TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μ...TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μm to 11 μm.TiO2 powders with different sizes were prepared by the solid state ceramic route. The effects of TiO2 particle size on the microstructure, density, moisture absorption, thermal conductivity and microwave dielectric properties of PTFE/TiO2 composites were investigated. The density showed an increasing trend as the TiO2 particle size increased, while the dielectric loss (tanδ) and moisture absorption decreased with the increase of TiO2 particle size. The dielectric constant (εr) and thermal conductivity (λ) decreased up to D50 = 6.5 μm and then sharply increased. Good properties with values of εr = 6.8, tanδ = 0.0012 and λ = 0.533 W?m?1?K?1 were obtained in PTFE/TiO2 composites when the particle size of TiO2 was 11 μm.展开更多
Objective: We conducted a preliminary study on the feasibility of preparing monoclonal antibody by umbilical cord blood cells systems. Methods: Collected umbilical cord blood cells and stimulated by Rubella virus, the...Objective: We conducted a preliminary study on the feasibility of preparing monoclonal antibody by umbilical cord blood cells systems. Methods: Collected umbilical cord blood cells and stimulated by Rubella virus, then incubated them and collected cell supernatant. By using Caprylic acid- saturated Ammonium sulfate method, monoclonal antibody was purified, and IgG subtype identification was conducted by their subtype classification kit of sigma. In traditional way, the preparation of monoclonal antibody cannot do without BABL/C mice and SP2/0 hybridoma cells. Consider this kinds of monoclonal antibody as a positive control, the reactivity and specificity of monoclonal antibodies were identified by Dot-ELISA. Results: By ELISA, we obtained four strains of positive umbilical cord blood cells. After subculture, cryopreservation and resuscitation in vitro, three of them were confirmed to secrete monoclonal antibody against rubella virus stably. The result of monoclonal antibody subtype classification showed that, both IgG1 and IgG2 types were detected. However, the quantity of monoclonal antibody prepared by umbilical cord blood cells was less than that from traditional method. Conclusions: The method of prepare monoclonal antibody using umbilical cord blood cells is feasible.展开更多
In this work, the polytetrafluoroethylene (PTFE)-based composite substrates were manufactured by mixing, calendering, hot-pressing sintering. The composition of all the samples was PTFE, SiO2 and chopped E-glass fiber...In this work, the polytetrafluoroethylene (PTFE)-based composite substrates were manufactured by mixing, calendering, hot-pressing sintering. The composition of all the samples was PTFE, SiO2 and chopped E-glass fibers. The effects of content of E-glass fibers on the properties of the SiO2 filled PTFE composites were investigated, including density, water absorption, dielectric properties (εr, tanδ), coefficient of thermal expansion (CTE) and temperature coefficient of dielectric constant (τε). The compositions of inorganic materials mixture are (62 ? x) % SiO2 + x % E-glass fiber (x: mass ratio to composites, x = 0, 1, 1.5, 2, 2.5, 3). The results show that as the content of E-glass fibers is 2.5 wt.%, this composite obtains optimal properties, including excellent dielectric properties (εr^2.9123, tanδ~0.0011), acceptable water absorption of 0.075%, temperature coefficient of dielectric constant of 10 ppm/?C and coefficient of thermal expansion of 15.87 ppm/?C.展开更多
In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% ...In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% to 16 wt% with a step size of 4 wt%. The effects of CaTiO3 loading on the density, moisture absorption, thermal expansion, microstructure and microwave dielectric properties were investigated. As CaTiO3 loading content increased from 0 wt% to 16 wt%, the thermal expansion initially displayed a sharp increase, and showed a slight enhancement when the content of CaTiO3 exceeded 12 wt%. The density experienced a continuous decrease with the addition of CaTiO3. The moisture absorption displayed a steady increase with the increasing CaTiO3 loading amount. The changing of dielectric constant (εr) and loss tangent (tanδ) were similar to that of the moisture absorption in a manner. Good dielectric properties with values of εr = 11.60, tanδ = 0.002 were obtained in the PTFE matrix with 16 wt% CaTiO3 and 45 wt% TiO2.展开更多
In this work,the effects of the frequency,pressure,gas composition,and secondary-electron emission coefficient on the discharge mode in capacitively coupled Ar/O_(2) plasmas were carefully studied through simulations....In this work,the effects of the frequency,pressure,gas composition,and secondary-electron emission coefficient on the discharge mode in capacitively coupled Ar/O_(2) plasmas were carefully studied through simulations.Three discharge modes,i.e.,α,γ,and drift-ambipolar(DA),were considered in this study.The results show that a mode transition from theγ-DA hybrid mode dominated by theγmode to the DA-αhybrid mode dominated by the DA mode is induced by increasing the frequency from 100 k Hz to 40 MHz.Furthermore,the electron temperature decreases with increasing frequency,while the plasma density first decreases and then increases.It was found that the electronegativity increases slightly with increasing pressure in the lowfrequency region,and it increases notably with increasing pressure in the high-frequency region.It was also observed that the frequency corresponding to the mode transition fromγto DA decreased when the secondary-electron emission coefficient was decreased.Finally,it was found that increasing the oxygen content weakens theγmode and enhances the DA mode.More importantly,the density of oxygen atoms and ozone will increase greatly with increasing oxygen content,which is of great significance for industrial applications.展开更多
The explosive process of 5G communication evokes the urgent demand of miniaturized and integrated dielectric ceramics filter It is a pressing need to advance the development of dielectric ceramics utilization of emerg...The explosive process of 5G communication evokes the urgent demand of miniaturized and integrated dielectric ceramics filter It is a pressing need to advance the development of dielectric ceramics utilization of emerging technology to design new materials and understand the polarization mechanism.This review provides the summary of the study of microwave dielectric ceramics(MWDCs)sintered higher than 1000℃ from 2010 up to now,with the purpose of taking a broad and historical view of these ceramics and illustrating research directions.To date,researchers endeavor to explain the structure-property relationship of ceramics with multitude of approaches and design a new formula or strategy to obtain excellent microwave dielectric properties.There are variety of factors that impact the permittivity,dielectric loss,and temperature stability of dielectric materials,covering intrinsic and extrinsic factors.Many of these factors are often intertwined,which can complicate new dielectric material discovery and the mechanism investigation.Because of the various ceramics systems,pseudo phase diagram was used to classify the dielectric materials based on the composition.In this review,the ceramics were firstly divided into ternary systems,and then brief description of the experimental probes and complementary theoretical methods that have been used to discern the intrinsic polarization mechanisms and the origin of intrinsic loss was mentioned.Finally,some perspectives on the future outlook for high-temperature MWDCs were offered based on the synthesis method,characterization techniques,and significant theory developments.展开更多
Sr_(0.7)Bi_(0.2)TiO_(3)(SBT)by increasing the proportion and size of polar nano-region.Meanwhile,the BDS remains a high level with x<0.38 attributed to the addition of KBT with a large band gap.As a result,the 0.62...Sr_(0.7)Bi_(0.2)TiO_(3)(SBT)by increasing the proportion and size of polar nano-region.Meanwhile,the BDS remains a high level with x<0.38 attributed to the addition of KBT with a large band gap.As a result,the 0.62SBT-0.38KBT exhibits a high energy storage density of 2.21 J/cm^(3)with high h of 91.4%at 220 kV/cm and superior temperature stability(-55~150℃),frequency stability(10~500 Hz)and fatigue resistance(105 cycles).Moreover,high pulsed discharge energy density(1.81 J/cm^(3)),high power density(49.5 MW/cm3)and great thermal stability(20~160℃)are achieved in 0.62SBT-0.38KBT.Based on these excellent properties,the 0.62SBT-0.38KBT are suitable for pulsed power systems.This work provides a novel strategy and systematic study for improving energy storage properties of SBT.展开更多
This article presents low-firing,low-loss and temperature stable ZnO-TiO_(2)-Nb_(2)O_(5) microwave dielectric composite ceramics with the assistance of lithium borosilicate(LBS)and zinc borosilicate(ZBS)glass frits.Th...This article presents low-firing,low-loss and temperature stable ZnO-TiO_(2)-Nb_(2)O_(5) microwave dielectric composite ceramics with the assistance of lithium borosilicate(LBS)and zinc borosilicate(ZBS)glass frits.There is a liquid phase(eutectic mixture)generated by LBS(ZBS)glass,and solid particles could be wetted and dissolved.Therefore,the migrations and rearrangements of particles could be performed.Besides,compared with ceramics undoped with glass frits,lower activation energies(E_(a))of ceramics doped with LBS and ZBS glass suggest that the low-temperature sintering behavior is easier to carry out.The results indicated that LBS and ZBS glass both are effective sintering aids to accelerate the sintering process and improve the microwave dielectric properties of composite ceramics by controlling the phase compositions under low temperature.Combination great properties of ZnO-TiO_(2)-Nb_(2)O_(5) ceramics were obtained when sintered at 900℃ for 4 h:ε_(r)=36.7,Q×f=20,000 GHz,τ_(f)=7 ppm/℃.展开更多
In this work,Raman spectra and dielectricity-temperature dependence measurements were used to investigate the B-site order degree in CuO-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)ferroelectric ceramics.The measurement ...In this work,Raman spectra and dielectricity-temperature dependence measurements were used to investigate the B-site order degree in CuO-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)ferroelectric ceramics.The measurement results indicated a typical relaxor characteristic for all samples.With the increasing of CuO doping content,the B-site order degree increased first and then decreased.However,the frequency dispersion and the relaxation degree decreased first and then increased while the CuO addition content was increasing,which was thought to be strongly correlated with the variations of the B-site order.The opposite variation tendency of the B-site order degree and the relaxation degree revealed that the phase transition dispersity is closely related to the order-disorder behaviors.展开更多
Oncogenic KRAS reprograms pancreatic ductal adenocarcinoma(PDAC) cells to a state that is awfully resistant to apoptosis.An alternative coping strategy is to trigger a nonapoptotic cell death.Herein,a multi specific p...Oncogenic KRAS reprograms pancreatic ductal adenocarcinoma(PDAC) cells to a state that is awfully resistant to apoptosis.An alternative coping strategy is to trigger a nonapoptotic cell death.Herein,a multi specific platinum complex SEP was constructed by conjugating a quinone derivative seratrodast to a prodrug of cisplatin.Interestingly,SEP-treated KRAS-mutant PDAC cells showed the characteristics of pyroptosis,apoptosis and necroptosis,similar to PANoptosis(a newfound inflammatory cell death).Mechanistically,SEP could enter cancer cells effectively,then damage nuclear DNA,boost mitochondrial superoxide anion radicals and affect various signaling pathways related to redox homeostasis and tumor metabolism.To our best knowledge,SEP is the first metal complex,even small molecule,to elicit PANoptosis(pyroptosis,apoptosis and necroptosis) in cancer cells,providing a new strategy to overcome apoptotic resistance of KRAS-mutant PDAC.展开更多
The Ba_(12)ReNb_(9)O_(36)(Re=Yb,Ce,Tm,Er,Y,Ho,Dy,Gd)ceramics are synthesized by solid-phase reaction method.The phase composition,crystal structure,microstructure,and microwave dielectric properties of the ceramics ar...The Ba_(12)ReNb_(9)O_(36)(Re=Yb,Ce,Tm,Er,Y,Ho,Dy,Gd)ceramics are synthesized by solid-phase reaction method.The phase composition,crystal structure,microstructure,and microwave dielectric properties of the ceramics are investigated by X-ray diffraction,X-ray photoelectron spectroscopy,Scanning electron microscopy and Raman spectrum.The optimal microwave dielectric properties(ε_(r)=37.23,Q×f=36600 GHz,andτ_(f)=34 ppm/℃)are obtained for Ba_(12)YbNb_(9)O_(36) ceramic sintered at 1420℃for 6 h.In this system,the variation of dielectric constant is dominated by polarizability.The Q×f is mainly affected by internal strain/fluctuation of d-spacing.The variation of τ_(f) is related to the temperature coefficient of dielectric constant and the oxygen octahedron distortion.Furthermore,the reduction of Ce^(4+) ions,the relative density,linear thermal expansion coefficient,and the second phase are also important factors affecting microwave dielectric properties.展开更多
文摘TiO2 filled polytetrafluoroethylene (PTFE) composite were fabricated for microwave circuit applications. PTFE/TiO2 composites were prepared by cold pressing and hot treating. The particle size of TiO2 varied from 5 μm to 11 μm.TiO2 powders with different sizes were prepared by the solid state ceramic route. The effects of TiO2 particle size on the microstructure, density, moisture absorption, thermal conductivity and microwave dielectric properties of PTFE/TiO2 composites were investigated. The density showed an increasing trend as the TiO2 particle size increased, while the dielectric loss (tanδ) and moisture absorption decreased with the increase of TiO2 particle size. The dielectric constant (εr) and thermal conductivity (λ) decreased up to D50 = 6.5 μm and then sharply increased. Good properties with values of εr = 6.8, tanδ = 0.0012 and λ = 0.533 W?m?1?K?1 were obtained in PTFE/TiO2 composites when the particle size of TiO2 was 11 μm.
文摘Objective: We conducted a preliminary study on the feasibility of preparing monoclonal antibody by umbilical cord blood cells systems. Methods: Collected umbilical cord blood cells and stimulated by Rubella virus, then incubated them and collected cell supernatant. By using Caprylic acid- saturated Ammonium sulfate method, monoclonal antibody was purified, and IgG subtype identification was conducted by their subtype classification kit of sigma. In traditional way, the preparation of monoclonal antibody cannot do without BABL/C mice and SP2/0 hybridoma cells. Consider this kinds of monoclonal antibody as a positive control, the reactivity and specificity of monoclonal antibodies were identified by Dot-ELISA. Results: By ELISA, we obtained four strains of positive umbilical cord blood cells. After subculture, cryopreservation and resuscitation in vitro, three of them were confirmed to secrete monoclonal antibody against rubella virus stably. The result of monoclonal antibody subtype classification showed that, both IgG1 and IgG2 types were detected. However, the quantity of monoclonal antibody prepared by umbilical cord blood cells was less than that from traditional method. Conclusions: The method of prepare monoclonal antibody using umbilical cord blood cells is feasible.
文摘In this work, the polytetrafluoroethylene (PTFE)-based composite substrates were manufactured by mixing, calendering, hot-pressing sintering. The composition of all the samples was PTFE, SiO2 and chopped E-glass fibers. The effects of content of E-glass fibers on the properties of the SiO2 filled PTFE composites were investigated, including density, water absorption, dielectric properties (εr, tanδ), coefficient of thermal expansion (CTE) and temperature coefficient of dielectric constant (τε). The compositions of inorganic materials mixture are (62 ? x) % SiO2 + x % E-glass fiber (x: mass ratio to composites, x = 0, 1, 1.5, 2, 2.5, 3). The results show that as the content of E-glass fibers is 2.5 wt.%, this composite obtains optimal properties, including excellent dielectric properties (εr^2.9123, tanδ~0.0011), acceptable water absorption of 0.075%, temperature coefficient of dielectric constant of 10 ppm/?C and coefficient of thermal expansion of 15.87 ppm/?C.
文摘In this paper, a detailed study was carried out on the PTFE reinforced with TiO2 and CaTiO3. The filler content of ceramic powder was a fixed value of 61 wt% and the content of CaTiO3 in PTFE matrix varied from 0 wt% to 16 wt% with a step size of 4 wt%. The effects of CaTiO3 loading on the density, moisture absorption, thermal expansion, microstructure and microwave dielectric properties were investigated. As CaTiO3 loading content increased from 0 wt% to 16 wt%, the thermal expansion initially displayed a sharp increase, and showed a slight enhancement when the content of CaTiO3 exceeded 12 wt%. The density experienced a continuous decrease with the addition of CaTiO3. The moisture absorption displayed a steady increase with the increasing CaTiO3 loading amount. The changing of dielectric constant (εr) and loss tangent (tanδ) were similar to that of the moisture absorption in a manner. Good dielectric properties with values of εr = 11.60, tanδ = 0.002 were obtained in the PTFE matrix with 16 wt% CaTiO3 and 45 wt% TiO2.
基金supported by National Natural Science Foundation of China(Nos.11805107 and 12275039)the Fundamental Research Funds in Heilongjiang Provincial Universities of China(No.145309625)。
文摘In this work,the effects of the frequency,pressure,gas composition,and secondary-electron emission coefficient on the discharge mode in capacitively coupled Ar/O_(2) plasmas were carefully studied through simulations.Three discharge modes,i.e.,α,γ,and drift-ambipolar(DA),were considered in this study.The results show that a mode transition from theγ-DA hybrid mode dominated by theγmode to the DA-αhybrid mode dominated by the DA mode is induced by increasing the frequency from 100 k Hz to 40 MHz.Furthermore,the electron temperature decreases with increasing frequency,while the plasma density first decreases and then increases.It was found that the electronegativity increases slightly with increasing pressure in the lowfrequency region,and it increases notably with increasing pressure in the high-frequency region.It was also observed that the frequency corresponding to the mode transition fromγto DA decreased when the secondary-electron emission coefficient was decreased.Finally,it was found that increasing the oxygen content weakens theγmode and enhances the DA mode.More importantly,the density of oxygen atoms and ozone will increase greatly with increasing oxygen content,which is of great significance for industrial applications.
基金supported by the National Natural Science Foundation of China(Grant No.51872037).
文摘The explosive process of 5G communication evokes the urgent demand of miniaturized and integrated dielectric ceramics filter It is a pressing need to advance the development of dielectric ceramics utilization of emerging technology to design new materials and understand the polarization mechanism.This review provides the summary of the study of microwave dielectric ceramics(MWDCs)sintered higher than 1000℃ from 2010 up to now,with the purpose of taking a broad and historical view of these ceramics and illustrating research directions.To date,researchers endeavor to explain the structure-property relationship of ceramics with multitude of approaches and design a new formula or strategy to obtain excellent microwave dielectric properties.There are variety of factors that impact the permittivity,dielectric loss,and temperature stability of dielectric materials,covering intrinsic and extrinsic factors.Many of these factors are often intertwined,which can complicate new dielectric material discovery and the mechanism investigation.Because of the various ceramics systems,pseudo phase diagram was used to classify the dielectric materials based on the composition.In this review,the ceramics were firstly divided into ternary systems,and then brief description of the experimental probes and complementary theoretical methods that have been used to discern the intrinsic polarization mechanisms and the origin of intrinsic loss was mentioned.Finally,some perspectives on the future outlook for high-temperature MWDCs were offered based on the synthesis method,characterization techniques,and significant theory developments.
基金We are grateful to the National Natural Science Foundation of China(Grant No.51672038).
文摘Sr_(0.7)Bi_(0.2)TiO_(3)(SBT)by increasing the proportion and size of polar nano-region.Meanwhile,the BDS remains a high level with x<0.38 attributed to the addition of KBT with a large band gap.As a result,the 0.62SBT-0.38KBT exhibits a high energy storage density of 2.21 J/cm^(3)with high h of 91.4%at 220 kV/cm and superior temperature stability(-55~150℃),frequency stability(10~500 Hz)and fatigue resistance(105 cycles).Moreover,high pulsed discharge energy density(1.81 J/cm^(3)),high power density(49.5 MW/cm3)and great thermal stability(20~160℃)are achieved in 0.62SBT-0.38KBT.Based on these excellent properties,the 0.62SBT-0.38KBT are suitable for pulsed power systems.This work provides a novel strategy and systematic study for improving energy storage properties of SBT.
基金financial supports from the National Natural Science Foundation of China(No.51872037).
文摘This article presents low-firing,low-loss and temperature stable ZnO-TiO_(2)-Nb_(2)O_(5) microwave dielectric composite ceramics with the assistance of lithium borosilicate(LBS)and zinc borosilicate(ZBS)glass frits.There is a liquid phase(eutectic mixture)generated by LBS(ZBS)glass,and solid particles could be wetted and dissolved.Therefore,the migrations and rearrangements of particles could be performed.Besides,compared with ceramics undoped with glass frits,lower activation energies(E_(a))of ceramics doped with LBS and ZBS glass suggest that the low-temperature sintering behavior is easier to carry out.The results indicated that LBS and ZBS glass both are effective sintering aids to accelerate the sintering process and improve the microwave dielectric properties of composite ceramics by controlling the phase compositions under low temperature.Combination great properties of ZnO-TiO_(2)-Nb_(2)O_(5) ceramics were obtained when sintered at 900℃ for 4 h:ε_(r)=36.7,Q×f=20,000 GHz,τ_(f)=7 ppm/℃.
基金supported by the Open Foundation of State Key Laboratory of Electronic Thin Films and Integrated Devices(KFJJ201207).
文摘In this work,Raman spectra and dielectricity-temperature dependence measurements were used to investigate the B-site order degree in CuO-doped Pb(Mg_(1/3)Nb_(2/3))O_(3)-PbTiO_(3)ferroelectric ceramics.The measurement results indicated a typical relaxor characteristic for all samples.With the increasing of CuO doping content,the B-site order degree increased first and then decreased.However,the frequency dispersion and the relaxation degree decreased first and then increased while the CuO addition content was increasing,which was thought to be strongly correlated with the variations of the B-site order.The opposite variation tendency of the B-site order degree and the relaxation degree revealed that the phase transition dispersity is closely related to the order-disorder behaviors.
基金supported by the National Natural Science Foundation of China (21731004,91953201,21907050,22107047)the Natural Science Foundation of Jiangsu Province (BK20202004)+1 种基金the Postdoctoral Research Funding Program of Jiangsu Province (003503)the Excellent Research Program of Nanjing University (ZYJH004)
文摘Oncogenic KRAS reprograms pancreatic ductal adenocarcinoma(PDAC) cells to a state that is awfully resistant to apoptosis.An alternative coping strategy is to trigger a nonapoptotic cell death.Herein,a multi specific platinum complex SEP was constructed by conjugating a quinone derivative seratrodast to a prodrug of cisplatin.Interestingly,SEP-treated KRAS-mutant PDAC cells showed the characteristics of pyroptosis,apoptosis and necroptosis,similar to PANoptosis(a newfound inflammatory cell death).Mechanistically,SEP could enter cancer cells effectively,then damage nuclear DNA,boost mitochondrial superoxide anion radicals and affect various signaling pathways related to redox homeostasis and tumor metabolism.To our best knowledge,SEP is the first metal complex,even small molecule,to elicit PANoptosis(pyroptosis,apoptosis and necroptosis) in cancer cells,providing a new strategy to overcome apoptotic resistance of KRAS-mutant PDAC.
文摘The Ba_(12)ReNb_(9)O_(36)(Re=Yb,Ce,Tm,Er,Y,Ho,Dy,Gd)ceramics are synthesized by solid-phase reaction method.The phase composition,crystal structure,microstructure,and microwave dielectric properties of the ceramics are investigated by X-ray diffraction,X-ray photoelectron spectroscopy,Scanning electron microscopy and Raman spectrum.The optimal microwave dielectric properties(ε_(r)=37.23,Q×f=36600 GHz,andτ_(f)=34 ppm/℃)are obtained for Ba_(12)YbNb_(9)O_(36) ceramic sintered at 1420℃for 6 h.In this system,the variation of dielectric constant is dominated by polarizability.The Q×f is mainly affected by internal strain/fluctuation of d-spacing.The variation of τ_(f) is related to the temperature coefficient of dielectric constant and the oxygen octahedron distortion.Furthermore,the reduction of Ce^(4+) ions,the relative density,linear thermal expansion coefficient,and the second phase are also important factors affecting microwave dielectric properties.
