To explore genetic diversity and estimate the genetic differences among populations of Lutraria maxima in the coastal waters off south to southeast China,the morphology of the species of five different geographical po...To explore genetic diversity and estimate the genetic differences among populations of Lutraria maxima in the coastal waters off south to southeast China,the morphology of the species of five different geographical populations(Beihai,Weizhou Island,Zhanjiang,Xiamen,and Fuzhou)in Guangxi,Guangdong,and Fujian provinces was studied statistically in combination with the microsatellite markers.As revealed by morphological principal component analysis(PCA),the cumulative contribution rate of the first three principal components was 72.596%.The discrimination accuracy ranged from 47.5%to 80.0%,and the scatter plots of principal component and discriminant analysis were consistent in overall,showing that the Xiamen and Fuzhou populations were overlapped obviously.For microsatellite markers,10 pairs of polymorphic primers were obtained by high-throughput transcriptome sequencing,and used for genetic diversity analysis.It was showed that the average number of alleles and eff ective alleles observed in each population ranged from 8.100 to 10.900,and from 3.497 to 4.228,respectively.The average observed heterozygosity(H_(o))and expected heterozygosity(H_(e))in the five populations ranged from 0.541 to 0.615,and from 0.642 to 0.733,respectively.The genetic distance(DA)ranged from 0.078 to 0.523,and the population genetic differentiation index(F_(ST))ranged from 0.027 to 0.139.The unweighted pair-population method with arithmetic means(UPGMA)and structure analysis showed that the five populations could be divided into two main clusters,the Beibu Gulf group(Beihai and Weizhou Island)and the Southeast China Sea group(Zhanjiang,Xiamen,and Fuzhou),suggesting that L.maxima has been separated geographically by the barrier of the Leizhou Peninsula into two groups in evolution,which provided us with a scientific clue to better protect the bioresource and establish an appropriate fishery management stocks for L.maxima populations in south China.展开更多
人类β-地中海贫血的发病机制与β-样珠蛋白基因异常表达息息相关。人类β-样珠蛋白基因以5′-ε-Gγ-Aγ-δ-β-3′的顺序排列于β-珠蛋白基因座,受5′LCR (locus control region)中5个超敏位点(hypersensitive site,HS)5′HS5~5′HS1...人类β-地中海贫血的发病机制与β-样珠蛋白基因异常表达息息相关。人类β-样珠蛋白基因以5′-ε-Gγ-Aγ-δ-β-3′的顺序排列于β-珠蛋白基因座,受5′LCR (locus control region)中5个超敏位点(hypersensitive site,HS)5′HS5~5′HS1和3′HS1调控。其中5′HS2是最重要的增强子,能产生增强子RNA(enhancerRNA)并调控ε-globin、γ-globin和β-globin的表达。为了进一步探究K562细胞中增强子5′HS2的功能,本研究首先通过染色质构象捕获技术在人慢性髓原白血病K562细胞中探测到5′HS2介导的染色质相互作用集中在以包含CTCF(CCCTC-bindingfactor)位点的3′HS1和5′HS5为边界的拓扑结构域中,5′HS2在三维空间上与HBE1、HBG2和HBG1启动子区域相互靠近。其次运用CRISPRDNA片段编辑技术在K562细胞系中删除了增强子5′HS2。最后通过RNA-seq和CUT&Tag (cleavage under target&tagmentation)实验分析两个5′HS2删除的单克隆细胞系的转录组和染色质H3K27ac组蛋白修饰,发现91个基因表达显著下调而且其启动子区的H3K27ac修饰程度显著降低。这些基因主要聚类于氧气运输、免疫应答、细胞粘附、抗氧化和维持血栓形成等与红细胞功能相关的生物过程中,表明K562细胞系中增强子5′HS2对红细胞功能相关基因的转录产生了广泛影响。展开更多
Mature wild-type yellow catfish( Pelteobagrus fulvidraco Richardson) individuals with excellent traits have been screened from the Yangtze River as broodstock to establish the germplasm bank of pure-line yellow catfis...Mature wild-type yellow catfish( Pelteobagrus fulvidraco Richardson) individuals with excellent traits have been screened from the Yangtze River as broodstock to establish the germplasm bank of pure-line yellow catfish by artificial gynogenesis technique and hormonal sex reversal method. Based on pure lines of yellow catfish,super-males and physiological females of yellow catfish were selected by GMT technique,hormonal sex reversal method and test-crossing to establish the germplasm bank of YY physiological females( YY♀). The propagation system of male yellow catfish( XY♂) was established based on the combination of super-males( YY♂) and pure-line female( XX♀) for large-scale production of pure-line yellow catfish males,which effectively overcome the disadvantages in the production of common fingerlings and male fingerlings using low-grade fish with slow growth and small size at the bottom of the fish grader as broodfish,such as progeny germplasm degeneration,loss of growth vigor and reduction of breeding benefits. The technical route of breeding pure-line YY physiological females( YY♀) and YY super-males( YY♂) laid the foundation for large-scale production of environmentally friendly yellow catfish males with pure germplasm and strong stress resistance,and provided an efficient,stable,healthy,environmentally friendly,energy-saving and income-increasing approach for sustainable development of yellow catfish breeding industry.展开更多
Microwave dielectric ceramics should be improved to advance mobile communication technologies further.In this study,we prepared Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics with nonstoichiometric Sr^(2+)ratios based on our ...Microwave dielectric ceramics should be improved to advance mobile communication technologies further.In this study,we prepared Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics with nonstoichiometric Sr^(2+)ratios based on our previously reported SrY_(2)O_(4) microwave dielectric ceramic,which has a low dielectric constant and an ultrahigh quality factor(Q value).The ceramic exhibited a 33.6% higher Q-by-frequency(Q×f)value(Q≈12,500)at x=0.02 than SrY_(2)O_(4).All Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited pure phase structures,although variations in crystal-plane spacings were observed.The ceramics are mainly composed of Sr-O,Y1-O,and Y_(2)-O octahedra,with the temperature coefficient of the resonant frequency(τ_(f))of the ceramic increasing with Y_(2)-O octahedral distortion.The ceramic comprises uniform grains with a homogeneous elemental distribution,clear grain boundaries,and no obvious cavities at x=0.02.The Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited good microwave dielectric properties,with optimal performance observed at x=0.02(dielectric constant(εr)=15.41,Q×f=112,375 GHz,and τ_(f)=-17.44 ppm/℃).The τ_(f) value was reduced to meet the temperaturestability requirements of 5G/6G communication systems by adding CaTiO_(3),with Sr_(1.02)Y_(2)O_(4.02)+2wt% CaTiO_(3) exhibiting ε_(r)=16.14,Q×f=51,004 GHz,andτf=0 ppm/℃.A dielectric resonator antenna prepared using Sr_(1.02)Y_(2)O_(4.02)+2wt%CaTiO_(3) exhibited a central frequency of 26.6 GHz,with a corresponding gain and efficiency of 3.66 dBi and 83.14%,respectively.Consequently,Sr_(1.02)Y_(2)O_(4).02-based dielectric resonator antennas are suitable for use in 5G millimeter-wave band(24.5-27.5 GHz)applications.展开更多
This paper describes the solid-state production of a unique yellowish-grey microwave dielectric ceramic,Ca_(3)Fe_(2)Ge_(3)O_(12)(CFG).Rietveld refinement demonstrated that CFG corresponds to a cubic system(space group...This paper describes the solid-state production of a unique yellowish-grey microwave dielectric ceramic,Ca_(3)Fe_(2)Ge_(3)O_(12)(CFG).Rietveld refinement demonstrated that CFG corresponds to a cubic system(space group 230:Ia 3 d).The relative density of the ceramic initially increased and then decreased with the sintering temperature,reaching a maximum of 96.92%at 1330℃.According to scanning electron mi-croscopy and energy-dispersive spectroscopy results,the CFG ceramic grains are spherical and consistent in size;furthermore,they have distinct grain boundaries and a uniform distribution of the four con-stituent elements.The CFG ceramic has a superior crystal structure and a high crystallinity,according to transmission electron microscopy.Raman spectroscopy revealed that the Q×f value of the ceramic and the full width at half maximum of the Raman peak are negatively correlated.The ceramic possesses the best overall dielectric characteristics after sintering at 1330℃for 4 h:ε_(r)=10.31,Q×f=82636 GHz,andτ_(f)=-45.66×10^(-6)℃^(-1),showing that it is a promising candidate for use in mobile devices.展开更多
(Ba1–xBi0.67xNa0.33x)(Ti1–xBi0.33xSn0.67x)O3(abbreviated as BBNTBS,0.02≤x≤0.12)ceramics were fabricated via a traditional solid state reaction method.The phase transition of BBNTBS from tetragonal to pseudo cubic ...(Ba1–xBi0.67xNa0.33x)(Ti1–xBi0.33xSn0.67x)O3(abbreviated as BBNTBS,0.02≤x≤0.12)ceramics were fabricated via a traditional solid state reaction method.The phase transition of BBNTBS from tetragonal to pseudo cubic is demonstrated by XRD and Raman spectra.The BBNTBS(x=0.1)ceramics have decent properties with a highεr(~2250),smallΔε/ε25℃ values of±15%over a wide temperature range from–58 to 171℃,and low tanδ≤0.02 from 10 to 200℃.The basic mechanisms of conduction and relaxation processes in the high temperature region were thermal activation,and oxygen vacancies might be the ionic charge transport carriers.Meanwhile,BBNTBS(x=0.1)exhibited decent energy storage density(Jd=0.58 J/cm3)and excellent thermal stability(the variation of Jd is less than 3% in the temperature range of 25–120℃),which could be a potential candidate for high energy density capacitors.展开更多
High-performance lead-free dielectric ceramics with simultaneously high energy storage density and power density are in high demanded for pulse power systems.To realize excellent energy-storage characteristics,a strat...High-performance lead-free dielectric ceramics with simultaneously high energy storage density and power density are in high demanded for pulse power systems.To realize excellent energy-storage characteristics,a strategy to enhance antiferroelectricity and construct a local random field simultaneously was proposed in this study.Based on the above strategy,a series of(1-x)NaNbO_(3)-xBi(Ni_(1/2)Sn_(1/2))O3[xBNS,x=0.05,0.10,0.15,0.20,and 0.22]solid solutions were designed and fabricated.An ultrahigh energy storage density(Utotal)of 7.35 J/cm^(3),and recoverable energy density(Urec)of 5.00 J/cm^(3) were achieved in the 0.10BNS ceramics.In addition,an adequate stability of energy storage properties at a range of temperatures(20e140℃),frequencies(1e100 Hz),and fatigue test durations(1e1-10^(4) cycles)were realized in 0.10BNS ceramics.0.10BNS ceramics displayed a high current density of 1005 A/cm2,an ultrahigh power density of 100.5 MW/cm^(3,)and an ultrashort discharge time of 46.5 ns?This remarkable performance not only justified our strategy but also confirmed 0.10BNS ceramics as a promising candidate for energy storage.展开更多
Ceramic dielectric capacitors have a broad scope of application in pulsed power supply devices.Relaxor behavior has manifested decent energy storage capabilities in dielectric materials due to its fast polarization re...Ceramic dielectric capacitors have a broad scope of application in pulsed power supply devices.Relaxor behavior has manifested decent energy storage capabilities in dielectric materials due to its fast polarization response.In addition,an ultrahigh energy storage density can also be achieved in NaNbO_(3)(NN)-based ceramics by combining antiferroelectric and relaxor characteristics.Most of the existing reports about lead-free dielectric ceramics,nevertheless,still lack the relevant research about domain evolution and relaxor behavior.Therefore,a novel lead-free solid solution,(1-x)NaNbO_(3)-xBi(Zn_(0.5)Sn_(0.5))O_(3)(abbreviated as xBZS,x=0.05,0.10,0.15,and 0.20)was designed to analyze the domain evolution and relaxor behavior.Domain evolutions in xBZS ceramics confirmed the contribution of the relaxor behavior to their decent energy storage characteristics caused by the fast polarization rotation according to the low energy barrier of polar nanoregions(PNRs).Consequently,a high energy storage density of 3.14 J/cm^(3)and energy efficiency of 83.30%are simultaneously available with 0.10 BZS ceramics,together with stable energy storage properties over a large temperature range(20-100℃)and a wide frequency range(1-200 Hz).Additionally,for practical applications,the 0.10 BZS ceramics display a high discharge energy storage density(W_(dis)≈1.05 J/cm^(3)),fast discharge rate(t_(0.9)≈60.60 ns),and high hardness(H≈5.49 GPa).This study offers significant insights on the mechanisms of high performance lead-free ceramic energy storage materials.展开更多
The design of three novel fatty nitrogen mustard-based anticancer agents with fluorophores incorporated into the alkene structure(CXL 118,CXL121,and CXL122)is described in this report.The results indicated that these ...The design of three novel fatty nitrogen mustard-based anticancer agents with fluorophores incorporated into the alkene structure(CXL 118,CXL121,and CXL122)is described in this report.The results indicated that these compounds are selectively located in lysosomes and exhibit effective antitumour activity.Notably,these compounds can directly serve as both reporting and imaging agents in vitro and in vivo without the need to add other fluorescent tagging agents.展开更多
Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant,lower dielectric loss and good temperature stability.Never-theless,mos...Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant,lower dielectric loss and good temperature stability.Never-theless,most reported dielectric ceramics have limitation of realizing large energy storage density(W_(rec))and high energy storage efficiency(h)simultaneously due to the low breakdown electric field(E_(b)),low maximum polarization and large remanent polarization(P_(r)).These issues above can be settled by raising the bulk resistivity of dielectric ceramics and optimizing domain structure.Therefore,we designed a new system by doping(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3)TiO_(3) into 0.9NaNbO_(3)-0.1Bi(Ni_(0.5)Zr_(0.5))O_(3) ceramics,which simulta-neously obtained a higher bulk resistivity by decreasing the grain size and achieved a smaller P_(r) by optimizing domain structure,thus the better E_(b) of 530 kV/cm and W_(rec) of 6.43 J/cm^(3) were achieved,h was improved from 34%to 82%.Besides,the 0.4BNST ceramics show excellent temperature,frequency and fatigue stability under the conditions of 20-180℃,1-100 Hz and 104 cycles,respectively.Mean-while,superior power density(P_(D)=107 MW/cm^(3)),large current density(C_(D)=1070 A/cm^(2))and discharge speed(1.025 m s)were achieved in 0.4BNST ceramic.Finally,the charge-discharge performance displayed good temperature stability in the temperature range of 30℃-180℃.The above results indicated that the ceramics have potential practical value in the field of energy storage capacitor.展开更多
This study investigates the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) series ceramics synthesised by solid-state reaction.According to the X-ray diffraction and micros...This study investigates the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) series ceramics synthesised by solid-state reaction.According to the X-ray diffraction and microstructural analyses,the as-prepared MgO-2B_(2)O_(3) ceramics possess a single-phase structure with a rod-like morphology.The effects of different quantities of H_(3)BO_(3) and BaCu(B_(2)O5)(BCB)on the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) ceramics were investigated.Accordingly,the optimal sintering temperature was obtained by adding 30 wt%H_(3)BO_(3) and 8 wt%BCB.We also reduced the sintering temperature to 825°C.Furthermore,the addition of 40 wt%H_(3)BO_(3) and 4 wt%BCB increased the quality factor,permittivity,and temperature coefficient of resonance frequency of MgO-2B_(2)O_(3) to 44,306 GHz(at 15 GHz),5.1,and-32 ppm/℃,respectively.These properties make MgO-2B_(2)O_(3) a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics.展开更多
To understand the current status of germplasm resources of Penaeus japonicus,in this study,genetic diversity was analyzed based on morphometric analysis and fluorescent microsatellite markers.For morphometric analysis...To understand the current status of germplasm resources of Penaeus japonicus,in this study,genetic diversity was analyzed based on morphometric analysis and fluorescent microsatellite markers.For morphometric analysis,the cumulative ratios of the PC1 and PC2(85.90%)were greater than 75%,which can explain the morphological variation among populations.For microsatellite analysis,the allele number in 10 microsatellite loci ranged from 27 to 53,and the effective allele number ranged from 21 to 42.The observed heterozygosity ranged from 0.463 to 0.983,whereas expected heterozygosity ranged from 0.932 to 0.966,and the average polymorphism information content was 0.947,which indicated a high level of genetic diversity.The unbiased genetic distance among populations ranged from 0.230 to 0.431,and the genetic similarity coefficient ranged from 0.654 to 0.782.Analysis of molecular variance(AMOVA)showed that the genetic variation within individuals was the main source of variation,accounting for 88.55%,and only 1.49%of the genetic variation came from among populations.展开更多
(1-x)LiCuNb_(3)O_(9)-Bi(Mg_(0.5)Zr_(0.5))O_(3) ceramics((1-x)LCN-xBMZ)with 0≤x≤0.08 were synthesized by a solid-state reaction method.The phase structure of(1-x)LCN-xBMZ ceramics was characterized by X ray diffracti...(1-x)LiCuNb_(3)O_(9)-Bi(Mg_(0.5)Zr_(0.5))O_(3) ceramics((1-x)LCN-xBMZ)with 0≤x≤0.08 were synthesized by a solid-state reaction method.The phase structure of(1-x)LCN-xBMZ ceramics was characterized by X ray diffraction(XRD),which revealed that the ceranics were distorted cubic perovskite structures.Apparent giant permitivity of 1.98× 10^(4)-1.05× 10^(5) at 100kHz over the measured temperature range(259℃-250℃)was observed in the sintered(1-x)LCN-xBMZ(0≤x≤0.08)ceramics.Especially for the sample of x=0.04,the temperature stability of permitivity was markedly increased(△ε/ε100℃≤±15%),and high relative permitivity(>8.3 × 10^(4))were obtained over a wide temperature range from 100℃ to 250℃at 100 kHz,which indicates that this ceramic is a promising dielectrice material for elevated temperature dielectrics.The giant dielectric property of(1-x)LCN-xBMZ ceramics are profoundly concerned with the Maxwell-Wagner effect.展开更多
基金Supported by the Science and Technology Major Project of Guangxi Province(No.AA17204088)。
文摘To explore genetic diversity and estimate the genetic differences among populations of Lutraria maxima in the coastal waters off south to southeast China,the morphology of the species of five different geographical populations(Beihai,Weizhou Island,Zhanjiang,Xiamen,and Fuzhou)in Guangxi,Guangdong,and Fujian provinces was studied statistically in combination with the microsatellite markers.As revealed by morphological principal component analysis(PCA),the cumulative contribution rate of the first three principal components was 72.596%.The discrimination accuracy ranged from 47.5%to 80.0%,and the scatter plots of principal component and discriminant analysis were consistent in overall,showing that the Xiamen and Fuzhou populations were overlapped obviously.For microsatellite markers,10 pairs of polymorphic primers were obtained by high-throughput transcriptome sequencing,and used for genetic diversity analysis.It was showed that the average number of alleles and eff ective alleles observed in each population ranged from 8.100 to 10.900,and from 3.497 to 4.228,respectively.The average observed heterozygosity(H_(o))and expected heterozygosity(H_(e))in the five populations ranged from 0.541 to 0.615,and from 0.642 to 0.733,respectively.The genetic distance(DA)ranged from 0.078 to 0.523,and the population genetic differentiation index(F_(ST))ranged from 0.027 to 0.139.The unweighted pair-population method with arithmetic means(UPGMA)and structure analysis showed that the five populations could be divided into two main clusters,the Beibu Gulf group(Beihai and Weizhou Island)and the Southeast China Sea group(Zhanjiang,Xiamen,and Fuzhou),suggesting that L.maxima has been separated geographically by the barrier of the Leizhou Peninsula into two groups in evolution,which provided us with a scientific clue to better protect the bioresource and establish an appropriate fishery management stocks for L.maxima populations in south China.
文摘人类β-地中海贫血的发病机制与β-样珠蛋白基因异常表达息息相关。人类β-样珠蛋白基因以5′-ε-Gγ-Aγ-δ-β-3′的顺序排列于β-珠蛋白基因座,受5′LCR (locus control region)中5个超敏位点(hypersensitive site,HS)5′HS5~5′HS1和3′HS1调控。其中5′HS2是最重要的增强子,能产生增强子RNA(enhancerRNA)并调控ε-globin、γ-globin和β-globin的表达。为了进一步探究K562细胞中增强子5′HS2的功能,本研究首先通过染色质构象捕获技术在人慢性髓原白血病K562细胞中探测到5′HS2介导的染色质相互作用集中在以包含CTCF(CCCTC-bindingfactor)位点的3′HS1和5′HS5为边界的拓扑结构域中,5′HS2在三维空间上与HBE1、HBG2和HBG1启动子区域相互靠近。其次运用CRISPRDNA片段编辑技术在K562细胞系中删除了增强子5′HS2。最后通过RNA-seq和CUT&Tag (cleavage under target&tagmentation)实验分析两个5′HS2删除的单克隆细胞系的转录组和染色质H3K27ac组蛋白修饰,发现91个基因表达显著下调而且其启动子区的H3K27ac修饰程度显著降低。这些基因主要聚类于氧气运输、免疫应答、细胞粘附、抗氧化和维持血栓形成等与红细胞功能相关的生物过程中,表明K562细胞系中增强子5′HS2对红细胞功能相关基因的转录产生了广泛影响。
基金Supported by Implementation Plan of Subsidy Project for the Reform and Construction of Grassroots Agricultural Technology Extension System
文摘Mature wild-type yellow catfish( Pelteobagrus fulvidraco Richardson) individuals with excellent traits have been screened from the Yangtze River as broodstock to establish the germplasm bank of pure-line yellow catfish by artificial gynogenesis technique and hormonal sex reversal method. Based on pure lines of yellow catfish,super-males and physiological females of yellow catfish were selected by GMT technique,hormonal sex reversal method and test-crossing to establish the germplasm bank of YY physiological females( YY♀). The propagation system of male yellow catfish( XY♂) was established based on the combination of super-males( YY♂) and pure-line female( XX♀) for large-scale production of pure-line yellow catfish males,which effectively overcome the disadvantages in the production of common fingerlings and male fingerlings using low-grade fish with slow growth and small size at the bottom of the fish grader as broodfish,such as progeny germplasm degeneration,loss of growth vigor and reduction of breeding benefits. The technical route of breeding pure-line YY physiological females( YY♀) and YY super-males( YY♂) laid the foundation for large-scale production of environmentally friendly yellow catfish males with pure germplasm and strong stress resistance,and provided an efficient,stable,healthy,environmentally friendly,energy-saving and income-increasing approach for sustainable development of yellow catfish breeding industry.
基金supported by the National Natural Science Foundation of China(Nos.61761015 and 11664008)the Natural Science Foundation of Guangxi(No.2018GXNSFFA050001)the High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes.
文摘Microwave dielectric ceramics should be improved to advance mobile communication technologies further.In this study,we prepared Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics with nonstoichiometric Sr^(2+)ratios based on our previously reported SrY_(2)O_(4) microwave dielectric ceramic,which has a low dielectric constant and an ultrahigh quality factor(Q value).The ceramic exhibited a 33.6% higher Q-by-frequency(Q×f)value(Q≈12,500)at x=0.02 than SrY_(2)O_(4).All Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited pure phase structures,although variations in crystal-plane spacings were observed.The ceramics are mainly composed of Sr-O,Y1-O,and Y_(2)-O octahedra,with the temperature coefficient of the resonant frequency(τ_(f))of the ceramic increasing with Y_(2)-O octahedral distortion.The ceramic comprises uniform grains with a homogeneous elemental distribution,clear grain boundaries,and no obvious cavities at x=0.02.The Sr_(1+x)Y_(2)O_(4+x)(x=0-0.04)ceramics exhibited good microwave dielectric properties,with optimal performance observed at x=0.02(dielectric constant(εr)=15.41,Q×f=112,375 GHz,and τ_(f)=-17.44 ppm/℃).The τ_(f) value was reduced to meet the temperaturestability requirements of 5G/6G communication systems by adding CaTiO_(3),with Sr_(1.02)Y_(2)O_(4.02)+2wt% CaTiO_(3) exhibiting ε_(r)=16.14,Q×f=51,004 GHz,andτf=0 ppm/℃.A dielectric resonator antenna prepared using Sr_(1.02)Y_(2)O_(4.02)+2wt%CaTiO_(3) exhibited a central frequency of 26.6 GHz,with a corresponding gain and efficiency of 3.66 dBi and 83.14%,respectively.Consequently,Sr_(1.02)Y_(2)O_(4).02-based dielectric resonator antennas are suitable for use in 5G millimeter-wave band(24.5-27.5 GHz)applications.
基金supported by Natural Science Foundation of China(Grant Nos.61761015,11664008)Natural Science Foundation of Guangxi(Grant No 2018GXNSFFA050001)the High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes.
文摘This paper describes the solid-state production of a unique yellowish-grey microwave dielectric ceramic,Ca_(3)Fe_(2)Ge_(3)O_(12)(CFG).Rietveld refinement demonstrated that CFG corresponds to a cubic system(space group 230:Ia 3 d).The relative density of the ceramic initially increased and then decreased with the sintering temperature,reaching a maximum of 96.92%at 1330℃.According to scanning electron mi-croscopy and energy-dispersive spectroscopy results,the CFG ceramic grains are spherical and consistent in size;furthermore,they have distinct grain boundaries and a uniform distribution of the four con-stituent elements.The CFG ceramic has a superior crystal structure and a high crystallinity,according to transmission electron microscopy.Raman spectroscopy revealed that the Q×f value of the ceramic and the full width at half maximum of the Raman peak are negatively correlated.The ceramic possesses the best overall dielectric characteristics after sintering at 1330℃for 4 h:ε_(r)=10.31,Q×f=82636 GHz,andτ_(f)=-45.66×10^(-6)℃^(-1),showing that it is a promising candidate for use in mobile devices.
基金supported by National Natural Science Foundation of China (Nos. 11664008 and 61761015)Natural Science Foundation of Guangxi (Nos. 2018GXNSFFA050001, 2017GXNSFDA198027, and 2017GXNSFFA198011)
文摘(Ba1–xBi0.67xNa0.33x)(Ti1–xBi0.33xSn0.67x)O3(abbreviated as BBNTBS,0.02≤x≤0.12)ceramics were fabricated via a traditional solid state reaction method.The phase transition of BBNTBS from tetragonal to pseudo cubic is demonstrated by XRD and Raman spectra.The BBNTBS(x=0.1)ceramics have decent properties with a highεr(~2250),smallΔε/ε25℃ values of±15%over a wide temperature range from–58 to 171℃,and low tanδ≤0.02 from 10 to 200℃.The basic mechanisms of conduction and relaxation processes in the high temperature region were thermal activation,and oxygen vacancies might be the ionic charge transport carriers.Meanwhile,BBNTBS(x=0.1)exhibited decent energy storage density(Jd=0.58 J/cm3)and excellent thermal stability(the variation of Jd is less than 3% in the temperature range of 25–120℃),which could be a potential candidate for high energy density capacitors.
基金supported by Natural Science Foundation of China(Nos.12064007,11664008 and 61761015)Natural Science Foundation of Guangxi(Nos.2018GXNSFFA050001,2017GXNSFDA198027and 2017GXNSFFA198011)。
文摘High-performance lead-free dielectric ceramics with simultaneously high energy storage density and power density are in high demanded for pulse power systems.To realize excellent energy-storage characteristics,a strategy to enhance antiferroelectricity and construct a local random field simultaneously was proposed in this study.Based on the above strategy,a series of(1-x)NaNbO_(3)-xBi(Ni_(1/2)Sn_(1/2))O3[xBNS,x=0.05,0.10,0.15,0.20,and 0.22]solid solutions were designed and fabricated.An ultrahigh energy storage density(Utotal)of 7.35 J/cm^(3),and recoverable energy density(Urec)of 5.00 J/cm^(3) were achieved in the 0.10BNS ceramics.In addition,an adequate stability of energy storage properties at a range of temperatures(20e140℃),frequencies(1e100 Hz),and fatigue test durations(1e1-10^(4) cycles)were realized in 0.10BNS ceramics.0.10BNS ceramics displayed a high current density of 1005 A/cm2,an ultrahigh power density of 100.5 MW/cm^(3,)and an ultrashort discharge time of 46.5 ns?This remarkable performance not only justified our strategy but also confirmed 0.10BNS ceramics as a promising candidate for energy storage.
基金supported by the National Natural Science Foundation of China(Nos.12064007,11664008,and 61761015)the Natural Science Foundation of Guangxi(Nos.2018GXNSFFA050001,2017GXNSFDA198027,and 2017GXNSFFA198011)High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes。
文摘Ceramic dielectric capacitors have a broad scope of application in pulsed power supply devices.Relaxor behavior has manifested decent energy storage capabilities in dielectric materials due to its fast polarization response.In addition,an ultrahigh energy storage density can also be achieved in NaNbO_(3)(NN)-based ceramics by combining antiferroelectric and relaxor characteristics.Most of the existing reports about lead-free dielectric ceramics,nevertheless,still lack the relevant research about domain evolution and relaxor behavior.Therefore,a novel lead-free solid solution,(1-x)NaNbO_(3)-xBi(Zn_(0.5)Sn_(0.5))O_(3)(abbreviated as xBZS,x=0.05,0.10,0.15,and 0.20)was designed to analyze the domain evolution and relaxor behavior.Domain evolutions in xBZS ceramics confirmed the contribution of the relaxor behavior to their decent energy storage characteristics caused by the fast polarization rotation according to the low energy barrier of polar nanoregions(PNRs).Consequently,a high energy storage density of 3.14 J/cm^(3)and energy efficiency of 83.30%are simultaneously available with 0.10 BZS ceramics,together with stable energy storage properties over a large temperature range(20-100℃)and a wide frequency range(1-200 Hz).Additionally,for practical applications,the 0.10 BZS ceramics display a high discharge energy storage density(W_(dis)≈1.05 J/cm^(3)),fast discharge rate(t_(0.9)≈60.60 ns),and high hardness(H≈5.49 GPa).This study offers significant insights on the mechanisms of high performance lead-free ceramic energy storage materials.
基金supported by Science and Technology Department of Sichuan Province(Nos.2020YJ0237,2018SZ0030,2019YFH0119)National Clinical Research Center for Geriatrics,West China Hospital,Sichuan University(Z20191006)the 135 Project for Disciplines of Excellence,West China Hospital,Sichuan University(Nos.ZYJC18025 and ZYJC18003).
文摘The design of three novel fatty nitrogen mustard-based anticancer agents with fluorophores incorporated into the alkene structure(CXL 118,CXL121,and CXL122)is described in this report.The results indicated that these compounds are selectively located in lysosomes and exhibit effective antitumour activity.Notably,these compounds can directly serve as both reporting and imaging agents in vitro and in vivo without the need to add other fluorescent tagging agents.
基金This work was supported by Natural Science Foundation of China(Nos.12064007 and 61761015)Natural Science Foundation of Guangxi(Nos.2018GXNSFFA050001,2017GXNSFDA198027 and 2017GXNSFFA198011)High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes.
文摘Lead-free ceramic capacitors have the application prospect in the dielectric pulse power system due to the advantages of large dielectric constant,lower dielectric loss and good temperature stability.Never-theless,most reported dielectric ceramics have limitation of realizing large energy storage density(W_(rec))and high energy storage efficiency(h)simultaneously due to the low breakdown electric field(E_(b)),low maximum polarization and large remanent polarization(P_(r)).These issues above can be settled by raising the bulk resistivity of dielectric ceramics and optimizing domain structure.Therefore,we designed a new system by doping(Bi_(0.5)Na_(0.5))_(0.7)Sr_(0.3)TiO_(3) into 0.9NaNbO_(3)-0.1Bi(Ni_(0.5)Zr_(0.5))O_(3) ceramics,which simulta-neously obtained a higher bulk resistivity by decreasing the grain size and achieved a smaller P_(r) by optimizing domain structure,thus the better E_(b) of 530 kV/cm and W_(rec) of 6.43 J/cm^(3) were achieved,h was improved from 34%to 82%.Besides,the 0.4BNST ceramics show excellent temperature,frequency and fatigue stability under the conditions of 20-180℃,1-100 Hz and 104 cycles,respectively.Mean-while,superior power density(P_(D)=107 MW/cm^(3)),large current density(C_(D)=1070 A/cm^(2))and discharge speed(1.025 m s)were achieved in 0.4BNST ceramic.Finally,the charge-discharge performance displayed good temperature stability in the temperature range of 30℃-180℃.The above results indicated that the ceramics have potential practical value in the field of energy storage capacitor.
基金supported by the National Natural Science Foundation of China(Nos.61761015 and 12064007)the Natural Science Foundation of Guangxi(Nos.2018GXNSFFA050001,2017GXNSFDA198027,and 2017GXNSFFA198011)High Level Innovation Team and Outstanding Scholar Program of Guangxi Institutes.
文摘This study investigates the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) series ceramics synthesised by solid-state reaction.According to the X-ray diffraction and microstructural analyses,the as-prepared MgO-2B_(2)O_(3) ceramics possess a single-phase structure with a rod-like morphology.The effects of different quantities of H_(3)BO_(3) and BaCu(B_(2)O5)(BCB)on the bulk density,sintering behaviour,and microwave dielectric properties of the MgO-2B_(2)O_(3) ceramics were investigated.Accordingly,the optimal sintering temperature was obtained by adding 30 wt%H_(3)BO_(3) and 8 wt%BCB.We also reduced the sintering temperature to 825°C.Furthermore,the addition of 40 wt%H_(3)BO_(3) and 4 wt%BCB increased the quality factor,permittivity,and temperature coefficient of resonance frequency of MgO-2B_(2)O_(3) to 44,306 GHz(at 15 GHz),5.1,and-32 ppm/℃,respectively.These properties make MgO-2B_(2)O_(3) a viable low-temperature co-fired ceramic with broad applications in microwave dielectrics.
基金This work was supported by Science and Technology Major Project of Guangxi(NO.AA17204088).
文摘To understand the current status of germplasm resources of Penaeus japonicus,in this study,genetic diversity was analyzed based on morphometric analysis and fluorescent microsatellite markers.For morphometric analysis,the cumulative ratios of the PC1 and PC2(85.90%)were greater than 75%,which can explain the morphological variation among populations.For microsatellite analysis,the allele number in 10 microsatellite loci ranged from 27 to 53,and the effective allele number ranged from 21 to 42.The observed heterozygosity ranged from 0.463 to 0.983,whereas expected heterozygosity ranged from 0.932 to 0.966,and the average polymorphism information content was 0.947,which indicated a high level of genetic diversity.The unbiased genetic distance among populations ranged from 0.230 to 0.431,and the genetic similarity coefficient ranged from 0.654 to 0.782.Analysis of molecular variance(AMOVA)showed that the genetic variation within individuals was the main source of variation,accounting for 88.55%,and only 1.49%of the genetic variation came from among populations.
基金supported by Natural Science Foundation of China(Nos.11664008,11464009 and 61761015)Natural Science Foundation of Guangxi(Nos.2017GXNSFDA198027,2017GXNSFFA198011 and 2015GXNSFDA139033)Project of Guangxi Scientific Research and Technical Development(No.1348020-11).
文摘(1-x)LiCuNb_(3)O_(9)-Bi(Mg_(0.5)Zr_(0.5))O_(3) ceramics((1-x)LCN-xBMZ)with 0≤x≤0.08 were synthesized by a solid-state reaction method.The phase structure of(1-x)LCN-xBMZ ceramics was characterized by X ray diffraction(XRD),which revealed that the ceranics were distorted cubic perovskite structures.Apparent giant permitivity of 1.98× 10^(4)-1.05× 10^(5) at 100kHz over the measured temperature range(259℃-250℃)was observed in the sintered(1-x)LCN-xBMZ(0≤x≤0.08)ceramics.Especially for the sample of x=0.04,the temperature stability of permitivity was markedly increased(△ε/ε100℃≤±15%),and high relative permitivity(>8.3 × 10^(4))were obtained over a wide temperature range from 100℃ to 250℃at 100 kHz,which indicates that this ceramic is a promising dielectrice material for elevated temperature dielectrics.The giant dielectric property of(1-x)LCN-xBMZ ceramics are profoundly concerned with the Maxwell-Wagner effect.