Function mechanism of Y2O3 additive in silicon powder nitridation

Effect of sole Y₂O₃ additive on the nitridation behavior of silicon powder was systematically studied using thermo gravimetry, differential thermal analysis, particle size analysis, X-ray diffraction analysis, X-ray photoelectron spectroscopy, scanning electron microscope and thermodynamic analysis in this paper. The thermo gravimetry results showed that Y₂O₃ additive can significantly decrease the initial nitriding temperature and increase the nitriding rate. This phenomenon can be attributed to the much lower reaction temperature of the silica film and Y₂O₃ additive than that of the silica film and silicon. In addition, Y₂O₃ additive has little effect on the nitridation of silicon powder at 1300°C. However, it can obviously enhance the nitridation of silicon powder and the formation of β-Si₃N₄ at 1400°C, which is evidenced by the fact that the overall conversion increases from 58.1% to 100% and the fraction of β-Si₃N₄ in generated Si₃N₄ increases from 7.9% to 68.2% with increasing the content of Y₂O₃ additive from 0 to 10 wt%.     

浅谈化工教学的与时俱进问题

面对化学工程新的发展态势,化工教学与时俱进的问题值得关注。文章以化工原理和传递过程两门课程为例,分析了教学内容的调整;以 MOOC和虚拟仿真教学为例,阐述了教学模式的改革。文章认为,化工教学的与时俱进是任课教师不断提升自身教学能力、改进教学方法的过程。     

Molecular imaging of advanced atherosclerotic plaques with folate receptor-targeted 2D nanoprobes

Vulnerable atherosclerotic plaques are responsible for most cardiovascular diseases (CVDs). Folate receptor (FR) positive activated macrophages were thought to be a prominent component in the development of vulnerable plaque. The objective of this study is to develop folate conjugated two-dimensional (2D) Pd@Au nanomaterials (Pd@Au-PEG-FA) for targeted multimodal imaging of the FRs in advanced atherosclerotic plaques. Pharmacokinetic and imaging studies (single photon emission computed tomography (SPECT), computed tomography (CT) and photoacoustic (PA) imaging) were performed to confirm the prolonged blood half-life and enrichment of radioactivity in atherosclerotic plaques. Strong signals were detected in vivo with SPECT, CT and PA imaging in heavy atherosclerotic plaques, which were significantly higher than those of the normal aortas after injection of Pd@Au-PEG-FA. Blocking studies with preinjection of excess FA could effectively reduce the targeting ability of Pd@Au-PEG-FA in atherosclerotic plaques, further demonstrating the specific binding of Pd@Au-PEG-FA for plaque lesions. Histopathological characterization revealed that the signal of probe was in accordance with the high-risk plaques. In summary, the Pd@Au-PEG-FA has favorable pharmacokinetic properties and provides a valuable approach for detecting high-risk plaques in the presence of FRs in atherosclerotic plaques.

     

放射性废物焚烧技术的发展历程和展望

焚烧是放射性废物的主要处理技术之一,同常规废物焚烧技术相比,放射性废物焚烧技术更关注对放射性核素的截留效果、系统的辐射安全和对废物的适应能力。随着废物特性的变化、环保要求的日益严格,焚烧技术也在不断的革新和改进,对塑料、橡胶和树脂等高分子聚合物适应性更强的第三代焚烧技术已成为主流,包括热解焚烧、蒸汽重整焚烧以及等离子体焚烧,分别适用于不同的废物类型。未来放射性废物焚烧技术的发展趋势以整体经济性和满足环保要求为前提,尽量提高废物的整体减容效果,对多种废物的兼容处理,并为满足特殊废物的处理要求开发针对性的焚烧技术。     

船用柴油发电机组变速发电及其关键技术综述

由于变速发电技术显示出优异的燃油经济性，其被逐步引入柴油发电技术中。总结了应用于交流、直流船舶电网中的变速发电技术并给出了相关的案例；着重讨论了变速节能运行及直流组网功率分配策略，可为工程应用及科研工作提供参考。     

Metal-polyphenol-network coated CaCO3 as pH-responsive nanocarriers to enable effective intratumoral penetration and reversal of multidrug resistance for augmented cancer treatments

Construction of multifunctional stimuli-responsive nanotherapeutics enabling improved intratumoral penetration of therapeutics and reversal of multiple-drug resistance (MDR) is potent to achieve effective cancer treatment. Herein, we report a general method to synthesize pH-dissociable calcium carbonate (CaCO₃) hollow nanoparticles with amorphous CaCO₃ as the template, gallic acid (GA) as the organic ligand, and ferrous ions as the metallic center via a one-pot coordination reaction. The obtained GA–Fe@CaCO₃ exhibits high loading efficiencies to both oxidized cisplatin prodrug and doxorubicin, yielding drug loaded GA–Fe@CaCO₃ nanotherapeutics featured in pH-responsive size shrinkage, drug release, and Fenton catalytic activity. Compared to nonresponsive GA–Fe@silica nanoparticles prepared with silica nanoparticles as the template, such GA–Fe@CaCO₃ confers significantly improved intratumoral penetration capacity. Moreover, both types of drug-loaded GA–Fe@CaCO₃ nanotherapeutics exhibit synergistic therapeutic efficacies to corresponding MDR cancer cells because of the GA–Fe mediated intracellular oxidative stress amplification that could reduce the efflux of engulfed drugs by impairing the mitochondrial-mediated production of adenosine triphosphate (ATP). As a result, it is found that the doxorubicin loaded GA–Fe@CaCO₃ exhibits superior therapeutic effect towards doxorubicin-resistant 4T1 breast tumors via combined chemodynamic and chemo-therapies. This work highlights the preparation of pH-dissociable CaCO₃-based nanotherapeutics to enable effective tumor penetration for enhanced treatment of drug-resistant tumors.

     

A new deep convolutional neural network model for classifying breast cancer histopathological images and the hyperparameter optimisation of the proposed model

The Journal of Supercomputing - Deep learning algorithms have yielded remarkable results in medical diagnosis and image analysis, besides their contribution to improvements in a number of fields...     

Efficient defect passivation for high performance perovskite solar cell by adding alizarin red S

Planar perovskite solar cells (PSCs) have excellent photoelectric properties and show great commercialization potential. However, there are a lot of crystal defects in the perovskite films prepared by solution method, which reduces the development process of solar cells. In this work, alizarin red s (ARS) was doped into MAPbI₃ films to passivate the defect. It was shown that the addition of ARS increased the quality of perovskite film and doped perovskite film exhibited improved light absorption. In addition, it was found that there was a strong interaction between ARS and perovskite, which reduced the density of defect states. The results showed that the passivated perovskite device had improved PL intensity, increased carrier lifetimes and reduced charge recombination. After passivation, the device obtained a higher open-circuit voltage (V_OC) of 1.103 V where the control device was 1.055 V, and the best power conversion efficiency (PCE) of the doped device was 18.82%, which is 11.36% higher than that of the control device of 16.90%.

Graphical abstract

     

保定市大气细颗粒物的来源解析

为了识别保定市大气细颗粒物的主要污染源及对环境污染的贡献率,采用功能分区布点法在市区内布设5个点位,2018年6～9月期间采集有效膜样品90个,分析细颗粒物的质量浓度及其化学成分.运用PMF源解析模型,确定污染源种类,定量地计算出各类污染源贡献率,从而为制定减排政策提供可靠的依据.