A novel method to enhance magnetic property of bioactive glass-ceramics for hyperthermia

In this study, a novel method was proposed to enhance the magnetic property of magnetic bioactive glass-ceramic (MBGC) using graphite-modified magnetite. The crystalline composition, chemical structure, in vitro bioactivity, magnetic property, heat generating ability, cytotoxicity and the hyperthermia treatment effectiveness of the synthesized material were investigated thoroughly. The results revealed that the addition of graphite could prevent the magnetite from being oxidized. The main phases of the as-prepared material were found to be Fe₃O₄, Ca_2.87Fe_0.13(SiO₃)₃ and Ca₂SiO₄ in the CaO-SiO₂-MgO-CaF₂-P₂O₅-Fe₃O₄ system. Moreover, the material was bioactive and hydroxyapatite was observed on the surface after soaking in simulated body fluid (SBF) for 10 d. Under a magnetic field of 1.6?×?10⁶ A?m^?1, the saturation magnetization of MGBC was about 10.6?A?m² Kg^?1, while that of the contrast sample was only 2.9?A?m² kg^?1. When exposed to an alternating magnetic field (252?kHz, 1.9?×?10³ A?m^?1) for about 20?s, a temperature rise of 20?°C could be observed on the sample surface. MTT assay results showed that the material had no cytotoxicity for VX2 cells. Moreover, the hyperthermia treatment experiments were carried out by exposing the block samples (Φ8?×?2?mm) and VX2 cells simultaneously to the alternating magnetic field for 20?min. Only about 30% cells survived after the treatment, and dead cells were observed around the material. Therefore, this novel material could have potential applications for clinical hyperthermia treatment.     

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

A new approach to generate a two‐photon up‐conversion photoluminescence (PL) by directly exciting the gap states with continuous‐wave (CW) infrared photoexcitation in solution‐processing quasi‐2D perovskite films [(PEA)₂(MA)₄Pb₅Br₁₆ with n = 5] is reported. Specifically, a visible PL peaked at 520 nm is observed with the quadratic power dependence by exciting the gap states with CW 980 nm laser excitation, indicating a two‐photon up‐conversion PL occurring in quasi‐2D perovskite films. Decreasing the gap states by reducing the n value leads to a dramatic decrease in the two‐photon up‐conversion PL signal. This confirms that the gap states are indeed responsible for generating the two‐photon up‐conversion PL in quasi‐2D perovskites. Furthermore, mechanical scratching indicates that the different‐n‐value nanoplates are essentially uniformly formed in the quasi‐2D perovskite films toward generating multi‐photon up‐conversion light emission. More importantly, the two‐photon up‐conversion PL is found to be sensitive to an external magnetic field, indicating that the gap states are essentially formed as spatially extended states ready for multi‐photon excitation. Polarization‐dependent up‐conversion PL studies reveal that the gap states experience the orbit–orbit interaction through Coulomb polarization to form spatially extended states toward developing multi‐photon up‐conversion light emission in quasi‐2D perovskites.     

Numerical study of scattering Legendre moments and effect of anisotropic scattering on SN shielding calculation

The main purpose of this work was to perform a rigorous computational study on scintimammography with a Mura-mask based on Monte Carlo simulation of voxelized breast phantoms. Three main objectives were addressed:(1) verification of Geant4 version 10.4,(2)optimization of the imaging setup, and(3) small tumor detection and localization. We successfully verified the Geant4-based imaging of a commonly used phantom in the field. We used a Mura-mask with a 41× 41 array pattern with adjustable thickness, material, and hole shape(box and cylinder); a low-energy high-resolution collimator with different hole shapes(cylinder and hexagon); and a voxelized breast phantom with different sizes(small, medium,and large) and glandularity percentages(low, medium, and high). We also compared the detector crystal outputs of CdZnTe and NaI(Tl). The simulation was followed by a deconvolution procedure, and the data(images) were statistically emphasized. Statistical metrics indicate that the Mura-mask(W material with 1.5 mm thickness and box holes) combined with a CdZnTe detector leads to the optimum point spread function. Finally, a preliminary study on small-sized tumor detection and localization was conducted with different tumor-to-background ratios(from2 to 12). Tumors with diameters of 5 and 8 mm could be detected, while those of 2 mm were undetectable. Nevertheless, this study enhances our understanding of the early detection of tumors in the field of scintimammography.     

Study of Sallen–Key digital filters in nuclear pulse signal processing

The Sallen–Key filter(S–K) is widely used in nuclear pulse signal processing because of its simple working principle and good performance. Related research has only reviewed the recursive numerical model of digital S–K using idealized parameters. The use of digital S–K thus has limitations under these circumstances. This paper comprehensively deduces a recursive numerical model of digital S–K and discusses the effects of resistance and capacitance on the filter quality factor, cutoff frequency and amplitude–frequency response. The numerical recursive function, transfer function and amplitude–frequency response are analyzed using different parameters. From a comparative analysis of the shaper in a simulation and an actual nuclear signal, an optimal parameter selection principle is obtained. Using different forming parameters,the energy resolution and pulse counting rate of the ~(55)Fe energy spectrum are compared and analyzed based on a SiPIN detector. Capacitance has a stronger influence on the Gaussian shape, whereas the influence of resistance is stronger on the shaping amplitude.     

Auto-registration of medium and high spatial resolution satellite images by integrating improved SIFT and spatial consistency constraints

Feature-based methods have been developed in the past decades for the registration of optical satellite images. However, it is still a challenging problem to handle well the registration between medium and high spatial resolution images due to the large difference of the spatial structural features and local details for the same objects. In this study, an automated co-registration technique is proposed that integrates an improved SIFT (I-SIFT) and a novel matching strategy called spatial consistency constraints (SCC) to cope with the large difference in spatial resolutions between the image pair. Three constraints on angle, distance, and ratio are introduced to re the initial matching features obtained by I-SIFT. Three groups of experiments were conducted to validate the effectiveness of the proposed method. The experiments used high resolution multispectral and panoramic SPOT 5/6 images and Landsat 5/8 orthorectification images. Experimental results show that the registration error lies in about 1 pixel of high-resolution images and demonstrate that the proposed I-SIFT-SCC approach is suitable for fine registration of optical satellite images from medium spatial resolution to high spatial resolution with resolution ratio up to 6.     

Intelligent Information‐Centric Networking routing scheme under imprecise information

Information‐Centric Networking (ICN) has been accepted to overcome some weaknesses of the current Internet architecture, showing that “what is being exchanged” is more important than “who are exchanging information.” Given the inadequate considerations on Quality of Service (QoS) and energy saving in ICN routing, we propose in this paper a routing algorithm to enhance the two aspects. At first, on one hand, Cauchy distribution is used as a fuzzy model to evaluate users' QoS requirements, such as bandwidth, delay, and error rate; on the other hand, we formulate energy saving problem to evaluate the green quality of routing algorithm. Then, we design a link selection approach by considering QoS and energy saving, which belongs to a multi‐objective decision problem resolved by intelligent drops algorithm. Finally, we implement the proposed algorithm and compare it with the famous adaptive forwarding mechanism in terms of some significant metrics, and the experimental results reveal that the proposed algorithm is more efficient.     

超低渗油藏在线分流酸化增注技术研究与应用

酸化是超低渗油藏最有效的增注措施之一，但由于储层物性差、非均质性强等问题，造成目前常规酸化措施普遍具有施工周期长、有效率低、有效作用距离短等不足，且酸化过程中存在指进现象和储层二次伤害。针对这一问题，选取鄂尔多斯盆地环江油田三叠系超低渗油藏为研究对象，提出了在线分流酸化技术，并配套研制了一种多元缓速螯合酸COA-1S和一种新型的水溶性分流剂COA-1P。通过室内评价实验和在线分流酸化模拟实验，发现该技术在缓速性、配伍性、水溶性、螯合能力和暂堵功能等方面均显著优于常规酸化；现场先导性实验结果表明，酸化后剖面吸水均匀程度从28.5%上升至50.9%，视吸水指数增加2倍左右，降压增注效果显著；同时，该技术还具有“不停井、不泄压、不动管柱、不返排”的特点，简化了常规分流酸化工序、降低了安全环保风险，是一种能够很好地适应超低渗油藏特征的酸化增注技术。     

高强度堵水剂裂缝细管模型堵水模拟实验

在裂缝性致密储层中，裂缝既是油流通道又是水驱窜流通道，在注水开发中由于裂缝的存在导致水驱波及效率低，从而形成无效注水开发。此外，裂缝性储层的封堵又存在大裂缝封堵效果差、有效期短等问题。鉴于此研制了水溶性酚醛树脂冻胶和单体地层聚合高强度堵剂体系，测定了堵剂在70℃下的成胶性能、稳定性以及封堵强度等。通过细管模拟裂缝研究了不同因素对堵剂突破压力的影响；通过可视化细管研究了堵剂在管中的突破方式以及影响因素。研究结果表明，水溶性酚醛树脂冻胶的突破压力随着冻胶强度的增加而增加，随着管径的增加而减小，随着注水速度的增加先减小、后增加，最后稳定；单体地层聚合堵剂的突破压力随着堵剂强度的增加而增加，随着管径的增加先增大、后减小。在可视化细管实验中，堵剂突破时并不完全沿细管中心突破，其堵剂的强度与黏附性等因素有关。