SYMMETRIES AND GROUP-INVARIANT SOLUTIONS OF DIFFERENTIAL EQUATIONS

ＳＹＭＭＥＴＲＩＥＳＡＮＤＧＲＯＵＰ－ＩＮＶＡＲＩＡＮＴＳＯＬＵＴＩＯＮＳＯＦＤＩＦＦＥＲＥＮＴＩＡＬＥＱＵＡＴＩＯＮＳＴＩＡＮＣＨＯＵＡｂｓｔｒａｃｔ：Ｆｏｒａｄｉｆｆｅｒｅｎｔｉａｌｅｑｕａｔｉｏｎ，ａｔｈｅｏｒｅｔｉｃａｌｐｒｏｏｆｏｆｔｈｅｒ...     

用光波导光模光谱技术研究DNA-DNA结合蛋白相互作用

探讨了应用光波导光模光谱(Optical waveguide lightmode spectroscopy,OWLS)技术研究DNA-DNA结合蛋白相互作用的可行性和灵敏性。以固定在传感器芯片表面的DNA探针为捕捉分子,溶液中同时含有探针结合序列和NF—κB结合位点序列的寡核苷酸与NF-κB亚单位p50同源二聚体形成的DNA-蛋白质复合物为检测分子,用光波导光模光谱检测技术建立非标记DNA-DNA结合蛋白相互作用检测研究体系。利用这一体系对不同样品中NF-κB p50浓度和具不同NF-κB结合位点序列的寡核苷酸与NF-κB p50亲合和力进行检测。样品中低至0．33 nmol/1的NF-κB p50被光波导光模光谱检测出,不同的NF-κB结合序列与NF-κB p50亲合力有显著的差异。研究发现,光波导光模光谱技术可以用于DNA-DNA结合蛋白相互作用研究,所建立的非标记检测研究体系可以进行样品中结合蛋白含量高灵敏检测和核酸序列与结合蛋白的亲合力的检测研究。     

大功率高温超导滤波器的设计与功率测试

本文在双面YBCO高温超导薄膜上设计并制备了两节大功率超导滤波器,根据滤波器功率承载能力与最大电流密度之间的关系,减小电流密度和分散电流密度的分布是提高功率承载能力的关键.本文采用增加超导谐振器尺寸、优化几何结构及改进馈线耦合方式的方法,设计了两节2 GHz频段梭型谐振器结构的滤波器.设计及测量结果显示了馈线结构及谐振器几何尺寸优化程度对超导滤波器功率承载能力有不同程度的影响,说明了在大功率超导滤波器设计中应选用无结点间隙耦合式馈线以抑制电流密度的聚集.采用优化后的谐振器结构制备的梭型两节超导滤波器经测试功率承载能力为2 W.超导滤波器的尺寸为25×12 mm LaAlO3基片,中心频率2.022 GHz,相对带宽为2.4%.同时给出了超导滤波器功率测试的结构和方法.     

H2S和H2S+的振动光谱和电子能谱计算

本文基于MOLPRO软件包使用从头算方法计算了星际分子H₂S及其阳离子H₂S⁺的势能面及光电子能谱.首先,在(U)CCSD/cc-pVQZ理论水平下获取了H₂S沿法线坐标展开的势能面,势能面直观描述了不同振动模式耦合对分子能量变化的影响,S-H键的非对称伸缩振动和面内弯曲振动共同作用使得系统势能变化范围明显变大.振动多组态相互作用方法被用来计算非谐振动频率和振动光谱,计算结果显示,倍频和组合频之间出现了强烈的费米共振,使得相应波段处的红外强度显著增强.最后,使用拉曼波函数和收缩不变Krylov子空间方法首次计算了H₂SΧ¹A₁→H₂S⁺ X²B₁的光电子能谱.此项研究有助于进一步理解星际分子的内部结构,并为实验研究及星际观测提供参考.     

CT and MRI Medical Image Fusion Using Noise-Removal and Contrast Enhancement Scheme with Convolutional Neural Network

Medical image fusion (MIF) has received painstaking attention due to its diverse medical applications in response to accurately diagnosing clinical images. Numerous MIF methods have been proposed to date, but the fused image suffers from poor contrast, non-uniform illumination, noise presence, and improper fusion strategies, resulting in an inadequate sparse representation of significant features. This paper proposes the morphological preprocessing method to address the non-uniform illumination and noise by the bottom-hat–top-hat strategy. Then, grey-principal component analysis (grey-PCA) is used to transform RGB images into gray images that can preserve detailed features. After that, the local shift-invariant shearlet transform (LSIST) method decomposes the images into the low-pass (LP) and high-pass (HP) sub-bands, efficiently restoring all significant characteristics in various scales and directions. The HP sub-bands are fed to two branches of the Siamese convolutional neural network (CNN) by process of feature detection, initial segmentation, and consistency verification to effectively capture smooth edges, and textures. While the LP sub-bands are fused by employing local energy fusion using the averaging and selection mode to restore the energy information. The proposed method is validated by subjective and objective quality assessments. The subjective evaluation is conducted by a user case study in which twelve field specialists verified the superiority of the proposed method based on precise details, image contrast, noise in the fused image, and no loss of information. The supremacy of the proposed method is further justified by obtaining 0.6836 to 0.8794, 0.5234 to 0.6710, and 3.8501 to 8.7937 gain for QFAB, CRR, and AG and noise reduction from 0.3397 to 0.1209 over other methods for objective parameters.     

Stable Zinc-Based Metal-Organic Framework Photocatalyst for Effective Visible-Light-Driven Hydrogen Production

Herein, a new Zn-MOF material, [Zn(L1)(L2)], 1, was built successfully through a one-pot solvothermal method. The 3D MOF structure was determined by Single X-ray diffraction analysis, IR, and elemental analysis. A series of PXRD tests of 1 after being immersed in different solvents and pH solutions demonstrated the good stability of 1. Interestingly, this material displayed high catalytic activity for the visible-light-driven hydrogen generation under the illumination of white LED in pure water or a mixture of DMF and H₂O without additional photosensitizers and cocatalysts. Besides, the studies also showed that the catalytic activity changed constantly as well as the solvent ratio adjustment of DMF and H₂O from 4:6 to 2:8. Additionally, the catalytic activity reached the best value (743 μmol g⁻¹ h⁻¹) when the solvent ratio was 4:6. The heterogeneous nature and recyclability of the MOF catalyst, as well as several factors that affect the catalytic activity, were investigated and described in detail. Moreover, the photocatalytic mechanism for the hydrogen generation of 1 was also proposed based on the fluorescence spectra and UV-vis absorption.     

GDP vs. LDP: A Survey from the Perspective of Information-Theoretic Channel

The existing work has conducted in-depth research and analysis on global differential privacy (GDP) and local differential privacy (LDP) based on information theory. However, the data privacy preserving community does not systematically review and analyze GDP and LDP based on the information-theoretic channel model. To this end, we systematically reviewed GDP and LDP from the perspective of the information-theoretic channel in this survey. First, we presented the privacy threat model under information-theoretic channel. Second, we described and compared the information-theoretic channel models of GDP and LDP. Third, we summarized and analyzed definitions, privacy-utility metrics, properties, and mechanisms of GDP and LDP under their channel models. Finally, we discussed the open problems of GDP and LDP based on different types of information-theoretic channel models according to the above systematic review. Our main contribution provides a systematic survey of channel models, definitions, privacy-utility metrics, properties, and mechanisms for GDP and LDP from the perspective of information-theoretic channel and surveys the differential privacy synthetic data generation application using generative adversarial network and federated learning, respectively. Our work is helpful for systematically understanding the privacy threat model, definitions, privacy-utility metrics, properties, and mechanisms of GDP and LDP from the perspective of information-theoretic channel and promotes in-depth research and analysis of GDP and LDP based on different types of information-theoretic channel models.     

Experimental synchronization of independent entangled photon sources

We report the generation of independent entangled photon pairs from two synchronized but mutually incoherent laser sources. The quality of synchronization is confirmed by observing a violation of Bell's inequality with 3.2 standard deviations in an entanglement swapping experiment. The techniques developed in our experiment are not only important for realistic linear optical quantum-information processing, but also enable new tests of local realism.     

Effect of Mn-site vacancies on the magnetic entropy change and the Curie temperature of La0.67Ca0.33Mn1−xO3 perovskite

Single-phase polycrystalline samples of La_0.67Ca_0.33Mn_1−xO₃ (x=0.00, 0.02, 0.04, 0.06) have been prepared using the sol-gel method. The structure, magnetocaloric properties and the Curie temperature of the samples with different Mn vacancy concentrations have been investigated. The experimental results show that vacancy doping at the Mn-sites has a significant influence on the magnetic properties of La_0.67Ca_0.33Mn_1−xO₃. The Curie temperature decreases monotonically with increasing the Mn-site vacancy concentration x. A remarkable enhancement of the magnetic entropy change has been obtained in the La_0.67Ca_0.33Mn_0.98O₃ sample. The entropy change reaches |ΔS_M|=3.10 J kg⁻¹ K⁻¹ at its Curie temperature (264 K) under an applied magnetic field H=10 kOe, which is almost the same value as that of pure Gd.     

AlN纳米线宏观阵列的制备

借助二次模板法成功的合成了AlN纳米线宏观阵列,并进行了表征.主要研究CVD法制备有一定取向,直径均匀的AlN纳米线宏观阵列的过程.通过气相沉积法和利用PS球自组装模板制备了金属纳米颗粒模板;再以模板上的金属纳米颗粒作为催化剂,利用化学气相沉积在模板上合成AlN纳米线宏观阵列.借助SEM,TEM观察所得样品,AlN纳米线阵列面积约为0.3 mm×0.2 mm,直径和长度分布均匀,平均直径约为41 nm,平均长度为1.8 μm左右,分散密度和覆盖率大的六角结构AlN纳米线宏观阵列.得到了可控制备AlN纳米线 关键词： AlN纳米线阵列 模板法 CVD法 SEM