Afterglow Implant for Arterial Embolization and Intraoperative Imaging

Transcatheter arterial embolization (TAE) is wildly used in clinical treatments. However, the online monitoring of the thrombosis formation is limited due to the challenges of the direct visualization of embolic agents and the real-time monitoring of dynamic blood flow. Thus, we developed a photochemical afterglow implant with strong afterglow intensity and a long lifetime for embolization and imaging. The liquid pre-implant injected into the abdominal aorta of mice was rapidly transformed into a hydrogel in situ to embolize the blood vessel. The vascular embolism position can be observed by the enhanced afterglow of the fixed implant, and the long lifetime of afterglow can also be used to monitor the effect of embolization. This provides an excellent candidate in bio-imaging to avoid the autofluorescence interference from continuous light excitation. The study suggests the potential usefulness of the implant as an embolic agent in TAE and artery imaging during a surgical procedure.     

Dye Sensitization Offers a Brighter Afterglow Nanoparticle Future for in vivo Recharged Luminescent Imaging

While concerns about improving recharged afterglow intensity in vivo still motivate further exploration, afterglow nanoparticles (AGNP) offer unique optical merit for autofluorescence-free biological imaging. Apart from efforts enhancing the afterglow emission properties of AGNP, improving afterglow excitation response to visible or near infrared light is important but has lacked success. Dye sensitization has been used to improve the optical response of photovoltaic nanomaterials and to enhance upconversion luminescence efficiency. This concept has recently been expanded and applied to AGNPs. As a new multifunctional nanoprobe, such dye-sensitized AGNP takes advantage of both high spatial resolution fluorescence imaging and sensitive afterglow imaging. This Concept introduces the background, the concept, mechanism, and related imaging application, as well as reviewing existing challenges and proposing future developmental directions for the dye-sensitized AGNPs.     

β-Ga_2O_3∶Cr~(3+)近红外长余辉纳米颗粒的制备及发光性能

以三乙二醇为表面配体,利用沉淀法制备了β-Ga_2O_3∶Cr~(3+)近红外(NIR)长余辉纳米颗粒.考察了反应条件对β-Ga_2O_3∶Cr~(3+)的发光性能和晶体结构的影响,并初步探讨了其NIR余辉发光机理.结果表明,当溶液的p H值为7,煅烧温度为700℃时,可获得高纯度的β-Ga_2O_3∶Cr~(3+)纳米颗粒,其平均粒径为30 nm,最大余辉发射波长可调控为750 nm,NIR余辉发光时间长于384 h.本方法得到的β-Ga_2O_3∶Cr~(3+)长余辉纳米颗粒不仅尺寸小,而且NIR余辉时间长,发射波长可调控,在低背景噪音的深组织活体成像中具有潜在的应用前景.     

Cathodoluminescence of Eu2+ in EuGa2S4 and Ga2S3:Eu2O3

We present the results of an investigation of the cathodoluminescence of the Eu²⁺ ion in gallium chalcogenides (Ga₂S₃) and europium thiogallate (EuGa₂S₄). We show that the intense wide-band radiation of these compounds is due to the 4f-5d transitions of the Eu²⁺ ions. With increase in the Eu²⁺ percent composition from 0.1 to 5.0 mol.% the luminescence brightness increases and then decreases. Translated from Zhurnal Prikladnoi Spektrskopii, Vol. 67, No. 2, pp. 268–270, March–April, 2000.     

高频介质阻挡放电烟气脱硫研究

采用高频介质阻挡放电的方式产生低温等离子体,研究在不加入NH₃的情况下流动态SO₂的去除情况.实验表明,在输入电压为12 kV,SO₂浓度为5400 mg/m³,气体流量为0.36 m³/h,相对湿度为55%时,脱硫率可达到70%以上;水气的存在对SO₂的去除有较大的促进作用,升高电压和增加O₂量对脱硫率的促进作用有限.对实验结果进行了解释,并提出了反应机理.     

实验优化设计Sr_2MgSi_2O_7:Eu~(2+),Dy~(3+)的合成及长余辉特性

为了得到最长有效余辉时间的Sr_2MgSi_2O_7:Eu~(2+),Dy~(3+)荧光粉,应用二次通用旋转组合设计对实验进行全程优化,建立了稀土离子掺杂浓度Eu~(2+),Dy~(3+)和有效余辉时间的二元二次回归方程模型,应用遗传算法计算得到有效余辉时间的理论最大值.采用高温固相法合成了最优掺杂浓度Sr_2MgSi_2O_7:0.5mol%Eu~(2+),1.0mol%Dy~(3+)的荧光粉,在370nm激发下观察到了465nm的特征发射,这归因于Eu~(2+)的4f65d1—4f7跃迁.测量了最优荧光粉的热释发光特性,计算得到了陷阱深度为0.688eV,讨论了长余辉发光的特性.     

Room‐Temperature Phosphorescence in Metal‐Free Organic Materials

Purely organic materials with room‐temperature phosphorescence (RTP) have attracted a growing interest for their potential applications in biological imaging, digital encryption, optoelectronic devices, and so on. To date, many strategies have succeeded in designing efficient organic RTP materials by overcoming the spin‐forbidden transition between singlet and triplet states. However, the underlying mechanisms of RTP still remain ambiguous. Such spin prohibition in phosphorescence are clarified, herein, from the perspective of perturbation theory, helping to understand the intrinsic relationship among various phosphorescence parameters, like phosphorescence efficiency, lifetime, intersystem crossing rate, as well as radiative and nonradiative rates. Taking into consideration the recent progress in organic RTP materials, these factors are further illustrated by a selection of the most relevant molecules. In addition, some novel RTP phenomena are also reviewed, thus providing an excellent guideline to constructing efficient RTP materials.     

长余辉材料SrAl2O4 ∶ Eu,Dy中Eu的 价态变化及对发光性能的影响

采用高温固相法,先在空气气氛下制备了SrAl₂O₄ ∶ Eu,Dy,后对其进行还原→氧化→还原处理。X射线衍射结果表明,经过还原→氧化→还原处理后样品的晶体结构没有改变。样品的发射光谱测试表明,在高温空气气氛下有少量的Eu³⁺还原成Eu²⁺。Eu³⁺和Eu²⁺有不同的发光特性,Eu³⁺产生的是线状特征光谱,发射峰值在592,616 nm。Eu²⁺产生的是带状光谱,带的中心位置在513 nm。经过还原处理的样品和经过氧化处理的样品相比,Eu²⁺的浓度得到显著提高,而Eu³⁺的浓度则急剧下降。对Eu²⁺的氧化、Eu³⁺的还原的机理进行了细致地讨论。另外,样品的热释光谱测试表明,经过氧化气氛处理和经过还原气氛处理过的样品的热释光峰值有很大的变化,但陷阱能级深度基本不变,在0.65 eV左右。这表明,对长余辉材料SrAl₂O₄ ∶ Eu,Dy进行还原→氧化→还原处理,Eu离子价态和发光强度会产生变化,并不影响其中Dy离子的陷阱能级。     

Comparison study of the luminescent properties of the white-light long afterglow phosphors: CaxMgSi2O5+x:Dy(x=1, 2, 3)

A series of Dy³⁺-doped calcium magnesium silicate phosphors: CaMgSi₂O₆:Dy³⁺, Ca₂MgSi₂O₇:Dy³⁺, and Ca₃MgSi₂O₈:Dy³⁺ with white long-lasting afterglow were prepared and investigated. The characteristic intra-configurational 4f emissions of Dy³⁺ were observed in the emission spectra as well as the afterglow spectra under ultraviolet excitation. The combination of the 480 nm blue emission corresponding to the ⁴F_9/2→⁶H_15/2 transition and the 575 nm yellow emission corresponding to the ⁴F_9/2→⁶H_13/2 transition yielded white-light emission. The white-coloured afterglow emission can last more than 1 h for most of the samples under study. The concentration dependence of the ratio of the yellow emission intensity with blue emission intensity was also examined and found to be varied for the different hosts. The thermoluminescence spectra above room temperature are employed for the discussion of the origin of the traps and the mechanism of the persistent luminescence.     

流动速度对核磁共振在线测量的影响及校正

流体流动的核磁共振（NMR）在线测量是一种高效、无损的探测方式,可广泛应用于管道流体输送过程、化学反应动态流程、河流流动等具有时移变化特点的过程在线检测.但是流动状态下样品流速会对NMR测量造成诸如磁化时间不充分、采集信号损失等不容忽视的影响.通过量化分析流动状态对NMR测量的影响因素,提出回波串校正方法,实现流动状态下的NMR流体测量.