Multi-focus optical fiber lens based on all-dielectric metasurface

A multi-focus optical fiber lens is numerically demonstrated based on an all-dielectric metasurface structure. The metasurface consists of an array of rectangular silicon resonators with varying widths in order to obtain the required phase distribution. The core diameter of the multimode fiber is large enough to contain sufficient resonance units. The spatial distribution of the dielectric resonators is dictated by spatial multiplexing, including interleaving meta-atoms and lens aperture division, to achieve multi-focus properties. The proposed optical fiber metalens can produce two or three focal points along the longitudinal direction with high focusing efficiency. The size of every focal point is close to the diffraction limit, and the relative intensity on each focus can be controlled by adjusting the number of the respective resonators. The proposed optical fiber lens will have a great potential in the fields of integrated optics and multifunctional micro/nano devices.     

Mitochondrial citrate accumulation drives alveolar epithelial cell necroptosis in lipopolysaccharide-induced acute lung injury

Necroptosis is the major cause of death in alveolar epithelial cells (AECs) during acute lung injury (ALI). Here, we report a previously unrecognized mechanism for necroptosis. We found an accumulation of mitochondrial citrate (citrate^mt) in lipopolysaccharide (LPS)-treated AECs because of the downregulation of Idh3α and citrate carrier (CIC, also known as Slc25a1). shRNA- or inhibitor–mediated inhibition of Idh3α and Slc25a1 induced citrate^mt accumulation and necroptosis in vitro. Mice with AEC-specific Idh3α and Slc25a1 deficiency exhibited exacerbated lung injury and AEC necroptosis. Interestingly, the overexpression of Idh3α and Slc25a1 decreased citrate^mt levels and rescued AECs from necroptosis. Mechanistically, citrate^mt accumulation induced mitochondrial fission and excessive mitophagy in AECs. Furthermore, citrate^mt directly interacted with FUN14 domain-containing protein 1 (FUNDC1) and promoted the interaction of FUNDC1 with dynamin-related protein 1 (DRP1), leading to excessive mitophagy-mediated necroptosis and thereby initiating and promoting ALI. Importantly, necroptosis induced by citrate^mt accumulation was inhibited in FUNDC1-knockout AECs. We show that citrate^mt accumulation is a novel target for protection against ALI involving necroptosis.Subject terms: Infection, Respiratory tract diseases     

A Two-Stage Culture Strategy for Scenedesmus sp. FSP3 for CO2 Fixation and the Simultaneous Production of Lutein under Light and Salt Stress

In this study, Scenedesmus sp. FSP3 was cultured using a two-stage culture strategy for CO₂ fixation and lutein production. During the first stage, propylene carbonate was added to the medium, with 5% CO₂ introduced to promote the rapid growth and CO₂ fixation of the microalgae. During the second stage of cultivation, a NaCl concentration of 156 mmol L⁻¹ and a light intensity of 160 μmol m⁻² s⁻¹ were used to stimulate the accumulation of lutein in the microalgal cells. By using this culture method, high lutein production and CO₂ fixation were simultaneously achieved. The biomass productivity and carbon fixation rate of Scenedesmus sp. FSP3 reached 0.58 g L⁻¹ d⁻¹ and 1.09 g L⁻¹ d⁻¹, with a lutein content and yield as high as 6.45 mg g⁻¹ and 2.30 mg L⁻¹ d⁻¹, respectively. The results reveal a commercially feasible way to integrate microalgal lutein production with CO₂ fixation processes.     

Effect of Co-Existing Cations and Anions on the Adsorption of Antibiotics on Iron-Containing Minerals

The adsorption of antibiotics on minerals is an important process in their environment behavior. The adsorption behavior of antibiotics on iron-containing minerals and the effect of co-existing cations and anions were studied in this work. Magnetite, hematite, goethite and kaolin were selected as the representative minerals and characterized by SEM, XRD and BET. A total of eight antibiotics, including three quinolones, three sulfonamides and two mycins were chosen as the research targets. Results showed a higher adsorption amount of quinolones than that of sulfonamides and mycins on the surface of iron-containing minerals in most mineral systems. The adsorption isotherms of quinolones can be well fitted using the Freundlich models. The effects of five cations and five anions on the adsorption of quinolones were investigated, among which Mg²⁺, Ca²⁺, HCO₃⁻ and H₂PO₄⁻ mainly showed significant inhibition on the adsorption, while the effects of K⁺, Na⁺, NH₄⁺, Cl⁻, NO₃⁻ and SO₄²⁻ showed less. Natural surface water samples were also collected and used as media to investigate the adsorption behavior of quinolones on iron-containing minerals. The buffering capacity of the natural water kept the reaction solution at circumneutral conditions, and the adsorption amount was mostly promoted in the goethite system (from 0.56~0.78 μmol/g to 0.52~1.43 μmol/g), but was inhibited in the other systems (magnetite: from 1.13~1.33 μmol/g to 0.45~0.76 μmol/g; hematite: from 0.52~0.65 μmol/g to 0.02~0.18 μmol/g; kaolin: from 1.98~1.99 μmol/g to 0.90~1.40 μmol/g). The results in this work help to further understand the transportation and fate of antibiotics in an aqueous environment.     

太空育种射干的X射线荧光及X射线衍射分析和表征

联用X射线荧光光谱(XRF)和粉末X射线衍射(PXRD)方法,对我国独创的第4代太空诱变育种射干中多种元素种类和含量及晶态物质进行了研究。结果表明:太空组射干K元素含量比地面组、对照品分别提高了1.03和0.31倍,Mg元素分别提高了1.44和0.06倍,Ca,Mn和Fe元素含量比地面组分别提高了0.95,0.30和0.29倍,Al元素比地面组、对照组分别降低了38.5%和85.5%,并在射干中鉴别出一水草酸钙(CaC2O4.H2O)晶体,晶体含量是地面组<太空组<对照品。从而可得出结论:太空射干中人体必需的矿质元素比地面组都更接近或优于对照品。文章研究结果和方法对筛选品质优良的太空药材籽种和推广种植太空药材以及建立中药材质量评价标准,有积极的作用和重要意义。     

TEM喇叭馈源与共面馈源脉冲辐射天线性能比较

在反射面尺寸一定的情况下,优化设计了 TEM喇叭馈源与共面馈源脉冲辐射天线,并对比了两种天线的辐射性能。分析了反射面型脉冲辐射天线的工作机理,通过准静态近似,分别得到了两种天线的远区辐射场解析解。通过理论求解,得到了两种馈源在反射面口径造成的场分布,为天线结构设计提供参考。通过分析不同脉冲宽度时两种天线的辐射情况,比较了这两种馈源性能的优劣。完成了上述两种GW级高功率高效率馈源的研制,并开展了对比实验,实验结果与理论分析相吻合。     

基于紊流状态的阻尼阀缝隙节流解析计算

提出了一种基于紊流状态的缝隙节流解析计算方法. 运用边界层理论给出紊流状态下流体的三层速度分布表达式,通过积分定理推导出平行平板的缝隙流量解析式,与CFD 软件数值解对比偏差很小,验证了方程的正确性. 以此为基础根据阻尼阀的结构特点又推导出同心环形缝隙的紊流流量公式,并分析不同物性参数对缝隙压差和流量的影响规律,填补了工程设计中没有紊流状态下缝隙节流解析式的空白,为提高阻尼阀的设计精度奠定了基础.     

基于遗传算法的同步感应线圈发射装置参数优化

发射速度和能量转换效率是同步感应线圈型电磁发射装置（SICEML）最重要的两项指标。驱动线圈和电枢的结构参数、驱动线圈匝数以及电枢初始触发位置都会对这两项指标产生影响。以上述参数为变量,以发射速度和能量转换效率之积为目标函数,引入遗传算法对单级SICEML参数进行了优化设计,并利用有限元软件进行了仿真验证。结果表明：在储能与发射装置总体体积不变的前提下,优化后的系统效率由5.38%提高到13.6%,出口速度由38 m/s提高到61 m/s,系统性能得到明显改善。利用单级SICEML样机进行了堵驻试验,结果与仿真结果吻合较好,验证了本文提出的遗传算法的可行性。     

电磁轨道炮高速滑动接触电阻的定量表征

从描述电磁轨道炮炮口电压波形的场路模型出发,构建了电枢/轨道高速滑动接触电阻与轨道电流波形、炮口电压波形、电枢膛内速度曲线和轨道结构参数之间的关系,依据此关系可定量表征电磁轨道炮高速滑动接触电阻。实例计算表明,电枢/轨道高速滑动接触电阻的变化依赖于轨道电流变化,对应电流上升段、平顶段和电流下降段。在平顶段接触电阻最小约0.2 m,在电流上升段和电流下降段,接触电阻达3 m。     

基于灰度曲线交点的结构光编码条纹边缘检测

在分析结构光编码白条纹扩散的原因和实际边缘形态的基础上,提出一种同时检测多边缘并消除扩散影响的亚像素精度方法--交点法.首先向被测表面投射互为反色的两组格雷编码图案,提取两组强度图像中灰度梯度较大的点作为边缘依据点,并对其进行曲线拟合,然后将对应拟合曲线的交点作为边缘.分析了交点法对结构光系统中常见的被测表面倾斜和离焦两个主要误差因素的适应能力.介绍了检测原理及误差因素分析,并进行了边缘检测实验.实验结果表明,对于宽度大于4 pixel的编码条纹,边缘检测相对误差小于1%,可消除被测表面倾斜和离焦的影响.