Influence of magnetic field upon the electric capacity of a flat capacitor having magnetorheological elastomer as a dielectric

The flat capacitor is built of two non-magnetic plates (with dimensions 0.065 m × 0.050 m) between which there is a layer of magnetorheological elastomer (MRE). The thickness of the layer is 0.0015 m ± 10%. MRE is based on silicone rubber and iron particles. The iron particles diameter ranges between 0.12 μm and 0.75 μm. The electric capacity, in absence of the magnetic field, is 377 ± 1 pF. In cross magnetic field with strengths up to 94 kA/m, the flat capacitor's capacity increases by up to 200%. For well chosen values of the intensity of the magnetic field, the capacity of the flat capacitor with MRE changes with time. The experimental results obtained in this manner are discussed.     

响应面法优化松多酚微粒制备工艺

依据聚电解质自组装原理,利用黑木耳多糖酸性片段（acidic polysaccharide fragments from Auricularia auricula,AAP）和多聚赖氨酸（polylysine,PLL）将松多酚（pine polyphenols from Pinus koraiensis,PPH）包裹为微粒以防止胃环境对多酚类化合物结构的破坏,并且采用响应面试验设计优化制备工艺。通过分析AAP、PLL和PPH的质量浓度3 个因素及其交互作用对PPH微粒包埋率的影响,建立该工艺的二次多项数学模型;利用扫描电镜观察优化后PPH微粒的形貌,并在模拟胃肠道环境中检测多酚释放率。结果显示响应面回归方程拟合性良好,AAP、PLL和PPH的质量浓度对响应值均有显著影响。在AAP质量浓度为900 μg/mL、PPH质量浓度为110 μg/mL以及PLL质量浓度为30 μg/mL的条件下,PPH微粒的包埋率为（86.57±1.07）%,载药量为（24.03±0.81）%。扫描电镜观察表明PPH微粒的直径为200～500 nm,其在模拟胃环境中释放缓慢而在模拟肠道环境中释放迅速。本研究中PPH微粒包埋率的实测值与预测值相比,相对误差较低,说明本研究方法是一种适合PPH微粒制备的方法,并且优化后的PPH微粒可以降低胃环境对PPH的降解。     

微流控模板法制备功能化非球形微颗粒研究新进展

功能化非球形微颗粒在生物医药、吸附、传感与检测等方面具有非常广泛的应用。相对于其他非球形微颗粒制备方法,近年来兴起的微流控技术,由于对微尺度流体具有超灵敏的操控特性,在制备和精确调控微米级功能材料方面具有很大的优势。通过精确控制流体在微尺度通道内的流动和剪切,微流控技术可以实现多种形态和结构的微尺度流体、乳液和纤维的可控构建,为非球形微颗粒的可控制造提供了优良的模板。同时,通过在制备过程中引入功能性材料,这些非球形微颗粒将具备更多的功能,从而极大地拓展和丰富了其应用范围。本文综述了近年来采用微流控技术制备功能化非球形微颗粒的研究新进展,重点介绍了以微流控技术构建得到的微流体、多相乳液及微纤维为模板可控制备功能化非球形微颗粒的研究现状。     

Formation of radioactive cesium microparticles originating from the Fukushima Daiichi Nuclear Power Plant accident: characteristics and perspectives

ABSTRACT

Following identification of radioactive Cs microparticles (CsMPs) in aerosol samples from the Fukushima Daiichi Nuclear Power Plant (FDNPP), numerous reports on CsMPs have been published. This paper reviews recent progress in the measurement and characterization of CsMPs by advanced analytical techniques, including advanced transmission electron microscopy (TEM) and synchrotron X-ray analysis. These analyses revealed that the CsMPs contained Si, Fe, Zn, Cs, and minor quantities of U together with some fission products. Uranium in the CsMPs was identified as being in the form of uraninite and (U,Zr)O₂. Detailed advanced TEM analysis has clarified some of the processes resulting in the alteration of constituents of the nuclear fuels and containment vessel materials during this severe accident. In addition, a detailed report on the elemental compositions and structures of the fuel debris fragments collected inside and outside of the primary containment vessel²⁵ highlighted the fact that the fuel debris fragments contained nanoparticles with the U and Zr components having similar structures to that of the CsMPs. This similarity in structures has stimulated further research on the structure and elemental constituents, especially for U and Zr in the CsMPs, and has opened up new avenues for studying the chemical characteristics of the fuel debris.     

Multifunctional Hydrophobized Microparticles for Accelerated Wound Healing after Endoscopic Submucosal Dissection

Endoscopic submucosal dissection (ESD) provides strong therapeutic benefits for early gastrointestinal cancer as a minimally invasive treatment. However, there is currently no reliable treatment to prevent scar contracture resulting from ESD which may lead to cicatricial stricture. Herein, a multifunctional colloidal wound dressing to promote tissue regeneration after ESD is demonstrated. This sprayable wound dressing, composed of hydrophobized microparticles, exhibits the multifunctionality necessary for wound healing including tissue adhesiveness, blood coagulation, re‐epithelialization, angiogenesis, and controlled inflammation based on hydrophobic interaction with biological systems. An in vivo feasibility study using swine gastric ESD models reveals that this colloidal wound dressing suppresses fibrosis and accelerates wound healing. Multifunctional colloidal and sprayable wound dressings have an enormous therapeutic potential for use in a wide range of biomedical applications including accelerated wound healing after ESD, prevention of perforation, and the treatment of inflammatory diseases.     

Spray-dried pH-sensitive microparticles: effectual methodology to ameliorate the bioavailability of acid labile pravastatin

Pravastatin is a promising drug utilized in the treatment of hyperlipidemia, yet, its main clinical limitation is due to gastric liability which fractions its oral bioavailability to less than 18%. The purpose of the current study is to encapsulate pravastatin into Eudragit^®-based spray-dried microparticles aspiring to overcome its acid liability. With the aim to optimize the microparticles, formulation and process parameters were studied through acid resistance challenging test. Physicochemical characterization of the optimized spray-dried pH-sensitive microparticles namely; in-vitro dissolution, surface morphology, compatibility, and solid-state studies were performed. Moreover, in-vivo evaluation of the microparticles and accelerated stability studies were carried out. The results outlined that polymer to drug ratio at 5:1 and pravastatin concentration at 1%w/w in spray-drying feed solution showed 38.55% and 53.97% encapsulation efficiency, respectively. The significance of process parameters specifically; the flow rate and the inlet temperature on microparticles surface integrity were observed, and optimized until encapsulating efficiency reached 72.37%. The scanning electron microscopical examination of the optimized microparticles illustrate uniform smooth surface spheres entrapping the drug in an amorphous state as proved through Differential Scanning Calorimetry (DSC) and Fourier Transfer Infrared (FTIR) studies. The in-vivo evaluation demonstrated a 5-fold enhancement in pravastatin bioavailability compared to the marketed product. The results provided evidence for the significance of spray-dried pH-sensitive microparticles as a promising carrier for pravastatin, decreasing its acid liability, and improving its bioavailability.     

Biomaterials as Tools to Decode Immunity

The immune system has remarkable capabilities to combat disease with exquisite selectivity. This feature has enabled vaccines that provide protection for decades and, more recently, advances in immunotherapies that can cure some cancers. Greater control over how immune signals are presented, delivered, and processed will help drive even more powerful options that are also safe. Such advances will be underpinned by new tools that probe how immune signals are integrated by immune cells and tissues. Biomaterials are valuable resources to support this goal, offering robust, tunable properties. The growing role of biomaterials as tools to dissect immune function in fundamental and translational contexts is highlighted. These technologies can serve as tools to understand the immune system across molecular, cellular, and tissue length scales. A common theme is exploiting biomaterial features to rationally direct how specific immune cells or organs encounter a signal. This precision strategy, enabled by distinct material properties, allows isolation of immunological parameters or processes in a way that is challenging with conventional approaches. The utility of these capabilities is demonstrated through examples in vaccines for infectious disease and cancer immunotherapy, as well as settings of immune regulation that include autoimmunity and transplantation.     

Characterization of agarose microparticles prepared by water-in-water emulsification

Microparticles have a wide range of applications in various areas. In this study, agarose microparticles (AGM) were successfully prepared by using a water-in-water (w/w) emulsification (WWEM) technique to eliminate the use of a surfactant. An aqueous agarose solution was employed as the dispersed phase, and polyethylene glycol (PEG) was used as the continuous phase. We evaluated how the characteristics of the microparticles were affected by different processing factors, including temperature, agitation speed, stirring time, concentration of agarose, and proportions of the two phases. The agarose microparticles obtained were nearly perfect spheres, and their particle sizes decreased with an increase in the agitation speed. Physicochemical characterization suggested that agarose microparticles, due to their ubiquitous stability, could be applied in most mild environments.     

Helical‐Like 3D Ultrathin Piezoelectric Element for Complicated Ultrasonic Field

The developments of personalized medicine, ultrasound imaging, and contactless “microscopic handle” techniques are pushing ultrasonic transducers toward features of high frequency, device miniaturization, and even novel function. However, the conventional ultrasonic transducer has severely limited the development of novel ideas for applications due to its ordinary ultrasonic field. Although transducer arrays and monolithic acoustic holograms are capable of producing the complicated ultrasonic field, it is still difficult to achieve high frequency, device miniaturization, and novel function simultaneously. Here, a simple but effective approach is introduced that aims at reconstructing the complicated and high‐frequency ultrasonic field via a compact single‐element ultrasonic transducer. The 3D ultrathin piezoelectric element with a complex configuration is demonstrated theoretically and experimentally to produce the desired complicated ultrasonic field. With helical‐like configuration, the single‐element ultrasonic transducer offers efficient noncontact trapping and manipulation of suspended microparticles and biological cells. Moreover, its strong trapping capability leads to the 3D stacking of microparticles, which is a novel and interesting phenomenon achieved by a single‐element ultrasonic transducer. This work brings the possibility of a complicated ultrasonic field for achieving novel high‐frequency ultrasound applications through the design of smart structure ultrathin piezoelectric materials.