Film mulching treatment inf luences dry matter and yield of oil flax in semi-arid area of China

A feld study was set up to compare dry matter accumulation and grain yield of 3 different types of flm mulching, namely FFC （full flm muched on tiny ridges covered with soil）, PFC （full flm muched covered with soil）, and PF （full flm muched with no cover）. The experiment was laid out in a complete random design with 3 replications at north-west （34°40′N, 105°06′E） of China. This study determined that （1） flm mulching treatment increased leaf area and dry matter accumulation of oil fax in semi-arid areas; （2） accu-mulation of dry matter under PFC treatment was markedly higher than other treatments except anthesis stage; （3） average grain yield of oil fax under flm mulching treatment was 52.67%-60.33% higher than fat plot without mulched or ridge （CK） treatment; （4） grain yield of oil fax was substantially correlated with plant height, grain number and 1,000 kernels weight. This study demonstrated that flm mulching has signifcant effects on crop grain yield improvement in the northwest of China.

A low-firing melilite ceramic Ba2CuGe207 and compositional modulation on microwave dielectric properties through Mg substitution

A melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties.Sintered at 960℃,the Ba2CuGe2O7 ceramic had a high relative density 97%,a low relative permittivity(εr)9.43,a quality factor(Q×f)of 20,000 GHz,and a temperature coefficient of resonance frequency(τf)-76 ppm/℃.To get a deep understanding of the relationship between composition,structure,and dielectric performances,magnesium substitution for copper in Ba2CuGe2O7 was conducted.Influences of magnesium doping on the sintering behavior,crystal structure,and microwave dielectric properties were studied.Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure,grain morphology,and size distribution,while induced visible variation in the local structure as revealed by Raman analysis.Microwave dielectric properties exhibit a remarkable dependence on composition.On increasing the magnesium content,the relative permittivity featured a continuous decrease,while both the quality factor and the temperature coefficient of resonance frequency increased monotonously.Such variations in dielectric performances were clarified in terms of the polarizability,packing fraction,and band valence theory.

Preparation, crystal structure, and dielectric characterization of Li_(2)W_(2)O_(7) ceramic at RF and microwave frequency range

Single phase Li_(2)W_(2)O_(7) with anorthic structure was prepared by the conventional solid-state reaction method at 550℃ and the anorthic structure was stable up to 660℃.The dielectric properties at radio frequency(RF)and microwave frequency range were characterized.The sample sintered at 640℃ exhibited the optimum microwave dielectric properties with a relative permittivity of 12.2,a quality factor value of 17,700 GHz(at 9.8 GHz),and a temperature coefficient of the resonant frequency of232 ppm/℃ as well as a high relative density~94.1%.Chemical compatibility measurement indicated Li_(2)W_(2)O_(7) did not react with aluminum electrodes when sintered at 640℃ for 4 h.

Current and future control of the wood-boring pest Anoplophora glabripennis

The Asian longhorn beetle (ALB) Anoplophora glabripennis is one of the most successful and most feared invasive insect species worldwide. This review covers recent research concerning the distribution of and damage caused by ALB, as well as major efforts to control and manage ALB in China. The distribution and destruction range of ALB have continued to expand over the past decade worldwide, and the number of interceptions has remained high. Detection and monitoring methods for the early discovery of ALB have diversified, with advances in semiochemical research and using satellite remote sensing in China. Ecological control of ALB in China involves planting mixtures of preferred and resistant tree species, and this practice can prevent outbreaks. In addition, strategies for chemical and biological control of ALB have achieved promising results during the last decade in China, especially the development of insecticides targeting different stages of ALB, and applying Dastarcus helophoroides and Dendrocopos major as biocontrol agents. Finally, we analyze recommendations for ALB prevention and management strategies based on native range and invasive area research. This information will hopefully help some invaded areas where the target is containment of ALB.

Entropy regulation in LaNbO_(4)-based fergusonite to implement high-temperature phase transition and promising dielectric properties

High-entropy effect is a novel design strategy to optimize properties and explore novel materials.In this work,(La_(1/5)Nd_(1/5)Sm_(1/5)Ho_(1/5)Y_(1/5))NbO_(4)(5RNO)high-entropy microwave dielectric ceramics were successfully prepared in the sintering temperature(S.T.)range of 1210–1290℃via a solid-phase reaction route,and medium-entropy(La_(1/3)Nd_(1/3)Sm_(1/3))NbO_(4) and(La_(1/4)Nd_(1/4)Sm_(1/4)Ho_(1/4))NbO_(4)(3RNO and 4RNO)ceramics were compared.The effects of the entropy(S)on crystal structure,phase transition,and dielectric performance were evaluated.The entropy increase yields a significant increase in a phase transition temperature(from monoclinic fergusonite to tetragonal scheelite structure).Optimal microwave dielectric properties were achieved in the high-entropy ceramics(5RNO)at the sintering temperature of 1270℃for 4 h with a relative density of 98.2%and microwave dielectric properties of dielectric permittirity(ε_(r))=19.48,quality factor(Q×f)=47,770 GHz,and resonant frequency temperature coefficient(τ_(f))=–13.50 ppm/℃.This work opens an avenue for the exploration of novel microwave dielectric material and property optimization via entropy engineering.

一种真核细胞分泌型重组融合蛋白rPC的构建、表达与纯化

抑制性免疫检查点PD-1或CTLA-4靶向治疗药物已用于肿瘤的临床治疗,但单一靶点药物会有耐药发生,联合使用同时封闭多个靶点可提高疗效,因此拟构建一个可封闭多个靶点的新型重组蛋白。首先设计并合成了一个由人类PD-1和CTLA-4两个受体的胞外功能域组成并且C端带6´His标签的分泌型重组融合蛋白rPC编码序列,插入真核细胞表达载体pLVX-IRES-ZsGreen1,稳定转染HEK293细胞,收集细胞培养上清,以亲和方法纯化重组蛋白rPC,通过实时荧光定量PCR检测多个人类肿瘤细胞系中PD-1配体PD-L1、PD-L2和CTLA-4配体CD80、CD86的表达,以选择相对高表达的细胞,利用细胞免疫荧光染色方法检验rPC与肿瘤细胞的结合能力,并用CCK-8法检测rPC是否对肿瘤细胞的生长有影响。结果表明,重组融合蛋白rPC可由稳定转染表达载体的HEK293细胞表达并分泌,纯化后的rPC可以与PD-1和CTLA-4配体表达相对较高的肺癌细胞NCI-H226结合,并且rPC处理对其生长并无直接影响,与预期一致。成功获得的重组融合蛋白rPC可用于进一步的体内外功能研究,也为今后研发新型多靶点肿瘤免疫治疗蛋白药物打下了坚实的基础。

Compositional modulation in ZnGa_(2)0_(4) via Zn^(2+)/Ge^(4+)co-doping to simultaneously lower sintering temperature and improve microwave dielectric properties

AB_(2)O_(4)-type spinels with low relative permittivity(ε_(τ))and high quality factor(Q×f)are crucial to high-speed signal propagation systems.In this work,Zn^(2+)/Ge^(4+) co-doping to substitute Ga in ZnGa_(2)O_(4) was designed to lower the sintering temperature and adjust the thermal stability of resonance frequency simultaneously.Zn_(1+2)Ga_(2-2x)Ge_(x)O_(4)(0.1≤x≤0.5)ceramics were synthesised by the conventional solid state method.Zn^(2+)/Ge^(4+) co-substitution induced minimal variation in the macroscopical spinel structure,which effectively lowered the sintering temperature from 1385 to 1250℃.All compositions crystallized in a normal spinel structure and exhibited dense microstructures and excellent microwave dielectric properties.The compositional dependent quality factor was related to the microstructural variation,being confirmed by Raman features.A composition with x=0.3 shows the best dielectric properties with ε_(τ) ≈10.09,Q×f≈112,700 THz,and ε_(τ) ≈-75.6 ppm/℃.The negative τf value was further adjusted to be near-zero through the formation of composite ceramics with TiO_(2).

Effects of zinc substitution on the dielectric properties of Ca_(5)Nb_(4)TiO_(17) microwave ceramics

Ca_(5)Nb_(4)TiO_(17) ceramics with 0≤x≤0.4 were prepared through a solid-state reaction method.Effects of zinc substitution on sintering behavior and microwave dielectric properties of Ca_(5)Nb_(4)TiO_(17) ceramics were investigated.The sintering temperature was significantly lowered from 1480℃for pure Ca_(5)Nb_(4)TiO_(17) to 1260℃ for x=0.4.The microwave dielectric properties are strongly correlated with the composition.It is worth noting that the temperature cofficient of resonant frequency(τf)displays a tendency toward positive value,ranging from-126.4 ppm/℃ to-8.6 ppm/℃.A temperature stable microwave ceramic with dielectric constant of 52 and Q×f value of 9937GHz is achieved at x=0.4 and is a potential candidate for application as cores in dielectrically loaded antennas.

Effects of barium substitution on the sintering behavior,dielectric properties of Ca_(2)Nb_(2)O_(7) ferroelectric ceramics

Barium-doped Ca_(2)Nb_(2)O_(7)ceramics were prepared in the form of Ca_(2-x)Ba_(x)Nb_(2)O_(7)(0≤x≤0.6)by solid-state reaction.The solubility limit of barium in Ca_(2)Nb_(2)O_(7)was found to be x=0.4 based on X-ray diffraction and Raman spectroscopy analysis.When x≤0.4,Ca_(2-x)Ba_(x)Nb_(2)O_(7)solid solutions with a monoclinic perovskites-like layered structure(PLS)were formed,whereas beyond x=0.4,a secondary phase CaNb_(2)O_(6) was detected.The dielectric properties obviously depended on the barium substitution.With increasing barium amount,the dielectric constant increased from 33.5 for pure Ca_(2)Nb_(2)O_(7)to 38.6 for x=0.4(f=1 MHz).The Curie temperature(T_(c)) of the x=0.1 sample was 1280±5℃.The phase transition was confirmed to be the second order.

Study on properties of tantalum-doped La_(2)Ti_(2)O_(7) ferroelectric ceramics

A series of ceramics with a general formula,La_(2)Ti_(2-x)Ta_(x)O_(7),in which x=0.05;0.1;0.2;and 0.3,were prepared by Spark Plasma Sintering(SPS).Effects of tantalum substitution for titanium on the structure,dielectric,and piezoelectric properties were studied.Results revealed that the structure changed gradually from 4-layer to 3-layer due to the higher valence of Ta.The solid solution limit of tantalum in La_(2)Ti_(2)O_(7)lattice was in the proximity of x=0.2.The ferroelectric Curie temperature(Tc)decreased with increasing tantalum doping content.dc resistivity reached a maximum value at x=0.2 with a value of~1.0×10^(8)Ωcm at 600℃.The influence of texture on the piezoelectric properties of La_(2)Ti_(2-x)Ta_(x)O_(7)ceramics was also investigated.A maximum d_(33)value~2:1 pC/N was obtained at x=0.2.

INFLUENCE OF n ON STRUCTURE AND MICROWAVE DIELECTRIC PROPERTIES OF SOME A_(n)B_(n-1)O_(3n)PEROVSKITES

Two series of B-site deficient perovskites Ba_(5+m)Ti_(m)Nb_(4)O_(15+3m)(m=1,2,3)and Sr_(3+m)LaTi_(m)Nb_(3)O_(12+3m)(m=0,1,2)with the general formula A_(n)B_(n-1)O_(3n)(n=4-8;A=Ba,Sr,La;B=Nb,Ti)have been synthesized,and their structure and microwave dielectric properties have been investigated.The effects of n(number of octahedra layers within a perovskite blocks)on structure and properties are investigated.The values of dielectric constantε_(r)and temperature coe±cient of resonant frequencyτ_(f)gradually increase,but quality factors Q×f values significantly decreases as the values of n increase.