Performance of near-infrared dyes as effective contrast agents for breast cancer detection through simulation of photoacoustic imaging

ABSTRACT

Targeted photoacoustic imaging using exogenous contrast agents can potentially improve early detection of breast cancer, even at significant depths inside the breast. In this study, computer simulations were performed to compare the photoacoustic performance of 11 different near-infrared (NIR) dyes for detecting tumours deep inside the breast tissue. It was observed that the three high performing NIR dyes produced at least two-fold contrast enhancement of a spherical breast tumour embedded at 4?cm depth inside the breast than those of the corresponding endogenous contrast agents. These three selected dyes were employed to visualize small blood vessels deep inside the breast tissue. Although methylene blue provided the best contrast in visualizing tumour blood vessels at depths beyond 3?cm, considering other factors such as availability of suitable targeting agent, indocyanine green at 800?nm may be preferred over all other dyes for deep breast imaging applications.     

镜面杂质与水汽吸放对露点仪影响的实验研究

显微成像露点仪在研制和测试过程中发现镜面杂质和内腔材质吸放水汽等影响测量精度的问题。针对镜面杂质对显微成像露点仪测量的影响开展了镜面图像特征的实验研究，结果表明：镜面杂质点处露珠凝结具有优先性，且反复凝结消散后镜面出现杂质沉降现象。针对水汽吸放对显微成像露点仪的影响开展了水汽释放与吸附效应的实验研究，结果表明：当温度发生变化时，显微成像露点仪感应舱内壁氧化铝材质存在释放（或吸附）水汽现象，使得显微成像露点仪测量值偏大（或偏小）。研究结果为露点仪在功能设置及镜面与腔体材料选择方面提供了参考。     

Poly(4-styrenesulfonic acid) doped polypyrrole/tungsten oxide/reduced graphene oxide nanocomposite films based surface acoustic wave sensors for NO sensing behavior

Poly(4-styrenesulfonic acid) (PSSA) doped polypyrrole (PPy)/tungsten oxide (WO₃)/reduced graphene oxide (rGO) hybrid nanocomposite have been successfully synthesized using appropriate amounts of PSSA, pyrrole monomer, WO₃, and rGO dispersed in aqueous solution through in situ chemical oxidation polymerization. Here, a simple spin coating method was used to fabricate a nitric oxide (NO) gas sensor composed of the aforementioned nanocomposite on a surface acoustic wave (SAW) resonator. This sensor can detect NO gas at concentrations of 1–110 parts per billion (ppb) at room temperature in dry air, with a sensitivity of 12 Hz/ppb and response and recovery times of <2 min. Moreover, its limit of detection (LOD) is 0.31 ppb for a signal to noise ratio of 3. It demonstrates repeatability, fast response, and recovery at room temperature. Moreover, its sensory performance remains highly stable over 30 days with only a 6.3% decrease in sensitivity. In addition, the sensor is highly selective for NO, even when nitrogen dioxide, ammonia, and carbon dioxide are applied as interfering gases. The inclusion of rGO (with large specific surface area) and the synergic effect of n-type WO₃ nanoparticles in the p-type PPy matrix (leading to p-n heterojunction region formation) possibly underlie the efficient sensing performance of our sensor.     

Stress field and damage evolution in C/SiC woven composites: Image-based finite element analysis and in situ X-ray computed tomography tests

The construction and examination of meso-structural finite element models of a Chemical-Vapor-Infiltrated (CVI) C/SiC composite is carried out based on X-ray microtomography digital images (IB-FEM). The accurate meso-structural features of the C/SiC composites, which are consisted of carbon fiber tows and CVI-SiC matrix, in particular the cavity defects, are reconstructed. With the IB-FEM, the damage evolution and fracture behaviors of the C/SiC composite are investigated. At the same time, an in situ tensile test is applied to the C/SiC composite under a CT real-time quantitative imaging system, aiming to investigate the damage and failure features of the material as well as to verify the IB-FEM. The IB-FEM results indicate that material damage initially occur at the defects, followed by propagating toward the fiber-tow/SiC-matrix interfaces, ultimately, combined into macro-cracks, which is in good agreement with the in situ CT experiment results.     

Squaraine Dyes for Photovoltaic and Biomedical Applications

Squaraine dyes (SQs) are an important class of polymethine dyes with a unique reasonable-stabilized zwitterionic structure, in which electrons are highly delocalized over the conjugated bridge. These dyes can not only be easily synthesized via a condensation, but also exhibit intense absorption and emission in the visible and near-infrared region with excellent photochemical stability, making them attractive material candidates for many photoelectric and biomedical applications. Thus, in this review, after an introduction of SQs, the recent advances of SQs in the photovoltaic field are comprehensively summarized including dye-sensitized solar cells, organic solar cells, and perovskite solar cells. Then, the important advances in the use of SQs as the biosensors, biological imaging, and photodynamic/photothermal therapy reagents in the biomedical field are also discussed. Finally, a summary and outlook will be provided with some new perspectives for the future design of SQs.     

主回路滞流分支管振动超标的原因分析与设计优化

在某核电厂热态功能试验中，巡视发现主回路的某滞流分支管振动超标。根据实测振动随温度变化的趋势、管道固有声模态分析和模态分析等，推测管道内流体的声振动激励引发管道共振。根据滞流管三通处流体的漩涡脱落频率计算和声振动频率计算，推测漩涡脱落与滞流管内流体的固有声振动频率锁定，引发声振动激励放大。综合分析计算和实测结果，确定滞流管振动超标的原因为流声固耦合振动。对管道支架进行了优化，以错开声固耦合共振频率，在三通处倒圆角削弱漩涡脱落，以降低流声耦合的声振动幅值。优化后的分支管振动会明显降低，以保证承压边界的安全。     

基于温度冲击的冷冻靶氘氘冰层结晶生长行为研究

惯性约束聚变冷冻靶中氘氘（D₂）冰层的质量对聚变实验的成功与否起重要作用。目前文献报道的制备冷冻靶D₂冰层的方法并不具备好的可操作性，且技术、工艺不定型，制约了高质量冰层的形成。因此，本文采用将温度梯度、降温速率和温度冲击相结合的技术实现燃料冰层在靶丸内的均化。通过温度控制以及施加温度冲击可控地形成残留冰，并在残留冰的控制技术基础上，实现了高质量冰层的可控结晶生长。同时，研究了温度控制对靶丸内D₂冰层品质的影响和D₂冰层结晶生长的过程，并应用晶体生长动力学理论分析了D₂冰层结晶生长行为。从背光阴影图像中的D₂冰层亮环可知，D₂冰层均匀度为85.2%、厚度为40.35 μm、内表面粗糙度为2.15 μm。本方法拓宽了超低温下D₂冰籽晶控制、晶体生长技术，为DT冷冻靶中冰层均化打下了坚实基础，并形成了一定的技术储备。     

Bacterium‐Templated Polymer for Self‐Selective Ablation of Multidrug‐Resistant Bacteria

The recognition and inactivation of specific pathogenic bacteria remain an enormous scientific challenge and an important therapeutic goal. Therefore, materials that can selectively target and kill specific pathogenic bacteria, without harming beneficial strains are highly desirable. Here, a material platform is reported that exploits bacteria as a template to synthesize polymers with aggregation‐induced emission (AIE) characteristic by copper‐catalyzed atom transfer radical polymerization for self‐selective killing of the bacteria that templates them with no antimicrobial resistance. The bacteria‐templated polymers show very weak fluorescence in aqueous media, however, the fluorescence is turned on upon recognition of the bacteria used as the template to synthesize the polymer even at a low concentration of 600 ng mL^?1. Moreover, the incorporated AIE fluorogens (AIEgens) can act as an efficient photosensitizer for reactive oxygen species (ROS) generation after bacteria surface binding, which endows the templated polymers with the capability for selective bacterial killing. The bacterium‐templated synthesis is generally applicable to a wide range of bacteria, including clinically isolated multidrug‐resistant bacterial strains. It is envisioned that the bacterium‐templated method provides a new strategy for bacteria‐specific diagnostic and therapeutic applications.     

Mapping haze-komi on rice koji grains using β-glucuronidase expressing Aspergillus oryzae and mass spectrometry imaging

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Stretchable Composite Acoustic Transducer for Wearable Monitoring of Vital Signs

A highly flexible, stretchable, and mechanically robust low‐cost soft composite consisting of silicone polymers and water (or hydrogels) is reported. When combined with conventional acoustic transducers, the materials reported enable high performance real‐time monitoring of heart and respiratory patterns over layers of clothing (or furry skin of animals) without the need for direct contact with the skin. The approach enables an entirely new method of fabrication that involves encapsulation of water and hydrogels with silicones and exploits the ability of sound waves to travel through the body. The system proposed outperforms commercial, metal‐based stethoscopes for the auscultation of the heart when worn over clothing and is less susceptible to motion artefacts. The system both with human and furry animal subjects (i.e., dogs), primarily focusing on monitoring the heart, is tested; however, initial results on monitoring breathing are also presented. This work is especially important because it is the first demonstration of a stretchable sensor that is suitable for use with furry animals and does not require shaving of the animal for data acquisition.