AIM: To explore hemodynamics and vasoactive substance levels during renal vein congestion that occurs in the anhepatic phase of liver transplantation.METHODS: New Zealand rabbits received ligation of the hepatic pedic...AIM: To explore hemodynamics and vasoactive substance levels during renal vein congestion that occurs in the anhepatic phase of liver transplantation.METHODS: New Zealand rabbits received ligation of the hepatic pedicle, supra-hepatic vena cava and infrahepatic vena cava [anhepatic phase group(APH); n = 8], the renal veins(RVL; n = 8), renal veins and hepatic pedicle [with the inferior vena cava left open)(RVHP; n = 8)], or a sham operation(SOP; n = 8). Hemodynamic parameters(systolic, diastolic, and mean arterial blood pressures) and the levels of serum bradykinin(BK) and angiotensin Ⅱ(ANGII) were measured at baseline(0 min), and 10 min, 20 min, 30 min, and 45 min after the surgery. Correlation analyses were performed to evaluate the associations between hemodynamic parameters and levels of vasoactive substances.RESULTS:All experimental groups(APH,RVL,and RVHP)showed significant decreases in hemodynamic parameters(systolic,diastolic,and mean arterial blood pressures)compared to baseline levels,as well as compared to the SOP controls(P<0.05 for all).In contrast,BK levels were significantly increased compared to baseline in the APH,RVL,and RVHP groups at all time points measured(P<0.05 for all),whereas no change was observed in the SOP controls.There were no significant differences among the experimental groups for any measure at any time point.Further analyses revealed that systolic,diastolic,and mean arterial blood pressures were all negatively correlated with BK levels,and positively correlated with ANGII levels in the APH,RVL,and RVHP groups(P<0.05 for all).CONCLUSION:In the anhepatic phase of orthotopic liver transplantation,renal vein congestion significantly impacts hemodynamic parameters,which correlate with serum BK and ANGII levels.展开更多
Highly dispersed gadolinium zirconate(GZ)nanoparticles with fluorite structure were successfully synthesized by co-precipitation method,and their phase composition and microstructure,formation mechanism,and grain grow...Highly dispersed gadolinium zirconate(GZ)nanoparticles with fluorite structure were successfully synthesized by co-precipitation method,and their phase composition and microstructure,formation mechanism,and grain growth kinetics were investigated.The results suggest that the nanoparticles were obtained through hydroxide dehydration and solid phase reaction.High dispersion was accomplished by ethanol solvent to reduce the hydrogen bond and sodium dodecyl benzene sulfonate(SDBS)surfactant to increase the electrostatic repulsion between the nanoparticles.The grain growth activation energy of GZ powders calcined at lower temperature(<1200°C)is 86.5 kJ/mol(Ql),and the grain growth activation energy of GZ powders calcined at higher temperature(>1200°C)is 148.4 kJ/mol(Qh).The current study shows that the optimal process to synthesize dispersed GZ nanoparticles includes ethanol solvent,3 wt.%SDBS surfactant,and 1100°C as calcining temperature.展开更多
BACKGROUND Apatinib is an orally bioavailable small-molecule receptor tyrosine kinase inhibitor.In December 2014,the China Food and Drug Administration made it the first anti-angiogenic therapy to be approved for trea...BACKGROUND Apatinib is an orally bioavailable small-molecule receptor tyrosine kinase inhibitor.In December 2014,the China Food and Drug Administration made it the first anti-angiogenic therapy to be approved for treating metastatic gastric cancer.It was specifically designated as a third-line or later treatment for metastatic gastric cancer.CASE SUMMARY Here,we present a case of advanced renal cell carcinoma(RCC)with multiple metastases(Stage IV)in a 48-year-old male with an extremely poor general status(Karnofsky 30%).He was initially given pazopanib as a targeted therapeutic.However,he experienced severe adverse reactions within two weeks,including grade IV oral mucositis.We,thus,tried switching his targeted treatment to an apatinib dose of 250 mg once daily since April 2018.The patient demonstrated striking benefits from this switch to the apatinib palliative treatment.Nearly one month later,his pain and other associated symptoms were alleviated.The patient was able to move freely and had an excellent general status(Karnofsky 90%).His progress has been followed up with regularly,allowing for a documented progression-free survival interval of approximately 32 mo.CONCLUSION This case suggests that,like other multi-target drugs,apatinib may be a useful first-line therapeutic drug for advanced RCC.It may be a particularly helpful curative option when patients are found to be intolerant of other targeted drugs.展开更多
Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical...Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical applications,such as the damage caused by external effects,leading to equipment failure,and the inability to perceive ambient temperature,resulting in single functionality.Herein,a stretchable,self-healing and dual temperature-strain sensitive hydrogel,with a physically-crosslinked network,is designed by constructing multiple dynamic reversible bonds.Graphene oxide(GO)and iron ions(Fe^(3+))act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding,rendering excellent stretchability to the hydrogel.The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties.Moreover,the incorporated N-isopropyl acrylamide(NIPAM)provides excellent temperature responsiveness to the hydrogel,facilitating the detection of external temperature changes.Meanwhile,the hydrogels exhibited strain-sensitivity,with a wide working range of 1%-300%,fast response and electrical stability,which can be used as flexible sensors to monitor body motions,e.g.,speaking and the bending of finger,wrist,elbow and knee.Overall,the hydrogel possesses dual sensory capabilities,combining external temperature and strain,for potential applications in wearable multifunctional sensing devices.展开更多
ZrO_(2)-7 wt% Y_(2)O_(3)(7YSZ)thermal barrier coatings(TBCs)with three different structures were prepared by atmospheric plasma spraying(APS),electron beam physical vapor deposition(EB-PVD)and plasma spray-physical va...ZrO_(2)-7 wt% Y_(2)O_(3)(7YSZ)thermal barrier coatings(TBCs)with three different structures were prepared by atmospheric plasma spraying(APS),electron beam physical vapor deposition(EB-PVD)and plasma spray-physical vapor deposition(PS-PVD).Al films were deposited onto the top 7YSZ TBCs by magnetron sputtering,and the Al-deposited 7YSZ TBCs were subjected to vacuum heat treatment.The effects of Al modification on the thermal insulation properties of 7YSZ TBCs were investigated.The results showed that Al modification could significantly improve the thermal insulation of 7YSZ TBCs at 1000℃.Moreover,the maximum improvement of thermal insulation for PS-PVD 7YSZ TBCs was approximately 100℃,but the improvement decreased with increasing temperature.This is mainly because with increasing temperature,the rate of radiation heat transfer increases,and the effects of convection heat transfer and thermal conductivity on thermal insulation are weakened.At the same temperature,Al modification of PS-PVD7YSZ TBCs provides better temperature insulation than those of APS 7YSZ TBCs and EB-PVD 7YSZ TBCs because of its wider and deeper inter-columnar gaps.When the temperature was 12000C,Al modification still caused a good insulation effect in PS-PVD 7YSZ TBCs;the improvement was approximately 50℃,but in APS and EB-PVD 7YSZ TBCs,the insulation effect disappeared.展开更多
The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of m...The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of mechanical properties due to a tribological design limit their practical applications.Here,a robust self-lubricating coating was fabricated by an in-situ synthesis of MoS_(2)/C within inherent defects of thermally sprayed yttria-stabilized zirconia(YSZ)coatings.The edge-pinning by noncoherent endows hybrid coatings with excellent interfacial strength,increasing their hardness(HV)and cohesive strength.Furthermore,owing to the formation of a well-covered robust lubricating film at a frictional interface,a coefficient of friction(COF)can be reduced by 79.6%to 0.15,and a specific wear rate(W)drops from 1.36×10^(−3) to 6.27×10^(−7) mm^(3)·N^(−1)·m^(−1).Combining outstanding mechanical properties and tribological performance,the hybrid coating exhibits great application potential in controlling friction and wear.Importantly,this strategy of introducing the target materials into the inherent defects of the raw materials to improve the relevant properties opens new avenues for the design and preparation of composite materials.展开更多
Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from l...Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from liquid splats, nano-sized clusters, and the vapor phase forming different structured coatings, which shows obvious advantages in contrast to conventional technologies like atmospheric plasma spray(APS) and electron beam-physical vapor deposition(EBPVD). In addition, it can be used to produce thin, dense, and porous ceramic coatings for special applications because of its special characteristics, such as high power, very low pressure, etc. These provide new opportunities to obtain different advanced microstructures, thus to meet the growing requirements of modern functional coatings. In this work, focusing on exploiting the potential of gas-phase deposition from PS-PVD, a series of 7 YSZ coating experiments with various process conditions was performed in order to better understand the deposition process in PS-PVD, where coatings were deposited on different substrates including graphite and zirconia. Meanwhile, various substrate temperatures were investigated for the same substrate. As a result, a deposition mechanism of heterogeneous nucleation has been presented showing that surface energy is an important influencing factor for coating structures. Besides, undercooling of the interface between substrate and vapor phase plays an important role in coating structures.展开更多
The YSZ coatings are prepared by the plasma spray-physical vapor deposition(PS-PVD)technology based on a specific experimental design.The structure,thickness and growth angle of YSZ coatings on the entire circumferent...The YSZ coatings are prepared by the plasma spray-physical vapor deposition(PS-PVD)technology based on a specific experimental design.The structure,thickness and growth angle of YSZ coatings on the entire circumferential surface of the cylindrical sample are studied.The results indicated that the structure,thickness and deflection growth angle of YSZ coatings are related to the orientation of deposition location.The numerical simulation of the multiphase mixed fluid near the substrate is carried out and the deposition regularity and mechanism of YSZ coatings prepared by PS-PVD is deduced.The growth rate is related to the local characteristics of the plasma flow field,and is directly proportional to the field pressure and inversely proportional to the field velocity.The growth angle of the coating is generally affected by the flow direction of the plasma jet.Especially,the normal component of velocity vector,V_(norm),mainly affects the speed at which the coating grows vertically upwards.The tangential component of velocity vector,V_(tan),determines the degree that the coating growth direction deviates from the vertical direction.When V_(tan)≠0,the coating forms a fine column with a certain deflection angle and finally develops into an oblique columnar structure.展开更多
A novel sound quality simulation approach was proposed to optimize the acoustic performance of a four-cylinder diesel engine.Finite element analysis,single-input and multiple-output technology,flexible multi-body dyna...A novel sound quality simulation approach was proposed to optimize the acoustic performance of a four-cylinder diesel engine.Finite element analysis,single-input and multiple-output technology,flexible multi-body dynamics,and boundary element codes were used to acquire the hexahedron-element model,experimental modal frequencies,vibration velocities,and structurally radiated noise of the block,respectively.The simulated modal frequencies and vibration velocities agreed well with the experimental data,which validated the finite-element block.The acoustic response showed that considerable acoustic power levels existed in 1500-1900 Hz and 2300-2800 Hz as the main frequency ranges to optimize the block acoustics.Then,the optimal block is determined in accordance with the novel approach,which reduces the overall value,high-frequency amplitudes,and peak values of acoustic power;thus,the loudness,sharpness,and roughness decline to make the sound quieter,lower-pitched,and smoother,respectively.Finally,the optimal block was cast and bench-tested.The results reveal that the sound quality of the optimal-block engine is substantially improved as numerically expected,which verifies the effectiveness of the research approach.展开更多
Quasi-columnar structure 7YSZ(yttria stabilized zirconia) thermal barrier coatings(TBCs) are prepared by plasma spray-physical vapor deposition(PS-PVD) onto pretreated and un-pretreated bond coating, respectivel...Quasi-columnar structure 7YSZ(yttria stabilized zirconia) thermal barrier coatings(TBCs) are prepared by plasma spray-physical vapor deposition(PS-PVD) onto pretreated and un-pretreated bond coating, respectively. An isothermal oxidation experiment of 7YSZ TBCs is carried out in the atmosphere of 950 °C in order to simulate the high-temperature oxidation process of engine blades. The isothermal oxidation process of 7YSZ thermal barrier coatings is investigated systematically by impedance spectroscopy. The electrochemical physical model and equivalent circuit of columnar 7YSZ coatings are established. Results show that the isothermal oxidation kinetic curve of columnar 7YSZ thermal barrier coatings appears to follow the parabolic law. A pretreatment of bond coating can reduce the growth rate of the thermally grown oxide(TGO) layer, restraining the initiation and propagation of microcracks between YSZ and TGO layers. The oxidation rate constants of 7YSZ coatings with pretreated and un-pretreated bond coating are 0.101×10^(-12) cm^2·s^(-1) and 0.115 × 10^(-13) cm^2 ·s^(-1), respectively. Impedance analysis shows that the content of oxygen vacancies decreases and the density increases after the TGO layer is oxidized for 150 h. In addition, shrinkage microcracks formed by sintering during the oxidation process is the main reason for an increase of the capacitance and a decrease of the resistance in the grain boundary of YSZ.展开更多
Spherical Gd_(2)Zr_(2)O_(7)hollow powders with a mean size of 8.8μm were fabricated as feedstock for thermal barrier coatings(TBCs)by spray-drying.The single-ceramic-layer(SCL)Gd_(2)Zr_(2)O_(7)TBCs and double-ceramic...Spherical Gd_(2)Zr_(2)O_(7)hollow powders with a mean size of 8.8μm were fabricated as feedstock for thermal barrier coatings(TBCs)by spray-drying.The single-ceramic-layer(SCL)Gd_(2)Zr_(2)O_(7)TBCs and double-ceramic-layer(DCL)Gd_(2)Zr_(2)O_(7)/YSZ TBCs with quasicolumnar structure were successfully fabricated by plasma spray-physical vapor deposition(PS-PVD).Tensile and water-quenching tests were applied to evaluate TBCs performances.The results show that adhesion strength of SCL Gd_(2)Zr_(2)O_(7)TBCs and DCL Gd_(2)Zr_(2)O_(7)/YSZ TBCs is36.5 MPa and 15.4 MPa,respectively.The delamination of SCL Gd_(2)Zr_(2)O_(7)TBCs and DCL Gd_(2)Zr_(2)O_(7)/YSZ TBCs in the tensile test takes place at the middle and bottom of Gd_(2)Zr_(2)O_(7)layer,respectively,due to relatively lower fracture toughness of Gd_(2)Zr_(2)O_(7)layer.After 40 cycles of water-quenching test,DCL Gd_(2)Zr_(2)O_(7)/YSZ TBC surface keeps relatively intact,while SCL Gd_(2)Zr_(2)O_(7)TBC surface shows 20%visible destroyed regions,which demonstrates that DCL Gd_(2)Zr_(2)O_(7)/YSZ TBCs have a better thermal shock resistance than SCL Gd_(2)Zr_(2)O_(7)TBCs.The cracks in the SCL system propagate near thermally grown oxide(TGO)due to thermal mismatch and TGO growing stress,while cracks in the DCL system propagate in the Gd_(2)Zr_(2)O_(7)layer due to its relatively lower fracture toughness.展开更多
We demonstrate a three-nanosecond equidistant sub-pulse multi-step Q-switched Nd:Y3 Al5 O12(Nd:YAG) laser.In the time interval of 100–1000 ns, three pulses with the same nanosecond interval and the same peak power ar...We demonstrate a three-nanosecond equidistant sub-pulse multi-step Q-switched Nd:Y3 Al5 O12(Nd:YAG) laser.In the time interval of 100–1000 ns, three pulses with the same nanosecond interval and the same peak power are obtained at the pulse width of 24 ns, 28 ns, and 36.6 ns, respectively.The energy is 32.5 m J, and the optical efficiency is 10.8%.The multi-step Q-switched method does not require the insertion of other optical elements into the traditional Q-switched laser, and it is very suitable to obtain pulse group output with several nanosecond pulse intervals.展开更多
7 YSZ coating was prepared by plasma sprayphysical vapor deposition(PS-PVD) technique based on a specific experimental design.The microstructure and deposition properties of 7 YSZ coating along the radius of plasma je...7 YSZ coating was prepared by plasma sprayphysical vapor deposition(PS-PVD) technique based on a specific experimental design.The microstructure and deposition properties of 7 YSZ coating along the radius of plasma jet were investigated in detail.Results show that the coating presents regional characteristic in the radial direction,which could be divided into three typical zones:In Zone Ⅰ,the coating is all composed of columnar structures with cauliflower structure,and the coating properties including the surface roughness and deposition efficiency(DE) are almost stable;in Zone Ⅲ,the coating is made up of solid particles,droplet and gas phase mixed without columnar structures;Zone Ⅱ is between Zone Ⅰ and ZoneⅢ, in which there are columns with domed top and small particles.Based on experiment results,a model on the state and distribution of particles in plasma jet was proposed to clarify the regional characteristic.This study is helpful to comprehend and control coatings deposition by PS-PVD technique.展开更多
Organic semiconductor materials with low reorganization energy have various applications such as in organic light-emitting diodes (OLEDs),organic field-effect transistor (OFETs) and organic solar cells (OSCs).In this ...Organic semiconductor materials with low reorganization energy have various applications such as in organic light-emitting diodes (OLEDs),organic field-effect transistor (OFETs) and organic solar cells (OSCs).In this work,we have designed a new class of gridspiroarenes (GS-SFX and GS-SITF) with #-shaped structures,which have novel crisscross geometrical structures compared to widely used spirocyclic arenes-SFX and SITF.The structure electronic properties,adiabatic ionization potentials (IPa),adiabatic electron affinities (EAa) and reorganization energies (λ) of GS-SFX and GS-SITF have been calculated using density functional theory (DFT) method.The calculated HOMO and LUMO spatial distributions suggest that GS-SFX and GS-SITF have better transport properties.The noncovalent interaction analysis shows the weak intramolecular interactions between their arms.The results indicate that the reorganization energies of GS-SFX and GS-SITF are significantly reduced compared to the dimer structures-DSFX and DSITF.Furthermore,the GS-SITF1 which is one of the isomers of GS-SITF exhibits the lowest values for λ(h)(0.067 eV) and λ(e)(0.153 eV).Therefore,we believe the predicted structure,electronic property,and reorganization energy are good indicator for transport materials.This work has systematically studied the effect of gridization,which provides insights to design organic semiconductor materials with excellent charge transport properties.展开更多
Plasma spray-physical vapor deposition(PS-PVD)as a novel process was used to prepare feather-like columnar thermal barrier coatings(TBCs).This special microstructure shows good strain tolerance and non-line-of-sight(N...Plasma spray-physical vapor deposition(PS-PVD)as a novel process was used to prepare feather-like columnar thermal barrier coatings(TBCs).This special microstructure shows good strain tolerance and non-line-of-sight(NLOS)deposition,giving great potential application in aero-engine.However,due to serious service environment of aero-engine,particle erosion performance is a weakness for PS-PVD 7YSZ TBCs.As a solution,an Al-modification approach was proposed in this investigation.Through in-situ reaction of Al and ZrO2,anα-Al2O3 overlay can be formed on the surface of 7YSZ columnar coating.The results demonstrate that this approach can improve particle erosion resistance since hardness improvement of Al-modified TBCs.Meanwhile,as another important performance of thermal cycle,it has a better optimization with 350-cycle water-quenching,compared with the as-sprayed TBCs.展开更多
基金Supported by Natural Science Foundation of Gansu Province,China,No.3ZS051-A25-104Clinical Medicine Research Special Funds of Chinese Medical Association,China,No.14040360573
文摘AIM: To explore hemodynamics and vasoactive substance levels during renal vein congestion that occurs in the anhepatic phase of liver transplantation.METHODS: New Zealand rabbits received ligation of the hepatic pedicle, supra-hepatic vena cava and infrahepatic vena cava [anhepatic phase group(APH); n = 8], the renal veins(RVL; n = 8), renal veins and hepatic pedicle [with the inferior vena cava left open)(RVHP; n = 8)], or a sham operation(SOP; n = 8). Hemodynamic parameters(systolic, diastolic, and mean arterial blood pressures) and the levels of serum bradykinin(BK) and angiotensin Ⅱ(ANGII) were measured at baseline(0 min), and 10 min, 20 min, 30 min, and 45 min after the surgery. Correlation analyses were performed to evaluate the associations between hemodynamic parameters and levels of vasoactive substances.RESULTS:All experimental groups(APH,RVL,and RVHP)showed significant decreases in hemodynamic parameters(systolic,diastolic,and mean arterial blood pressures)compared to baseline levels,as well as compared to the SOP controls(P<0.05 for all).In contrast,BK levels were significantly increased compared to baseline in the APH,RVL,and RVHP groups at all time points measured(P<0.05 for all),whereas no change was observed in the SOP controls.There were no significant differences among the experimental groups for any measure at any time point.Further analyses revealed that systolic,diastolic,and mean arterial blood pressures were all negatively correlated with BK levels,and positively correlated with ANGII levels in the APH,RVL,and RVHP groups(P<0.05 for all).CONCLUSION:In the anhepatic phase of orthotopic liver transplantation,renal vein congestion significantly impacts hemodynamic parameters,which correlate with serum BK and ANGII levels.
基金This study was supported by the National Key Research and Development Program of China(grant 2017YFB0306100)the Natural Science Foundation of Hunan Province(grant 2018JJ2524)the International scientific technological cooperation projects of China(grants 2015DFR50580 and 2013DFA31440).
文摘Highly dispersed gadolinium zirconate(GZ)nanoparticles with fluorite structure were successfully synthesized by co-precipitation method,and their phase composition and microstructure,formation mechanism,and grain growth kinetics were investigated.The results suggest that the nanoparticles were obtained through hydroxide dehydration and solid phase reaction.High dispersion was accomplished by ethanol solvent to reduce the hydrogen bond and sodium dodecyl benzene sulfonate(SDBS)surfactant to increase the electrostatic repulsion between the nanoparticles.The grain growth activation energy of GZ powders calcined at lower temperature(<1200°C)is 86.5 kJ/mol(Ql),and the grain growth activation energy of GZ powders calcined at higher temperature(>1200°C)is 148.4 kJ/mol(Qh).The current study shows that the optimal process to synthesize dispersed GZ nanoparticles includes ethanol solvent,3 wt.%SDBS surfactant,and 1100°C as calcining temperature.
文摘BACKGROUND Apatinib is an orally bioavailable small-molecule receptor tyrosine kinase inhibitor.In December 2014,the China Food and Drug Administration made it the first anti-angiogenic therapy to be approved for treating metastatic gastric cancer.It was specifically designated as a third-line or later treatment for metastatic gastric cancer.CASE SUMMARY Here,we present a case of advanced renal cell carcinoma(RCC)with multiple metastases(Stage IV)in a 48-year-old male with an extremely poor general status(Karnofsky 30%).He was initially given pazopanib as a targeted therapeutic.However,he experienced severe adverse reactions within two weeks,including grade IV oral mucositis.We,thus,tried switching his targeted treatment to an apatinib dose of 250 mg once daily since April 2018.The patient demonstrated striking benefits from this switch to the apatinib palliative treatment.Nearly one month later,his pain and other associated symptoms were alleviated.The patient was able to move freely and had an excellent general status(Karnofsky 90%).His progress has been followed up with regularly,allowing for a documented progression-free survival interval of approximately 32 mo.CONCLUSION This case suggests that,like other multi-target drugs,apatinib may be a useful first-line therapeutic drug for advanced RCC.It may be a particularly helpful curative option when patients are found to be intolerant of other targeted drugs.
基金financially supported by the National Natural Science Foundation of China(No.52173301)International Science and Technology Cooperation Project of Sichuan Province(No.2022YFH0019)Innovative Research Team of Southwest Petroleum University(No.2017CXTD01)。
文摘Flexible hydrogels have shown promise as strain sensors in medical monitoring,human motion detection and intelligent robotics.For a hydrogel strain sensor,certain challenges need to be urgently addressed for practical applications,such as the damage caused by external effects,leading to equipment failure,and the inability to perceive ambient temperature,resulting in single functionality.Herein,a stretchable,self-healing and dual temperature-strain sensitive hydrogel,with a physically-crosslinked network,is designed by constructing multiple dynamic reversible bonds.Graphene oxide(GO)and iron ions(Fe^(3+))act as dynamic bridges in the cross-linked network and are mediated by the covalent and hydrogen bonding,rendering excellent stretchability to the hydrogel.The reversible features of coordination interactions and hydrogen interactions endow excellent recoverability and self-healing properties.Moreover,the incorporated N-isopropyl acrylamide(NIPAM)provides excellent temperature responsiveness to the hydrogel,facilitating the detection of external temperature changes.Meanwhile,the hydrogels exhibited strain-sensitivity,with a wide working range of 1%-300%,fast response and electrical stability,which can be used as flexible sensors to monitor body motions,e.g.,speaking and the bending of finger,wrist,elbow and knee.Overall,the hydrogel possesses dual sensory capabilities,combining external temperature and strain,for potential applications in wearable multifunctional sensing devices.
基金financially supported by the National Natural Science Foundation of China(Nos.51801034 and 52172067)Guangdong Province Outstanding Youth Foundation(No.2021B1515020038)+2 种基金Guangdong Special Support Program(No.2019BT02C629)Key R&D project in ShanXi Province(No.2019ZDLGY01-07)Guangdong Academy of Sciences Program(No.2020GDASYL-20200104030)。
文摘ZrO_(2)-7 wt% Y_(2)O_(3)(7YSZ)thermal barrier coatings(TBCs)with three different structures were prepared by atmospheric plasma spraying(APS),electron beam physical vapor deposition(EB-PVD)and plasma spray-physical vapor deposition(PS-PVD).Al films were deposited onto the top 7YSZ TBCs by magnetron sputtering,and the Al-deposited 7YSZ TBCs were subjected to vacuum heat treatment.The effects of Al modification on the thermal insulation properties of 7YSZ TBCs were investigated.The results showed that Al modification could significantly improve the thermal insulation of 7YSZ TBCs at 1000℃.Moreover,the maximum improvement of thermal insulation for PS-PVD 7YSZ TBCs was approximately 100℃,but the improvement decreased with increasing temperature.This is mainly because with increasing temperature,the rate of radiation heat transfer increases,and the effects of convection heat transfer and thermal conductivity on thermal insulation are weakened.At the same temperature,Al modification of PS-PVD7YSZ TBCs provides better temperature insulation than those of APS 7YSZ TBCs and EB-PVD 7YSZ TBCs because of its wider and deeper inter-columnar gaps.When the temperature was 12000C,Al modification still caused a good insulation effect in PS-PVD 7YSZ TBCs;the improvement was approximately 50℃,but in APS and EB-PVD 7YSZ TBCs,the insulation effect disappeared.
基金support from the National Natural Science Foundation of China (51905212)Guangdong Key Laboratory of Modern Surface Engineering Technology (2020B1212060049)+2 种基金Science and Technology Project of Guangdong Academy (2021GDASYL-20210103062)Young Scientific and Technological Talents Promotion Project of Guangzhou Science and Technology Association (X20210201061)Foshan Taoyuan Institute of Advanced Manufacturing (TYKF202203003).
文摘The self-lubricating ceramic coatings that can control friction and wear have attracted researchers’widespread attention.However,the poor interfacial bonding between lubricants and ceramics and the deterioration of mechanical properties due to a tribological design limit their practical applications.Here,a robust self-lubricating coating was fabricated by an in-situ synthesis of MoS_(2)/C within inherent defects of thermally sprayed yttria-stabilized zirconia(YSZ)coatings.The edge-pinning by noncoherent endows hybrid coatings with excellent interfacial strength,increasing their hardness(HV)and cohesive strength.Furthermore,owing to the formation of a well-covered robust lubricating film at a frictional interface,a coefficient of friction(COF)can be reduced by 79.6%to 0.15,and a specific wear rate(W)drops from 1.36×10^(−3) to 6.27×10^(−7) mm^(3)·N^(−1)·m^(−1).Combining outstanding mechanical properties and tribological performance,the hybrid coating exhibits great application potential in controlling friction and wear.Importantly,this strategy of introducing the target materials into the inherent defects of the raw materials to improve the relevant properties opens new avenues for the design and preparation of composite materials.
基金financial supports from National Key Research Program (2017YFB0306100)Guangdong Academy of Sciences (No. 2017GDASCX-0843)+3 种基金Guangdong Technical Research Program (Nos. 201707010385, 2014B070706026, 2013B061800053)Guangdong Natural Science Foundation (No. 2016A030312015)National Natural Science Foundation of China (No. 51501044)Guangzhou Technical Research Program (No. 201707010385)
文摘Plasma spray-physical vapor deposition(PS-PVD) as a novel coating process based on low-pressure plasma spray(LPPS) has been significantly used for thermal barrier coatings(TBCs).A coating can be deposited from liquid splats, nano-sized clusters, and the vapor phase forming different structured coatings, which shows obvious advantages in contrast to conventional technologies like atmospheric plasma spray(APS) and electron beam-physical vapor deposition(EBPVD). In addition, it can be used to produce thin, dense, and porous ceramic coatings for special applications because of its special characteristics, such as high power, very low pressure, etc. These provide new opportunities to obtain different advanced microstructures, thus to meet the growing requirements of modern functional coatings. In this work, focusing on exploiting the potential of gas-phase deposition from PS-PVD, a series of 7 YSZ coating experiments with various process conditions was performed in order to better understand the deposition process in PS-PVD, where coatings were deposited on different substrates including graphite and zirconia. Meanwhile, various substrate temperatures were investigated for the same substrate. As a result, a deposition mechanism of heterogeneous nucleation has been presented showing that surface energy is an important influencing factor for coating structures. Besides, undercooling of the interface between substrate and vapor phase plays an important role in coating structures.
基金the financial support from National Natural Science Foundation of China(51771059)R&D Program in Key Fields of Guangdong Province of China(2019B010936001)+2 种基金National Science and Technology Major Project of China(2017-VI-0010-0081)Science and Technology Project of Guangdong Province of China(2017A070701027,2014B070705007)Sciences Project of Guangdong Academy of China(2019GDASYL-0104022)。
文摘The YSZ coatings are prepared by the plasma spray-physical vapor deposition(PS-PVD)technology based on a specific experimental design.The structure,thickness and growth angle of YSZ coatings on the entire circumferential surface of the cylindrical sample are studied.The results indicated that the structure,thickness and deflection growth angle of YSZ coatings are related to the orientation of deposition location.The numerical simulation of the multiphase mixed fluid near the substrate is carried out and the deposition regularity and mechanism of YSZ coatings prepared by PS-PVD is deduced.The growth rate is related to the local characteristics of the plasma flow field,and is directly proportional to the field pressure and inversely proportional to the field velocity.The growth angle of the coating is generally affected by the flow direction of the plasma jet.Especially,the normal component of velocity vector,V_(norm),mainly affects the speed at which the coating grows vertically upwards.The tangential component of velocity vector,V_(tan),determines the degree that the coating growth direction deviates from the vertical direction.When V_(tan)≠0,the coating forms a fine column with a certain deflection angle and finally develops into an oblique columnar structure.
文摘A novel sound quality simulation approach was proposed to optimize the acoustic performance of a four-cylinder diesel engine.Finite element analysis,single-input and multiple-output technology,flexible multi-body dynamics,and boundary element codes were used to acquire the hexahedron-element model,experimental modal frequencies,vibration velocities,and structurally radiated noise of the block,respectively.The simulated modal frequencies and vibration velocities agreed well with the experimental data,which validated the finite-element block.The acoustic response showed that considerable acoustic power levels existed in 1500-1900 Hz and 2300-2800 Hz as the main frequency ranges to optimize the block acoustics.Then,the optimal block is determined in accordance with the novel approach,which reduces the overall value,high-frequency amplitudes,and peak values of acoustic power;thus,the loudness,sharpness,and roughness decline to make the sound quieter,lower-pitched,and smoother,respectively.Finally,the optimal block was cast and bench-tested.The results reveal that the sound quality of the optimal-block engine is substantially improved as numerically expected,which verifies the effectiveness of the research approach.
基金financial supports from National Key Research Program (No. 2017YFB0306100)Guangdong Academy of Sciences (No. 2017GDASCX-0843)+3 种基金Guang-dong Technical Research Program (No’s. 201707010385, 2014B070706026, and 2013B061800053)Guangdong Natural Science Foundation (No. 2016A030312015)National Natural Science Foundation of China (No. 51501044)Guangzhou Technical Research Program (No. 201707010385)
文摘Quasi-columnar structure 7YSZ(yttria stabilized zirconia) thermal barrier coatings(TBCs) are prepared by plasma spray-physical vapor deposition(PS-PVD) onto pretreated and un-pretreated bond coating, respectively. An isothermal oxidation experiment of 7YSZ TBCs is carried out in the atmosphere of 950 °C in order to simulate the high-temperature oxidation process of engine blades. The isothermal oxidation process of 7YSZ thermal barrier coatings is investigated systematically by impedance spectroscopy. The electrochemical physical model and equivalent circuit of columnar 7YSZ coatings are established. Results show that the isothermal oxidation kinetic curve of columnar 7YSZ thermal barrier coatings appears to follow the parabolic law. A pretreatment of bond coating can reduce the growth rate of the thermally grown oxide(TGO) layer, restraining the initiation and propagation of microcracks between YSZ and TGO layers. The oxidation rate constants of 7YSZ coatings with pretreated and un-pretreated bond coating are 0.101×10^(-12) cm^2·s^(-1) and 0.115 × 10^(-13) cm^2 ·s^(-1), respectively. Impedance analysis shows that the content of oxygen vacancies decreases and the density increases after the TGO layer is oxidized for 150 h. In addition, shrinkage microcracks formed by sintering during the oxidation process is the main reason for an increase of the capacitance and a decrease of the resistance in the grain boundary of YSZ.
基金financially supported by the National Key Research and Development Program of China(No.2017YFB0306100)the National Natural Science Foundation of China(No.51771059)+2 种基金the Natural Science Foundation of Hunan Province(No.2018JJ2524)the International Scientific Technological Cooperation Projects of China(Nos.2015DFR50580 and 2013DFA31440)the Science and Technology Planning Project of Guangdong Province(No.2017A070701027)。
文摘Spherical Gd_(2)Zr_(2)O_(7)hollow powders with a mean size of 8.8μm were fabricated as feedstock for thermal barrier coatings(TBCs)by spray-drying.The single-ceramic-layer(SCL)Gd_(2)Zr_(2)O_(7)TBCs and double-ceramic-layer(DCL)Gd_(2)Zr_(2)O_(7)/YSZ TBCs with quasicolumnar structure were successfully fabricated by plasma spray-physical vapor deposition(PS-PVD).Tensile and water-quenching tests were applied to evaluate TBCs performances.The results show that adhesion strength of SCL Gd_(2)Zr_(2)O_(7)TBCs and DCL Gd_(2)Zr_(2)O_(7)/YSZ TBCs is36.5 MPa and 15.4 MPa,respectively.The delamination of SCL Gd_(2)Zr_(2)O_(7)TBCs and DCL Gd_(2)Zr_(2)O_(7)/YSZ TBCs in the tensile test takes place at the middle and bottom of Gd_(2)Zr_(2)O_(7)layer,respectively,due to relatively lower fracture toughness of Gd_(2)Zr_(2)O_(7)layer.After 40 cycles of water-quenching test,DCL Gd_(2)Zr_(2)O_(7)/YSZ TBC surface keeps relatively intact,while SCL Gd_(2)Zr_(2)O_(7)TBC surface shows 20%visible destroyed regions,which demonstrates that DCL Gd_(2)Zr_(2)O_(7)/YSZ TBCs have a better thermal shock resistance than SCL Gd_(2)Zr_(2)O_(7)TBCs.The cracks in the SCL system propagate near thermally grown oxide(TGO)due to thermal mismatch and TGO growing stress,while cracks in the DCL system propagate in the Gd_(2)Zr_(2)O_(7)layer due to its relatively lower fracture toughness.
基金supported by the National Natural Science Foundation of China (NSFC)(No.11974060)the Natural Science Foundation of Jilin Province (No.20190201266JC)。
文摘We demonstrate a three-nanosecond equidistant sub-pulse multi-step Q-switched Nd:Y3 Al5 O12(Nd:YAG) laser.In the time interval of 100–1000 ns, three pulses with the same nanosecond interval and the same peak power are obtained at the pulse width of 24 ns, 28 ns, and 36.6 ns, respectively.The energy is 32.5 m J, and the optical efficiency is 10.8%.The multi-step Q-switched method does not require the insertion of other optical elements into the traditional Q-switched laser, and it is very suitable to obtain pulse group output with several nanosecond pulse intervals.
基金financially supported by Guangdong Natural Science Foundation (No.2016A030312015)the Science and Technology Cooperation Project of Guangdong Province (No.2013B050800027)the Science and Technology Cooperation Project of Guangzhou (No.201508030001)。
文摘7 YSZ coating was prepared by plasma sprayphysical vapor deposition(PS-PVD) technique based on a specific experimental design.The microstructure and deposition properties of 7 YSZ coating along the radius of plasma jet were investigated in detail.Results show that the coating presents regional characteristic in the radial direction,which could be divided into three typical zones:In Zone Ⅰ,the coating is all composed of columnar structures with cauliflower structure,and the coating properties including the surface roughness and deposition efficiency(DE) are almost stable;in Zone Ⅲ,the coating is made up of solid particles,droplet and gas phase mixed without columnar structures;Zone Ⅱ is between Zone Ⅰ and ZoneⅢ, in which there are columns with domed top and small particles.Based on experiment results,a model on the state and distribution of particles in plasma jet was proposed to clarify the regional characteristic.This study is helpful to comprehend and control coatings deposition by PS-PVD technique.
基金This work was supported by the National Natural Science Foundation of China (Nos. 21503114, 21774061, 61605090, 91833306)Synergetic Innovation Centre for Organic Electronics and In formation Displays, Nanji ng Un iversity of Posts a nd Telecommunications Scientific Foundation NUPTSF (NY215056, NY21417& NY215172, 2016XSG03)the Six Peak Talents Foundation of Jiangsu Province (XCL-CXTD-009), and the High Performanee Computing Center of Nanjing Tech University.
文摘Organic semiconductor materials with low reorganization energy have various applications such as in organic light-emitting diodes (OLEDs),organic field-effect transistor (OFETs) and organic solar cells (OSCs).In this work,we have designed a new class of gridspiroarenes (GS-SFX and GS-SITF) with #-shaped structures,which have novel crisscross geometrical structures compared to widely used spirocyclic arenes-SFX and SITF.The structure electronic properties,adiabatic ionization potentials (IPa),adiabatic electron affinities (EAa) and reorganization energies (λ) of GS-SFX and GS-SITF have been calculated using density functional theory (DFT) method.The calculated HOMO and LUMO spatial distributions suggest that GS-SFX and GS-SITF have better transport properties.The noncovalent interaction analysis shows the weak intramolecular interactions between their arms.The results indicate that the reorganization energies of GS-SFX and GS-SITF are significantly reduced compared to the dimer structures-DSFX and DSITF.Furthermore,the GS-SITF1 which is one of the isomers of GS-SITF exhibits the lowest values for λ(h)(0.067 eV) and λ(e)(0.153 eV).Therefore,we believe the predicted structure,electronic property,and reorganization energy are good indicator for transport materials.This work has systematically studied the effect of gridization,which provides insights to design organic semiconductor materials with excellent charge transport properties.
基金We would like to acknowledge the financial support from the National Natural Science Foundation of China(52172067)Guangdong Province Outstanding Youth Foundation(2021B1515020038)+1 种基金Guangdong Special Support Program(2019BT02C629)Guangdong Academy of Sciences Program(2020GDASYL-20200104030).
文摘Plasma spray-physical vapor deposition(PS-PVD)as a novel process was used to prepare feather-like columnar thermal barrier coatings(TBCs).This special microstructure shows good strain tolerance and non-line-of-sight(NLOS)deposition,giving great potential application in aero-engine.However,due to serious service environment of aero-engine,particle erosion performance is a weakness for PS-PVD 7YSZ TBCs.As a solution,an Al-modification approach was proposed in this investigation.Through in-situ reaction of Al and ZrO2,anα-Al2O3 overlay can be formed on the surface of 7YSZ columnar coating.The results demonstrate that this approach can improve particle erosion resistance since hardness improvement of Al-modified TBCs.Meanwhile,as another important performance of thermal cycle,it has a better optimization with 350-cycle water-quenching,compared with the as-sprayed TBCs.