Target detection for low angle radar based on multi-frequency order-statistics

For radar targets flying at low altitude, multiple pathways produce fade or enhancement relative to the level that would be expected in a free-space environment. In this paper, a new detec- tion method based on a wide-ranging multi-frequency radar for low angle targets is proposed. Sequential transmitting multiple pulses with different frequencies are first applied to decorrelate the cohe- rence of the direct and reflected echoes. After receiving all echoes, the multi-frequency samples are arranged in a sort descending ac- cording to the amplitude. Some high amplitude echoes in the same range cell are accumulated to improve the signal-to-noise ratio and the optimal number of high amplitude echoes is analyzed and given by experiments. Finally, simulation results are presented to verify the effectiveness of the method.

Emerging applicability of two-dimensional boron for energy catalysis

Due to their unique physical and chemical properties,two-dimensional(2D)boron nanosheets have received tremendous research attention and demonstrated substantial value in electronic devices,biomedicine,and energy conversion.In the preparation of boron nanosheets,compared with the bottom-up synthesis predominantly employed for electronics,the top-down synthesis route offers more facile and scalable production.In this mini-review,we mainly discuss the recent advances in the synthesis of boron nanosheets using the top-down strategy and the relevant applications in energy catalysis.Finally,inspired by our recent works on the novel applications of 2D silicon,we put forward prospects for designing boron nanosheets,providing insights into developing viable techniques for high-performance heterogeneous catalysis.

Two‐dimensional germanium for photocatalysis

Succeeding graphene a series of two‐dimensional materials(2D M)have been developed and applied in various fields.As an analog of silicene,2D germa-nium(2D Ge)has garnered vast attention owing to its novel structures and prolific properties,demonstrating substantial promise in semiconductor,catal-ysis,devices,and other burgeoning fields.Specifically,2D Ge is advantageous in providing a massive specific surface area,preferable transport properties,a tunable band gap structure,and confinement effects.Endowed with unique features,functionalized 2D Ge has become a competitive candidate for pho-tocatalysis.In this review,we catalog various synthetic methods of 2D Ge,discuss its fundamental properties,and summarize recent applications.We also present a few perspectives to provide fresh insights into designing and exploring 2D germanium in future photocatalysis.

Transformation of plant young proembryos by electroporation

It is first reported that plant young proembryos expressed exogenous reporter genes by electroporation. Young proembryos with 8-32 cells and globular proembryos with 250-400 cells could be isolated by enzymatic maceration combined with microdissection. After electroporation with GUS or GFP genes, the proembryos were cultured for 1 -2 d in KM8p medium. At the field strength of electroporation 500-1 500 V/cm, blue reaction of GUS or green fluorescence of GFP could be observed in the proembryos. The highest transient expression frequency of young proembryos (2.2%) was obtained at the field strength of 750 V/cm, whereas the highest frequency of globular proembryos (5.9%) was obtained at the field strength of 1 250 V/cm. Taking the proportion of transformed cells in the whole cells of proembryos as efficient transformation frequency, the efficient transformation frequency of the young proembryos was 7 times that of the globular proembryos.