Foundation of China University of Petroleum,Beijing(No.2462018YJRC009)the China Postdoctoral Science Foundation(No.2018T110187)。
文摘Developing microwave absorption(MA)materials with satisfied comprehensive performance is a great challenge for tackling severe electromagnetic pollution.In particular,the magnetic component/carbon hybrids absorbers always suffer from high filler loading.Herein,we propose a feasible strategy to construct hierarchical porous carbon with tightly embedded Ni nanoparticles(Ni@NPC).These highly dispersed Ni nanoparticles produce strong magnetic coupling networks to enhance magnetic loss abilities.Moreover,the interconnected hierarchical dielectric carbon network affords favorable dipolar/interfacial polarization,conduction loss,multiple reflection and scattering.Impressively,with an ultralow filler loading of 5 wt.%,the resultant Ni@NPC/paraffin composite achieves an excellent MA performance with a minimum reflection loss of as high as-72.4 dB and a broad absorption bandwidth of 5.0 GHz.This capability outperforms most current magnetic-dielectric hybrids counterparts.Furthermore,the MA capacity can be easily tuned with adjustments in thickness,content and type of magnetic material.Thus,this work opens up new avenues for the development of high-performance and lightweight MA materials.
基金financially supported by the National Natu-ral Science Foundation of China(Grant Nos.22178384,22238012 and 52002363)the Science Foundation of China University of Petroleum,Beijing(Grant No.ZX20220079)the Aeronautical Science Foundation of China(Grant No.2020Z054025002).
文摘Most reported electromagnetic wave absorption(EWA)materials show significant effective absorption in a certain frequency range,but their performances deteriorate dramatically as the frequency changes.As the range of working frequencies for electronic devices is gradually widening,it is of great interest to explore frequency-insensitive EWA materials that can achieve efficient absorption in every waveband by simply changing the absorption thickness.To this end,a multi-scale absorber(Fe/Fe_(3) C@NC)is rationally synthesized by chemical foaming and in-situ growth strategy.By controlling the growth of carbon nan-otubes,the Fe/Fe_(3) C@NC-2 exhibits a well-constructed 3D multi-scale architecture.Thanks to dipole po-larization,interface polarization and magnetic-dielectric energy conversion,the Fe/Fe_(3) C@NC-2 overcomes the frequency dispersion behavior and keeps a stable dielectric attenuation capability across the entire frequency range.Consequently,it delivers a superb full-band absorption of-50.1,-59.83,-55.87 and-51.91 dB in the S,C,X and Ku bands,respectively.The maximum radar cross-sectional reduction reaches 35.44 dB m^(-2) when the incidentθis 20°,testifying its impressive performance.Surprisingly,this EWA material also shows a remarkable resistance to oxidation and corrosion derived from the tightly coated carbon layers.This work provides new insight into the design of multi-band and stable EWA materials for practical application.
文摘Thrombotic thrombocytopenic purpura(TTP) is a multisystem disorder that essentially can affect any organ in the human body. The hallmark of the pathogenesis in TTP is the large von Willebrand factor multimers on plateletmediated micro-thrombi formation, leading to microvascular thrombosis.Autopsy studies showed that cardiac arrest and myocardial infarction are the most common immediate causes of death in these patients. Clinical manifestations of cardiac involvement in TTP vary dramatically, from asymptomatic elevation of cardiac biomarkers, to heart failure, MI and sudden cardiac death. There is limited knowledge about optimal cardiac evaluation and management in patients with TTP. The absence of typical cardiac symptoms,combined with complicated multi-organ involvement in TTP, may contribute to the under-utilization of cardiac evaluation and treatment. Prompt diagnosis and timely initiation of effective therapy could be critically important in selected cases. Based on our experience and this review of the literature, we developed several recommendations for focused cardiac evaluation for patients with acute TTP:(1) patients with suspected or confirmed TTP should be screened for the potential presence of cardiac involvement with detailed history and physical,electrocardiogram and cardiac enzymes;(2) clinical deterioration of TTP patients warrants immediate cardiac reevaluation;(3) TTP patients with clinical evidence of cardiac involvement should be monitored for telemetry, cardiac biomarkers and evaluated with transthoracic echocardiography. These patients require urgent targeted TTP treatment as well as cardiac-specific treatment. Aspirin therapy is indicated for all TTP patients. Since epicardial coronary artery involvement is rare, cardiac catheterization is usually not required, given the high risk for hemorrhage and kidney injury;(4) we recommend evidence-based medical therapy for ischemic symptoms and heart failure. TTP patients with evidence of cardiac involvement would also benefit from routine cardiology follow up during remission.
基金the National Natural Science Foundation of China(Nos.51706103,51822605,51776181)the Fundamental Research Funds for the Central Universities,China,(Nos.CEPE2019010,30920031103)+1 种基金the Open Project of State Key Laboratory of Clean Energy Utilization,Zhejiang University,China,(Nos.ZJU-CEU2017011)great support given by the China Scholarship Council(No.201906845024)。
文摘In this study,the low emission combustion technology of Rich-Quench-Lean(RQL)has been applied in Trapped-Vortex Combustor(TVC),and the combinative RQL-TVC shows a promising low emissions performance.By utilizing a quench orifice plate combined with a bluffbody,a lab-scale RQL-TVC was designed.The flow fields of RQL-TVC were measured by 2-D PIV and predicted by 3-D numerical simulation.Flow structures,radial profiles of normalized mean axial velocity,turbulence intensity and mixing level of the quench zone were analyzed.Results reveal that the dual-vortex and the single-vortex flow patterns both exist in cavities and quench zone of RQL-TVC,and the turbulence intensity is strong in the quench zone with some reverse flows.The spiral vortex was discussed by 3-D streamlines and the detail flow structures of the quench zone were analyzed based on the numerical results.The mixing level of the quench zone was determined,and results show that the quench device enhances the mixing level compared with TVC.Combustion efficiency and emissions performance were investigated experimentally,and results demon-strate that RQL-TVC has relatively higher combustion efficiency and lower emission index of CO,UHC and NO_xthan the same size lab-scale TVC in present work.
基金financially supported by the National Natural Science Foundation of China(Nos.51704087 and 51574100)the University Nursing Program for Young Scholars with Creative Talents in Heilongjiang Province(No.UNPYSCT-2016033)。
文摘In this study,a novel method termed hydrothermal carbonized deposition on chips(HTCDC)is proposed to prepare aluminum alloy-amorphous carbon(Al/APC)composites.The influences of glucose concentration in hydrothermally reaction on the microstructure and wear resistance of the Al/APC composites were thoroughly studied.Amorphous carbon was deposited by HTCDC onto Al–20Si chips as a supporter.The Al/APC composites were prepared by hot extrusion from the chips.The results indicated that a uniform carbon film was successfully synthesized on the surface of the chips,improving the wear resistance of the Al/APC composites.With increasing concentration of glucose solution,the size and the number of delamination on the wear surface and the coefficient of friction decreased,and the wear rate decreased at first and then increased.In addition,the dehydration and carbonization processes in the hydrothermal reaction of glucose were analyzed.A schematic model of the wear surface of the Al/APC composites was established and the wear mechanisms were discussed.
基金support from Maanshan Iron&Steel Co.,Ltd.and student research training project of University of Science and Technology Beijing.
文摘The microstructure and mechanical properties of a traditional Ti-microalloyed weathering steel were analyzed,and the strength was improved by proposing an optimized Ti content.The yield strength and elongation of the steel were 640 MPa and 25.5%,respectively.The microstructure was ferrite and pearlite,and the average grain size was 5.4μm.The precipitates were mainly TiC with the size below 20 nm,and the average diameter was 18.2 nm.The yield strength of the newly proposed weathering steel with Ti content of 0.018%higher than that of the traditional steel reached up to 709 MPa,and the elongation was 23.5%.The ferrite grain was refined to 3.8μm,the fraction of TiC under 10 nm was obviously increased,and the average diameter of particles was 9.8 nm.The increase in Ti also promoted the recrystallization process,thus leading to the reduction in dislocation density.The yield strength of the newly proposed weathering steel was increased to higher than 700 MPa by adjusting the Ti content mainly resulting from three aspects:grain refinement,precipitation and dislocation strengthening.The contributed values were 45,64 and–40 MPa,respectively.
基金This work is supported by the National Natural Science Foundation of China (No. 61402002, 61472002) the Natural Science Foundation of Anhui Higher Education Institutions of China (No. KJ2014A015, KJ2013A007).
文摘Though weighted voting matching is one of most successful image matching methods, each candidate correspondence receives voting score from all other candidates, which can not apparently distinguish correct matches and incorrect matches using voting scores. In this paper, a new image matching method based on mutual k-nearest neighbor (k-nn) graph is proposed. Firstly, the mutual k-nn graph is constructed according to similarity between candidate correspondences.Then, each candidate only receives voting score from its mutual k nearest neighbors. Finally, based on voting scores, the matching correspondences are computed by a greedy ranking technique. Experimental results demonstrate the effectiveness of the proposed method.
文摘Effective language strategies play an essential role in traditional teaching.However,the benefits of nonverbal behavior teaching strategy in the classroom have been underestimated.Facial expressions,gestures,and eye contact are all instantaneous nonverbal behaviors that play a significant part in exchanging information in classroom.This study aims to examine how different nonverbal teaching strategies affect teaching and learning and discover what it is used for and how important they are in education.Finally,some suggestions for improving teachers’use of nonverbal behaviors from a teacher professional development perspective are presented.
