针对丢失放射源快速定位需求，设计了一套NaI（Tl）探测阵列装置，基于阵列探测器间的阴影效应，通过蒙特卡罗模拟软件，获得计数率与入射射线角度之间的变化响应曲线。利用支持向量机（Support Vector Machine，SVM）方法建立探测阵列计数-入射射线角度预测模型。搭建放射源定位物理实验平台，开展多种条件下的探测阵列-放射源角度响应实验与位置响应实验，并使用计数率-角度响应模型对放射源定位，测试结果表明：¹³⁷Cs点源角度预测平均最大偏差为9.21°，最小偏差为1.77°，该方法可实现对放射源的快速、精确定位。

Recently, multifarious deformation approaches in nature have promoted dynamic manipulation for electromagnetic (EM) waves in metamaterials, and those representative strategies are mainly focused on the modulation of spectral parameters. Several works have also achieved tunable phase-gradient meta-devices. Here, to broaden the modulation freedom of mechanical deformation, we initially propose two reconfigurable metamaterials consisting of mirrored S-shaped meta-atoms selectively bonded on biaxially pre-stretched substrates. Planar meta-atoms with spin-insensitive transmittance are buckled into 3D morphologies to break residual symmetries by releasing the stress and to facilitate spin-dependent transmittance under circularly polarized incidence. Owing to the geometric anisotropy of S-shaped meta-atoms along the x and y axes, 3D chiral meta-atoms exhibit discriminate circularly cross-polarized transmittance under opposite spins. The underlying physical mechanism reveals that EM resonance originates from the excitation of electric dipoles and magnetic dipoles, and their cross coupling finally triggers the chiral effects of 3D meta-atoms. By introducing the gradient-phase design that keeps unchanged under various strains, two types of meta-atoms with specified orientations are interleaved to design a double-foci metalens, and its 2D-to-3D morphology transformation shortens the focusing length and facilitates the intensity change of two foci. Our approach in designing reconfigurable EM metamaterials with 2D-to-3D buckling transformability can be further extended toward terahertz even optical wavebands, and it may assist with deriving more applicable multi-functionalities in the aspects of imaging, sensing, and holograms.

通过磷酸(H₃PO₄)和焦磷酸(H₄P₂O₇)对生物炭改性能够使其更适于农业应用。 探明H₃PO₄和H₄P₂O₇改性生物炭的P赋存形态与结合方式, 将有助于揭示其表面P的生物有效性。 以麦秆生物炭(WBC)与棉秆生物炭(CBC)为原料, 分别通过H₃PO₄和H₄P₂O₇制备了H₃PO₄改性生物炭(P-WBC和P-CBC)和H₄P₂O₇改性生物炭(PA-WBC和PA-CBC)。 利用拉曼光谱(Raman)与扫描电镜能谱(SEM-EDS)对改性生物炭结构与P分布变化进行表征, 采用傅里叶红外光谱(FTIR)和X射线光电子能谱(XPS)探究改性生物炭表面P结合方式, 并结合Hedley磷分级方法与可见分光光度法, 定量分析改性前后生物炭中P形态及含量变化。 结果表明, H₃PO₄和H₄P₂O₇改性后生物炭I_G/I_D值增大, 石墨化结构增强, 形成了含P颗粒状结构。 H₃PO₄和H₄P₂O₇改性促进了生物炭表面羧基(—COOH)、 P—O—P和P—H等酸性官能团与含P基团的形成, 且H₃PO₄改性生物炭和H₄P₂O₇改性生物炭表面官能团种类相似。 XPS结果显示, 与WBC和CBC相比, 改性处理中的O(1s)峰相对含量显著增加了13.15%~32.44%, P(2s)峰相对含量显著增加了18.54%~27.02%(p<0.05)。 反褶积分峰将P(2s)与O(1s)分为C—P—O, C—O—P, O=P—O C=O与(或) P=O C—O—C与(或)P—O—C和P—O—P六类。 较H₃PO₄改性而言, H₄P₂O₇改性能够促进更多C—O—P, O=P—O C—O—C与(或)P—O—C和P—O—P键的形成。 改性也使得生物炭中总P含量显著增加, 且PA-WBC和PA-CBC中P含量显著高于P-WBC和P-CBC。 与WBC和CBC相比, 改性处理中活性P含量显著提高2.36~14.77 g·kg^-1, 稳定态P含量显著降低0.06~0.17 g·kg^-1(p<0.05)。 与P-WBC和P-CBC相比, PA-WBC和PA-CBC的活性P、 中等活性P分别显著增加了5.27~15.66和0.53~0.64 g·kg^-1, 稳定态P含量减少了0.03~0.34 g·kg^-1(p<0.05)。 H₃PO₄和H₄P₂O₇改性改变了P在生物炭表面的结合方式, 同时增加了P的活性。 H₃PO₄和H₄P₂O₇改性生物炭间, 不同形态P含量和结合方式的差异对进一步探究P的生物有效性具有重要意义。