Porous high-entropy rare-earth phosphate(REPO_(4),RE=La,Sm,Eu,Ce,Pr and Gd)ceramics with excellent thermal insulation performance via pore structure tailoring

Thermal insulation materials play an increasingly important role in protecting mechanical parts functioning at high temperatures.In this study,a new porous high-entropy(La_(1/6)Ce_(1/6)Pr_(1/6)Sm_(1/6)Eu_(1/6)Gd_(1/6))PO_(4)(HE(6RE_(1/6))PO_(4))ceramics was prepared by combining the high-entropy method with the pore-forming agent method and the effect of different starch contents(0–60vol%)on this ceramic properties was systematically investigated.The results show that the porous HE(6RE_(1/6))PO_(4)ceramics with 60vol%starch exhibit the lowest thermal conductivity of 0.061 W·m^(-1)·K^(-1)at room temperature and good pore structure stability with a linear shrinkage of approximately1.67%.Moreover,the effect of large regular spherical pores(>10μm)on its thermal insulation performance was discussed,and an optimal thermal conductivity prediction model was screened.The superior properties of the prepared porous HE(6RE_(1/6))PO_(4)ceramics allow them to be promising insulation materials in the future.

Discussion on Fresh Agricultural Products Ordering and Preservation Strategy under New Normal Carbon Emission Constraint

The paper mainly discusses the influence of chemical,physical and biological preservation technology improvement on the preservation strategy of fresh agricultural products.Meantime,the relationship between fresh agricultural products ordering and preservation in the environment of new normal carbon emission constraint is analyzed,and the e-commerce strategy in the digital era is put forward to achieve the win-win situation of consumers,farmers and dealers,so as to achieve good ecological,economic and social benefits.

Control Effect and Application of Solar Intelligent Insect Killer at Vegetable Farms

[Objective]The paper was to study the control effect and application of solar intelligent insect killer on vegetable insects.[Method]The solar intelligent insect killer was installed at vegetable farms in Shenzhen and other cities.[Result]The insect killer had strong killing effect on many kinds of vegetable insects and sanitary pests,which could kill 27 species of insects,belonging to 17 families,7 orders,and seldom harm the natural enemies.Meantime,it could be used for insect prediction and forecast.[Conclusion]The solar insect killer is featured by deinsectization of many pests,wide range,energy saving and environmental protection,simple operation and low cost,and has obvious ecological,economic,and social benefits in production practice for the vegetable farmer.

Analysis on Development Characteristics of Agricultural Product Processing Industry under the New Normal

From the beginning of the 21^(st)century to 2013,the economic income of main business of agricultural products processing enterprises in China had maintained above double digits for a long time.The current traditional high-speed growth will be transformed to high-quality,mediumhigh-speed development,and the development trend is in line with economic laws and macro situation characteristics.With the acceleration of spa-tial distribution and cluster development of agricultural processing industry,the late-mover advantages in the central and western regions of China are gradually emerging.With the support of Internet+and e-commerce online shopping platforms,the integrative development with related industries has been deepened.Led by the new concept of green development,the demand of processing industry of green,healthy,specific functional food(such as diabetes,hypertension and other specific groups)is booming.In the aspect of development strategy,it is appropriate to build multivariate information service platform,improve the technical cooperation platform,and provide software and hardware facilities for further development of agricultural product processing industry.Combined with local economic development advantages,resource advantages and industrial advantages and other factors,the way of differentiation,regionalization and characterization should be taken according to local conditions and following the law,so as to energize the rural revitalization.

Analysis on the Factors Influencing Pollution-free Vegetable Production: A Case Study of Shenzhen Huantong Farming Products Co. Ltd.

More than 170 vegetable farmers and vegetable production in 4 vegetable farms of Shenzhen Huantong Farming Products Co.Ltd.were investigated,and the factors affecting the quality of vegetable products were analyzed.The development strategies of pollution-free vegetables,such as strengthening training of vegetable farmers,reducing vegetable farmers’mobility and vegetable brand building,were put forward.

Influence of Nd^(3+) concentration on mid-infrared emission in PbF_(2) crystal co-doped with Ho^(3+) and Nd^(3+) ions

A promising series of Ho_(y)Nd_(x)Pb_((1-x-y))F_2(x = 0, 0.01, 0.02, 0.03, 0.04;y = 0.02) crystals was grown by the Bridgman method. The influence of the Nd^(3+)ions concentration on mid-infrared(~2.0, ~2.9 and ~3.9 μm)fluorescence emissions of Ho^(3+)ions in the PbF_(2) crystal excited by 808 nm laser diode was investigated in this work. The energy transfer mechanism between Nd^(3+)ions and Ho~(3+)ions under different concentrations of the Nd^(3+)ions was systematically analyzed. The results show that the Nd^(3+)ions have good sensitization and deactivation effect on the Ho^(3+)ions to stimulate the mid-infrared fluorescence emissions. The experimental analysis proves that the sensitization efficiency of the Nd^(3+)ions is relatively stable at around 93.45% with varying Nd^(3+)-doping concentrations. Concentration dependence studies indicate that the concentration of the Nd^(3+)ions has significant influence on mid-infrared emissions.When the doping concentration of the Nd^(3+)ions is up to 2.0 at%, the intensity of ~2.0, ~2.9 and ~3.9 μm emissions all reach the maximum. The output characteristics of a 3.9 μm laser are simulated, and it is found that with the increase of the Nd^(3+)-doping concentration, the peak power, pulse width, and peak energy all meet the trend of first increasing and then decreasing, and Ho_(0.02)Nd_(0.02)Pb_(0.96)F_(2) crystal displays the best performance. All the results show that the Nd^(3+)/Ho^(3+)co-doped PbF_(2) crystals might act as a useful optical medium for mid-infrared laser applications.

Xenotime-type high-entropy(Dy_(1/7)Ho_(1/7)Er_(1/7)Tm_(1/7)Yb_(1/7)Lu_(1/7)Y_(1/7))PO_(4):A promising thermal/environmental barrier coating material for SiCf/SiC ceramic matrix composites

Rare-earth phosphates(REPO4)are regarded as one of the promising thermal/environmental barrier coating(T/EBC)materials for SiCf/SiC ceramic matrix composites(SiC-CMCs)owing to their excellent resistance to water vapor and CaO–MgO–Al_(2)O_(3)–SiO_(2)(CMAS).Nevertheless,a relatively high thermal conductivity(κ)of the REPO_(4) becomes the bottleneck for their practical applications.In this work,novel xenotime-type high-entropy(Dy_(1/7)Ho_(1/7)Er_(1/7)Tm_(1/7)Yb_(1/7)Lu_(1/7)Y_(1/7))PO4(HE(7RE_(1/7))PO_(4))has been designed and synthesized for the first time to solve this issue.HE(7RE_(1/7))PO_(4) with a homogeneous rare-earth element distribution exhibits high thermal stability up to 1750℃and good chemical compatibility with SiO_(2) up to 1400℃.In addition,the thermal expansion coefficient(TEC)of HE(7RE_(1/7))PO_(4)(5.96×10^(−6)℃^(−1) from room temperature(RT)to 900℃)is close to that of the SiC-CMCs.What is more,the thermal conductivities of HE(7RE_(1/7))PO_(4)(from 4.38 W·m^(−1)·K^(−1) at 100℃to 2.25 W·m^(−1)·K^(−1) at 1300℃)are significantly decreased compared to those of single-component REPO4 with the minimum value ranging from 9.90 to 4.76 W·m^(−1)·K^(−1).These results suggest that HE(7RE_(1/7))PO_(4) has the potential to be applied as the T/EBC materials for the SiC-CMCs in the future.